Search

Climate tipping elements are large-scale subsystems of the Earth that may transgress critical thresholds (tipping points) under ongoing global warming, with substantial impacts on the biosphere and human societies. Frequently studied examples of such tipping elements include the Greenland Ice Sheet, the Atlantic Meridional Overturning Circulation (AMOC), permafrost, monsoon systems, and the Amazon rainforest. While recent scientific efforts have improved our knowledge about individual tipping elements, the interactions between them are less well understood. Also, the potential of individual tipping events to induce additional tipping elsewhere or stabilize other tipping elements is largely unknown. Here, we map out the current state of the literature on the interactions between climate tipping elements and review the influences between them. To do so, we gathered evidence from model simulations, observations, and conceptual understanding, as well as examples of paleoclimate reconstructions where multi-component or spatially propagating transitions were potentially at play. While uncertainties are large, we find indications that many of the interactions between tipping elements are destabilizing. Therefore, we conclude that tipping elements should not only be studied in isolation, but also more emphasis has to be put on potential interactions. This means that tipping cascades cannot be ruled out on centennial to millennial timescales at global warming levels between 1.5 and 2.0 ∘C or on shorter timescales if global warming surpassed 2.0 ∘C. At these higher levels of global warming, tipping cascades may then include fast tipping elements such as the AMOC or the Amazon rainforest. To address crucial knowledge gaps in tipping element interactions, we propose four strategies combining observation-based approaches, Earth system modeling expertise, computational advances, and expert knowledge.

This chapter reviews interactions between climate tipping systems and assesses the potential risk of cascading effects. After a definition of tipping system interactions, we map out the current state of the literature on specific interactions between climate tipping systems that may be important for the overall stability of the climate system. For this, we gather evidence from model simulations, observations and conceptual understanding, as well as archetypal examples of palaeoclimate reconstructions where propagating transitions were potentially at play. This chapter concludes by identifying crucial knowledge gaps in tipping system interactions that should be resolved in order to improve risk assessments of cascading transitions under future climate change scenarios.

Understanding the Indian Summer Monsoon (ISM) behaviour during the late Pleistocene has been largely based on the wind-driven upwelling records from the Arabian Sea. However, it remains unclear the extent to which these records can also be used to infer a concomitant signal of monsoon rainfall, or how the two ISM components, rainfall and wind, are linked on millennial timescales. In order to isolate a primary signal of ISM rainfall, we exploit two deep sea sediment cores from the northern Bay of Bengal (Site U1446) and Andaman Sea (Site U1448), both situated proximal to the South Asian continent, and thus ideally situated for capturing ISM rainfall and fluvial runoff. By comparing our multi-proxy ISM rainfall and runoff records with published ISM wind-driven records from the Arabian Sea, we observe pronounced decoupling of the rainfall and wind components of the ISM across Marine Isotope Stage 5/6 (∼140–70 thousand years ago). We reveal that the relative dominance of barometric dynamics (wind) and the thermodynamic (rainfall) components of the monsoon shifts with changes in background climate state. This finding constitutes an important consideration for the interpretation of past monsoon reconstructions. By comparing our new ISM rainfall records with high latitude climate records, we show that moisture export from low-latitudes, via the monsoon, could have preconditioned the high latitudes for ice sheet growth during glacial inceptions.

