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1. Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene

Author: Schüpbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, Anna, Twarloh, Birthe, Wolff, Katrin, Schmidt, Kerstin, Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J.-H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., Wolff, E. W., Schüpbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, Anna, Twarloh, Birthe, Wolff, Katrin, Schmidt, Kerstin, Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J.-H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., and Wolff, E. W.
Abstract: The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.
Published: 2018

2. Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene

Author: Schupbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J. -H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, Margareta, Iizuka, Yoshinori, Oyabu, Ikumi, Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., Wolff, E. W., Schupbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J. -H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, Margareta, Iizuka, Yoshinori, Oyabu, Ikumi, Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., and Wolff, E. W.
Abstract: The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.
Published: 2018
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3. Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene

Author: Schüpbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, Robert, Abram, Nerilie J., Fleet, Louise, Frey, Markus M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J.-H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., Wolff, E. W., Schüpbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, Robert, Abram, Nerilie J., Fleet, Louise, Frey, Markus M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J.-H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., and Wolff, E. W.
Abstract: The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.
Published: 2018

4. Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene

Author: Schüpbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, Anna, Twarloh, Birthe, Wolff, Katrin, Schmidt, Kerstin, Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J.-H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., Wolff, E. W., Schüpbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, Anna, Twarloh, Birthe, Wolff, Katrin, Schmidt, Kerstin, Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J.-H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., and Wolff, E. W.
Abstract: The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.
Published: 2018

5. Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene

Author: Schüpbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, Robert, Abram, Nerilie J., Fleet, Louise, Frey, Markus M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J.-H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., Wolff, E. W., Schüpbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, Robert, Abram, Nerilie J., Fleet, Louise, Frey, Markus M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J.-H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., and Wolff, E. W.
Abstract: The Northern Hemisphere experienced dramatic changes during the last glacial, featuring vast ice sheets and abrupt climate events, while high northern latitudes during the last interglacial (Eemian) were warmer than today. Here we use high-resolution aerosol records from the Greenland NEEM ice core to reconstruct the environmental alterations in aerosol source regions accompanying these changes. Separating source and transport effects, we find strongly reduced terrestrial biogenic emissions during glacial times reflecting net loss of vegetated area in North America. Rapid climate changes during the glacial have little effect on terrestrial biogenic aerosol emissions. A strong increase in terrestrial dust emissions during the coldest intervals indicates higher aridity and dust storm activity in East Asian deserts. Glacial sea salt aerosol emissions in the North Atlantic region increase only moderately (50%), likely due to sea ice expansion. Lower aerosol concentrations in Eemian ice compared to the Holocene are mainly due to shortened atmospheric residence time, while emissions changed little.
Published: 2018

6. Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene

Author: Schupbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J. -H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., Schupbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J. -H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., and McConnell, J.
Published: 2018

7. Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene

Author: Schupbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J. -H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., Schupbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J. -H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., and McConnell, J.
Published: 2018

8. Fire in ice: two millennia of boreal forest fire history from the Greenland NEEM ice core

Author: Zennaro, P, Kehrwald, N, Mcconnell, J, Schüpbach, S, Maselli, O, Marlon, J, Vallelonga, P, Leuenberger, D, Zangrando, R, Spolaor, A, Borrotti, M, Barbaro, E, Gambaro, A, Barbante, C, Zennaro, P., Kehrwald, N., McConnell, J. R., Schüpbach, S., Maselli, O. J., Marlon, J., Vallelonga, P., Leuenberger, D., Zangrando, R., Spolaor, A., Borrotti, M., Barbaro, E., Gambaro, A., Barbante, C., Zennaro, P, Kehrwald, N, Mcconnell, J, Schüpbach, S, Maselli, O, Marlon, J, Vallelonga, P, Leuenberger, D, Zangrando, R, Spolaor, A, Borrotti, M, Barbaro, E, Gambaro, A, Barbante, C, Zennaro, P., Kehrwald, N., McConnell, J. R., Schüpbach, S., Maselli, O. J., Marlon, J., Vallelonga, P., Leuenberger, D., Zangrando, R., Spolaor, A., Borrotti, M., Barbaro, E., Gambaro, A., and Barbante, C.
Abstract: Biomass burning is a major source of greenhouse gases and influences regional to global climate. Pre-industrial fire-history records from black carbon, charcoal and other proxies provide baseline estimates of biomass burning at local to global scales spanning millennia, and are thus useful to examine the role of fire in the carbon cycle and climate system. Here we use the specific biomarker levoglucosan together with black carbon and ammonium concentrations from the North Greenland Eemian (NEEM) ice cores (77.49 degrees N, 51.2 degrees W; 2480 ma.s.l) over the past 2000 years to infer changes in boreal fire activity. Increases in boreal fire activity over the periods 1000-1300 CE and decreases during 700-900 CE coincide with high-latitude NH temperature changes. Levoglucosan concentrations in the NEEM ice cores peak between 1500 and 1700 CE, and most levoglucosan spikes coincide with the most extensive central and northern Asian droughts of the past millennium. Many of these multi-annual droughts are caused by Asian monsoon failures, thus suggesting a connection between low-and high-latitude climate processes. North America is a primary source of biomass burning aerosols due to its relative proximity to the Greenland Ice Cap. During major fire events, however, isotopic analyses of dust, back trajectories and links with levoglucosan peaks and regional drought reconstructions suggest that Siberia is also an important source of pyrogenic aerosols to Greenland
Published: 2014

9. Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya)

Author: Spolaor, A., Opel, Thomas, McConnel, J. R., Maselli, O. J., Spreen, G., Varin, C., Kirchgeorg, T., Fritzsche, Diedrich, Saiz-Lopez, Alfonso, Vallelonga, P., Spolaor, A., Opel, Thomas, McConnel, J. R., Maselli, O. J., Spreen, G., Varin, C., Kirchgeorg, T., Fritzsche, Diedrich, Saiz-Lopez, Alfonso, and Vallelonga, P.
Abstract: The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere–ocean heat and gas exchange. Here we present a reconstruction of 1950 to 1998 AD sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The chemistry of halogens bromine (Br) and iodine (I) is strongly active and influenced by sea ice dynamics, in terms of physical, chemical and biological process. Bromine reacts on the sea ice surface in autocatalyzing "bromine explosion" events, causing an enrichment of the Br / Na ratio and hence a bromine excess (Brexc) in snow compared to that in seawater. Iodine is suggested to be emitted from algal communities growing under sea ice. The results suggest a connection between Brexc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. The correlation coefficients obtained between Brexc and spring sea ice (r = 0.44) as well as between iodine and summer sea ice (r = 0.50) for the Laptev Sea suggest that these two halogens could become good candidates for extended reconstructions of past sea ice changes in the Arctic.
Published: 2016

10. Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya)

Author: Spolaor, A., Opel, Thomas, McConnel, J. R., Maselli, O. J., Spreen, G., Varin, C., Kirchgeorg, T., Fritzsche, Diedrich, Saiz-Lopez, Alfonso, Vallelonga, P., Spolaor, A., Opel, Thomas, McConnel, J. R., Maselli, O. J., Spreen, G., Varin, C., Kirchgeorg, T., Fritzsche, Diedrich, Saiz-Lopez, Alfonso, and Vallelonga, P.
Abstract: The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere–ocean heat and gas exchange. Here we present a reconstruction of 1950 to 1998 AD sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The chemistry of halogens bromine (Br) and iodine (I) is strongly active and influenced by sea ice dynamics, in terms of physical, chemical and biological process. Bromine reacts on the sea ice surface in autocatalyzing "bromine explosion" events, causing an enrichment of the Br / Na ratio and hence a bromine excess (Brexc) in snow compared to that in seawater. Iodine is suggested to be emitted from algal communities growing under sea ice. The results suggest a connection between Brexc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. The correlation coefficients obtained between Brexc and spring sea ice (r = 0.44) as well as between iodine and summer sea ice (r = 0.50) for the Laptev Sea suggest that these two halogens could become good candidates for extended reconstructions of past sea ice changes in the Arctic.
Published: 2016

11. Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya)

Author: Spolaor, A., Opel, T., McConnell, J. R., Maselli, O. J., Spreen, Gunnar, Varin, C., Kirchgeorg, T., Fritzsche, D., Saiz-Lopez, A., Vallelonga, P., Spolaor, A., Opel, T., McConnell, J. R., Maselli, O. J., Spreen, Gunnar, Varin, C., Kirchgeorg, T., Fritzsche, D., Saiz-Lopez, A., and Vallelonga, P.
Abstract: The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere-ocean heat and gas exchange. Here we present a reconstruction of 1950 to 1998 AD sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The chemistry of halogens bromine (Br) and iodine (I) is strongly active and influenced by sea ice dynamics, in terms of physical, chemical and biological process. Bromine reacts on the sea ice surface in autocatalyzing >bromine explosion> events, causing an enrichment of the Br/Na ratio and hence a bromine excess (Br) in snow compared to that in seawater. Iodine is suggested to be emitted from algal communities growing under sea ice. The results suggest a connection between Brexc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. The correlation coefficients obtained between Br and spring sea ice (r = 0.44) as well as between iodine and summer sea ice (r = 0.50) for the Laptev Sea suggest that these two halogens could become good candidates for extended reconstructions of past sea ice changes in the Arctic.
Published: 2016

