1. What would be the most urgent adaptation measures in a country like Germany?
"In Germany, we are at a point where we need a legal basis for the implementation of climate adaptation measures. The federal, state and local governments must prioritize climate adaptation as a joint task, with all that this entails, and that is, above all, financing. The problems we are facing as a result of heat, long periods of drought and heavy rain will get worse in the coming years. At the moment, we are responding here and there, often on a voluntary basis. But most people have never heard of climate adaptation measures, and the issue also keeps getting lost on the political radar - unless there's a supraregional extreme weather event at the moment. In concrete terms, the aim of such a law is, among other things, to empower municipalities to make more land available locally for adaptation to climate change. So, quite simply, an area is free. What do I do on it? Do I build affordable housing that people urgently need? Parking spaces? Sports facilities? Buildings store heat, sealed ground prevents rainwater from running off. Or do I preserve a brownfield site in the sense of climate adaptation, where cold air can develop and rainwater can seep away better? This sounds like either-or, but there are also multifunctional options: Parking lots and streets can be sealed with special asphalt that allows water to percolate better. Green roofs on buildings can retain water during heavy rainfall and help to cool the building through evaporation. In Hamburg, for example, there are subsidies for active green roofs. In Düsseldorf, proactive homeowners pay less in wastewater fees. However, such incentives are often lacking, and since their implementation initially means additional expense, they are hardly ever implemented on a broad scale at present. A window could also open in the course of the mobility revolution. If planted green spaces for cool neighborhood meetings were created where parking lots are today, for example with mist showers that spray very fine drops of water. I don't hope that all buildings will be cooled with conventional air conditioning systems in the future. In old people's or nursing homes or hospitals, more active cooling will certainly be needed. But even in a perfect future with 100 percent green electricity, air conditioners would still contribute to heating up the microclimate because they transport warm air outside. That increases heat pressure on all those who don't have air conditioning, including people living on the street, for example."
Christian Kind works as "Head of Program Adaptation" at the climate think-and-do tank Adelphi.
2. What happens if the 1.5 degree target is exceeded?
"There are elements in the climate system that can tip - at the center of which are then self-reinforcing processes. But the global mean temperature is not such a tipping element. For such a process, you need a positive feedback that dominates the dynamics of the system. In the case of the warming of the Earth, however, by far the strongest feedback is negative: the warmer the Earth becomes, the more heat it radiates into space, which automatically dampens the warming. In contrast, there are positive feedbacks, but they are much weaker. The most important is that as the Earth warms, more water vapor enters the air, acting as a greenhouse gas. Also clear is the effect of light sea ice melting and exposing the dark ocean, so less radiation is reflected. Methane escaping from thawing permafrost is a distant second, as are dying forests.
Even assuming the worst everywhere, however, this is not nearly enough to completely destabilize the climate system. True, there is unavoidable additional warming due to water vapor, sea ice melt, methane from permafrost, beyond just the CO₂ effect. That's really cause for concern, too. But it's not unstoppable warming; that's an important distinction. If we stopped emitting greenhouse gases today - a completely hypothetical scenario - the temperature would probably remain roughly stable.
So the 1.5 degrees is not a hard line between safe and not safe. Some things will be lost before then, many corals for example, others will only happen with significantly higher warming. But for the risks, every tenth of a degree counts. Unfortunately, we won't be able to maintain the 1.5 degrees, but we shouldn't exceed the two-degree limit, and I'm optimistic that this will work out, just about. What scares me is that society, our democracy, our constitutional state, will collapse under climate change. At a certain level of warming, the weather extremes will come so frequently and violently that we won't be able to clean up in between. What then? The direct climate risks are much clearer to assess than the risks to social cohesion."
Anders Levermann is a physicist and heads the Complexity Research Department at the Potsdam Institute for Climate Impact Research (PIK).