The geological history of the South Asian monsoon (SAM) before the Pleistocene is not well-constrained, primarily due to a lack of available continuous sediment archives. Previous studies have noted an intensification of SAM precipitation and atmospheric circulation during the middle Miocene (∼14 Ma), but no records are available to test how the monsoon changed prior to this. In order to improve our understanding of monsoonal evolution, geochemical and sedimentological data were generated for the Oligocene-early Miocene (30–20 Ma) from Indian National Gas Hydrate Expedition 01 Site NGHP-01-01A in the eastern Arabian Sea, at 2,674 m water depth. We find the initial glaciation phase (23.7–23.0 Ma) of the Oligocene-Miocene transition (OMT) to be associated with an increase in water column ventilation and water mass mixing, suggesting an increase in winter monsoon type atmospheric circulation, possibly driven by a relative southward shift of the intertropical convergence zone. During the latter part of the OMT, or “deglaciation” phase (23.0–22.7 Ma), a long-term decrease in Mn (suggestive of deoxygenation), increase in Ti/Ca and dissolution of the biogenic carbonate fraction suggest an intensification of a proto-summer SAM system, characterized by the formation of an oxygen minimum zone in the eastern Arabian Sea and a relative increase of terrigenous material delivered by runoff to the site. With no evidence at this site for an active SAM prior to the OMT we suggest that changes in orbital parameters, as well as possibly changing Tethyan/Himalayan tectonics, caused this step change in the proto-monsoon system at this intermediate-depth site.

Executive Statement: Geology is the science of how the Earth functions and has evolved and, as such, it can contribute to our understanding of the climate system and how it responds to the addition of carbon dioxide (CO2) to the atmosphere and oceans. Observations from the geological record show that atmospheric CO2 concentrations are now at their highest levels in at least the past 3 million years. Furthermore, the current speed of human-induced CO2 change and warming is nearly without precedent in the entire geological record, with the only known exception being the instantaneous, meteorite-induced event that caused the extinction of non-bird-like dinosaurs 66 million years ago. In short, whilst atmospheric CO2 concentrations have varied dramatically during the geological past due to natural processes, and have often been higher than today, the current rate of CO2 (and therefore temperature) change is unprecedented in almost the entire geological past. The geological record shows that changes in temperature and greenhouse gas concentrations have direct impacts on sea-level, the hydrological cycle, marine and terrestrial ecosystems, and the acidification and oxygen depletion of the oceans. Important climate phenomena, such as the El Niño–Southern Oscillation (ENSO) and the monsoons, which today affect the socio-economic stability and food and water security of billions of people, have varied markedly with past changes in climate. Climate reconstructions from around the globe show that climate change is not globally uniform, but tends to exhibit a consistent pattern, with changes at the poles larger than elsewhere. This polar amplification is seen in ancient warmer-than-modern time intervals like the Eocene epoch, about 50 million years ago and, more recently, in the Pliocene, about 3 million years ago. The warmest intervals of the Pliocene saw the disappearance of summer sea ice from the Arctic. The loss of ice cover during the Pliocene was one of the many rapid cl

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Clemens, S. C., Yamamoto, M., Thirumalai, K., Giosan, L., Richey, J. N., Nilsson-Kerr, K., Rosenthal, Y., Anand, P., & McGrath, S. M. Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: a test for future predictions. Science Advances, 7(23), (2021): eabg3848, https://doi.org/10.1126/sciadv.abg3848., South Asian precipitation amount and extreme variability are predicted to increase due to thermodynamic effects of increased 21st-century greenhouse gases, accompanied by an increased supply of moisture from the southern hemisphere Indian Ocean. We reconstructed South Asian summer monsoon precipitation and runoff into the Bay of Bengal to assess the extent to which these factors also operated in the Pleistocene, a time of large-scale natural changes in carbon dioxide and ice volume. South Asian precipitation and runoff are strongly coherent with, and lag, atmospheric carbon dioxide changes at Earth’s orbital eccentricity, obliquity, and precession bands and are closely tied to cross-equatorial wind strength at the precession band. We find that the projected monsoon response to ongoing, rapid high-latitude ice melt and rising carbon dioxide levels is fully consistent with dynamics of the past 0.9 million years., S.C.C. and S.M.M. were supported by U.S. NSF OCE1634774. M.Y. was funded by JSPS grants JPMXS05R2900001 and 19H05595 and JAMSTEC Exp. 353 postcruise study. K.N.-K. and P.A. were supported by UK-IODP, Open University, and NERC (NE/L002493/1), K.T. was supported by the Technology and Research Initiative Fund, Arizona Board of Regents.

