Project

Discipline

polar ice cores; climate dynamics and modelling; paleoclimate; groundwater; stable isotopes in the environment; water cycle; greenhouse gases; radionuclides

Lead
Forschung in Klima- und Umweltphysik umfasst Beobachtungen, theoretische Modellbildung, und Modellsimulationen. Mit diesen Mitteln, die in diesem Projekt weiterentwickelt werden, wird das Verständnis der Klimaentwicklung der vergangenen 1'000'000 Jahre vertieft. Damit werden Abschätzungen künftiger Klimaänderungen, verursacht durch den vom Menschen verursachten Anstieg der Treihausgaskonzentrationen verbessert.
Lay summary
Klimaforschung ist von unmittelbarer gesellschaftlicher Bedeutung, da die Reaktionen des Erd-Systems auf die veränderte Zusammensetzung der Atmosphäre, besonders die Treibhausgase, verstanden werden müssen. Umfassende Klimaforschung ruht auf drei Pfeilern: Beobachtungen, theoretisches Verständnis durch Modellbildung, und Modellsimulationen. In diesem kollaborativen Projekt kombinieren wir die drei Pfeiler, indem vergangene Klimaänderungen der letzten 800'000 Jahre rekonstruiert, Modelle entwickelt, und umfassende Simulationen ausgeführt werden. Im ersten Pfeiler bauen wir hoch-präzise analytische Methoden um Gaskonzentrationen, Isotopenverhältnisse und chemische Stoffe in polaren Eisbohrkernen zu messen. Von besonderem Interesse sind abrupte Klimaschwankungen, die in Messungen hoher zeitliche Auslösung gefunden werden, sowie die Abschätzung ihrer Auswirkungen und räumlichen Verteilung im Klimasystem. Daneben werden in diesem Projekt auch sehr geringe Konzentrationen natürlicher Radionuklide gemessen, um die Speicherung und Erneuerung von verschiedenen Grundwasserträgern weltweit zu quantifizieren. Wir verwenden eine Hierarchie von Klimamodellen, die von Prozessmodellen, über Modelle reduzierter Komplexität, bis zu vollständigen Erd-System Modellen reicht. Der zweite Pfeiler der Forschung besteht aus der Entwicklung dieser Modelle und Elemente, die einzelne Klimasystemkomponenten darstellen. Schliesslich werden diese im dritten Pfeiler verwendet, um verschiedene Klimagrössen direkt zu simulieren. Mit denselben Modellen werden Auswirkungen von Klimaszenarien berechnet, um wahrscheinlichkeitsbasierte Abschätzungen globaler Veränderungen des Klimasystems zu erreichen.

Direct link to Lay Summary

Last update: 30.03.2015

Lead
Comprehensive climate and environmental research carried out in this project combines observations, theoretical understanding through model development, and model simulations. With this tool box, which combines high-precision analytical methods with model simulations, both further developed in this project, we aim to improve the understanding of the climate evolution of the past 1,000,000 years and the estimate of the response of the Earth System to the increase of anthropogenic greenhouse gases.
Lay summary
Climate research is of immediate relevance to society because we need to understand how the complex Earth System reacts to human-caused changes in the composition of the atmosphere, in particular greenhouse gases. Comprehensive climate research rests on three pillars: Observation, theoretical understanding and model development, and climate model simulations. In a large collaborative effort we combine the three pillars. For the first pillar, we develop and apply high-precision methods to measure concentrations of gases and their isotopes, and chemical substances on polar ice cores. We focus on abrupt climate change found in high-resolution records, their effects on the various components of the climate system, and their regional expression. In addition we measure very low concentrations of some unique radio-isotopes to estimate groundwater storage and renewal in reservoirs around the world. An essential element is the development of climate models including biogeochemical components which are tested by modern observations. We employ a hierarchy of climate models ranging from process models, models of reduced complexity, to comprehensive climate models. Model development and testing constitutes the second pillar of this project. The third pillar is extensive model simulations of many paleoclimatic variables and a direct comparison of the results with the paleoclimatic records. In many cases we aim at simulating changes in the past which have not yet been measured in paleoclimatic archives. This involves simulations over complete ice age cycles, in particular before 800,000 years before the present. These same models are then used to project, in a probabilistic framework, anthropogenic climate change with the goal to learn more about the global responses and sensitivity of the climate system to this unprecedented perturbation.

