SPIEGEL: Mr. Storch, Germany has recently seen major flooding. Is global warming the culprit?

Storch: I’m not aware of any studies showing that floods happen more often today than in the past. I also just attended a hydrologists’ conference in Koblenz, and none of the scientists there described such a finding.

SPIEGEL: Would you say that people no longer reflexively attribute every severe weather event to global warming as much as they once did?

Storch: Yes, my impression is that there is less hysteria over the climate. There are certainly still people who almost ritualistically cry, “Stop thief! Climate change is at fault!” over any natural disaster. But people are now talking much more about the likely causes of flooding, such as land being paved over or the disappearance of natural flood zones — and that’s a good thing.

SPIEGEL: Will the greenhouse effect be an issue in the upcoming German parliamentary elections? Singer Marius Müller-Westernhagen is leading a celebrity initiative calling for the addition of climate protection as a national policy objective in the German constitution.

Storch: It’s a strange idea. What state of the Earth’s atmosphere do we want to protect, and in what way? And what might happen as a result? Are we going to declare war on China if the country emits too much CO2 into the air and thereby violates our constitution?

SPIEGEL: What could be wrong with the models?

Storch: There are two conceivable explanations — and neither is very pleasant for us. The first possibility is that less global warming is occurring than expected because greenhouse gases, especially CO2, have less of an effect than we have assumed. This wouldn’t mean that there is no man-made greenhouse effect, but simply that our effect on climate events is not as great as we have believed. The other possibility is that, in our simulations, we have underestimated how much the climate fluctuates owing to natural causes.