Heavy rainfall causing the level of the Elbe to rise sharply in Dresden, Germany. Credit: Imago/ZUMA
HAMBURG — For some time now, climate scientists have been discussing a troubling hypothesis: Is global warming accelerating? The German Physics Society and the German Meteorological Society are now warning of this in a joint statement. German weekly Die Zeit has discussed the issue with Klaus Richter, who is resident of the German Physical Society, and Frank Böttcher, chairman of the German Meteorological Society.
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DIE ZEIT: Frank Böttcher, Klaus Richter, the professional associations of meteorologists and physicists in Germany warn that the Earth could have warmed by 3 °C by 2050. That is only 25 years away. Do you really think that is realistic?
KLAUS RICHTER: The risk is increasing that we will miss the goal of keeping global warming below 2 °C. We believe the trend toward a 3 °C rise can no longer be ruled out, especially given current global politics. We therefore call for decisive action and stronger climate protection to minimize this risk.
FRANK BÖTTCHER: We have entered a new stage of climate change: Global warming now appears to be accelerating. We see it in Germany too. The data is so compelling that members of our societies felt they had a duty to speak out, despite all the uncertainty and the usual caution.
That forecast is far more dramatic than current research. Taking climate policies into account, most projections put warming at about 2.7 °C by the end of the century. By 2050, that would be roughly 2 °C. How do you reach 3 °C by 2050?
KR: We are looking 25 years ahead and beyond. So this is not a forecast in the strict sense. But current observations give reason to fear that such extreme warming is possible. The 2.7 °C projection is based on the Intergovernmental Panel on Climate Change (IPCC)’s mid-range scenarios. The risk of 3 °C by 2050 falls within the IPCC’s worst-case scenarios. And unfortunately, recent data aligns more closely with those.
Did the IPCC underestimate the situation?
FB: The last IPCC report is now a decade old. The data looks very different today. We see a clear acceleration in warming: Since industrialization, it took 65 years for the world to heat by 0.5 °C. It then took just 28 years to reach 1 °C. We could breach the 1.5 °C threshold in only 17 more years, possibly as early as next year. The half-degree steps are coming faster and faster. Then there is the issue of ocean temperatures. Oceans have long been a massive buffer against warming. But for two and a half years now we have seen a sharp spike. If this continues, the oceans will absorb less of the extra energy caused by greenhouse gases, and temperatures in the atmosphere will climb faster.
A person with a helmet is seen in front of the illuminated cooling tower of the Schwarze Pumpe coal-fired power plant in Spremberg, Germany, on August 4, 2025. – Source: Florian Gaertner/dpa/ZUMA
Two and a half years is a short period. Is that enough to draw such conclusions?
KR: The rise in ocean temperatures fits a broader pattern, as several indicators point to an acceleration of climate change. Around 15 scientists from our two societies spent 18 months compiling current findings. They debated, for example, whether the sharp rises in global temperature in recent years were just statistical noise or whether they reveal a clear trend. New studies suggest climate sensitivity may be higher than thought, meaning the same amount of CO₂ raises temperatures more than we assumed. This backs the idea that a trend exists.
Do international scientists go as far as you do, or are German societies taking the lead here?
KR: Our appeal focuses on the observable acceleration of climate change. Whether it will continue is part of the global debate. A 3 °C rise by 2050, which we cannot rule out, is already within the range of the IPCC’s scenarios. As professional societies, we carry a social responsibility to point out potential risks early. That is what we are doing now.
In summer, meteorological records could reach up to 50 °C.
For years, people said the IPCC’s worst-case scenarios had been averted, since the world had agreed on climate goals and emissions had grown less than feared.
FB: The purpose of climate conferences was to slow the rise of CO₂ and ideally reverse it. Yet despite all the pledges, carbon dioxide in the atmosphere is still climbing. Looking at the political response, I would sum it up like this: too little, too slow, too late.
KR: The gaps are obvious in Germany, too. Our targets are not enough to reach climate neutrality by 2045. At the same time, we are not even doing enough to meet those inadequate targets.
If we play this out: What would 3 °C of warming mean in 25 years? What would the world look like?
FB: We would all live in different climate zones. Open an old world atlas and you see a huge red patch for the Sahara. With 3 °C of warming, that zone would stretch into parts of Spain. Vegetation, rainfall weather patterns, all would look very different.
And what would 3 °C mean for Germany?
FB: In summer, meteorological records could reach up to 50 °C. Three degrees of global warming does not mean hot days will just be 3 or 4 degrees hotter. It could mean up to 10 degrees hotter. We would also face much longer droughts.
Looking outside a light rail vehicle in Lower Saxony, Germany. – Source: Julian Stratenschulte/dpa/ZUMA
Can you still get this message across, especially now, when climate change barely features in politics or public debate?
FB: We wrestled with that. None of us wants to be accused of alarmism. But the data has pushed so many of us to speak up. As a result, for the first time since 1987, our two societies reached a broad consensus.
KR: Germany’s new federal government has said little so far about climate policy. But maybe now is the right moment to put it back on the agenda. Our climate future is not an unavoidable fate we must resign ourselves to.
What else can be done?
KR: Many studies have laid out potential pathways to a climate-neutral economy. Based on that work, there is still scope to keep further warming in check.
FB: And we need adaptation strategies to protect society from the risks. To put it simply, I cannot tell you the exact time and place a fire will start, but I can advise that we keep a fire department ready.
We also need to consider where to retreat from the current coastline.
Among your 10 specific demands to policymakers is one that calls for “debating a withdrawal from low-lying coastal regions of the North and Baltic Seas.” Until now, this has been taboo.
KR: In the very long run, over many decades to a century or more, sea levels could rise sharply. That is why we must start discussing it now. If we act early, we will have the time for careful adjustments.
FB: We won’t be able to defend some areas against the sea in the long term. We also need to consider where to retreat from the current coastline. For Hamburg, for instance, we need a plan to move the city 30 or 50 kilometers inland to the northeast by 2200. To be clear, no one is suggesting mass relocation tomorrow. But we can already ask whether it makes sense to build a new technology park or major production site right by the shore.
You also call for “ensuring that society is provided with science-based information.” Is that under threat?
KR: Yes, in some parts of the world. Our colleagues in the United States, in particular, are under heavy pressure, especially in climate science. But limiting global warming requires the input of nearly every scientific discipline in dialogue with society, far beyond the natural sciences.
