Potsdam Institute for Climate Impact Research

About: Potsdam Institute for Climate Impact Research is a facility organization based out in Potsdam, Germany. It is known for research contribution in the topics: Climate change & Global warming. The organization has 1519 authors who have published 5098 publications receiving 367023 citations.

Terrestrial vegetation redistribution and carbon balance under climate change

Abstract: Dynamic Global Vegetation Models (DGVMs) compute the terrestrial carbon balance as well as the transient spatial distribution of vegetation. We study two scenarios of moderate and strong climate change (2.9 K and 5.3 K temperature increase over present) to investigate the spatial redistribution of major vegetation types and their carbon balance in the year 2100. The world's land vegetation will be more deciduous than at present, and contain about 125 billion tons of additional carbon. While a recession of the boreal forest is simulated in some areas, along with a general expansion to the north, we do not observe a reported collapse of the central Amazonian rain forest. Rather, a decrease of biomass and a change of vegetation type occurs in its northeastern part. The ability of the terrestrial biosphere to sequester carbon from the atmosphere declines strongly in the second half of the 21st century. Climate change will cause widespread shifts in the distribution of major vegetation functional types on all continents by the year 2100.

On multiple solutions of the atmosphere–vegetation system in present‐day climate

Abstract: An asynchronously coupled global atmosphere–biome model is used to assess the stability of the atmosphere–vegetation system under present-day conditions of solar irradiation and sea-surface temperatures. When initialized with different land-surface conditions (1, the continents, except for regions of inland ice, completely covered with forest; 2, with grassland; 3, with (dark) desert; and 4, with (bright) sand desert), the atmosphere–biome model finds two equilibrium solutions: the first solution yields the present-day distribution of subtropical deserts, the second reveals a moister climate in North Africa and Central East Asia and thereby a northward shift of vegetation particularly in the south-western Sahara. The first solution is obtained with initial condition 4, and the second with 1, 2, 3. When comparing these results with an earlier study of biogeophysical feedback in the African and Asian monsoon area, it can be concluded that North Africa is probably the region on Earth which is most sensitive considering bifurcations of the atmosphere–vegetation system at the global scale.

Quantifying the Strength and Delay of Climatic Interactions: The Ambiguities of Cross Correlation and a Novel Measure Based on Graphical Models

Abstract: Lagged cross-correlation and regression analysis are commonly used to gain insights into interaction mechanisms between climatological processes, in particular to assess time delays and to quantify the strength of a mechanism. Exemplified on temperature anomalies in Europe and the tropical Pacific and Atlantic, the authors study lagged correlation and regressions analytically for a simple model system. A strong dependence on the influence of serial dependencies or autocorrelation is demonstrated, which can lead to misleading conclusions about time delays and also obscures a quantification of the interaction mechanism. To overcome these possible artifacts, the authors propose a two-step procedure based on the concept of graphical models recently introduced to climate research. In the first step, graphical models are used to detect the existence of (Granger) causal interactions that determine the time delays of a mechanism. In the second step, a certain partial correlation and a regression measure are introduced that allow one to specifically quantify the strength of an interaction mechanism in a well interpretable way that enables the exclusion of misleadingeffects of serial correlation as well as more generaldependencies. The potential of the approachto quantify interactions between two and more processes is demonstrated by investigating teleconnections of ENSO and the mechanism of the Walker circulation. The article is intended to serve as a guideline to interpret lagged correlations and regressions in the presence of autocorrelation and introduces a powerful approach to analyze time delays and the strength of an interaction mechanism.