Stefan Rahmstorf: “Austria is heading towards 5 to 6 degrees warming”
Is it right that even if the whole world stopped emitting greenhouse gases tomorrow, would the earth continue to warm for a while?
No, that is not exactly the state of the art; we have two opposing effects. On the one hand, there is thermal inertia, which means it takes a while for the ocean water to warm up. If you heat a pot of water, it will take time for the water to get hot. On the other hand, there is also the fact that if we stop emitting CO2, the concentration in the air will drop for a few more decades because the oceans have a lag not only in terms of heat absorption, but also in terms of CO2 absorption. And according to the latest model simulations, this will be about the same, so that at the point where we have reached zero emissions, the temperatures will probably not rise any further.
The problem is the CO2 that’s in the atmosphere. Are there actually any ideas and possibilities to get this CO2 out and down again?
Yes, there are different options. What many of these IPCC scenarios also include is bioenergy with CCS. Plants absorb CO2 during photosynthesis and if you use them as bioenergy, e.g. wood in a power plant or biogas, then you can theoretically capture the CO2 in the chimney and generate so-called negative emissions with carbon capture and storage. However, it is very questionable whether we have enough land to bind large amounts of CO2 in this way.
The second option is technical, a pilot plant has now gone into operation in Iceland. There, CO2 is technically withdrawn from the atmosphere and then into the Underground rocks pressed where it is chemically combined and petrified and should be stored stable for millions of years. That is theoretically possible. It’s just very, very expensive. You can participate and pay 1000 euros for every ton of CO2 that is extracted from the atmosphere. In any case, it is cheaper to avoid the emissions straight away, to compensate for getting out of fossil fuels as quickly as possible and switching to renewables than to distribute fossil CO2 first in the whole atmosphere and then very expensive and then back againto fetch.
There are already possibilities, for example when you travel by air, that you can offset your CO2. Is that actually wise from your point of view? And what actually happens then?
Well, it definitely doesn’t hurt. Whether it is of much use is another question. Depending on the provider, the money is spent on projects that are intended to help avoid CO2 emissions. Most of the time, the most necessary options are used. Low-hanging fruits also practically die in avoidance costs. But of course there are not so many such low-hanging fruits, where you can avoid CO2 cheaply. It can be a partial contribution to problem solving. In any case, it makes a lot of sense, but it has to be done die Solution. We just have to get rid of emissions that are difficult to avoid in order to achieve zero emissions.
Do you expect more great technical inventions, great technical breakthroughs that can help us in the fight against global warming and with the greenhouse gas problem?
Since we can halve the world’s emissions by 2030, when we can meet the Paris climate targets, we cannot wait for a completely new technology. But we already have the technologies with which we can get the climate crisis under control. Progress WILL be in mass application, which has already led to breathtaking price reductions, for example in photovoltaics or battery technology. I think that the technological progress that we can make use of really lies there, not in completely new inventions, but in improvements and, above all, cost advantages of the technologies that we already know in principle.
Now everyone is relying on renewable energies such as water, wind and photovoltaics. The criticism, or the concern, is what happens in a “dark doldrums”, when there is only weak solar radiation for a long time, when there is no wind, when the rivers also have little water – we are not running in a time of Low energy?
The topic has of course been known for decades and the energy experts know that and have calculated everything accordingly, for example in Germany. Just last year the Fraunhofer Institute presented a new study on how we can achieve a 100 percent renewable energy supply in Germany. Of course, this requires storage capacity. It’s all calculated exactly. You need daily cycle memories, with which you can get through the night, that can be achieved in the battery storage. Especially in combination with electromobility, when a large number of people have cars parked on the grid with their batteries, that is a large storage volume. And then we need seasonal storage to get through such phases with weak energy generation, which you need a few weeks a year, all of which has been calculated with daily real weather data. And there you can, for example, if wind power is urgently available, you can generate hydrogen and have it in large gas storage facilities, if there is very little renewable electricity in the grid.
Is nuclear power an alternative for you?
Well, dying nuclear power has recently been significantly more expensive than renewable energies, because the latter have become dramatically cheaper, while dying nuclear power has become more and more expensive in recent years. Therefore, you get more climate protection if you invest in renewables than in nuclear energy. And fromOf the accident risks, the problem with nuclear waste is also completely unsolved.
You have been a fighter for climate protection for years, for years you have been warning of the climate catastrophe that is about to die. What do you actually think will be in 20 years, in 40 years, in 60 years?
That is a difficult question. I think people see that the predictions climatologists have made for 50 years are all now coming true. And I think we are at a societal tipping point where climate protection will actually get serious. This is not least thanks to the young people from Fridays for Future who take to the streets. And I notice how a climate election campaign is being conducted for the first time in German politics, where this is a very important issue. I do hope that we are now on the threshold of serious climate protection that has to meet the Paris goals.