Diversity, at every step along the scientific path, drives innovative research. Scientific societies, like the Geochemical Society (GS) and the European Association of Geochemistry (EAG), have a significant influence over which discoveries and innovators are celebrated. Such choices impact the future of research, and therefore influence the evolution of our discipline and its relationship to the global community. Our professional societies are well positioned to define and promote the success of all scientists, including those from under-represented groups, through proactive advocacy, inclusive mentorship, awards, and leadership. At present, only binary gender data are available to examine the distribution of under-represented groups among memberships, awardees, and leadership positions. To assess gender diversity in the geochemistry and cosmochemistry community, we have reviewed available records of GS and EAG membership through Goldschmidt Conference attendees, and compared these to awardees and leadership data. Awards have in the past been disproportionately given to white men, though this is changing. The GS and EAG have taken positive steps to increase both diversity of awardees (e.g., broadened definition of Fellows criteria) and inclusion (e.g., mentoring efforts aimed at early career and underrepresented minority scientists). This work identifies strategies to continue to improve professional societies’ recognition of excellent science resulting in a more diverse representation of awardees. The strategies (e.g., revisions to award criteria and procedures to enlarge and diversify nomination pools) will require ongoing analysis and modifications. Future work is needed to address historically under-represented groups. We must work together to create a legacy of inclusion.

Diversity, at every step along the scientific path, drives innovative research. Scientific societies, like the Geochemical Society (GS) and the European Association of Geochemistry (EAG), have a significant influence over which discoveries and innovators are celebrated. Such choices impact the future of research, and therefore influence the evolution of our discipline and its relationship to the global community. Our professional societies are well positioned to define and promote the success of all scientists, including those from under-represented groups, through proactive advocacy, inclusive mentorship, awards, and leadership. At present, only binary gender data are available to examine the distribution of under-represented groups among memberships, awardees, and leadership positions. To assess gender diversity in the geochemistry and cosmochemistry community, we have reviewed available records of GS and EAG membership through Goldschmidt Conference attendees, and compared these to awardees and leadership data. Awards have in the past been disproportionately given to white men, though this is changing. The GS and EAG have taken positive steps to increase both diversity of awardees (e.g. broadened definition of Fellows criteria) and inclusion (e.g. mentoring efforts aimed at early career and underrepresented minority scientists). This work identifies strategies to continue to improve professional societies’ recognition of excellent science resulting in a more diverse representation of awardees. The strategies (e.g. revisions to award criteria and procedures to enlarge and diversify nomination pools) will require ongoing analysis and modifications. Future work is needed to address historically under-represented groups. We must work together to create a legacy of inclusion., SCOPUS: re.j, info:eu-repo/semantics/published

Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 21(2), (2020): e2019GC008414, doi:10.1029/2019GC008414., X‐ray fluorescence (XRF) core scanning of marine and lake sediments has been extensively used to study changes in past environmental and climatic processes over a range of timescales. The interpretation of XRF‐derived element ratios in paleoclimatic and paleoceanographic studies primarily considers differences in the relative abundances of particular elements. Here we present new XRF core scanning data from two long sediment cores in the Andaman Sea in the northern Indian Ocean and show that sea level related processes influence terrigenous inputs based proxies such as Ti/Ca, Fe/Ca, and elemental concentrations of the transition metals (e.g., Mn). Zr/Rb ratios are mainly a function of changes in median grain size of lithogenic particles and often covary with changes in Ca concentrations that reflect changes in biogenic calcium carbonate production. This suggests that a common process (i.e., sea level) influences both records. The interpretation of lighter element data (e.g., Si and Al) based on low XRF counts is complicated as variations in mean grain size and water content result in systematic artifacts and signal intensities not related to the Al or Si content of the sediments. This highlights the need for calibration of XRF core scanning data based on discrete sample analyses and careful examination of sediment properties such as porosity/water content for reliably disentangling environmental signals from other physical properties. In the case of the Andaman Sea, reliable extraction of a monsoon signal requires accounting for the sea level influence on the XRF data., The staff at the Bremen Core Repository is thanked for their help with core handling and Sam Müller at the University of Kiel provided technical assistance with the XRF scanner. We thank two anonymous reviewers for their insightful comments that improved the manuscript significantly. This work was partially funded through DFG Grant HA 5751/3. P. A. and K. N.‐K. acknowledge support from UK‐IODP and Natural and Environment Research Council, UK. The authors express their thanks to all those who contributed to the success of the National Gas Hydrate Program Expedition 01 (NGHP01) and Expedition 353. The data set supporting the conclusions of this article is available in the PANGEA repository (doi: https://doi.pangaea.de/10.1594/PANGAEA.910533)., 2020-07-10

