Rajendra K. Pachauri, chief of the Intergovernmental Panel on Climate Change, was recently in Oslo working with his colleagues on their next assessment of the state of our climate. The result will be presented in December 2014, although drafts of some parts have already leaked. Before that, three 1000-page long scientific reports will be published.

 – Could you tell us about some of the main differences in the upcoming assessment report from the latest assessment report?

– This is still work in progress. Till it’s completed and approved it’s not possible for me to come up with any of the findings. Since 2007 we have a lot more literature … so I expect in several areas we will have new knowledge, we will have new facts, all of which will be assessed and put into the report.  I expect we will have a lot more regional details. We are covering geoengineering, aerosols and cloud cover.

– There have been floods and extreme weather especially in Europe over recent weeks. Is this a result of climate change or is it just natural variation? 

– You can’t really link any single or specific event to climate change. As you’re aware we brought out a special report on extreme events and disasters where all these phenomena were really highlighted as becoming more frequent, more intense, particularly heatwaves and extreme precipitation events.

 If you look at the trend, if you look at the manner in which these [events] are increasing, the finding is very clear, but to pick up one single event and say this is the result of climate change is not possible.

– Is it “dangerous” for a climate scientist to say that?

– I would say it’s not scientifically approprate to say that because I don’t think you can link any single event with climate change.  There is a difference between the weather and the climate and we have to be conscious of that.

– Does that make it more difficult to communicate the science of climate change?

– Not really, because you know if you look at the last century, for instance, we know that in the Fourth Assessment Report we came out with the finding that the average increase in temperature globally has been 0.74 degrees Celsius and that the increase in the sea level has been about 17cm. Once people got to know the facts, they would obviously be influenced by them. So I don’t think it’s that difficult to communicate these findings, though the scientific community needs to improve the way it communicates with the public. We are determined to make sure that in an area like climate change which has such major implications for public policy that we really are able to inform the public, to inform leaders and decisions makers, and we hope we can do that better.  We have not done that well enough in the past. 

– Quite a few climate scientists say that the 2-degree-goal is out of reach, and that we will reach this level of global warming around 2050 even with the most optimistic scenarios of emission reductions. Do you agree?

– We are asessing options available to us [in the fifth asessment report]. I expect we will have a little more about what is possible and what the economics would be. I hope this question will be answered much better once the report comes out.

Rajendra K. Pachauri. Wikimedia/Mikhail Evstafiev. Some rights reserved

– United Nations Environment Program said in their latest emission gap report that the systems of transportation, production, buildings and other infrastructure are stuck in a high energy regime, that will take years to change - and therefore it’s a big challenge to reduce the emissions fast enough to avoid dangerous climate change. Do you agree?

– Frankly I don’t know the basis on which UNEP has made that statement … so I won’t be able to comment on it. What I would say as far as the IPCC is concerned is that we do all our work based on published literature. The manner we do it in requires expert review, government review of various stages, and an explicit incorporation of the comments that we receive as part of these reviews.   It is a very robust process and what we come up with is something no other scientific body has been able to come up with so far.

– What will be the main sources of emissions in years to come?

– We’ll come up with a set of scenarios that are based on how the economy will change, how technology will develop and how a range of other factors will change in the future. A great deal also depends on human behaviour and changes in lifestyle. That is not easy to project. Because who knows how human society will respond.

– Are you a technology optimist?

– Technology has achieved a lot and is changing rapidly. I don’t think we should underestimate the role of human actions and behaviour. In the fourth assessment report we clearly pointed out life style changes as an important mitigating factor.

– Are there any technological developments you see that can help in this situation?

– In 2011 we brought out the report on renewable energy and climate change mitigation. There are several technologies that are very favourable compared to conventional sources of energy. In the fourth assessment report we estimated that by 2030 there would be 6 gigatonnes of CO2 equivalent mitigation potential that can be achieved at net negative cost.  There are solutions available to us that in fact are economically viable and  in some cases could even be achieved at negative cost. All the technologies that you need are available or would be commercially available in the near future.

– What is your opinion regarding carbon capture and storage?

– We brought out a special report ten years ago and will provide some assessment on this in the next assessment report. The reality is that very little has changed since then.

