Search

Climate change yields both challenges and opportunities. In both cases, costly adaptations and transformations are necessary and desirable, and these must be based on realistic and relevant climate information. However, it is often difficult for climate scientists to communicate this information to decision-makers and stakeholders, and it can be equally difficult for such actors to interpret and put the information to use. In this essay, we discuss experiences and present recommendations for scientists producing climate services. The basis is our work in several climate service projects. One of them aimed to provide local-scale climate data for municipalities in western Norway and to explore how the data were interpreted and implemented. The project was first based solely on climate science expertise, and the participants did not have sufficient competence on coproduction and knowledge about the regulatory and political landscape in which municipalities operate. Initially, we also subscribed to an outdated idea of climate services, where knowledge providers (climate scientists) "deliver" their information to knowledge users (e.g., municipal planners). Increasingly, as stressed in the literature on coproduction of knowledge, we learned that climate service should be an iterative process where actionable information is coproduced through two-way dialogue. On the basis of these and other lessons learned the hard way, we provide a set of concrete recommendations on how to embed the idea of coproduction from the preproposal stage to beyond the end of climate service projects. [ABSTRACT FROM AUTHOR]

The article reflects on anthropogenically induced climate change has created intriguing scientific problems pertaining to the seas and the oceans on earth that can be monitored, analysed, modelled and understood. The land-based perspective is rewarding and is also limiting in its lack of three-dimensionality as the vastness of the seas and the oceans is so much more than the surface they observe from a distance.

ABSTRACT Observational data show that climate in the Southern Ocean region is rapidly changing. However, past the instrumental period, our understanding of climate variability in the region is limited by a scarcity of high-resolution palaeoclimate records. Alpine glaciers, present on many Southern Ocean islands, may provide such data because changes in their mass balance, extent and erosion rates often mark a response to climate shifts. Rock flour, the fine-grained fraction of the glacial erosion process, is suspended in meltwater streams and transferred into the sediments of downstream lakes, continuously recording glacier variations. Here, we utilize this relationship to present a reconstruction of the Late Holocene glacier history of subantarctic South Georgia, using sediments from the glacier-fed Middle Hamberg Lake. To fingerprint a glacial erosion/size signal, we used titanium counts, validated against changes in sediment density and grain size, allowing a continuous reconstruction of glacier variations over the past ∼1250 years. Together with local moraine evidence and supporting evidence from other Southern Hemisphere glaciers on New Zealand and in Patagonia, our findings reveal a series of consecutively diminishing Late Holocene advances. In addition to a glacier maximum before 1250 cal a BP, these include a two-stage Litle Ice Age with advances around 300 and 120 cal a BP, in line with evidence from southern Patagonia. In addition, we present evidence for an unreported retreat behind present limits around 500 cal BP. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In explaining the rapid transitions associated with the Younger Dryas cooling, a reduced meridional overturning circulation has traditionally been invoked, but such a scenario has been difficult to reproduce in model studies without adding excessive amounts of freshwater to the North Atlantic. More recent studies challenge this view and indicate that the role of an extensive sea ice cover may have been as important in promoting abrupt climate change as reorganisations of the North Atlantic Ocean [Gildor, H., Tziperman, E., 2003. Sea-ice switches and abrupt climate change. Philosophical Transactions Of The Royal Society Of London Series A—Mathematical Physical And Engineering Sciences 361, 1935–1942]. Based on glacier evidence from eastern Greenland [Denton, G.H., Alley, R.B., Comer, G.C., Broecker, W.S., 2005. The role of seasonality in abrupt climate change. Quaternary Science Reviews 24, 1159–1182] suggest that the seasonal temperature amplitude increased by about 20°C during the Younger Dryas. Such a ‘switching of seasonality’ lends support to the idea of a fast-expanding sea ice cover, because it allows for extremely cold winters that are balanced by relatively mild summers. However, climatic interpretations based on the geometry and length of glaciers under such conditions as in Scoresby Sund is not well understood, and equilibrium-line-altitude (ELA) estimates should, therefore, be regarded as tentative. Here, we discuss the absolute seasonal amplitude during the Younger Dryas by taking winter precipitation into account and show that the changes in seasonality may have been limited to 10°C. We propose that by reducing the seasonal response in Greenland compared with western Europe we better understand the hinged-door modus operandi [COHMAP, 1988. Climatic changes of the last 18,000 years: observations and model simulations. Science 241, 1043–1052] of the polar front and sea-ice cover, where the absolute southward migration of sea-ice is highest in the East Atlantic region. [Copyright &y& Elsevier]

Abstract: In an effort to improve the understanding of floods and how they relate to climate we have developed a method that objectively identifies the sedimentary imprint of individual river floods in downstream lake basins. The method is applied to a high-resolution lake sediment core retrieved from Southern Norway, resulting in a detailed record of Holocene river-flood activity covering the last 10,000 years, including floods also recorded by instrumental and historical data. The minimum number of individual floods recorded for this period is ∼100. On multidecadal to centennial timescales significant change in flood frequency is observed that arguably can be attributed to large-scale climatic changes such as the varying amount of winter precipitation and summer rainstorms. Flood frequency was low during the early Holocene (9770–7700 cal yr BP), and even lower for the period that followed, lasting until 5500 cal yr BP. For the next 2500 years, a modest increase in flood activity followed. This trend was truncated 2500 cal yr BP by a sudden shift towards increased flooding frequency. With the exception of a short interval around 1000 cal yr BP, when the number of floods again was low, this tendency of increased flood activity prevailed until present; including “Stor-Ofsen”, a large flood that occurred in AD 1789, and also three other historically documented river floods. [ABSTRACT FROM AUTHOR]