Introduction: Helicobacter pylori are gram-negative bacillus. It is noninvasive and live in gastric mucus, with the small proportion of bacteria adherent to the mucosa. Its spiral shape and flagella render Helicobacter pylori motile in mucus environment. Helicobacter pylori is an important pathogen in human causing chronic gastritis and playing a major role in the development of peptic ulcers and gastric cancer. Material and Methods: Study was conducted in Mahatma Gandhi Medical College and hospital, Jaipur (from Jan 2014 to March 2015). 57 Gastrointestinal biopsies were taken who have symptom of dyspepsia. All biopsies taken from different sites were brought in 10%buffered formalin. After overnight fixation in formalin, the tissues were processed in automated tissue processor for dehydration, clearing, and paraffin embedding. Section were cut in rotary microtome at 4 micrometer thickness. The section was stained for Hematoxylin and Eosin stain and Geimsa overnight stain. Result: The present studyincluded 57 cases of upperGIT biopsies (gastro esophageal duodenal biopsies). The incidence of Helicobacter Pylori was seen with chronic gastritis in our study. Conclusion: H.pyloriareetiologically associated with chronic active gas triti s, duodenal ulcer, gastric ulcer, primarygastric B-cell lymphoma or mucosalassociated lymphoid type lymphoma (MALT lymphoma) and gastric adenocarcinoma. Helicobacter pylori induced chronic gas trit is were encountered in 16(47.22%) casesofthe presentstudy. Overnight Giemsa stain was done on all the patients and a histopathological diagnosis was made along with the study of the incidence of Helicobacterpylori positivity in all these patients.

Background: C-reactive protein (CRP) is a phylogenetically highly conserved plasma protein, with homologous in vertebrates and many invertebrates that participate in the systemic response to inflammation. So the significance of this study is to detect the levels of CRP in RA patients and its association with different age groups. Objectives: 1. To detect the levels of CRP in RA patients. 2. To compare the CRP levels in different age groups. Material and Methods: A hospital based study was conducted among 180 rheumatoid arthritis patients who attended the medicine OPD in 1 year. A predesigned questionnaire was used to collect the particulars of the patient. 5ml blood sample was collected from patients after informed consent. CRP levels were detected by semi-quantitative method. Appropriate statistical methods were used for defining the objectives. Epi info software was used for analysis purpose. Results: as the age increases the CRP levels increases (2.960.816, CI= 2.78-3.14) for the age group of 20-40 years. And (3.120.932, CI= 3.02-3.39) for 41-60 and above. Also the level of CRP increases it is considered only in mild category. Conclusion: Proper investigation during the signs and symptoms must be done. As CRP increases with age all the necessary prevention and diagnostic techniques must be used.

