In the future, people will above all feel climate change in the form of changes to their own homes. Accordingly, in the Climate Initiative REKLIM, experts from nine Helmholtz Centres and various universities are working to better understand the regional impacts of climate change. A further goal is to make the scientific expertise and advances directly available to societal actors and the general public. (Author: Tim Schröder)

It’s roughly 1 500 kilometres from Berlin to the Arctic Circle. That may seem like quite a distance, but the Arctic is actually closer to our own ‘doorstep‘ than e.g. Madrid. Given the dramatic changes in the High North, this is why especially we Central Europeans have to ask ourselves: how will climate change affect our home? That’s precisely the pressing question that scientists are investigating in the Helmholtz Climate Initiative REKLIM (Regional Climate Change), which involves experts from nine Helmholtz Centres and various universities.  “The best part about the initiative is that it brings together researchers from disciplines that normally don’t have the chance to work together,” says Dr Klaus Grosfeld, an AWI geo­physicist and Managing Director of ­REKLIM. REKLIM has a total of eight focus areas – including sea level changes and their effects on coastal regions, the composition of the atmosphere and its repercussions for the
climate, etc.

How quickly is the climate changing? The phenomena known as ‘abrupt climate changes‘ are particularly interesting. Klaus Grosfeld explains what the term means: “In the course of our planet’s history, there has always been climate change. Normally, it has been a very slow process that takes thousands of years. Yet scientific evidence also indicates that there have occasionally been phases in which the climate changed massively within only a few decades.”
That’s troubling news, since, thanks to anthropogenic climate change, the human race may start experiencing precisely these abrupt changes firsthand in the near future. “We believe there are certain points at which the climate system can suddenly switch to a new status,” relates Klaus Grosfeld.
Since no one can know the future, researchers instead look to the past. In the context of the REKLIM focus area ‘Abrupt Climate Change Derived from Proxy Data‘, they are now seeking to identify phases in the Earth’s history that were characterised by these tipping points. Their hope is that, by arriving at a better grasp of past events, they can better predict whether or not the climate change we’re
now experiencing will produce such points.
That’s a highly complex question and can only realistically be answered by pooling the expertise of researchers from different disciplines, which is what REKLIM does. In the ­search for abrupt climate changes in the past, marine sediments are an important factor: depending on the respective climatic conditions, different organisms live in the water. When they die, they sink and their physical remains become preserved in the sediment. By analysing these sediment layers, scientists can determine when certain organisms lived and what the prevailing climatic conditions must have been at the time.
The AWI geologist Prof Ralf Tiedemann is one of the experts capable of unlocking the sediments’ secrets and has specialised in marine sediments. As he explains, “One problem we now face is that we only have data from a few measuring points, which makes it hard to tell whether specific climate changes were global or only regional. For instance, we have data from the Atlantic and Pacific – but not from Central Europe.”
To remedy this dearth of information, in REKLIM he is collaborating with Prof Achim Brauer from the German Research Centre for Geosciences (GFZ) in Potsdam, who has been working with sediments in lakes for many years – e.g. at Lake Ammer and at several lakes in Italy. Working together, they are comparing their respective information on climate changes with the data that AWI glaciologists and experts from Heidelberg University have gleaned from millennia-old ice cores; after all, three sources are bound to offer more certainty than just one.

Collaboration yields new discoveries But REKLIM has much more to offer. Once new data is generated, it is also discussed with the AWI’s climate modellers, who use it to simulate the climate of the past. This approach has already yielded a number of interesting discoveries: in the phase before the last glacial period, for example, there were apparently warm periods that continued for several thousands of years, but then ‘tipped over‘ into extremely cold phases within just a few decades. In turn, these were followed by long cold phases that were rapidly replaced by warm ones, until the glacial period finally began, covering huge regions of the Northern Hemisphere in ice.
Further, comparing data from marine sediment, lake sediment and ice shows that
during these abrupt transitions, there were also significant changes in ocean currents and the atmosphere throughout the Northern Hemisphere. “Without REKLIM, we could never have arrived at these results,” claims Achim Brauer from the GFZ. “Thanks to the workshops, we have the chance to get to know other researchers and what they’re working on. Moreover, the initiative creates a sense of purpose that truly promotes collaboration; we have a concrete shared mission, which is a bit different than sharing a cup of coffee and talking about ‘maybe doing some work together someday.’”

Comprehensive approach to regional climate change In terms of its scope and collaboration between different disciplines, REKLIM covers an
enormous spectrum of topics. Two examples: in connection with the topic ‘Coupled Modelling of Regional Earth Systems‘, the researchers are working to develop new methods that will allow them to more accurately model the regional effects of global climate change. In turn, the experts working on the topic ‘Modelling and Understanding Extreme Meteorological Events‘ are exploring extreme weather events like hailstorms, which can produce insurance claims amounting to billions of euros – by harming or destroying solar parks, glass roofs, or agricultural crops. One of the key questions is how to adapt if these extreme events become more frequent. “In terms of the diverse range of regional climate aspects that the network addresses and combines, it’s unique in Europe,” says Klaus Grosfeld.

Sharing advances with the public

Further, investigating regional climate change is also – and especially – interesting because it directly concerns people’s day-to-day lives. Accordingly, one of REKLIM’s objectives is to share the latest advances with the public – e.g. through the project ‘klimafit (fit for the climate)‘, which was jointly launched by REKLIM, the WWF and the regional educational institutions fesa e.V. and ifpro in March 2017. According to Dr Renate Treffeisen, ­klimafit Coordinator at REKLIM and Head of the AWI’s Climate Office for Polar Regions and Sea Level Rise, “The project is intended to disseminate experts’ knowhow to multipliers ­–­ architects, farmers, urban planners, teachers, or municipal climate protection managers – through courses offered at community colleges.” In addition to fundamental information on climate change, the courses also offer suggestions on how people living in the respective region can adapt to it. “To date, this is the first project of its kind in Germany,” says Bettina Münch-Epple, Head of Education
at the WWF Germany. “The course draws heavily on the ‘blended learning’ concept. In other words, we not only work with instructors in the classroom, but also with climate experts who can contribute by video live-stream.” This direct communication between the participants and researchers make the course especially appealing. “klimafit” is currently being rolled out in six municipalities across southwest Germany, a region that is already feeling the effects of climate change. “In some regions of Baden-Württemberg, the average temperature has risen by more than 1.5 degrees,” says Bettina Münch-Epple. As she explains, this affects agriculture; further, the number of extremely hot days has increased, as has the frequency of storms and heavy rains. “Last year we tried out the course on a pilot basis in the city of Emmendingen, near Freiburg. The response was so overwhelmingly positive that we’re now confident of the project’s success,” stresses Renate Treffeisen. The goal for the next few years is to gradually establish the courses in further regions of Germany. “Essentially, we hope to create a snowball effect,” says Klaus Grosfeld, “so the topic of climate change reaches every corner of society. A welcome side-effect: this will show the researchers contributing to REKLIM just how important their work is.”