12. Observing and modeling the influence of layering on bubble trapping in polar firn

Author: Mitchell, LE, Mitchell, LE, Buizert, C, Brook, EJ, Breton, DJ, Fegyveresi, J, Baggenstos, D, Orsi, A, Severinghaus, J, Alley, RB, Albert, M, Rhodes, RH, McConnell, JR, Sigl, M, Maselli, O, Gregory, S, Ahn, J, Mitchell, LE, Mitchell, LE, Buizert, C, Brook, EJ, Breton, DJ, Fegyveresi, J, Baggenstos, D, Orsi, A, Severinghaus, J, Alley, RB, Albert, M, Rhodes, RH, McConnell, JR, Sigl, M, Maselli, O, Gregory, S, and Ahn, J
Abstract: Interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubbles in the firn-ice transition region has limited the ability to constrain the effect of bubble closure processes. Here we present high-resolution measurements of firn density, methane concentrations, nitrogen isotopes, and total air content that show layering in the firn-ice transition region at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Using the notion that bubble trapping is a stochastic process, we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach. We include the process of bubble trapping into an open-porosity firn air transport model and obtain a good fit to the firn core data. We find that layering broadens the depth range over which bubbles are trapped, widens the modeled gas age distribution of air in closed bubbles, reduces the mean gas age of air in closed bubbles, and introduces stratigraphic irregularities in the gas age scale that have a peak-to-peak variability of ~10 years at WAIS Divide. For a more complete understanding of gas occlusion and its impact on ice core records, we suggest that this experiment be repeated at sites climatically different from WAIS Divide, for example, on the East Antarctic plateau.
Published: 2015

13. Timing and climate forcing of volcanic eruptions for the past 2,500 years

Author: Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Büntgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, S., Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schüpbach, S., Steffensen, J. P., Vinther, B. M., Woodruff, T. E., Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Büntgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, S., Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schüpbach, S., Steffensen, J. P., Vinther, B. M., and Woodruff, T. E.
Abstract: Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.
Published: 2015

14. Timing and climate forcing of volcanic eruptions for the past 2,500 years

Author: Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Büntgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, Sepp, Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schüpbach, S., Steffensen, J. P., Vinther, B. M., Woodruff, T. E., Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Büntgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, Sepp, Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schüpbach, S., Steffensen, J. P., Vinther, B. M., and Woodruff, T. E.
Abstract: Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.
Published: 2015

15. Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya)

Author: Spolaor, A., Opel, Thomas, McConnell, J. R., Maselli, O., Spreen, G., Varin, C., Kirchgeorg, T., Fritzsche, Diedrich, Vallelonga, P., Spolaor, A., Opel, Thomas, McConnell, J. R., Maselli, O., Spreen, G., Varin, C., Kirchgeorg, T., Fritzsche, Diedrich, and Vallelonga, P.
Abstract: The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere-ocean heat and gas exchange. Here we present a reconstruction of AD1950 to 1998 sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The halogens bromine (Br) and iodine (I) are strongly influenced by sea ice processes. Bromine reacts with the sea ice surface in auto-catalyzing “Bromine explosion” events causing an enrichment of the Br / Na ratio and the bromine excess (Brexc) in snow compared to that in seawater. Iodine is emitted from algal communities growing under sea ice. The results suggest a connection between Brexc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. These two halogens are therefore good candidates for extended reconstructions of past sea ice changes in the Arctic.
Published: 2015

16. Observing and modeling the influence of layering on bubble trapping in polar firn

Author: Mitchell, LE, Mitchell, LE, Buizert, C, Brook, EJ, Breton, DJ, Fegyveresi, J, Baggenstos, D, Orsi, A, Severinghaus, J, Alley, RB, Albert, M, Rhodes, RH, McConnell, JR, Sigl, M, Maselli, O, Gregory, S, Ahn, J, Mitchell, LE, Mitchell, LE, Buizert, C, Brook, EJ, Breton, DJ, Fegyveresi, J, Baggenstos, D, Orsi, A, Severinghaus, J, Alley, RB, Albert, M, Rhodes, RH, McConnell, JR, Sigl, M, Maselli, O, Gregory, S, and Ahn, J
Abstract: Interpretation of ice core trace gas records depends on an accurate understanding of the processes that smooth the atmospheric signal in the firn. Much work has been done to understand the processes affecting air transport in the open pores of the firn, but a paucity of data from air trapped in bubbles in the firn-ice transition region has limited the ability to constrain the effect of bubble closure processes. Here we present high-resolution measurements of firn density, methane concentrations, nitrogen isotopes, and total air content that show layering in the firn-ice transition region at the West Antarctic Ice Sheet (WAIS) Divide ice core site. Using the notion that bubble trapping is a stochastic process, we derive a new parameterization for closed porosity that incorporates the effects of layering in a steady state firn modeling approach. We include the process of bubble trapping into an open-porosity firn air transport model and obtain a good fit to the firn core data. We find that layering broadens the depth range over which bubbles are trapped, widens the modeled gas age distribution of air in closed bubbles, reduces the mean gas age of air in closed bubbles, and introduces stratigraphic irregularities in the gas age scale that have a peak-to-peak variability of ~10 years at WAIS Divide. For a more complete understanding of gas occlusion and its impact on ice core records, we suggest that this experiment be repeated at sites climatically different from WAIS Divide, for example, on the East Antarctic plateau.
Published: 2015

17. Timing and climate forcing of volcanic eruptions for the past 2,500 years

Author: Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Büntgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, Sepp, Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schüpbach, S., Steffensen, J. P., Vinther, B. M., Woodruff, T. E., Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Büntgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, Sepp, Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schüpbach, S., Steffensen, J. P., Vinther, B. M., and Woodruff, T. E.
Abstract: Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.
Published: 2015

18. Halogen-based reconstruction of Russian Arctic sea ice area from the Akademii Nauk ice core (Severnaya Zemlya)

Author: Spolaor, A., Opel, Thomas, McConnell, J. R., Maselli, O., Spreen, G., Varin, C., Kirchgeorg, T., Fritzsche, Diedrich, Vallelonga, P., Spolaor, A., Opel, Thomas, McConnell, J. R., Maselli, O., Spreen, G., Varin, C., Kirchgeorg, T., Fritzsche, Diedrich, and Vallelonga, P.
Abstract: The role of sea ice in the Earth climate system is still under debate, although it is known to influence albedo, ocean circulation, and atmosphere-ocean heat and gas exchange. Here we present a reconstruction of AD1950 to 1998 sea ice in the Laptev Sea based on the Akademii Nauk ice core (Severnaya Zemlya, Russian Arctic). The halogens bromine (Br) and iodine (I) are strongly influenced by sea ice processes. Bromine reacts with the sea ice surface in auto-catalyzing “Bromine explosion” events causing an enrichment of the Br / Na ratio and the bromine excess (Brexc) in snow compared to that in seawater. Iodine is emitted from algal communities growing under sea ice. The results suggest a connection between Brexc and spring sea ice area, as well as a connection between iodine concentration and summer sea ice area. These two halogens are therefore good candidates for extended reconstructions of past sea ice changes in the Arctic.
Published: 2015

19. Timing and climate forcing of volcanic eruptions for the past 2,500 years

Author: Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Büntgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, S., Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schüpbach, S., Steffensen, J. P., Vinther, B. M., Woodruff, T. E., Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Büntgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, S., Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schüpbach, S., Steffensen, J. P., Vinther, B. M., and Woodruff, T. E.
Abstract: Volcanic eruptions contribute to climate variability, but quantifying these contributions has been limited by inconsistencies in the timing of atmospheric volcanic aerosol loading determined from ice cores and subsequent cooling from climate proxies such as tree rings. Here we resolve these inconsistencies and show that large eruptions in the tropics and high latitudes were primary drivers of interannual-to-decadal temperature variability in the Northern Hemisphere during the past 2,500 years. Our results are based on new records of atmospheric aerosol loading developed from high-resolution, multi-parameter measurements from an array of Greenland and Antarctic ice cores as well as distinctive age markers to constrain chronologies. Overall, cooling was proportional to the magnitude of volcanic forcing and persisted for up to ten years after some of the largest eruptive episodes. Our revised timescale more firmly implicates volcanic eruptions as catalysts in the major sixth-century pandemics, famines, and socioeconomic disruptions in Eurasia and Mesoamerica while allowing multi-millennium quantification of climate response to volcanic forcing.
Published: 2015

20. Timing and climate forcing of volcanic eruptions for the past 2,500 years

Author: Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Buentgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, S., Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schuepbach, S., Steffensen, J. P., Vinther, B. M., Woodruff, T. E., Sigl, M., Winstrup, M., McConnell, J. R., Welten, K. C., Plunkett, G., Ludlow, F., Buentgen, U., Caffee, M., Chellman, N., Dahl-Jensen, D., Fischer, H., Kipfstuhl, S., Kostick, C., Maselli, O. J., Mekhaldi, F., Mulvaney, R., Muscheler, R., Pasteris, D. R., Pilcher, J. R., Salzer, M., Schuepbach, S., Steffensen, J. P., Vinther, B. M., and Woodruff, T. E.
Published: 2015

21. Antarctic-wide array of high-resolution ice core records reveals pervasive leadpollution began in 1889 and persists today