3. Can we switch completely to renewable energies in Germany?
"Yes, we can - if we master four tasks: For a climate-neutral energy system, we need four times as much green electricity as today. Second, we need more flexibility in the power system and hydrogen as a back-up when wind and sun deliver little energy. Third, we need to expand the power grids so that the electricity gets to where it is needed. And fourth, we need to use electricity more efficiently. The expansion of renewable energies can finally pick up speed with the recently adopted Easter package. At the same time, interest in photovoltaics and storage is higher than ever due to the Ukraine war and the associated price shock for gas and electricity. However, there is a lack of components and craftsmen. And securing raw materials, such as rare earths and lithium, will also keep us busy in the coming years. In a climate-neutral energy system, we consume twice as much electricity as we do today. Almost all cars will be electric, houses will be heated with heat pumps or district heating, industry will use electrode boilers or large heat pumps, and electrolysers will convert electricity into green hydrogen. A large proportion of these new electricity consumers are flexible and can use the electricity when the wind is blowing strongly or the sun is shining. And of course we also have classic battery storage. In addition, Germany is connected to other countries via many power lines. This helps to balance out fluctuations in generation and gives us access to the large storage lakes in Scandinavia and the Alpine region. As a backup, we can generate electricity from green hydrogen. But hydrogen will also be used in other areas. In our study "Climate-neutral Germany 2045" we assume that a good third can be produced domestically in 2045. The rest will be imported. The biggest problem in building the hydrogen economy is that the picture is not yet complete. Never before in industrial history have we had to build up demand, production, transport, storage and import of an energy carrier simultaneously in a very short time. In which areas should hydrogen be used, and in which not? Where should electrolysers be located? In the north, where production is cheap, or next to consumers to save on transport infrastructure? The current gas crisis also complicates things: When we build the LNG terminals, we have to think hydrogen so that we can use the terminals without natural gas. But that depends on whether we import the hydrogen molecules in liquid form or as ammonia. There are still a lot of questions there."
Inka Ziegenhagen, energy economist at Prognos AG.
4. Is the war in Ukraine an accelerant for change or a giant step backward?
"There are entries on both sides of the scale. For me, the predominant fear at the moment is that climate protection will go under. But we have no choice but to : stay the course and keep going. The positive accelerating effects, if you can call them that at all, are that it has once again become clearer how urgently we need a transformation to renewables. This will now be enshrined in law, in Germany, but also at the European level and despite the crisis. Joe Biden's Inflation Reduction Act is also amazing, because he dares to think about the connection between the various crises, i.e. climate protection, health and a fair tax system. We in Germany can learn a thing or two from this. Unfortunately, on the other hand, some countries are reacting by reactivating coal because gas has become so expensive. This is a huge problem for global climate protection. In addition, the high gas and oil prices provide enough incentive to explore fossil resources, and things are happening like now in the Congo, where oil deposits are suddenly to be dug out of the ground. In Germany, it is also striking how much intellectual energy the war and the energy crisis are tying up that would actually be needed for climate protection. Many people are busy saving our economy day in, day out, instead of thinking about the next steps in the energy transition. In addition, I fear that in the current situation we are creating some path dependencies, i.e. structures that are actually not up to date but appear necessary in the short term in the current situation and are then continued to be used beyond that. On a large scale, I'm thinking of LNG terminals, for example, where the liquefied gas is landed by ships and which, unfortunately, are probably not suitable for hydrogen. On a smaller scale, this would be the climate-damaging fan heater that someone buys, which, by the way, will never pay off. But if it is there, it will be used for a few years, even after the acute crisis has been overcome. Overall, I fear that the geopolitical upheavals caused by this war are much greater than the question of "Will we freeze for two months next winter? What happens to China? Who will be reliable partners in the future? Will there be a food crisis in Africa? These uncertainties also offer a lot of potential for great social discontent. It is therefore important that we now also look at further relief and social balance. And care must be taken not to forget climate protection, even though it is perhaps the most important issue of all, because it affects our long-term livelihood.
