While preparing for the famous Rio environment summit in 1992 (the United Nations Conference on Environment and Development), the then German science minister Heinz Riesenhuber noted a worldwide lack of research on the possible consequences of anthropogenic climate change. To help remedy this deficit, the Potsdam Institute for Climate Impact Research (PIK) was founded that same year. Starting with a handful of researchers, PIK has since grown to almost 150 employees.

“...PIK’s goal is to advance a flourishing knowledge enterprise that provides both in-depth analyses as well as adequate strategic solutions in the context of climate change and its impacts.” Photo: Hans Bach, Copyright: PIK

After 14 years of work, PIK has established a sound reputation around the world as one of the leading institutions in the field of global change research, and the interdisciplinary approach pioneered at PIK has been adopted by several institutions in other countries. The institute is now at the transition point from "laying the foundations" to "building on them." Today, PIK’s goal is to advance a flourishing knowledge enterprise that provides both in-depth analyses as well as adequate strategic solutions in the context of climate change and its impacts.

We feel that bringing together excellent researchers from widely differing fields (e.g., physics, ecology, economics, and political science, to name just a few) to work on an important, common issue has created an exciting brew: a stimulating, creative working atmosphere at PIK. PIK scientists are generally encouraged to break new ground and move beyond the traditional disciplinary boundaries. One of our goals is "agenda setting," rather than just following a well-established research agenda.

Our mission can be summarized as follows:

• The Institute addresses crucial scientific questions in the fields of global change, climate impacts, and sustainable development.
• Researchers from the natural and social sciences work jointly to generate interdisciplinary insights and to provide society with sound information for decision making.
• The main methodologies are systems and scenarios analysis, modeling, computer simulation, and data integration.

The research areas are very diverse, including, e.g., Earth system analysis (where we have gathered a reputation, for example, in understanding the mechanisms of natural climate changes in Earth’s history), or the study of climate impacts on regions and economic sectors.

From a societal or policymaking point of view, a key research area is "Sustainable Solutions." This research domain’s objective is to derive mitigation and adaptation strategies for a post-Kyoto climate policy architecture.

The land biosphere constantly exchanges a massive amount of carbon with the atmosphere and thereby has a very significant influence on climate; however, to measure this effect directly is completely impossible, since it involves every single living organism on the planet. Over the years, many different methods have been proposed to "bracket" the net flux. For this particular paper, a broad community of authors had been brought together by Schimel and colleagues in order to produce an update just in time for the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). As such it represented the state of the art of the time and ended up being widely cited.

Our Potsdam contribution to the work came from a very large investment into the comparison of simulation model results made by about 17 major research groups worldwide. Starting in 1994 under the auspices of the International Geosphere-Biosphere Programme, Potsdam turned to be the effective "world center" for such comparisons, and it was frequently assumed that the sum of model results assembled here could yield some kind of "agreed number" for the carbon flux estimates. In our view this was a somewhat unfortunate development since the real scientific value of the intercomparisons was much more its capacity to highlight disagreements between models, often leading to the identification of flaws in them which could be improved later on.

It should be noted that, despite the continuing high citations, the Schimel et al. paper was only a step along the way. Its quantitative estimates are now superseded by further improvements of the assessment, and this process must definitely continue.

There are quite a few papers, including (ordered by date):

S. Rahmstorf, "A semi-empirical approach to projecting future sea-level rise," Science 315(5810): 368-70, 14 Dec. 2006

The study suggests that sea level may be rising faster in the coming decades than previously expected. Based on observational data for the 20th century, Rahmstorf found a close link between the amount of global warming and the rate of sea-level change: the warmer it gets, the faster sea levels rise. The analysis was motivated by the fact that computer models of climate significantly underestimate the sea-level rise that has already occurred.

Edenhofer, O., Lessmann, K., Kemfert, C., Grubb M., Koehler J., "Technological change: exploring its implication for the economics of atmospheric stabilisation," The Energy Journal Special Issue, Endogenous Technological Change and the Economics of Atmospheric Stabilization, 57-107, 2006

The study of Ottmar Edenhofer's team of researchers was quoted and endorsed by the British Stern Review, published in September 2006, affirming that the economic costs of climate protection would decrease through a proactive climate policy geared towards stimulating technological change. The costs of achieving the 2°C climate target adopted by the European Union and some other countries is just 1% of global GDP—equivalent to no more than a three-month delay to economic growth by the year 2030.

