No clear pattern

If Himalayan glaciers are not melting as fast as predicted, does that mean that South Asians need not worry?
No, absolutely not. Global warming is happening: we can measure it and there is no explanation published in a refereed scientific journal without considering the impact of greenhouse gases. The sea level is rising, that has not changed either. As far as the Himalayan glaciers themselves are concerned, even they could still start to melt faster if, for example, soot particles are deposited on the ice and absorb solar energy. But this is pure speculation, not a sure thing. There is a difference between what we know and what we imagine to be plausible, and we have to handle that distinction with care.

Must the governments of developing countries in Asia and Africa prepare for new monsoon patterns? The long dry spell in India last year was abnormal, and so were the heavy rains that followed.
So far, it is impossible to come up with reliable hypotheses about if and how the monsoon will change. We cannot say exactly what weather conditions will result from climate change when and how often. Don’t expect too much from science. The phenomena you mentioned may relate to global warming, but they could just as well have come about anyway. Unusual weather was always known in the past, after all.

You sound as if nothing special was going on.
No, don’t get me wrong. There is simply no clear pattern so far. We cannot say for sure what exactly the consequences of climate change will be, except that we believe that the more intense the changes are, the worse the consequences will be. Actually, much uncertainty is a good reason to act on climate change, and to do so fast.

Has the credibility of the IPCC suffered because of the glacier mistake?
It is too early to tell, but, as a matter of principle, accuracy and precision always matter when dealing with data. This mistake must not be treated lightly. In the future, we’ll have to be more careful in checking what data is included in the reports and what data must stay out. It plainly does not make sense to use statistics from questionable sources only to get this or that institute from this or that country on board. This time, the inaccurate information came from a developing country, but that could just as well happen in a rich nation. Precisely because the reports have far-reaching political implications, it is important to handle data with care.

But it is human to make mistakes. Is there really any way to get a completely mistake-free (flawless?) assessment report with four volumes and several thousand pages, authored by experts from all over the world?
No, of course not. But one must actively seek and point out mistakes. Had that been done, the mess-up with the Himalayan glaciers would have been avoided. We also need corrigendum pages so that flawed information is pointed out in public. Solid research is about dealing with mistakes aggressively, and the IPCC can and must do so too.

Your colleague Hans Joachim Schellnhuber of the Potsdam Institute for Climate Impact Research has said that the IPCC should be freed from all political influence and that its chairman, Rajendra Pachauri, should step down. What do you think?
In regards to Pachauri, I would rather not comment. And yes, in an ideal world politicians would keep their hands off scientific endeavors, because otherwise rigorous scientific standards cannot be enforced.

Are policy-makers taking climate change less seriously because of the glacier mistake?
No, I have not noticed any of that, nor, for that matter, do the business leaders I am in touch with consider climate change any less serious. All these people see the mistake for what it was: preventable, and only a tiny issue that does not change the alarming big picture at all.

What do you think of the pledges that many governments made to the UNFCCC (United Nations Framework Convention on Climate Change) secretariat at the end of January? They basically stuck to what they were prepared to commit to in Copenhagen, without raising the stakes. The professional world, however, agreed that what was on offer in Copenhagen was not enough to limit global warming to two degrees.
Pledges are nice, but an actual treaty would be better, and it isn’t too late for that to happen. The next climate summit will be held in Mexico this year; it can still reach a global agreement. If politicians are really serious about climate protection, they’ll have to prove it there.