Toasty winters

DW: The 2012 Christmas holidays in Munich were the warmest on record. But superlatives are easy to come by these days. Are we experiencing the winter of the century?

Mojib Latif: Well, of course, you have to look at this over the long term to evaluate the situation. I always like to compare it with rolling loaded dice. If the number six is loaded, then the six will come up more often, but the other numbers get rolled, too. What we have experienced over the last decade is an increase in mild winters. The current winter fits into that picture. I would say it is another small pebble in a mosaic pointing out to us that we are already in the middle of global warming.

At the same time we are sitting outside in German cafés, we hear about the situation in Russia where hundreds of people have died from the cold and the United States, where snowstorms have blanketed parts of the country. How do such opposing phenomena occur?

It's important not to confuse weather with climate. The weather is always going to have opposites. When you have very warm air somewhere, as we currently do in Western Europe, then there has to be somewhere else that is correspondingly cold. That is currently the case in Russia. There cannot be only low pressure systems - there have to also be high pressure systems somewhere.

So that means Russia's weather pattern could just as easily have hit Germany?

It could have also happened to us. But the situation in Russia has a small additional component. We researchers have speculated about whether the recession of Arctic ice could be promoting this development - at least temporarily, over the course of a few decades. Our models are showing us that the receding ice in the Barents Sea allows high pressure areas to develop more easily over Russia. They can even extend into Europe, including Germany - our cold winters in the past few years could perhaps have something to do with that. But in the longer term, if ice continues to melt in the Arctic, then it will get warmer and warmer in Siberia.

Many Germans still recall the snow catastrophe in the winter of 1978/79, and some remember the post-war winters that were legendarily difficult and cold. In 1962/63, it was the same, and even Lake Constance was frozen over. How probable is it that these extreme winters will be repeated?

The likelihood decreases the more global warming advances. But for now, the temperature change is still relatively slight - such that we can still expect to see extreme temperatures every winter. We saw that in the years past: Last winter, we had two weeks that were extremely cold. So winters like that are not going to disappear. However, if we continue down this path and end up with global warming of four or five degrees by the end of the century, then the likelihood of us still seeing these kinds of conditions will probably drop to zero.

In what ways can we detect that it's human actions that are having effects on the climate and on these developments?

We can only continue to say that the greenhouse gas emissions to date, and CO₂ emissions above all, have come from the industrialized nations. But these nations will not necessarily have to deal with the worst consequences. Instead, it will be precisely those who have released relatively little CO₂ into the air. That's a huge injustice that we must keep pointing out. And we should also not forget: If the difference in living standards continued to develop in such a way that those in southern countries have a much more difficult time than we do, that will have an effect in one way or another on the world's security.

As such, we cannot believe that we live in isolation here. We live in a globalized world. It doesn't matter if something happens, it will - in some fashion - have an effect on us.

Mojib Latif is one of Germany's most renowned climate researchers. He is a professor at the Helmholtz Center for Ocean Research Kiel, where he heads the research division Ocean Circulation and Climate Dynamics.

Interview: Martin Koch / gsw