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.

Attributing the impacts of land-cover changes in temperate regions on surface temperature and heat fluxes to specific causes: Results from the first LUCID set of simulations

Abstract: [1] Surface cooling in temperate regions is a common biogeophysical response to historical Land-Use induced Land Cover Change (LULCC). The climate models involved in LUCID show, however, significant differences in the magnitude and the seasonal partitioning of the temperature change. The LULCC-induced cooling is directed by decreases in absorbed solar radiation, but its amplitude is 30 to 50% smaller than the one that would be expected from the sole radiative changes. This results from direct impacts on the total turbulent energy flux (related to changes in land-cover properties other than albedo, such as evapotranspiration efficiency or surface roughness) that decreases at all seasons, and thereby induces a relative warming in all models. The magnitude of those processes varies significantly from model to model, resulting on different climate responses to LULCC. To address this uncertainty, we analyzed the LULCC impacts on surface albedo, latent heat and total turbulent energy flux, using a multivariate statistical analysis to mimic the models' responses. The differences are explained by two major ‘features’ varying from one model to another: the land-cover distribution and the simulated sensitivity to LULCC. The latter explains more than half of the inter-model spread and resides in how the land-surface functioning is parameterized, in particular regarding the evapotranspiration partitioning within the different land-cover types, as well as the role of leaf area index in the flux calculations. This uncertainty has to be narrowed through a more rigorous evaluation of our land-surface models.

The nature of millennial-scale climate variability during the past two glacial periods.

Abstract: Periodic iceberg discharges during the last glacial period led to a slowdown of the Atlantic meridional overturning circulation Sediment records from the Portuguese margin show that similar events punctuated the penultimate glacial period as well, although their duration and broader climatic impacts were modified by different background climate conditions During the last glacial period, iceberg discharges into the North Atlantic disrupted the meridional overturning circulation, leading to cooling in the Northern Hemisphere and warming in Antarctica1,2 This asymmetric response can be explained by a bipolar see-saw mechanism3,4,5, whereby changes in the strength of the meridional overturning circulation lead to changes in the interhemispheric heat transport It is unclear, however, to what extent the response of the overturning circulation is a function of freshwater flux and boundary climate conditions4 Here we use foraminiferal isotope and pollen records from the Portuguese margin to reconstruct surface- and deep-water hydrography and atmospheric changes during the last and penultimate glacial periods When we compare our records with temperature reconstructions from Antarctica6, we find that the bipolar see-saw was a characteristic feature of both glacial periods However, the comparison also underlines the dependence of the bipolar see-saw on background climate and magnitude of iceberg discharge It also suggests that an intensified hydrological cycle may lead to a weaker overturning circulation with a smaller disruption threshold and extended North Atlantic stadial durations

Modeling thermoelectric power generation in view of climate change

Abstract: In this study we investigate how thermal power plants with once-through cooling could be affected by future climate change impacts on river water temperatures and stream flow. We introduce a model of a steam turbine power plant with once-through cooling at a river site and simulate how its production could be constrained in scenarios ranging from a one degree to a five degree increase of river temperature and a 10–50% decrease of stream flow. We apply the model to simulate a large nuclear power plant in Central Europe. We calculate annual average load reductions, which can be up to 11.8%, assuming unchanged stream flow, which leads to average annual income losses of up to 80 million €. Considering simultaneous changes in stream flow will exacerbate the problem and may increase average annual costs to 111 million € in a worst-case scenario. The model demonstrates that power generation could be severely constrained by typical climate impacts, such as increasing river temperatures and decreasing stream flow.