Brigitte Knopf is a climate scientist and Secretary General of the Berlin Climate Research Institute MCC.
5. Will regions become uninhabitable because it gets too hot to live there?
"All the evidence suggests that there is a natural limit of temperature and humidity that humans cannot survive if exposed to for extended periods of time. Heat stress can become too extreme in one of two ways: Either the air is hot and at the same time so humid that sweat evaporates too slowly to effectively cool the body. Or the temperatures are so high that sweat cannot be produced fast enough. Sick or elderly people are at risk even in much milder conditions.
Extreme humidity-heat events are highly localized and therefore often underestimated. But both in the past and in climate models, there is a strong correlation between such extremes and global average temperature. Thus, these events are expected to increase, especially in regions such as Southeast Asia, northern India or Pakistan. In principle, adaptation is possible with the help of technology, but it is unlikely that the majority of the population in all affected regions will have reliable access to, say, air conditioning. Therefore, the problem is reminiscent of sea level rise: It is technically possible to protect every piece of land with solutions. But it is unlikely to happen."
Colin Raymond researches heat extremes at Nasa's Jet Propulsion Laboratory in Pasadena, California.
6. What are the most threatening tipping points, and how are these related?
"Tipping elements in the climate system can go through major changes, some of them irreversible. It's like a kayak, if you lean out too far, it becomes unstable and tips over, and it takes a lot of force to get it back up. This applies, for example, to the ice sheets of Greenland and West Antarctica, the Atlantic circulation, the Amazon rainforest, and coral reefs. Some of these are particularly vulnerable. For example, Greenland's ice sheet or parts of West Antarctica could already have passed their respective tipping points today or in the near future and thus be slowly but inexorably melting. It is impossible to say for sure, because ice sheets in particular have very long reaction times. But we are already seeing accelerated ice loss.
What distinguishes tipping elements is a self-reinforcing mechanism that leads to the system's momentum taking over at a certain point. In Greenland, melting is moving the surface of the ice sheet into deeper and thus warmer layers of air, which in turn accelerates melting. In West Antarctica, the self-reinforcing processes take place predominantly on the underside of the ice. In the Amazon rainforest, as forest area is lost to fire or deforestation, evaporation decreases, making it less and less able to maintain its humid climate, destroying even more forest.
I am particularly concerned about domino effects: The tipping of one element can bring others after it. If Greenland's ice sheet melts, for example, more freshwater enters the ocean, which could slow Atlantic circulation and thereby accelerate Antarctic ice loss in the long run. Such effects can reach across the globe and also change the climate in Europe or monsoon precipitation. Exactly what will happen then, and when, cannot yet be predicted, but there is too much at stake to gamble that it will end smoothly."
Ricarda Winkelmann is head of the ice dynamics group at the Potsdam Institute for Climate Impact Research.
7. Do we need to recover CO₂ from the air and store it? How does that work?"
CO₂ stays in the atmosphere for centuries to millennia. That's why its concentration keeps rising and driving up temperatures as long as we're emitting, so net emissions have to stop. However, about ten percent of emissions cannot be avoided by the middle of the century, and we have to offset this share. In Germany, that's about three kilograms per person per day.
About a quarter of these residual emissions are concentrated, for example in waste incineration, cement production or fertilizer production. It's relatively easy to capture that directly. We have to recapture the rest from the air. Up to a quarter of the residual emissions can be captured with near-natural solutions. In Germany, reforestation will not contribute much to this. We will be lucky if we have as much forest in the next few decades as we have today, despite climate damage. But fallow land, seagrass meadows or salt marshes on the coast can store a lot of CO₂ and still have positive side effects for ecology or coastal protection.
For the remaining residual emissions, we need technical processes such as bioenergy with CO₂ storage (BECCS). In other words, we need to grow energy crops that take the CO₂ out of the air and capture the CO₂ released when biogas, for example, is burned. However, this requires a lot of land, and there are conflicts with food production and species protection. Filtering from the air ('Direct Air Capture', DAC) is therefore similarly important, and a lot of investment is being made in this worldwide, even though the technology consumes a lot of energy, so more electricity still needs to be generated from renewables. But both technologies are established.