Author: McConnell, J., Maselli, O., Sigl, M., Vallelonga, P, Neumann, T., Anschϋtz, H., Bales, R., Curran, M., Das, S., Edwards, Peter, Kipfstuhl, S., Layman, L., Thomas, E., McConnell, J., Maselli, O., Sigl, M., Vallelonga, P, Neumann, T., Anschϋtz, H., Bales, R., Curran, M., Das, S., Edwards, Peter, Kipfstuhl, S., Layman, L., and Thomas, E.
Abstract: Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 – beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.
Published: 2014

22. Accelerated deglaciation linked to volcanic eruptions 17.8k years ago

Author: McConnell, J. R., Dunbar, N. W., Köhler, Peter, Thomas, J. L., Chellman, N. J., Layman, L. R., Maselli, O. J., Pasteris, D. R., Sigl, M., Adkins, J., Baggenstos, D., Brook, E. J., Buizert, C., Burke, A., Cole-Dai, J., Fleet, L. G., Fudge, T. J., Knorr, Gregor, Grieman, M., Marcott, Shaun A., McGwire, K. C., Mulvaney, R., Paris, G., Rhodes, R., Saltzman, E.S., Severinghaus, J. P., Steffensen, J. P., Taylor, K. C., Winckler, G., McConnell, J. R., Dunbar, N. W., Köhler, Peter, Thomas, J. L., Chellman, N. J., Layman, L. R., Maselli, O. J., Pasteris, D. R., Sigl, M., Adkins, J., Baggenstos, D., Brook, E. J., Buizert, C., Burke, A., Cole-Dai, J., Fleet, L. G., Fudge, T. J., Knorr, Gregor, Grieman, M., Marcott, Shaun A., McGwire, K. C., Mulvaney, R., Paris, G., Rhodes, R., Saltzman, E.S., Severinghaus, J. P., Steffensen, J. P., Taylor, K. C., and Winckler, G.
Published: 2014

23. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

Author: McConnell, J. R., Maselli, O. J., Sigl, M., Vallelonga, P., Neumann, T., Anschütz, H., Bales, R. C., Curran, M. A. J., Das, S. B., Edwards, R., Kipfstuhl, Sepp, Layman, L., Thomas, E. R., McConnell, J. R., Maselli, O. J., Sigl, M., Vallelonga, P., Neumann, T., Anschütz, H., Bales, R. C., Curran, M. A. J., Das, S. B., Edwards, R., Kipfstuhl, Sepp, Layman, L., and Thomas, E. R.
Abstract: Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 – beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.
Published: 2014

24. Accelerated deglaciation linked to volcanic eruptions 17.8k years ago

Author: McConnell, J. R., Dunbar, N. W., Köhler, Peter, Thomas, J. L., Chellman, N. J., Layman, L. R., Maselli, O. J., Pasteris, D. R., Sigl, M., Adkins, J., Baggenstos, D., Brook, E. J., Buizert, C., Burke, A., Cole-Dai, J., Fleet, L. G., Fudge, T. J., Knorr, Gregor, Grieman, M., Marcott, Shaun A., McGwire, K. C., Mulvaney, R., Paris, G., Rhodes, R., Saltzman, E.S., Severinghaus, J. P., Steffensen, J. P., Taylor, K. C., Winckler, G., McConnell, J. R., Dunbar, N. W., Köhler, Peter, Thomas, J. L., Chellman, N. J., Layman, L. R., Maselli, O. J., Pasteris, D. R., Sigl, M., Adkins, J., Baggenstos, D., Brook, E. J., Buizert, C., Burke, A., Cole-Dai, J., Fleet, L. G., Fudge, T. J., Knorr, Gregor, Grieman, M., Marcott, Shaun A., McGwire, K. C., Mulvaney, R., Paris, G., Rhodes, R., Saltzman, E.S., Severinghaus, J. P., Steffensen, J. P., Taylor, K. C., and Winckler, G.
Published: 2014

25. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

Author: McConnell, J. R., Maselli, O. J., Sigl, M., Vallelonga, P., Neumann, T., Anschütz, H., Bales, R. C., Curran, M. A. J., Das, S. B., Edwards, R., Kipfstuhl, Sepp, Layman, L., Thomas, E. R., McConnell, J. R., Maselli, O. J., Sigl, M., Vallelonga, P., Neumann, T., Anschütz, H., Bales, R. C., Curran, M. A. J., Das, S. B., Edwards, R., Kipfstuhl, Sepp, Layman, L., and Thomas, E. R.
Abstract: Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 – beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.
Published: 2014

26. Fire in ice: two millennia of boreal forest fire history from the Greenland NEEM ice core

Author: Zennaro, P., Kehrwald, N., McConnell, J. R., Schuepbach, S., Maselli, O. J., Marlon, J., Vallelonga, P., Leuenberger, D., Zangrando, R., Spolaor, A., Borrotti, M., Barbaro, E., Gambaro, A., Barbante, C., Zennaro, P., Kehrwald, N., McConnell, J. R., Schuepbach, S., Maselli, O. J., Marlon, J., Vallelonga, P., Leuenberger, D., Zangrando, R., Spolaor, A., Borrotti, M., Barbaro, E., Gambaro, A., and Barbante, C.
Published: 2014

27. Insights from Antarctica on volcanic forcing during the Common Era

Author: Sigl, M., McConnell, J., Toohey, M., Curran, M., Das, S., Edwards, Peter, Isaksson, E., Kawamura, K., Kipfstuhl, S., Krüger, K., Layman, L., Maselli, O., Motizuki, Y., Motoyama, H., Pasteris, D., Severi, M., Sigl, M., McConnell, J., Toohey, M., Curran, M., Das, S., Edwards, Peter, Isaksson, E., Kawamura, K., Kipfstuhl, S., Krüger, K., Layman, L., Maselli, O., Motizuki, Y., Motoyama, H., Pasteris, D., and Severi, M.
Abstract: Assessments of climate sensitivity to projected greenhouse gas concentrations underpin environmental policy decisions, with such assessments often based on model simulations of climate during recent centuries and millennia. These simulations depend critically on accurate records of past aerosol forcing from global-scale volcanic eruptions, reconstructed from measurements of sulphate deposition in ice cores. Non-uniform transport and deposition of volcanic fallout mean that multiple records from a wide array of ice cores must be combined to create accurate reconstructions. Here we re-evaluated the record of volcanic sulphate deposition using a much more extensive array of Antarctic ice cores. In our new reconstruction, many additional records have been added and dating of previously published records corrected through precise synchronization to the annually dated West Antarctic Ice Sheet Divide ice core7, improving and extending the record throughout the Common Era. Whereas agreement with existing reconstructions is excellent after 1500, we found a substantially different history of volcanic aerosol deposition before 1500; for example, global aerosol forcing values from some of the largest eruptions (for example, 1257 and 1458) previously were overestimated by 20–30% and others underestimated by 20–50%.
Published: 2014

28. Fire in ice: two millennia of boreal forest fire history from the Greenland NEEM ice core

Author: Zennaro, P., Kehrwald, N., McConnell, J. R., Schuepbach, S., Maselli, O. J., Marlon, J., Vallelonga, P., Leuenberger, D., Zangrando, R., Spolaor, A., Borrotti, M., Barbaro, E., Gambaro, A., Barbante, C., Zennaro, P., Kehrwald, N., McConnell, J. R., Schuepbach, S., Maselli, O. J., Marlon, J., Vallelonga, P., Leuenberger, D., Zangrando, R., Spolaor, A., Borrotti, M., Barbaro, E., Gambaro, A., and Barbante, C.
Published: 2014

29. Comparison of water isotope ratio determinations using two cavity ringdown instruments and classical mass spectrometry in continuous ice‐core analysis

Author: Maselli, O., Fritzsche, Diedrich, Layman, L., McConnell, J.R., Meyer, Hanno, Maselli, O., Fritzsche, Diedrich, Layman, L., McConnell, J.R., and Meyer, Hanno
Abstract: We present a detailed comparison between subsequent versions of commercially available wavelength-scanned cavity ring-down water isotope analysers (L2120-i and L2130-i, Picarro Inc.). The analysers are used in parallel in a continuous mode by adaption of a low-volume flash evaporation module. Application of the analysers to ice-core analysis is assessed by comparison between continuous water isotope measurements of a glacial ice-core from Severnaya Zemlya with discrete isotope-ratio mass spectrometry measurements performed on parallel samples from the same ice-core. The great advances between instrument versions, particularly in the measurement of δ2H, allow the continuous technique to achieve the same high level of accuracy and precision obtained using traditional isotope spectrometry techniques in a fraction of the experiment time. However, when applied to continuous ice-core measurements, increased integration times result in a compromise of the achievable depth resolution of the ice-core records.
Published: 2013