Zickfeld, K., B. Knopf, V. Petoukhov, and H. J. Schellnhuber, "Is the Indian summer monsoon stable against global change?" Geophysical Research Letters, 32: L15707, 2005

Zickfeld et al. discovered a mechanism which could lead to a failure of the Indian summer monsoon: increasing air pollution with airborne particles ("aerosols") over India—caused by fires and the consumption of fossil fuels—as well as forest clearance, could lead to a regional increase of the Earth's brightness ("planetary albedo").

Lucht, W., I.C. Prentice, R.B. Myneni, S. Sitch, P. Friedlingstein, W. Cramer, P. Bousquet, W. Buermann, and B. Smith, "Climatic control of the high-latitude vegetation greening trend and Pinatubo effect," Science 296, 1687-1689, 2002

Satellite measurements have shown that the length of the growing season of high-latitude forests has been increasing over the past 20 years. Lucht et al. employed a dynamic vegetation model and found that the main cause was the temperature increase during that period. Also, with that model the decrease in vegetation that accompanied the cooling produced by the 1991 volcanic eruption of Mt. Pinatubo could be simulated.

Our work on better quantification of global biospheric carbon fluxes has been most substantially improved when actual observations began to be integrated. The Lucht et al. 2002 paper in Science demonstrates this very nicely on the basis of satellite observations which could be tracked by the simulation model in remarkable detail.

Ganopolski, A. and S. Rahmstorf, "Simulation of rapid glacial climate changes in a coupled climate model," Nature, 409: 153-158, 2001

This paper proposed a theoretical explanation for some of the most abrupt and dramatic climate shifts of Earth’s history, the Dansgaard-Oeschger events that repeatedly occurred during the last Ice Age. Understanding such abrupt climate shifts of the past is a prerequisite for understanding possible "tipping points" of the climate system as we move into a greenhouse world.

Cramer W, Kicklighter DW, Bondeau A, Moore B III, Churkina G, Nemry B, Ruimy A, Schloss AL & Participants of "Potsdam'95," "Comparing global models of terrestrial net primary productivity (NPP): Overview and key results," Gl Ch Biol 5 (Suppl.1):1-15, 1999

Cramer W, Bondeau A, Woodward FI, Prentice IC, Betts RA, Brovkin V, Cox PM, Fisher V, Foley J, Friend AD, Kucharik C, Lomas MR, Ramankutty N, Sitch S, Smith B, White A & Young-Molling C, "Global response of terrestrial ecosystem structure and function to CO2 and climate change: results from six dynamic global vegetation models," Gl Ch Biol 7(4):357-373, 2001

These two publications built the foundation for the Schimel et al. Nature paper of 2001 and appeared in Global Change Biology. In our view this high-impact journal clearly qualifies as "geosciences" as well and might well usefully be included in this analysis—our papers are amongst the most-cited papers there (the 2001 paper being the third most-cited paper in GCB ever, with 260 citations).

It is part of PIK’s overall mission to provide society with sound information for decision making. Therefore, we are of course happy that the kind of knowledge we have been working on for the past 14 years is now in high demand, both from the policy side (where PIK’s director John Schellnhuber was appointed as direct advisor on climate issues to the German chancellor Angela Merkel in the lead-up to the June G8 summit) and from the private sector (where many leading corporations seek advice from PIK scientists). The current upsurge in interest from outside creates a huge amount of work, though, so a number of our scientists are really stretched to their physical limits and are looking forward to a bit quieter times!

For the future we are working on an even stronger integration of the different disciplines—in fact we are now completely getting rid of disciplinary departments within the Institute. We are orienting our work along a direct axis from understanding the physical and ecological properties of the climate system, via analysis of impacts of climate change, straight to solutions of the problem.

We hope to be a node in an ever-growing network of institutions providing the scientific underpinning of a global sustainability transition—creating the knowledge base for world society that it needs to develop a sustainable economic basis for the future.

Professor Stefan Rahmstorf
Potsdam Institute for Climate Change Research
Potsdam, Germany