Direct link to Lay Summary

Last update: 30.03.2015

Title	Year

Number	Title	Start	Funding scheme

Earth System models, ranging from reduced-complexity to comprehensive, are developed and used to address questions of past and future climate change. Reduced-complexity models are coupled to dynamical carbon cycle modules, water mass tracers for paleoceanographic studies, and a dynamic vegetation model with peat and wetland processes for CH4 and N2O budgets. For the comprehensive model we will complete the development of a carbon isotope module for the land processes. In the coming funding period we will employ these models to investigate new paleoceanographic tracers (9Be, 10Be) and perform joint simulations with the entire water mass tracers over glacial-interglacial cycles before and after the Mid-Pleistocene Revolution, and through a series abrupt climate events typical of the last ice age. Simulations will include the noble gas tracers in the ocean and the results will be applied to emerging new ice core data from our division for whole-ocean temperature reconstructions. Fully coupled climate-carbon cycle model experiments address the question of climate-carbon sensitivity and transient carbon budgets in peat and wetland areas. They will also provide the basis for consistent interpretation of novel isotopic data from polar ice cores. Comprehensive models will also be used to investigate atmospheric dynamics and their role during the past millennium for specific climate periods. Finally, we will perform ensemble simulations for future climate change to investigate mitigation delay sensitivities of the climate system.Reconstructing past climate change will be based primarily on comprehensive measurements of greenhouse gas concentrations and air components, including most of their stable isotopes, and the palette of high-resolution chemical compounds in ice cores from Greenland and Antarctica. Interpretations of these measurements will be facilitated, where possible, with dedicated climate-carbon cycle models to constrain the history of exchange fluxes of carbon. In the coming two years we will close the low-resolution gap in CO2 measurements between 150 and 450,000 years. ?13CO2 measurements will focus on one entire glacial cycle and on milder interglacials before 450,000 years before present. The continuous flow analyses (CFA) will be used to unravel past atmospheric dynamics and modes of variability on the Greenland and Antarctic ice sheets. The focus will lie on a high-resolution comparison of Eemian and Holocene records to gain further insight into the characteristic differences of these warm phases. This study will be enabled by simulations using a comprehensive climate model. A deep ice core drilling in the Neumayer Hinterland, Antarctica, is projected for the austral season 2015/16 in a German-Swiss cooperation. If successful we will obtain new ice which will provide unique access to Holocene greenhouse gas concentrations and Antarctic climate variability in high resolution.Isotope analyses is a state-of-the-art tool in environmental physics. They provide independent constraints of fluxes, permit the estimate of reservoir sizes, and the determination of age or renewal times of constituents. We utilize our unique palette of natural radio-nuclides (14C, 81Kr, 85Kr, 37Ar, 39Ar) to date groundwaters and to estimate underground production, both natural and anthropogenic. In the coming two years we will investigate the contamination of aquifers by the industrial use of salt on roads during winter time and the dynamics of arsenic pollution. Such studies require a reliable dating of the aquifer which is enabled by our radionuclide concentrations. Very old waters are dated using 81Kr, which requires a complex purification step prior to atom trap trace analysis. The very old waters also contain climate information through concentrations of noble gases. In the coming two years we strengthen the new collaborations with the ice core community to date very old ice from blue ice zones in Antarctica.Innovation of the experimental infrastructure will be continued. For the CFA device we are developing a new dust size sensor. This important quantity provides a wealth of information regarding atmospheric flow, precipitation origin and deposition history. Dust concentration and size will be determined by the classical Coulter Counter principle adjusted to the specific CFA setup. In the next two years we will complete our new ice drilling equipment for field testing in Greenland. The goal is to drill within a few days a thin hole down to bedrock using a small-diameter hydro-powered drill. Such a hole will provide rapid access to temperature and dust profile measurements and recovery of deep ice samples to aid site selection in the "Oldest Ice" project.