30. Eemian interglacial reconstructed from a Greenland folded ice core

Author: Dahl-Jensen, D., Albert, M. R., Aldahan, Ala, Azuma, N., Balslev-Clausen, D., Baumgartner, M., Berggren, Ann-Marie, Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Buchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davies, S. M., Ditlevsen, P., Eicher, O., Fischer, H., Fisher, D. A., Fleet, L. G., Gfeller, G., Gkinis, V., Gogineni, S., Goto-Azuma, K., Grinsted, A., Gudlaugsdottir, H., Guillevic, M., Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S. D., Huybrechts, P., Hvidberg, C. S., Iizuka, Y., Jenk, T., Johnsen, S. J., Jones, T. R., Jouzel, J., Karlsson, N. B., Kawamura, K., Keegan, K., Kettner, E., Kipfstuhl, S., Kjaer, H. A., Koutnik, M., Kuramoto, T., Koehler, P., Laepple, T., Landais, A., Langen, P. L., Larsen, L. B., Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, H., Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Orsi, A. J., Paden, J., Panton, C., Pattyn, F., Petit, J. -R, Pol, K., Popp, T., Possnert, Göran, Prie, F., Prokopiou, M., Quiquet, A., Rasmussen, S. O., Raynaud, D., Ren, J., Reutenauer, C., Ritz, C., Rockmann, T., Rosen, J. L., Rubino, M., Rybak, O., Samyn, D., Sapart, C. J., Schilt, A., Schmidt, A. M. Z., Schwander, J., Schuepbach, S., Seierstad, I., Severinghaus, J. P., Sheldon, S., Simonsen, S. B., Sjolte, J., Solgaard, A. M., Sowers, T., Sperlich, P., Steen-Larsen, H. C., Steffen, K., Steffensen, J. P., Steinhage, D., Stocker, T. F., Stowasser, C., Sturevik, A. S., Sturges, W. T., Sveinbjornsdottir, A., Svensson, A., Tison, J. -L, Uetake, J., Vallelonga, P., van de Wal, R. S. W., van der Wel, G., Vaughn, B. H., Vinther, B., Waddington, E., Wegner, A., Weikusat, I., White, J. W. C., Wilhelms, F., Winstrup, M., Witrant, E., Wolff, E. W., Xiao, C., Zheng, J., Dahl-Jensen, D., Albert, M. R., Aldahan, Ala, Azuma, N., Balslev-Clausen, D., Baumgartner, M., Berggren, Ann-Marie, Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Buchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davies, S. M., Ditlevsen, P., Eicher, O., Fischer, H., Fisher, D. A., Fleet, L. G., Gfeller, G., Gkinis, V., Gogineni, S., Goto-Azuma, K., Grinsted, A., Gudlaugsdottir, H., Guillevic, M., Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S. D., Huybrechts, P., Hvidberg, C. S., Iizuka, Y., Jenk, T., Johnsen, S. J., Jones, T. R., Jouzel, J., Karlsson, N. B., Kawamura, K., Keegan, K., Kettner, E., Kipfstuhl, S., Kjaer, H. A., Koutnik, M., Kuramoto, T., Koehler, P., Laepple, T., Landais, A., Langen, P. L., Larsen, L. B., Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, H., Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Orsi, A. J., Paden, J., Panton, C., Pattyn, F., Petit, J. -R, Pol, K., Popp, T., Possnert, Göran, Prie, F., Prokopiou, M., Quiquet, A., Rasmussen, S. O., Raynaud, D., Ren, J., Reutenauer, C., Ritz, C., Rockmann, T., Rosen, J. L., Rubino, M., Rybak, O., Samyn, D., Sapart, C. J., Schilt, A., Schmidt, A. M. Z., Schwander, J., Schuepbach, S., Seierstad, I., Severinghaus, J. P., Sheldon, S., Simonsen, S. B., Sjolte, J., Solgaard, A. M., Sowers, T., Sperlich, P., Steen-Larsen, H. C., Steffen, K., Steffensen, J. P., Steinhage, D., Stocker, T. F., Stowasser, C., Sturevik, A. S., Sturges, W. T., Sveinbjornsdottir, A., Svensson, A., Tison, J. -L, Uetake, J., Vallelonga, P., van de Wal, R. S. W., van der Wel, G., Vaughn, B. H., Vinther, B., Waddington, E., Wegner, A., Weikusat, I., White, J. W. C., Wilhelms, F., Winstrup, M., Witrant, E., Wolff, E. W., Xiao, C., and Zheng, J.
Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
Published: 2013
Full Text: View/download PDF

31. Eemian interglacial reconstructed from a Greenland folded ice core

Author: Dahl-Jensen, D., Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, D., Baumgartner, M., Berggren, A. -M, Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Buchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davies, S. M., Ditlevsen, P., Eicher, O., Fischer, H., Fisher, D. A., Fleet, L. G., Gfeller, G., Gkinis, V., Gogineni, S., Goto-Azuma, K., Grinsted, A., Gudlaugsdottir, H., Guillevic, M., Hansen, S. B., Hansson, Margareta, Hirabayashi, M., Hong, S., Hur, S. D., Huybrechts, P., Hvidberg, C. S., Iizuka, Yoshinori, Jenk, T., Johnsen, S. J., Jones, T. R., Jouzel, J., Karlsson, N. B., Kawamura, K., Keegan, K., Kettner, E., Kipfstuhl, S., Kjaer, H. A., Koutnik, M., Kuramoto, T., Koehler, P., Laepple, T., Landais, A., Langen, P. L., Larsen, L. B., Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, H., Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Orsi, A. J., Paden, J., Panton, C., Pattyn, F., Petit, J. -R, Pol, K., Popp, T., Possnert, G., Prie, F., Prokopiou, M., Quiquet, A., Rasmussen, S. O., Raynaud, D., Ren, J., Reutenauer, C., Ritz, C., Rockmann, T., Rosen, J. L., Rubino, M., Rybak, O., Samyn, D., Sapart, C. J., Schilt, A., Schmidt, A. M. Z., Schwander, J., Schuepbach, S., Seierstad, I., Severinghaus, J. P., Sheldon, S., Simonsen, S. B., Sjolte, J., Solgaard, A. M., Sowers, T., Sperlich, P., Steen-Larsen, H. C., Steffen, K., Steffensen, J. P., Steinhage, D., Stocker, T. F., Stowasser, C., Sturevik, A. S., Sturges, W. T., Sveinbjornsdottir, A., Svensson, A., Tison, J. -L, Uetake, J., Vallelonga, P., van de Wal, R. S. W., van der Wel, G., Vaughn, B. H., Vinther, B., Waddington, E., Wegner, A., Weikusat, I., White, J. W. C., Wilhelms, F., Winstrup, M., Witrant, E., Wolff, E. W., Xiao, C., Zheng, J., Dahl-Jensen, D., Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, D., Baumgartner, M., Berggren, A. -M, Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Buchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davies, S. M., Ditlevsen, P., Eicher, O., Fischer, H., Fisher, D. A., Fleet, L. G., Gfeller, G., Gkinis, V., Gogineni, S., Goto-Azuma, K., Grinsted, A., Gudlaugsdottir, H., Guillevic, M., Hansen, S. B., Hansson, Margareta, Hirabayashi, M., Hong, S., Hur, S. D., Huybrechts, P., Hvidberg, C. S., Iizuka, Yoshinori, Jenk, T., Johnsen, S. J., Jones, T. R., Jouzel, J., Karlsson, N. B., Kawamura, K., Keegan, K., Kettner, E., Kipfstuhl, S., Kjaer, H. A., Koutnik, M., Kuramoto, T., Koehler, P., Laepple, T., Landais, A., Langen, P. L., Larsen, L. B., Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, H., Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Orsi, A. J., Paden, J., Panton, C., Pattyn, F., Petit, J. -R, Pol, K., Popp, T., Possnert, G., Prie, F., Prokopiou, M., Quiquet, A., Rasmussen, S. O., Raynaud, D., Ren, J., Reutenauer, C., Ritz, C., Rockmann, T., Rosen, J. L., Rubino, M., Rybak, O., Samyn, D., Sapart, C. J., Schilt, A., Schmidt, A. M. Z., Schwander, J., Schuepbach, S., Seierstad, I., Severinghaus, J. P., Sheldon, S., Simonsen, S. B., Sjolte, J., Solgaard, A. M., Sowers, T., Sperlich, P., Steen-Larsen, H. C., Steffen, K., Steffensen, J. P., Steinhage, D., Stocker, T. F., Stowasser, C., Sturevik, A. S., Sturges, W. T., Sveinbjornsdottir, A., Svensson, A., Tison, J. -L, Uetake, J., Vallelonga, P., van de Wal, R. S. W., van der Wel, G., Vaughn, B. H., Vinther, B., Waddington, E., Wegner, A., Weikusat, I., White, J. W. C., Wilhelms, F., Winstrup, M., Witrant, E., Wolff, E. W., Xiao, C., and Zheng, J.
Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 +/- 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 +/- 250 metres, reaching surface elevations 122,000 years ago of 130 +/- 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future., AuthorCount:133
Published: 2013
Full Text: View/download PDF

