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08/17/2010

SPIEGEL: Mr. Schellnhuber, Russia is burning and floods have inundated Pakistan. Are such extreme weather phenomena increasing because of gradual climate change?

Hans Joachim Schellnhuber: Such events certainly do correspond to what we expect from a warmer world. We have seen record average global temperatures for more than a year now, and that increases the likelihood of regional heat waves like the one in western Russia at the moment. Besides, our climate models show that the South Asian monsoon is becoming more temperamental as a result of anthropogenic changes to the environment.

SPIEGEL: There have also been forest fires and floods in the past. Isn't it too easy to automatically link natural disasters to climate change?

Schellnhuber: Of course it would be wrong, from a scientific perspective, to establish this relationship indiscriminately. But it would be just as unscientific to stop searching for such relationships, merely because the public's interest in climate change has temporarily diminished.

SPIEGEL: In Russia, in particular, fire prevention has failed. The forest service was abolished, and fire departments in many places are in terrible condition. Do these major fires show that extreme weather situations don't necessarily lead to catastrophes, but that poor crisis management is really to blame?

Schellnhuber: That's undoubtedly correct. In most cases, it's social mismanagement that creates the conditions for social catastrophes. Often one can get away with having inadequate precautionary measures, provided the weather plays along. But extreme weather relentlessly exposes human mistakes and our crimes against nature. The German state of Brandenburg (editor's note: where the Potsdam Institute for Climate Impact Research is based) offers an example of the right way to do things. Even though there are more forest fires here than in the past, due to global warming, the surface area burned by the fires has decreased substantially, thanks to improved monitoring with smoke detectors.

SPIEGEL: As climate adviser to the chancellor, you have a particularly high profile. Because of your frequently ominous predictions, critics have dubbed you the "Cassandra of Potsdam," after the figure in Greek mythology whose predictions always went unheard. Why do you always have to scare people?

Schellnhuber: Let me answer your provocative question in an objective way. As an expert, it's possible that I tend to point to dangers and risks more than to opportunities and possibilities -- similarly to an engineer who builds a bridge and has to make people aware of everything that could cause it to collapse. Warning against a possible accident is in fact intended to reduce the likelihood of an accident. And a sudden shift in the climate could have truly catastrophic consequences. Besides, in Greek mythology Cassandra was always right -- unfortunately.

SPIEGEL: Does that justify constantly predicting the end of the world?

Schellnhuber: Naturally, we have to be careful not to dramatize things. After all, scientific credibility is our unique selling point. But I do confess that when you have the feeling that people just aren't listening, it becomes very tempting to turn up the volume. Naturally, we have to resist this temptation. On the other hand, the media often portray my statements in one-sided ways…

SPIEGEL: Can you give us an example?

Schellnhuber: Take agriculture, for example. If temperatures rise, harvests will suffer, in cereal crops, for example. But at the same time the higher level of CO2 in the atmosphere will lead to improved fertilization of plants. This fertilization from the air will make up for a large portion of the heat damage, perhaps even overcompensating for it. In other words, we could even get higher yields for a certain amount of time, provided there is enough water. In talks I give on the subject, I always mention both effects: the heat damage and the CO2 fertilization. But such subtleties are lost when it comes to how the issue is perceived by the general public.

SPIEGEL: It wasn't just misunderstandings that shook public confidence in climate research in recent months. A number of statements in a report by the Intergovernmental Panel on Climate Change (IPCC), such as one on the supposedly rapid melting of the Himalayan glaciers, turned out to be appalling errors.

Schellnhuber: There were only a few slip-ups, but they were extremely vexing. The IPCC is in the public eye, and there is so much at stake that we cannot allow mistakes of this magnitude to be made. The IPCC now needs to do its homework to overcome the credibility crisis that's occurred. We received a kick in the pants that probably did us a lot of good.

SPIEGEL: A scientific investigation panel in the Dutch parliament accuses the IPCC of overemphasizing the negative consequences of climate change.

Schellnhuber: On balance, this accusation is unjustified. It's not like the IPCC is hiding its true face, which is characterized by ugly exaggerations, behind a mask. For example, the IPCC has deliberately made cautious and restrained predictions regarding the rise in sea levels. The IPCC is set up in such a way that it smoothes things out as much as possible and uses conservative wording, so that all scientists involved can ultimately support the report.

SPIEGEL: Anyone who soberly asks for a cost-benefit analysis of climate change is demonized as a heretic. Why is it such a taboo to talk about the advantages of global warming?

Schellnhuber: You're right -- we do have to highlight the opportunities and benefits for some regions of the world more than we have done so far. There will certainly be winners, at least temporarily, especially in the northern latitudes. At a conference in Moscow, Russian Prime Minister Vladimir Putin told me quite openly: We are looking forward to global warming. We won't need to heat as much, our fleet will be able to operate in an ice-free sea, and we'll have more fertile land to farm. But is this really true? The current forest and peat fires show that global warming could also have drawbacks for Russia. The problem is that the consequences of climate change, both good and bad, have not been adequately studied yet. More than 90 percent of funding is still being used to investigate scientifically if humans are responsible for climate change. But this question has already been answered a long time ago: They are.

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• Part 1: 'We Received a Kick in the Pants'
• Part 2: 'We Are Very Much in the Dark'