The earth is warming up, and this is also noticeable in northern Germany. Sustainability researcher Dr Leena Karrasch reveals the effects of climate change in East Frisia in the second KinderUniversität lecture on 5 September - and here in an interview.
QUESTION: The whole of the north is suffering from heat and drought in the summer of 2018. Will we see more weather like this in the future?
ANSWER: As far as we know, such extreme weather periods will indeed occur more frequently due to climate change. But we must not neglect the difference between weather and climate.
QUESTION: What is the difference?
ANSWER: Weather refers to the current state of the atmosphere, for example rain, wind, sun, heat or cold. It is really what we perceive at the moment. When we talk about climate, on the other hand, we mean the average weather events over a long period of time. This is usually at least 30 years. If you want to find out whether the climate is changing, you have to look at it: What has changed in the last 30 years compared to the 30 years before that? So you can't necessarily speak of climate change for a single heatwave.
QUESTION: How do we know that the climate is actually warming?
ANSWER: Through long-term measurements. Such data shows, for example, that the average annual temperature in Germany rose by a total of 1.4 degrees Celsius between 1881 and 2013. The increase has been particularly strong in the last 30 years, with temperatures rising by 0.7 degrees Celsius in this period alone.
Droughts are becoming more frequent
QUESTION: What does this mean for our region? Will the climate continue to change in the future?
ANSWER: Longer periods of drought will probably occur more frequently in summer. Here in the low-lying areas, however, we will normally still have enough water available. However, farmers in southern Lower Saxony are already noticing the lack of water, with many having to irrigate in summer. This will certainly become even more acute in the future. For us here on the coast, however, water shortages will probably not be the most urgent problem.
QUESTION: But?
ANSWER: It will rain much more frequently in northern Germany, especially in autumn, winter and spring. We also have to expect more extreme rainfall events. This means that much more rain will fall within a short period of time. That will have the biggest impact on the region here.
QUESTION: What problems can we expect as a result?
ANSWER: If it rains more and more areas are built on at the same time, the water will run off faster and flooding may occur. Fields or even settlements are then simply under water because the ditches overflow. Another consequence of climate change is rising sea levels: in the 20th century, sea levels rose by an average of around 19 centimetres worldwide. A further rise of 30 to 100 centimetres is expected by the year 2100. Together, these two factors will make drainage in coastal areas difficult.
How does the water get into the sea?
QUESTION: What does that mean?
ANSWER: Normally, rainwater flows into the sea via streams and rivers. But if the sea level rises by 50 centimetres, for example, then it is not only raised at high tide, but always - even at low tide. In East Frisia, many areas are very low, sometimes even below sea level. The water from the drainage ditches therefore only flows into the sea of its own accord at low tide. In the future, rainwater may no longer flow naturally into the sea in some areas because the land is lower than the sea even at low tide. The system will no longer be able to drain the water as it should, especially when it rains heavily.
QUESTION: Is there anything that can be done about this?
ANSWER: One possibility is to pump the water out to sea - which is already happening. It may be necessary to expand the pumping stations that pump the water directly from the coast into the North Sea. However, we can also look at creating rainwater retention areas inland where the water can be temporarily stored. We investigated this, for example, in the COMTESS project, a large collaborative research project involving nine universities.
QUESTION: What was that about?
ANSWER: In our sub-project, we looked at whether the Freepsumer Meer in the municipality of Krummhörn north of Emden could be used to collect water when there is extreme rainfall. The Freepsumer Meer is the lowest point in Lower Saxony, lying around 2.50 metres below sea level. You can imagine it like a bathtub: if it rains too heavily, the water could simply flow into it and be stored temporarily.
QUESTION: What do local people think of the idea of submerging an agricultural area?
ANSWER: In the project, we worked together with the mayor, the Chamber of Agriculture, the lower nature conservation authority, the drainage association, the dyke associations and regional planning, among others. All interest groups sat around a table and were able to openly discuss whether the jointly developed plan was a possible solution for the future. The idea was largely well received: Water areas are interesting from a tourism perspective, for example, but also from a nature conservation perspective. Even farmers benefit if fewer fields are flooded. And in summer, they can use the water for irrigation. In the meantime, the Freepsumer Meer has been included as a potential water retention area in the regional spatial planning programme for the district of Aurich.
"We will not go under"
QUESTION: What about the safety of the dykes if the sea level rises?
ANSWER: We also asked ourselves this question in our project. Will there be more flooding and storm surges? Will the dykes have to be higher? It has turned out that way: In the project area between Emden and Norden, the dykes are already very well developed. Of course, there is no one hundred per cent safety in the event of higher storm surge levels. But it can be said that the dykes are quite safe and everything is being done to keep them that way. So we can cope with rising sea levels. We won't sink (laughs).
QUESTION: Are you personally more optimistic or pessimistic about whether we can adapt to climate change here in the region?
ANSWER: I am an optimistic person and I believe that it makes a difference if everyone makes a small contribution to climate protection. If we save energy, use renewable energies, perhaps cycle more often and not drive - if we consume a lot less CO₂ overall, then hopefully the greenhouse effect won't be so strong and there won't be so much warming.
QUESTION: So it's all half as bad?
ANSWER: No, I also take a critical view of many things: we always talk about saving energy and reducing CO₂ emissions from cars, for example. Ultimately, however, we all drive bigger cars, which then blow more CO₂ into the air. I believe that society as a whole needs to change. Consumer behaviour also needs to change.
Date note:
Advance ticket sales for the KinderUniversity has started! In August and September, the Audimax will once again open its doors on three afternoons for eight to twelve-year-olds. Leena Karrasch will be on Wednesday, 5 September, from 4.30 to 5.30 pm with the topic "Why East Frisia is a bathtub - and how we keep our feet dry".
Further dates:
29 August, 4.30 to 5.30 p.m.: Prof. Dr Dr Joachim Willems, "Christmas in summer"
19 September, 4.30 to 5.30 p.m.: Prof. Dr Michael Komorek, "What astronauts need to know"