32. Eemian interglacial reconstructed from a Greenland folded ice core

Author: Dahl-Jensen, D., Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, D., Baumgartner, M., Berggren, A.-M., Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Buchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davies, S. M., Ditlevsen, P., Eicher, O., Fischer, H., Fisher, D. A., Fleet, L. G., Gfeller, G., Gkinis, V., Gogineni, S., Grinsted, A., Goto-Azuma, K., Gudlaugsdottir, H., Guillevic, M., Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S. D., Huybrechts, P., Hvidberg, C. S., Jenk, T., Iizuka, Y., Johnsen, S. J., Jones, T. R., Jouzel, J., Karlsson, N. B., Kawamura, K., Keegan, K., Kettner, E., Kipfstuhl, Sepp, Kjær, H. A., Koutnik, M., Kuramoto, T., Köhler, Peter, Laepple, Thomas, Landais, A., Langen, P. L., Larsen, L. B., Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, Heinrich, Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Paden, J., Orsi, A. J., Panton, C., Pattyn, F., Petit, J.-R., Pol, K., Popp, T., Possnert, G., Prié, F., Prokopiou, M., Quiquet, A., Rasmussen, S. O., Raynaud, D., Ren, J., Reutenauer, C., Ritz, C., Röckmann, T., Rosen, J. L., Rubino, M., Rybak, O., Samyn, D., Sapart, C. J., Schilt, A., Schmidt, A. M. Z., Schüpbach, S., Schwander, J., Seierstad, I., Severinghaus, J. P., Sheldon, S., Simonsen, S. B., Sjolte, J., Solgaard, A. M., Sowers, T., Sperlich, P., Steen-Larsen, H. C., Steffen, K., Steffensen, J. P., Steinhage, Daniel, Stocker, T. F., Stowasser, C., Sturevik, A. S., Sturges, W. T., Sveinbjörnsdottir, A., Svensson, A., Tison, J.-L., Uetake, J., Vallelonga, P., van de Wal, R. S. W., van der Wel, G., Vaughn, B. H., Vinther, B., Waddington, E., Wegner, Anna, Weikusat, Ilka, White, J. W. C., Wilhelms, Frank, Winstrup, M., Witrant, E., Wolff, E. W., Xiao, C., Zheng, J., Dahl-Jensen, D., Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, D., Baumgartner, M., Berggren, A.-M., Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Buchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davies, S. M., Ditlevsen, P., Eicher, O., Fischer, H., Fisher, D. A., Fleet, L. G., Gfeller, G., Gkinis, V., Gogineni, S., Grinsted, A., Goto-Azuma, K., Gudlaugsdottir, H., Guillevic, M., Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S. D., Huybrechts, P., Hvidberg, C. S., Jenk, T., Iizuka, Y., Johnsen, S. J., Jones, T. R., Jouzel, J., Karlsson, N. B., Kawamura, K., Keegan, K., Kettner, E., Kipfstuhl, Sepp, Kjær, H. A., Koutnik, M., Kuramoto, T., Köhler, Peter, Laepple, Thomas, Landais, A., Langen, P. L., Larsen, L. B., Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, Heinrich, Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Paden, J., Orsi, A. J., Panton, C., Pattyn, F., Petit, J.-R., Pol, K., Popp, T., Possnert, G., Prié, F., Prokopiou, M., Quiquet, A., Rasmussen, S. O., Raynaud, D., Ren, J., Reutenauer, C., Ritz, C., Röckmann, T., Rosen, J. L., Rubino, M., Rybak, O., Samyn, D., Sapart, C. J., Schilt, A., Schmidt, A. M. Z., Schüpbach, S., Schwander, J., Seierstad, I., Severinghaus, J. P., Sheldon, S., Simonsen, S. B., Sjolte, J., Solgaard, A. M., Sowers, T., Sperlich, P., Steen-Larsen, H. C., Steffen, K., Steffensen, J. P., Steinhage, Daniel, Stocker, T. F., Stowasser, C., Sturevik, A. S., Sturges, W. T., Sveinbjörnsdottir, A., Svensson, A., Tison, J.-L., Uetake, J., Vallelonga, P., van de Wal, R. S. W., van der Wel, G., Vaughn, B. H., Vinther, B., Waddington, E., Wegner, Anna, Weikusat, Ilka, White, J. W. C., Wilhelms, Frank, Winstrup, M., Witrant, E., Wolff, E. W., Xiao, C., and Zheng, J.
Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling (‘NEEM’) ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 ± 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 ± 250 metres, reaching surface elevations 122,000 years ago of 130 ± 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
Published: 2013

33. Eemian interglacial reconstructed from a Greenland folded ice core

Author: Dahl-Jensen, D., Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, D., Baumgartner, M., Berggren, A.-M., Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Buchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davies, S. M., Ditlevsen, P., Eicher, O., Fischer, H., Fisher, D. A., Fleet, L. G., Gfeller, G., Gkinis, V., Gogineni, S., Grinsted, A., Goto-Azuma, K., Gudlaugsdottir, H., Guillevic, M., Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S. D., Huybrechts, P., Hvidberg, C. S., Jenk, T., Iizuka, Y., Johnsen, S. J., Jones, T. R., Jouzel, J., Karlsson, N. B., Kawamura, K., Keegan, K., Kettner, E., Kipfstuhl, Sepp, Kjær, H. A., Koutnik, M., Kuramoto, T., Köhler, Peter, Laepple, Thomas, Landais, A., Langen, P. L., Larsen, L. B., Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, Heinrich, Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Paden, J., Orsi, A. J., Panton, C., Pattyn, F., Petit, J.-R., Pol, K., Popp, T., Possnert, G., Prié, F., Prokopiou, M., Quiquet, A., Rasmussen, S. O., Raynaud, D., Ren, J., Reutenauer, C., Ritz, C., Röckmann, T., Rosen, J. L., Rubino, M., Rybak, O., Samyn, D., Sapart, C. J., Schilt, A., Schmidt, A. M. Z., Schüpbach, S., Schwander, J., Seierstad, I., Severinghaus, J. P., Sheldon, S., Simonsen, S. B., Sjolte, J., Solgaard, A. M., Sowers, T., Sperlich, P., Steen-Larsen, H. C., Steffen, K., Steffensen, J. P., Steinhage, Daniel, Stocker, T. F., Stowasser, C., Sturevik, A. S., Sturges, W. T., Sveinbjörnsdottir, A., Svensson, A., Tison, J.-L., Uetake, J., Vallelonga, P., van de Wal, R. S. W., van der Wel, G., Vaughn, B. H., Vinther, B., Waddington, E., Wegner, Anna, Weikusat, Ilka, White, J. W. C., Wilhelms, Frank, Winstrup, M., Witrant, E., Wolff, E. W., Xiao, C., Zheng, J., Dahl-Jensen, D., Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, D., Baumgartner, M., Berggren, A.-M., Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Buchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davies, S. M., Ditlevsen, P., Eicher, O., Fischer, H., Fisher, D. A., Fleet, L. G., Gfeller, G., Gkinis, V., Gogineni, S., Grinsted, A., Goto-Azuma, K., Gudlaugsdottir, H., Guillevic, M., Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S. D., Huybrechts, P., Hvidberg, C. S., Jenk, T., Iizuka, Y., Johnsen, S. J., Jones, T. R., Jouzel, J., Karlsson, N. B., Kawamura, K., Keegan, K., Kettner, E., Kipfstuhl, Sepp, Kjær, H. A., Koutnik, M., Kuramoto, T., Köhler, Peter, Laepple, Thomas, Landais, A., Langen, P. L., Larsen, L. B., Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, Heinrich, Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Paden, J., Orsi, A. J., Panton, C., Pattyn, F., Petit, J.-R., Pol, K., Popp, T., Possnert, G., Prié, F., Prokopiou, M., Quiquet, A., Rasmussen, S. O., Raynaud, D., Ren, J., Reutenauer, C., Ritz, C., Röckmann, T., Rosen, J. L., Rubino, M., Rybak, O., Samyn, D., Sapart, C. J., Schilt, A., Schmidt, A. M. Z., Schüpbach, S., Schwander, J., Seierstad, I., Severinghaus, J. P., Sheldon, S., Simonsen, S. B., Sjolte, J., Solgaard, A. M., Sowers, T., Sperlich, P., Steen-Larsen, H. C., Steffen, K., Steffensen, J. P., Steinhage, Daniel, Stocker, T. F., Stowasser, C., Sturevik, A. S., Sturges, W. T., Sveinbjörnsdottir, A., Svensson, A., Tison, J.-L., Uetake, J., Vallelonga, P., van de Wal, R. S. W., van der Wel, G., Vaughn, B. H., Vinther, B., Waddington, E., Wegner, Anna, Weikusat, Ilka, White, J. W. C., Wilhelms, Frank, Winstrup, M., Witrant, E., Wolff, E. W., Xiao, C., and Zheng, J.
Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling (‘NEEM’) ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 ± 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 ± 250 metres, reaching surface elevations 122,000 years ago of 130 ± 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
Published: 2013

34. A new bipolar ice core record of volcanism from WAIS Divide and NEEM and implications for climate forcing of the last 2000 years

Author: Sigl, M., McConnell, J.R., Layman, L., Maselli, O., McGwire, K., Pasteris, D., Dahl-Jensen, Dorthe, Steffensen, Jørgen Peder, Vinther, Bo Møllesøe, Edwards, R., Mulvaney, R., Kipfstuhl, S., Sigl, M., McConnell, J.R., Layman, L., Maselli, O., McGwire, K., Pasteris, D., Dahl-Jensen, Dorthe, Steffensen, Jørgen Peder, Vinther, Bo Møllesøe, Edwards, R., Mulvaney, R., and Kipfstuhl, S.
Published: 2013

