No room for doubt

DW: Recently there have been bush fires and scorching temperatures in Australia and a comparatively mild winter in Germany. Is it fair to say that climate change is speeding up?

Clemens Simmer: Yes, but not necessarily from these observations.Climatehas been changing forever, it's not constant. But what we do seem to observe is that during the last 100 years or maybe even more during the last 30 or 40 years we have an increased change of climate. We have now been reliably measuring temperatures for about 100 years or even more. The globe has increased its temperature about one degree over the last 100 years. Globally, half of that degree came about in the last 30 years. So, there is a speeding up.

What sort of effect is that having on the planet?

Well, of course it's getting warmer. At the moment it's getting warmer faster than ever before. This has several affects. We also have to take into account that this increase in temperature is different across the world: its low over the ocean, high over the continents, low over the tropics, high over the mid latitudes and high latitudes. So this changes temperature contrasts and it induces changes in the atmospheric circulation. So, circulation patterns are slowly changing.

If you had to name one reason for this climate change that's taking place, what would say is the main cause?

At least for these rapid changes we are experiencing in the last 50 years or so, the main cause is anthropogenic emission of green house gases. This, I suppose, is undebated. We are talking about emissions from public transportation and from private transportation, airplanes and industry. And power production, of course.

You say it's undebated. But there are many climate sceptics out there, even here in Germany, a country with a strong environmental record. What do you say to them when you meet them?

Climate sceptics do not doubt the increase in temperature, because this is now a fact. But they doubt the increased carbon dioxide in the atmosphere by mankind is the main cause. I tell these people to come to my lecture. I do this in my introductory course in meteorology and actually some come along. After that they know, and do not further disagree with it because it's very simple to explain.

Can you explain it quickly now?

Actually, you need an hour for it, but I can try. With more CO2 in the atmosphere, the radiation which is always going downwards to the surface simply increases because the atmosphere becomes thicker. Its just more radiation coming down than before, that's all. This heats up the lower atmosphere. Also, we see the opposite trend in the stratosphere where the atmosphere is cooling. It's easily explained and it has been known for more than 100 years.

There are conventions and agreements worldwide, we had the convention in Doha at the end of last year, for example. What can countries do to solve the problems now facing the world?

That's a bit outside my expertise. But, it's simple. They have to develop a society which does not emit additional CO2 into the atmosphere. It's an easy thing, because the energy which we need is already there. The sun provides enough energy, we just have to develop the technology for that and this is a matter of money. I guess there are other problems that are more difficult to solve, actually. Like overpopulation or economics problems - they are more difficult than fighting climate change.

So you place a lot of hope on renewables, like solar energy?

Sure. But, we have to develop tools to better store energy because this is what makes the renewable energy not so easy to employ. So, a lot of technology development is still necessary. But, basically, we have everything that we need to deal with the problem.

On an individual basis, what can people do to minimize their green house gas emissions?

What we put into the system now as CO2 stays in the atmosphere for hundreds of years. Everything you do not put into the atmosphere reduces climate change. So, don't use your car, don't fly to your holiday destination if you don't need to, use your bicycle to go to work and back. It also keeps you healthy. There are many things you can do. Just think about when you do something if it does emit additional CO2 and you can save a lot.

Professor Clemens Simmer is a lecturer and researcher at the University of Bonn's Meteorological Institute, in Germany.