Other processes, on the other hand, are still being tested, such as ocean alkalization, for example, by introducing lime or other minerals, which increases CO₂ sequestration in the ocean, or plant carbon. I hope that with each of these processes you can bind maybe ten to 20 percent of the residual emissions, but we don't yet know exactly how big the potential or the side effects are, so a lot of research is still needed.
With the already established BECCS and DAC processes, the captured CO₂ must be stored safely. For Germany, I assume about 30 million metric tons of CO₂ per year, which corresponds to about a quarter of current natural gas consumption. Countries such as Norway, the UK, the Netherlands and Iceland are already storing CO₂ and expanding this considerably, in some cases in old natural gas deposits under the sea. There is never one hundred percent certainty; there can always be leaks. But the natural gas was stored there stably for millions of years. In addition, the CO₂ is converted to carbonate rock in the long term.
In Germany, CO₂ storage is not permitted, although there would be suitable storage sites here as well, for example under the North Sea. In addition to safety concerns, there are fears that this will only prolong the fossil fuel era, because people might be tempted to keep power plants running longer. I understand this concern. But we don't throw our plastic waste into nature to force the plastics industry to produce less. This CO₂ is our waste, and at the moment we are simply using the atmosphere as a landfill. We need to look at responsible disposal, as we do with other waste."
Andreas Oschlies heads the Biogeochemical Modeling research unit at Geomar Helmholtz Centre for Ocean Research Kiel.
8. What does climate change have to do with my health?
"Climate change is making healthy people sick and sicker people even sicker. Cardiovascular disease, diabetes, lung disease, but also mental illnesses like dementia are increasing. During the last heatwave summer in 2018, we had about 9000 heat deaths in Germany alone. This should be a reason to finally develop early warning systems, for example wearables for the elderly, i.e. pulse watches that let you know when your body is getting too hot or you urgently need to drink something. If in doubt, they alert the emergency services directly.
In Germany, heat is still not taken seriously. We forget our children in cars and go jogging during our lunch break. Our cities are heat islands where it is five to ten degrees warmer than elsewhere. In the air hangs an unhealthy soup of pollutants, UV rays and just far too hot air, which goes to the mucous membranes, but also to the lungs and nerve cells of people.
Allergy sufferers or people with atopic diseases such as neurodermatitis, who account for 40 percent of the population in Germany, also suffer particularly badly. Climate change is altering ecosystems and thus also pollen concentrations. There is much more pollen on the move, and it flies around on many more days of the year. The pollen itself is more aggressive because it releases more proteins due to climate change. So-called thunderstorm asthma was first described in Melbourne: There, there were more than a thousand hospitalizations of people with pre-existing conditions whose lungs spasmed, triggered by pollen bursting in the electromagnetic forces of the thunderstorm.
Another problem is diseases transmitted by mosquitoes or ticks. The number of Borrelia infections has doubled in Germany in the past six years. Suddenly we have West Nile fever or leishmaniasis, all of which I learned in my studies were tropical diseases. In addition, there are bacterial diseases, for example from lakes or the warmed Baltic Sea.
Yes, I know, it all sounds terrible, but I think it's worth it not to gloss over the matter. And then to make sure that we adapt - but most importantly, that we slow down and fight climate change. In the end, we could all gain a healthier life as a result."
Claudia Traidl-Hoffmann heads the University Outpatient Clinic for Environmental Medicine at Augsburg University Hospital and the Institute for Environmental Medicine at Helmholtz Munich.