35. Eemian interglacial reconstructed from a Greenland folded ice core

Author: Dahl-Jensen, Dorthe, Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, David Morten, Baumgartner, M., Berggren, A.-M., Bigler, M., Binder, Thomas, Blunier, Thomas, Bourgeois, J.C., Brook, E.J., Buchardt, Susanne Lilja, Buizert, Christo, Capron, E., Chappellaz, J., Chung, J., Clausen, Henrik Brink, Cvijanovic, Ivana, Davies, S.M., Ditlevsen, Peter, Eicher, O., Fischer, H., Fisher, D. A., Fleet, L.G., Gfeller, G., Gkinis, Vasileios, Gogineni, S., Goto-Azuma, K., Grinsted, Aslak, Gudlaugsdottir, H., Guillevic, Myriam, Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S.D., Huybrechts, P., Hvidberg, Christine Schøtt, Iizuka, Y., Jenk, Theo Manuel, Johnsen, Sigfus Johann, Jones, T.R., Jouzel, J., Karlsson, Nanna Bjørnholt, Kawamura, K., Keegan, K., Kettner, Ernesto, Kipfstuhl, S., Kjær, Helle Astrid, Koutnik, M., Kuramoto, T., Köhler, P., Laepple, T., Landais, A., Langen, Peter Lang, Larsen, Lars Berg, Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, H., Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Orsi, A.J., Paden, J., Panton, Christian, Pattyn, F., Petit, J.-R., Pol, K., Popp, Trevor James, Possnert, G., Prié, F., Prokopiou, M., Quiquet, A., Rasmussen, Sune Olander, Raynaud, D., Ren, J., Reutenauer, Corentin, Ritz, C., Röckmann, T., Rosen, J.L., Rubino, Mauro, Rybak, O., Samyn, D., Sapart, C.J., Schilt, A., Schmidt, Astrid Mariah Zelma, Schwander, J., Schüpbach, S., Seierstad, Inger Kathrine, Severinghaus, J. P., Sheldon, S., Simonsen, Sebastian Bjerregaard, Sjolte, Jesper, Solgaard, Anne Munck, Sowers, T., Sperlich, Peter, Steen-Larsen, Hans Christian, Steffen, K., Steffensen, Jørgen Peder, Steinhage, D., Stocker, T.F., Stowasser, Christopher, Sturevik, A.S., Sturges, W.T., Sveinbjörnsdottir, A., Svensson, Anders, Tison, J.-L., Uetake, J., Vallelonga, Paul Travis, Van De Wal, R.S.W., Van Der Wel, G., Vaughn, B.H., Vinther, Bo Møllesøe, Waddington, E., Wegner, A., Weikusat, I., White, J. W. C., Wilhelms, F., Winstrup, Mai, Witrant, E., Wolff, E.W., Xiao, C., Zheng, Jin, Dahl-Jensen, Dorthe, Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, David Morten, Baumgartner, M., Berggren, A.-M., Bigler, M., Binder, Thomas, Blunier, Thomas, Bourgeois, J.C., Brook, E.J., Buchardt, Susanne Lilja, Buizert, Christo, Capron, E., Chappellaz, J., Chung, J., Clausen, Henrik Brink, Cvijanovic, Ivana, Davies, S.M., Ditlevsen, Peter, Eicher, O., Fischer, H., Fisher, D. A., Fleet, L.G., Gfeller, G., Gkinis, Vasileios, Gogineni, S., Goto-Azuma, K., Grinsted, Aslak, Gudlaugsdottir, H., Guillevic, Myriam, Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S.D., Huybrechts, P., Hvidberg, Christine Schøtt, Iizuka, Y., Jenk, Theo Manuel, Johnsen, Sigfus Johann, Jones, T.R., Jouzel, J., Karlsson, Nanna Bjørnholt, Kawamura, K., Keegan, K., Kettner, Ernesto, Kipfstuhl, S., Kjær, Helle Astrid, Koutnik, M., Kuramoto, T., Köhler, P., Laepple, T., Landais, A., Langen, Peter Lang, Larsen, Lars Berg, Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, H., Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Orsi, A.J., Paden, J., Panton, Christian, Pattyn, F., Petit, J.-R., Pol, K., Popp, Trevor James, Possnert, G., Prié, F., Prokopiou, M., Quiquet, A., Rasmussen, Sune Olander, Raynaud, D., Ren, J., Reutenauer, Corentin, Ritz, C., Röckmann, T., Rosen, J.L., Rubino, Mauro, Rybak, O., Samyn, D., Sapart, C.J., Schilt, A., Schmidt, Astrid Mariah Zelma, Schwander, J., Schüpbach, S., Seierstad, Inger Kathrine, Severinghaus, J. P., Sheldon, S., Simonsen, Sebastian Bjerregaard, Sjolte, Jesper, Solgaard, Anne Munck, Sowers, T., Sperlich, Peter, Steen-Larsen, Hans Christian, Steffen, K., Steffensen, Jørgen Peder, Steinhage, D., Stocker, T.F., Stowasser, Christopher, Sturevik, A.S., Sturges, W.T., Sveinbjörnsdottir, A., Svensson, Anders, Tison, J.-L., Uetake, J., Vallelonga, Paul Travis, Van De Wal, R.S.W., Van Der Wel, G., Vaughn, B.H., Vinther, Bo Møllesøe, Waddington, E., Wegner, A., Weikusat, I., White, J. W. C., Wilhelms, F., Winstrup, Mai, Witrant, E., Wolff, E.W., Xiao, C., and Zheng, Jin
Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 ± 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 ± 250 metres, reaching surface elevations 122,000 years ago of 130 ± 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
Published: 2013

36. A new bipolar ice core record of volcanism from WAIS Divide and NEEM and implications for climate forcing of the last 2000 years

Author: Sigl, M., McConnell, J.R., Layman, L., Maselli, O., McGwire, K., Pasteris, D., Dahl-Jensen, Dorthe, Steffensen, Jørgen Peder, Vinther, Bo Møllesøe, Edwards, R., Mulvaney, R., Kipfstuhl, S., Sigl, M., McConnell, J.R., Layman, L., Maselli, O., McGwire, K., Pasteris, D., Dahl-Jensen, Dorthe, Steffensen, Jørgen Peder, Vinther, Bo Møllesøe, Edwards, R., Mulvaney, R., and Kipfstuhl, S.
Published: 2013