Highlights • Records of seawater εNdεNd are highly unradiogenic across the OMT at Ceara Rise. • Strong influence of Amazon particulate Nd on seawater εNdεNd at Ceara Rise. • Point-sourced riverine Nd influences seawater far from continental shelf. • Regional sedimentary Nd flux can be confused with water mass mixing signals. Abstract Dissolved and particulate neodymium (Nd) are mainly supplied to the oceans via rivers, dust, and release from marine sediments along continental margins. This process, together with the short oceanic residence time of Nd, gives rise to pronounced spatial gradients in oceanic 143Nd/144Nd ratios (εNdεNd). However, we do not yet have a good understanding of the extent to which the influence of riverine point-source Nd supply can be distinguished from changes in mixing between different water masses in the marine geological record. This gap in knowledge is important to fill because there is growing awareness that major global climate transitions may be associated not only with changes in large-scale ocean water mass mixing, but also with important changes in continental hydroclimate and weathering. Here we present εNdεNd data for fossilised fish teeth, planktonic foraminifera, and the Fe–Mn oxyhydroxide and detrital fractions of sediments recovered from Ocean Drilling Project (ODP) Site 926 on Ceara Rise, situated approximately 800 km from the mouth of the River Amazon. Our records span the Mi-1 glaciation event during the Oligocene–Miocene transition (OMT; ∼23 Ma). We compare our εNdεNd records with data for ambient deep Atlantic northern and southern component waters to assess the influence of particulate input from the Amazon River on Nd in ancient deep waters at this site. εNdεNd values for all of our fish teeth, foraminifera, and Fe–Mn oxyhydroxide samples are extremely unradiogenic (εNd≈−15εNd≈−15); much lower than the εNdεNd for deep waters of modern or Oligocene–Miocene age from the North Atlantic (εNd≈−10εNd≈−10) and South Atlantic

Highlights: • High-precision glacial–interglacial 87Sr/86Sr record from planktic foraminifera. • Major oceans yield indistinguishable 87Sr/86Sr values at ±5 ppm level of precision. • Foraminifera show no resolvable 87Sr/86Sr variation since last glacial interval. • These data accommodate a ±12% variation for the steady-state weathering flux. • A short-term weathering pulse during de-glaciation is not accommodated by the data. Abstract Existing strontium radiogenic isotope (87Sr/86Sr) measurements for foraminifera over Quaternary glacial–interglacial climate cycles provide no evidence for variations in the isotope composition of seawater at the ±9–13 ppm level of precision. However, modelling suggests that even within this level of uncertainty significant (up to 30%) variations in chemical weathering of the continents are permitted, accounting for the longer-term rise in 87Sr/86Sr over the Quaternary, and the apparent imbalance of Sr in the oceans at the present-day. This study presents very high-precision 87Sr/86Sr isotope data for modern seawater from each of the major oceans, and a glacial–interglacial seawater record preserved by planktic foraminifera from Ocean Drilling Program (ODP) Site 758 in the north-east Indian ocean. Strontium isotope 87Sr/86Sr measurements for modern seawater from the Atlantic, Pacific and Indian Oceans are indistinguishable from one another (87Sr/86Sr = 0.7091792 ± 0.0000021, n=17n=17) at the level of precision obtained in this study (±4.9 ppm 2σ). This observation is consistent with the very long residence time of Sr in seawater, and underpins the utility of this element for high precision isotope stratigraphy. The 87Sr/86Sr seawater record preserved by planktic foraminifera shows no resolvable glacial–interglacial variation (87Sr/86Sr = 0.7091784 ± 0.0000035, n=10n=10), and limits the response of seawater to variations in the chemical weathering flux and/or composition to ±4.9 ppm or less. Calculations suggest that a variation of ±12%