9. Does it matter what we do in Germany if China doesn’t move faster?
"Quite the opposite. This self-defeating argument has already squandered decades of necessary climate action, particularly in the United States. The Federal Constitutional Court made two important points on this issue in its landmark decision in the spring of 2021. First, it said, the Basic Law's climate protection obligation is not diminished by the fact 'that climate and global warming are global phenomena and that the problems of climate change cannot therefore be solved by a state's climate protection contributions alone.' Secondly, there is the complementary duty of the German state to seek a solution to the climate protection problem precisely at the supranational level. This leverage effect of international embedding would enable national climate protection measures to have the effect required by the Basic Law.
Germany's obligation to achieve zero emissions as quickly as possible therefore exists in any case. Those in Germany, historically one of the largest emitters of greenhouse gases, who point the finger at others - in this case China - are also pointing four fingers at themselves.
When leading industrialized nations show that there are new models of prosperity without greenhouse gas emissions, this has an enormous spillover effect in the world. All the more so if developing countries and emerging economies are enabled through climate partnerships to make very rapid progress along this development path. Despite all the tensions in other areas, it is also important to promote cooperation opportunities with China, because although the country is already a leader in renewable energies and electromobility, it is still not making fast enough progress overall in climate protection. This year, China has been hit by a massive drought. Perhaps this, too - in addition to the opportunities in the race for a new model of prosperity - will give an additional jolt for more climate protection before the important party congress this fall.
China as an argument for doing nothing, by the way, is an old argument of the fossil fuel lobby. Before the Kyoto Protocol, the then head of Exxon traveled to China to implore the government there not to accept reduction targets at Kyoto 1997. At the same time, Exxon led an industry group in the U.S. that was largely responsible for the U.S. Congress then deciding not to ratify Kyoto unless China accepted reduction commitments. Eighteen years of serious climate protection in the USA were thus thwarted.
It is worth fighting for every tenth of a degree of global temperature increase avoided. For this, we need serious climate protection at home and the necessary pressure and cooperation internationally. The existence of millions of people and many ecosystems depends on it."
Christoph Bals is executive director of the German environmental organization Germanwatch.
10. Why does so little still happen?
"First of all, the question of how humanity can get into action more quickly and comprehensively is not a purely psychological question; it also depends on a complex multifactorial interplay of politics and economics. But facing up to the mechanisms of one's own inaction and gradually dismantling them is nevertheless sensible.
One psychological aspect, for example, is cognitive dissonance, that is, the inner tension that arises from the contradictions between behavior and knowledge when we fly on vacation, for example, even though the climate is also very important to us. This is a psychological burden for most people. To reduce it, we have all kinds of options. Unfortunately, we usually match our attitude to our behavior rather than the other way around, making behavioral change less likely. It is easier to turn off the radio or to tell ourselves that everything is not so bad or, on the contrary, that it is too late for any kind of reaction anyway.
Other perceptual biases are also at play, such as the present bias, which ensures that we find everything that happens in the here and now much more important than things that will happen sometime later. The single action bias makes us feel that we are already doing enough, for example by eating a little less meat - flying must still be in the mix. In addition, there are social psychological phenomena such as the bystander effect, i.e., the scientifically proven fact that the more people witness an emergency, the less likely it is that the individual will take action.
These biases usually don't occur all at once or to everyone, but basically everyone is affected by them, they are just very normal perceptual reflexes.
Accepting that we are all at the mercy of these ways of thinking is an important step. What I find even more exciting is the question: What brings people into action nevertheless? How do we get out of our problem trance? To do this, I believe that, above all, we need to consistently point out low-threshold options for action that are effective and go beyond individual behavioral changes, such as all forms of political participation. Ideally, politics would also create structures so that people don't have to make any special effort to behave in a climate-friendly way.
I see an opportunity in what is called 'heroic behavior' in psychology: behavior in which one endures discomfort for a higher purpose. Going to the dentist would be a very mundane example of this. We won't be able to do entirely without heroic behavior in relation to the climate crisis. We could do this, for example, by celebrating much more the people who fundamentally change their behavior."
Lea Dohm is a psychologist, psychotherapist, book author and works at the German Alliance for Climate Change and Health (KLUG).