37. Eemian interglacial reconstructed from a Greenland folded ice core

Author: Dahl-Jensen, Dorthe, Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, David Morten, Baumgartner, M., Berggren, A.-M., Bigler, M., Binder, Thomas, Blunier, Thomas, Bourgeois, J.C., Brook, E.J., Buchardt, Susanne Lilja, Buizert, Christo, Capron, E., Chappellaz, J., Chung, J., Clausen, Henrik Brink, Cvijanovic, Ivana, Davies, S.M., Ditlevsen, Peter, Eicher, O., Fischer, H., Fisher, D. A., Fleet, L.G., Gfeller, G., Gkinis, Vasileios, Gogineni, S., Goto-Azuma, K., Grinsted, Aslak, Gudlaugsdottir, H., Guillevic, Myriam, Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S.D., Huybrechts, P., Hvidberg, Christine Schøtt, Iizuka, Y., Jenk, Theo Manuel, Johnsen, Sigfus Johann, Jones, T.R., Jouzel, J., Karlsson, Nanna Bjørnholt, Kawamura, K., Keegan, K., Kettner, Ernesto, Kipfstuhl, S., Kjær, Helle Astrid, Koutnik, M., Kuramoto, T., Köhler, P., Laepple, T., Landais, A., Langen, Peter Lang, Larsen, Lars Berg, Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, H., Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Orsi, A.J., Paden, J., Panton, Christian, Pattyn, F., Petit, J.-R., Pol, K., Popp, Trevor James, Possnert, G., Prié, F., Prokopiou, M., Quiquet, A., Rasmussen, Sune Olander, Raynaud, D., Ren, J., Reutenauer, Corentin, Ritz, C., Röckmann, T., Rosen, J.L., Rubino, Mauro, Rybak, O., Samyn, D., Sapart, C.J., Schilt, A., Schmidt, Astrid Mariah Zelma, Schwander, J., Schüpbach, S., Seierstad, Inger Kathrine, Severinghaus, J. P., Sheldon, S., Simonsen, Sebastian Bjerregaard, Sjolte, Jesper, Solgaard, Anne Munck, Sowers, T., Sperlich, Peter, Steen-Larsen, Hans Christian, Steffen, K., Steffensen, Jørgen Peder, Steinhage, D., Stocker, T.F., Stowasser, Christopher, Sturevik, A.S., Sturges, W.T., Sveinbjörnsdottir, A., Svensson, Anders, Tison, J.-L., Uetake, J., Vallelonga, Paul Travis, Van De Wal, R.S.W., Van Der Wel, G., Vaughn, B.H., Vinther, Bo Møllesøe, Waddington, E., Wegner, A., Weikusat, I., White, J. W. C., Wilhelms, F., Winstrup, Mai, Witrant, E., Wolff, E.W., Xiao, C., Zheng, Jin, Dahl-Jensen, Dorthe, Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, David Morten, Baumgartner, M., Berggren, A.-M., Bigler, M., Binder, Thomas, Blunier, Thomas, Bourgeois, J.C., Brook, E.J., Buchardt, Susanne Lilja, Buizert, Christo, Capron, E., Chappellaz, J., Chung, J., Clausen, Henrik Brink, Cvijanovic, Ivana, Davies, S.M., Ditlevsen, Peter, Eicher, O., Fischer, H., Fisher, D. A., Fleet, L.G., Gfeller, G., Gkinis, Vasileios, Gogineni, S., Goto-Azuma, K., Grinsted, Aslak, Gudlaugsdottir, H., Guillevic, Myriam, Hansen, S. B., Hansson, M., Hirabayashi, M., Hong, S., Hur, S.D., Huybrechts, P., Hvidberg, Christine Schøtt, Iizuka, Y., Jenk, Theo Manuel, Johnsen, Sigfus Johann, Jones, T.R., Jouzel, J., Karlsson, Nanna Bjørnholt, Kawamura, K., Keegan, K., Kettner, Ernesto, Kipfstuhl, S., Kjær, Helle Astrid, Koutnik, M., Kuramoto, T., Köhler, P., Laepple, T., Landais, A., Langen, Peter Lang, Larsen, Lars Berg, Leuenberger, D., Leuenberger, M., Leuschen, C., Li, J., Lipenkov, V., Martinerie, P., Maselli, O. J., Masson-Delmotte, V., McConnell, J. R., Miller, H., Mini, O., Miyamoto, A., Montagnat-Rentier, M., Mulvaney, R., Muscheler, R., Orsi, A.J., Paden, J., Panton, Christian, Pattyn, F., Petit, J.-R., Pol, K., Popp, Trevor James, Possnert, G., Prié, F., Prokopiou, M., Quiquet, A., Rasmussen, Sune Olander, Raynaud, D., Ren, J., Reutenauer, Corentin, Ritz, C., Röckmann, T., Rosen, J.L., Rubino, Mauro, Rybak, O., Samyn, D., Sapart, C.J., Schilt, A., Schmidt, Astrid Mariah Zelma, Schwander, J., Schüpbach, S., Seierstad, Inger Kathrine, Severinghaus, J. P., Sheldon, S., Simonsen, Sebastian Bjerregaard, Sjolte, Jesper, Solgaard, Anne Munck, Sowers, T., Sperlich, Peter, Steen-Larsen, Hans Christian, Steffen, K., Steffensen, Jørgen Peder, Steinhage, D., Stocker, T.F., Stowasser, Christopher, Sturevik, A.S., Sturges, W.T., Sveinbjörnsdottir, A., Svensson, Anders, Tison, J.-L., Uetake, J., Vallelonga, Paul Travis, Van De Wal, R.S.W., Van Der Wel, G., Vaughn, B.H., Vinther, Bo Møllesøe, Waddington, E., Wegner, A., Weikusat, I., White, J. W. C., Wilhelms, F., Winstrup, Mai, Witrant, E., Wolff, E.W., Xiao, C., and Zheng, Jin
Abstract: Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling ('NEEM') ice core and show only a modest ice-sheet response to the strong warming in the early Eemian. We reconstructed the Eemian record from folded ice using globally homogeneous parameters known from dated Greenland and Antarctic ice-core records. On the basis of water stable isotopes, NEEM surface temperatures after the onset of the Eemian (126,000 years ago) peaked at 8 ± 4 degrees Celsius above the mean of the past millennium, followed by a gradual cooling that was probably driven by the decreasing summer insolation. Between 128,000 and 122,000 years ago, the thickness of the northwest Greenland ice sheet decreased by 400 ± 250 metres, reaching surface elevations 122,000 years ago of 130 ± 300 metres lower than the present. Extensive surface melt occurred at the NEEM site during the Eemian, a phenomenon witnessed when melt layers formed again at NEEM during the exceptional heat of July 2012. With additional warming, surface melt might become more common in the future.
Published: 2013

38. Black carbon concentrations and fluxes since the Last Glacial Maximum in Greenland and Antarctic ice cores

Author: McConnell, J. R., Sigl, M., Baggenstos, D., Fritzsche, Diedrich, Dahl-Jensen, D., Das, S., Kreutz, K., Maselli, O., McGwire, K. C., Nolan, M., Opel, Thomas, Severinghaus, J., Steffensen, J. P., McConnell, J. R., Sigl, M., Baggenstos, D., Fritzsche, Diedrich, Dahl-Jensen, D., Das, S., Kreutz, K., Maselli, O., McGwire, K. C., Nolan, M., Opel, Thomas, Severinghaus, J., and Steffensen, J. P.
Abstract: Warming from increased carbon dioxide and other greenhouse gas concentrations is the long-term driver of climate change but short-lived aerosols such as black carbon (BC) and continental dust also are important components of climate forcing. BC and dust in snow are especially important in the high latitudes because of their strong impact on albedo. With their short lifetimes in the atmosphere, aerosol concentrations and deposition rates are dominated by regional – rather than global – sources and intra- and inter-annual variability is high. Because most dust and BC aerosols in high latitudes originate in lower latitudes, changes in long range transport processes and pathways may dominate over changes in source strength in determining concentrations and deposition rates in the Polar Regions. However, detailed understanding of past and present concentrations, deposition rates, sources, and transport pathways of BC and dust is lacking. Here we present and discuss detailed measurements of BC, dust, and related source tracers in the WAIS Divide and NEEM deep ice cores. Our records at both sites extend from the Last Glacial Maximum to the Early Holocene and also span the last two millennia. Similar measurements in a Taylor Glacier horizontal core and section of GISP2, as well as in a broad array of Greenland and Antarctic cores spanning recent centuries to decades, help elucidate spatial variability within each region during the last glacial to interglacial transition and recent past, respectively.
Published: 2012

39. Black carbon concentrations and fluxes since the Last Glacial Maximum in Greenland and Antarctic ice cores

Author: McConnell, J. R., Sigl, M., Baggenstos, D., Fritzsche, Diedrich, Dahl-Jensen, D., Das, S., Kreutz, K., Maselli, O., McGwire, K. C., Nolan, M., Opel, Thomas, Severinghaus, J., Steffensen, J. P., McConnell, J. R., Sigl, M., Baggenstos, D., Fritzsche, Diedrich, Dahl-Jensen, D., Das, S., Kreutz, K., Maselli, O., McGwire, K. C., Nolan, M., Opel, Thomas, Severinghaus, J., and Steffensen, J. P.
Abstract: Warming from increased carbon dioxide and other greenhouse gas concentrations is the long-term driver of climate change but short-lived aerosols such as black carbon (BC) and continental dust also are important components of climate forcing. BC and dust in snow are especially important in the high latitudes because of their strong impact on albedo. With their short lifetimes in the atmosphere, aerosol concentrations and deposition rates are dominated by regional – rather than global – sources and intra- and inter-annual variability is high. Because most dust and BC aerosols in high latitudes originate in lower latitudes, changes in long range transport processes and pathways may dominate over changes in source strength in determining concentrations and deposition rates in the Polar Regions. However, detailed understanding of past and present concentrations, deposition rates, sources, and transport pathways of BC and dust is lacking. Here we present and discuss detailed measurements of BC, dust, and related source tracers in the WAIS Divide and NEEM deep ice cores. Our records at both sites extend from the Last Glacial Maximum to the Early Holocene and also span the last two millennia. Similar measurements in a Taylor Glacier horizontal core and section of GISP2, as well as in a broad array of Greenland and Antarctic cores spanning recent centuries to decades, help elucidate spatial variability within each region during the last glacial to interglacial transition and recent past, respectively.
Published: 2012

40. Translational and rotational energy content of benzene molecules IR-desorbed from an in vacuo liquid surface

Author: Maselli, O., Gascooke, J., Shoji, M., Buntine, Mark, Maselli, O., Gascooke, J., Shoji, M., and Buntine, Mark
Abstract: Benzene molecules were desorbed from an in vacuo aqueous liquid beam by direct irradiation of the beam with an IR laser tuned to the 2.85 mm absorption band of water. Spectroscopic interrogation of the desorbed benzene molecules was performed via 1 + 1 Resonance-Enhanced Multi-photon Ionisation (REMPI). Rotational contour analyses of the 6 1/0 vibronic transition of benzene were performed to determine the rotational temperature of those molecules ejected during the desorption event. At the peak of the desorption plume density, the rotational temperatures were found to be up to ~100 K lower than that recorded for molecules spontaneously evaporating from the liquid surface. At longer IR-UV laser delay times the benzene rotational temperatures are found to return to those observed following spontaneous evaporation. No evidence of IR desorbed neutral or cationic benzene-containing clusters was observed. However, ionic clusters were observed to be formed after REMPI of the benzene monomer. Analysis of the benzene intensity and that of post-REMPI formed clusters as a function of IR-UV delay shows that number density and local translational temperature vary along the desorption plume.
Published: 2012

