The climate research summit in Potsdam is 94 metres high. In Brandenburg, surrounded by flat river and lake landscapes with lots of pinewoods, that is a considerable height. Telegrafenberg, a hill on the outskirts of Brandenburg’s capital, is the location of the Albert Einstein Science Park. It was already an outstanding scientific site in the 19th century. Today three internationally renowned institutes devoted to researching the Earth and its atmosphere are based on the hill: Potsdam is one of the world’s most important centres of climate research. The Potsdam Research Unit of the Alfred Wegener Institute for Polar and Marine Research (AWI) concentrates on studying the Arctic land masses. The German Research Centre for Geosciences (GFZ) investigates the deep interior of “System Earth”. And the Potsdam Institute for Climate Impact Research (PIK) uses an interdisciplinary approach involving natural and social scientists to develop models for describing the consequences of climate change.
Scientists used to observe the heavens from the Telegrafenberg. Today it is a landscape garden crisscrossed by paths and full of beautiful brick buildings. Many of these buildings still have metal domes where the telescopes were once installed. Do the researchers appreciate the aura of this location? “I enjoy it every day,” says Hans-Wolfgang Hubberten. The head of the AWI Research Unit in Potsdam is one of the people who were here from the very start. Since 1992 he has been in charge of the unit that continues the tradition of GDR Arctic and Antarctic research. Hubberten works in the field of periglacial dynamics and is therefore at the very heart of climate research. One phenomenon has become particularly well-known: thawing permafrost is releasing methane, a dangerous greenhouse gas. Is it possible to estimate how much methane will escape from melting permafrost in the future?
Professor Hubberten explains this complex process. Although many questions still remain open, he concludes with the assumption that increasingly deeper thawing of the permafrost is also strengthening the greenhouse effect. Almost incidentally, the meeting also revealed something that becomes a recurring theme in encounters on Telegrafenberg: man-made processes and geological phenomena, although already complex enough in their own right, must be understood in terms of their even more complex interactions. Eons of geology and 200 years of industrialization are the very different time scales under examination. Looking into the future, however, the deadlines left for us to act are becoming even shorter. That is the view of the PIK scientists who develop simulations of coming decades on the basis of what we know today. In that sense it is rather fortunate that we are only able to meet Malte Meinshausen for a short discussion. The pace of work at PIK has speeded up somewhat, because the conference in Copenhagen in December is already fast approaching. Meinshausen is the lead author of a study that was recently published in Nature, the result of a three-year project by scientists from Germany, Great Britain and Switzerland. Its central question: What needs to be done to achieve the target, agreed by more than 100 countries, of not allowing the average global temperature to increase by more than two degrees Celsius? The answer: We can only permit emissions of one thousand billion tonnes of carbon dioxide between the years 2000 and 2050. However, one third of this amount has already been released into the atmosphere in the last nine years. It’s no wonder that Meinshausen expectantly awaits the negotiations in Copenhagen. PIK produces its models and scenarios in complicated calculations that can only be achieved using computers. Some 1,000 chronological emissions reduction simulations were run for the latest study.
Hans Joachim Schellnhuber, PIK director, also advises the Federal Government and want to help “avoid the uncontrollable and control the unavoidable”. This formula also relates to the two-degree target, since crossing this threshold is likely to trigger insidious processes whose effects are practically unforeseeable. PIK has identified 16 potential anthropogenic tipping points in the Earth’s climate system (see page 24). Schellnhuber’s colleague Stefan Rahmstorf is co-author of the United Nations World Climate Report that attracted a great deal of attention in 2007. He is certain that the greatest dangers lie in extreme events: heat waves, droughts, flooding and storm tides as a result of rising sea levels. Climate change will also affect Germany: Climreg is the name of the PIK project that will appraise the climate impacts on the country. Meteorologist Peter C. Werner, one of the 23 members of the project, describes in an understandable way how the vegetation period is now two weeks longer than in the first half of the last century and apple trees blossom one week earlier.
On your way back from PIK you pass the magnetic observatory dating from 1888. Today this building is used by the German Research Centre for Geosciences (GFZ). The GFZ became well-known for developing the tsunami early warning system for Asia in which scientist Jörn Lauterjung played a major part. Since 1995 the GFZ has been studying the Earth’s gravitational field with the aid of satellites and has supplied precise data used in climate modelling. In collaboration with US colleagues, GFZ scientists have just simulated the interplay between solar radiation, the atmosphere and the ocean. Reinhard Hüttl, GFZ executive director, believes the study demonstrates just how important it is to fully “understand the underlying natural climate changes” to gain a better understanding of the climate changes caused by human activity. The causes of the former have by no means been adequately researched.
Klaus Dethloff, head of the atmospheric research group at AWI Potsdam, wants to make climate modelling more precise. He is working on models for the polar regions, which play a key role for climate researchers, but continue to remain “data-poor regions”. Dethloff assembles climate model systems that combine the physical processes in the ocean, atmosphere and ice masses to form a climate description. He received new and interesting data from meteorological technician Jürgen Graeser, who was the first foreign researcher to take part in a seven-month drift expedition with colleagues from St. Petersburg. This adventure involved drifting 850 kilometres across the Arctic Ocean on an ice floe. Graeser completed an extensive measuring programme at temperatures of up to minus 40 degrees Celsius. It was the first time the winter atmosphere over the central Arctic was documented in such a complete fashion. Series of measurements like these are precisely what Klaus Dethloff needs for his work.
Potsdam will soon grow even larger as a centre of climate research: IASS, the Institute for Advanced Studies in Climate, Earth System and Sustainability, will commence work this autumn. Initiator and founding director is Klaus Töpfer, former federal environment minister and executive director of the United Nations Environment Programme (UNEP). Töpfer wants the IASS to focus on “linking scientific research and decision-making processes within politics and society”. Reinhart Hüttl and Hans Joachim Schellnhuber are also involved in the new project. Klaus Töpfer aims to bring top international scientists to Potsdam: 25 colleagues will be employed at the IASS and an additional 25 visiting scientists will work on their research projects with the Potsdam-based colleagues for periods of two years.
The walk down from the Potsdam climate research summit gives you time to think. The Earth that you had in your head has changed after all these discussions with scientists: it has become more unstable, unpredictable, full of currents and movements, icing up and thawing, radiated by the sun, drilled full of holes by researchers, populated by more and more human beings. An impressive, but vulnerable globe.