To better understand the links between the carbon cycle and changes in past climate over tectonic timescales we need new geochemical proxy records of secular change in silicate weathering rates. A number of proxies are under development, but some of the most promising (e.g. palaeoseawater records of Li and Nd isotope change) can only be employed on such large samples of mono-specific foraminifera that application to the deep sea sediment core archive becomes highly problematic. “Dentoglobigerina” venezuelana presents a potentially attractive target for circumventing this problem because it is a typically large (> 355 μm diameter), abundant and cosmopolitan planktic foraminifer that ranges from the early Oligocene to early Pliocene. Yet considerable taxonomic and ecological uncertainties associated with this taxon must first be addressed. Here, we assess the taxonomy, palaeoecology, and ontogeny of “D.” venezuelana using stable isotope (oxygen and carbon) and Mg/Ca data measured in tests of late Oligocene to early Miocene age from Ocean Drilling Program (ODP) Site 925, on Ceara Rise, in the western equatorial Atlantic. To help constrain the depth habitat of “D.” venezuelana relative to other species we report the stable isotope composition of selected planktic foraminifera species within Globigerina, Globigerinoides, Paragloborotalia and Catapsydrax. We define three morphotypes of “D.” venezuelana based on the morphology of the final chamber and aperture architecture. We determine the trace element and stable isotope composition of each morphotype for different size fractions, to test the validity of pooling these morphotypes for the purposes of generating geochemical proxy datasets and to assess any ontogenetic variations in depth habitat. Our data indicate that “D.” venezuelana maintains a lower thermocline depth habitat at Ceara Rise between 24 and 21 Ma. Comparing our results to published datasets we conclude that this lower thermocline depth ecology for the Olig

Geochemistry provides useful research tools related to fundamental processes in Earth, Environmental and Planetary Sciences. It has a distinct identity among the academic communities in these subjects, yet there is no specific data on workforce diversity among geochemists. We present the first demographic data of UK geochemists from a voluntary anonymous survey. We scrutinise the data with respect to protected characteristics (e.g., age, ethnicity, gender identity, sexual orientation and disability) and seniority of those within the community. We furthermore use this UK data to compare the career progression of geochemists who belong to multiply-privileged identities with those who belong to multiply-disadvantaged identities, to assess their representations with increased seniority on the academic career. This UK based case study on diversity and inclusion suggests that the career paths of geochemists belonging to multiple disadvantaged groups are restricted, including overrepresentation among those on fixed-term contracts or in service roles for laboratory support. Our data highlight that there is a decrease in diversity with an increase in seniority; specifically, UK geochemists from sexual and gender minorities, neurodiverse, and women from ethnic minority groups were not represented among the participants of our survey at the top of the academic ladder. There are many reasons for the loss of diversity in the UK geochemistry community with increased seniority. In order to address this and the underrepresentation of particular groups in senior leadership roles, our findings suggest that the career progression of geochemists requires an intersectional lens to examine the complexity of identity data. Such an approach would enable a better understanding of the impact of multiple and compounded disadvantages, biases, negative experiences and discrimination faced by multiply-disadvantaged identities.

Geochemistry provides useful research tools related to fundamental processes in Earth, Environmental and Planetary Sciences. It has a distinct identity among the academic communities in these subjects, yet there is no specific data on workforce diversity among geochemists. We present the first demographic data of UK geochemists from a voluntary anonymous survey. We scrutinise the data with respect to protected characteristics (e.g., age, ethnicity, gender identity, sexual orientation and disability) and seniority of those within the community. We furthermore use this UK data to compare the career progression of geochemists who belong to multiply-privileged identities with those who belong to multiply-disadvantaged identities, to assess their representations with increased seniority on the academic career. This UK based case study on diversity and inclusion suggests that the career paths of geochemists belonging to multiple disadvantaged groups are restricted, including overrepresentation among those on fixed-term contracts or in service roles for laboratory support. Our data highlight that there is a decrease in diversity with an increase in seniority; specifically, UK geochemists from sexual and gender minorities, neurodiverse, and women from ethnic minority groups were not represented among the participants of our survey at the top of the academic ladder. There are many reasons for the loss of diversity in the UK geochemistry community with increased seniority. In order to address this and the underrepresentation of particular groups in senior leadership roles, our findings suggest that the career progression of geochemists requires an intersectional lens to examine the complexity of identity data. Such an approach would enable a better understanding of the impact of multiple and compounded disadvantages, biases, negative experiences and discrimination faced by multiply-disadvantaged identities.