41. Changes in Arctic black carbon concentrations, deposition, transport, and sources during recent centuries

Author: McConnell, J. R., Dahl-Jensen, D., Flanner, M., Fritzsche, Diedrich, Kreutz, K., Lamarque, J. F., Lawrence, R., Maselli, O., Nolan, M., Opel, Thomas, Pasteris, D., Sigl, M., Steffensen, J. P., McConnell, J. R., Dahl-Jensen, D., Flanner, M., Fritzsche, Diedrich, Kreutz, K., Lamarque, J. F., Lawrence, R., Maselli, O., Nolan, M., Opel, Thomas, Pasteris, D., Sigl, M., and Steffensen, J. P.
Abstract: Rates of climate change in the Arctic are among the highest on Earth. Warming from increased carbon dioxide and other greenhouse gas concentrations is the long-term driver of Arctic climate change, but reductions in short-lived aerosols such as black carbon (BC) that contribute to climate warming offer the possibility of slowing Arctic climate change in the near-term. BC in snow and water is especially important to climate forcing in the Arctic because of its impact on albedo. Detailed understanding of past and present concentrations, deposition rates, sources, and transport pathways of BC to and within the Arctic is critical, however, to the design of effective mitigation policies. With their short lifetimes in the atmosphere, aerosol concentrations and deposition in the Arctic are dominated by regional, rather than global, sources, transport processes, and pathways. Such aerosols consist of continental dust, sea spray, particulates including BC and organic matter from combustion processes, sulfur and trace metals from volcanic emissions, and, during recent centuries, industrial activities. Further, intra- and inter-annual variability of aerosol deposition is large. As a result, spatially distributed measurements of historical, high-time-resolution records with a broad range of analytes are required to understand aerosol concentrations, sources, and variability while providing adequate information for evaluating global circulation, snowpack radiation, and other modeling results. Arrays of ice cores from polar and alpine glaciers and ice sheets offer the potential to provide spatially distributed historical records with very high time resolution and a broad spectrum of aerosols and source tracers, particularly when using a continuous flow analytical system. Here we present and discuss recent findings from measurements of BC and related source tracers in a developing array of ice cores from around the Arctic. We use 1850 to 2000 general circulation modeling to evalua
Published: 2011

42. Changes in Black Carbon Concentrations, Deposition Rates, Sources, and Transport Pathways in the Arctic during Recent Centuries

Author: McConnell, J. R., Flanner, M., Fritzsche, Diedrich, Kreutz, K., Lamarque, J. F., Larson, L. B., Lawrence, R., Maselli, O., Nolan, M., Sigl, M., Steffen, K., Steffensen, J. P., McConnell, J. R., Flanner, M., Fritzsche, Diedrich, Kreutz, K., Lamarque, J. F., Larson, L. B., Lawrence, R., Maselli, O., Nolan, M., Sigl, M., Steffen, K., and Steffensen, J. P.
Published: 2011

43. Changes in Arctic black carbon concentrations, deposition, transport, and sources during recent centuries

Author: McConnell, J. R., Dahl-Jensen, D., Flanner, M., Fritzsche, Diedrich, Kreutz, K., Lamarque, J. F., Lawrence, R., Maselli, O., Nolan, M., Opel, Thomas, Pasteris, D., Sigl, M., Steffensen, J. P., McConnell, J. R., Dahl-Jensen, D., Flanner, M., Fritzsche, Diedrich, Kreutz, K., Lamarque, J. F., Lawrence, R., Maselli, O., Nolan, M., Opel, Thomas, Pasteris, D., Sigl, M., and Steffensen, J. P.
Abstract: Rates of climate change in the Arctic are among the highest on Earth. Warming from increased carbon dioxide and other greenhouse gas concentrations is the long-term driver of Arctic climate change, but reductions in short-lived aerosols such as black carbon (BC) that contribute to climate warming offer the possibility of slowing Arctic climate change in the near-term. BC in snow and water is especially important to climate forcing in the Arctic because of its impact on albedo. Detailed understanding of past and present concentrations, deposition rates, sources, and transport pathways of BC to and within the Arctic is critical, however, to the design of effective mitigation policies. With their short lifetimes in the atmosphere, aerosol concentrations and deposition in the Arctic are dominated by regional, rather than global, sources, transport processes, and pathways. Such aerosols consist of continental dust, sea spray, particulates including BC and organic matter from combustion processes, sulfur and trace metals from volcanic emissions, and, during recent centuries, industrial activities. Further, intra- and inter-annual variability of aerosol deposition is large. As a result, spatially distributed measurements of historical, high-time-resolution records with a broad range of analytes are required to understand aerosol concentrations, sources, and variability while providing adequate information for evaluating global circulation, snowpack radiation, and other modeling results. Arrays of ice cores from polar and alpine glaciers and ice sheets offer the potential to provide spatially distributed historical records with very high time resolution and a broad spectrum of aerosols and source tracers, particularly when using a continuous flow analytical system. Here we present and discuss recent findings from measurements of BC and related source tracers in a developing array of ice cores from around the Arctic. We use 1850 to 2000 general circulation modeling to evalua
Published: 2011

44. Changes in Black Carbon Concentrations, Deposition Rates, Sources, and Transport Pathways in the Arctic during Recent Centuries

Author: McConnell, J. R., Flanner, M., Fritzsche, Diedrich, Kreutz, K., Lamarque, J. F., Larson, L. B., Lawrence, R., Maselli, O., Nolan, M., Sigl, M., Steffen, K., Steffensen, J. P., McConnell, J. R., Flanner, M., Fritzsche, Diedrich, Kreutz, K., Lamarque, J. F., Larson, L. B., Lawrence, R., Maselli, O., Nolan, M., Sigl, M., Steffen, K., and Steffensen, J. P.
Published: 2011

45. The dynamics of evaporation from a liquid surface

Author: Maselli, O, Gascooke, J., Lawrance, W., Buntine, Mark, Maselli, O, Gascooke, J., Lawrance, W., and Buntine, Mark
Abstract: We explore the collisional energy transfer dynamics of benzene molecules spontaneously evaporating from an in vacuo water -ethanol liquid beam. We find that rotations are cooled significantly more than the lowest-energy vibrational modes, while the rotational energy distributions are Boltzmann. Within experimental uncertainty, the rotational temperatures of vibrationally-excited evaporating molecules are the same as the ground state. Collision-induced gas phase energy transfer measurements reveal that benzene undergoes fast rotational relaxation, from which we deduce that the rotational temperature measured in the evaporation experiments (200-230 K) is an indication of the translational energy of the evaporate. Conversely, vibrational relaxation of the high frequency mode, m6, is very inefficient, suggesting that the m6 temperature (260-270 K) is an indication of the liquid surface temperature. Modelling of the relaxation dynamics by both 'temperature gap' and 'Master Equation' approaches indicates that the equivalent of 150-260 hard-sphere collisions occur during the transition from liquid to vacuum.
Published: 2011

46. Benzene Internal Energy Distributions Following Spontaneous Evaporation from a Water-Ethanol Solution

Author: Maselli, O., Gascooke, J., Lawrance, W., Buntine, Mark, Maselli, O., Gascooke, J., Lawrance, W., and Buntine, Mark
Abstract: We use the liquid microjet technique coupled with laser spectroscopy to measure the rotational and vibrational energy content of benzene spontaneously evaporating from a water-ethanol solution. We find different temperatures for rotation (206 K) and for the two low-lying vibrational modes, nu(6) (256 K) and nu(16) (229 K). Collision-induced energy-transfer measurements reveal efficient rotational relaxation, from which we deduce that the rotational temperature indicates the translational energy of the evaporate. Conversely, the relaxation of nu(6) is very inefficient, suggesting that the nu(6) temperature indicates the surface temperature of the liquid. Modeling the relaxation of nu(16) indicates that > 10(2) collisions are occurring during the transition from liquid to vacuum, which is an order of magnitude more than has been reported to occur in the gas phase immediately above the liquid surface. Our results reveal that evaporative molecular energy transfer involves many collisions, resulting in moderate collisional cooling as molecules pass from liquid to vapor.
Published: 2009

47. Measuring the Internal Energy Content of Molecules Transported Across the Liquid-Gas Interface

Author: Maselli, O., Gascooke, J., Lawrance, W., Buntine, Mark, Maselli, O., Gascooke, J., Lawrance, W., and Buntine, Mark
Abstract: Many details concerning the mechanism associated with the liberation of molecules from a liquid surface remain to be elucidated. We use the liquid microjet technique coupled with laser spectroscopy to measure the rotational and vibrational energy content of benzene spontaneously evaporating from a water-ethanol solution. These measurements provide molecular level insight into the mass and energy transfer processes associated with evaporation.
Published: 2009

48. Rotational energy distributions of benzene liberated from aqueous liquid microjets: A comparison between evaporation and infrared desorption

Author: Maselli, O., Gascooke, J., Kobelt, S., Metha, G., Buntine, Mark, Maselli, O., Gascooke, J., Kobelt, S., Metha, G., and Buntine, Mark
Abstract: We have measured the rotational energy distribution of benzene molecules both evaporated and desorbed by an IR laser from a liquid microjet. Analysis of the 6(0)(1) vibronic band of benzene has shown that the benzene molecules evaporating from the liquid microjet surface have a rotational temperature of 157 +/- 7 K. In contrast, the rotational temperature of benzene molecules desorbed from the liquid microjet by a 1.9 mu m laser pulse is 82 +/- 5 K. However, in both cases careful inspection of the spectral profiles shows that the experimental rotational distributions are non-Boltzmann, displaying an underpopulation of high rotational states and a relative overpopulation of the low rotational states. The non-equilibrium evaporation and desorption spectral profiles are consistent with a model that involves transfer of internal energy into translation upon liberation from the condensed phase.
Published: 2006

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