– Are you disappointed because not much has changed?

– You know, I’m an optimist. I would expect that at some stage human society will use the knowledge we have and come up with a solution to the challenge we have. There are major intra-generational reasons and intergenerational reasons why we should do that, because even today we live in a world with huge disparities. There are some that face the impacts of climate change far more than others. They are the poorest of the poor, who are the most vulnerable. I believe that we have to continue to provide the knowledge on the basis of which human society will act, and I am optimistic that things will happen in the right direction.

–  If I was a climate skeptic, what would you say if I claimed global warming is mainly because of solar activity.

– I would only say please read the reports of the IPCC where we look at both human and natural factors that are responsible for climate change. If you go through it in depth and still have doubt, let’s have a talk about it and look at the facts. We have absolutely no hesitation in receiving contradictory opinions and being questioned because science thrives on questioning. But the dialogue has to be well informed, objective and fact based. I’m sure people who really go into these questions in some depth and read what the IPCC brings out will be convinced. I have no doubt about that.

– And if I say there’s no consensus among the scientists.

– I know for a fact that several national bodies and surveys clearly show that there is an overwhelming consensus among the scientific community on  the link between human actions and climate change. 

– What if I say that climate’s changed before and the warming is only part of a natural variation.

– Over geological timeframes of course the climate has changed. But as we clearly brought out in the fourth assessment report, most of the warming that has taken place since the middle of the last century is very likely the result of human induced increase in concentration of greenhouse gases.  When we use the term ‘very likely’ it represents a probability of over 90 percent. This is informed scientific judgment, based on published evidence and thousands of people having carried out research on the subject.

Yes of course over geological timescales, glacial periods, interglacial periods, there have been fluctations in temperature, differences in the sea level. But what we are doing today and what we have been doing since the middle of the last century is resulting in far more rapid climate change than what one would expect through natural variation.

– Then I say that the climate’s actually cooling, just look at the cold winters of Europe in recent years.

– There again I would separate the weather from the climate. For instance if you have extreme precipitation, if you have very heavy snowfall as a result of climate change, you will locally get a cooling effect. But to look at single occurrences and changes in the weather and then draw conclusions about the climate is not scientifically valid.

High water under the Griesbrücke in Jena, Germany, June 2nd 2013. Flickr/Andreas. Some rights reserved.

– I say that the models are not good enough.

– Models today are extremely robust and very reliable. They have been run by what you can call back casting, you go back in time over the twentieth century. You look at the observed changes in temperature, you find a very reliable fit between the observation and the outputs of the models when you put in the drivers. I would say that the models have reached a very high level of sophistication and that their reliability is extremely high today.

– The scientists just choose the evidence that build upon their conclusions.

– You have the best scientists from all over the world. These are people of enormous credibility who have produced work that has gone through peer review in some of the most prestigious journals of the world. How can you ignore that fact? The IPCC assesses published literature from across the globe.. We take into account peer reviewed and credible non peer reviewed literature that has gone through careful scrutiny by some of the best scientists in the world. 

– What if I said that the scandal with the leaked emails is evidence of a whole conspiracy?

– No fewer than three separate investigations largely exonerated the scientists whose emails were stolen. The results of those investigations speak for themselves. I think the only question that should be asked is who was responsible for the hacking of those emails. If you find out who arranged for that hacking maybe a lot of other questions would follow rather rapidly.

– Why this skepticism? And who are they?

– I really don’t know. I think that’s up to the people that are in the business of investigative journalism to find out. We have enough to do getting out a rigorous assessment of science in the entire field of climate change and we are trying to do the best we can.

– There have been a lot of discussion about the communication of climate change science and you have also touched on the subject. Have you as an institution learnt anything from the recent debates: have you changed your media strategy?

– We have been learning continuously and we are certainly trying to address the weaknesses and shortfalls in communication. As a scientific body this has not really been our strength. We are trying to fill the gap now and have a new senior communications officer. We hope that our other partners would pick up the findings of the reports and help to disseminate them. I would expect the media again would play an important role. But we in the IPCC try the best we can. One good experience was the publishing of our special report on extreme events and disasters. This was supported by the Government of Norway in the outreach effort. We believe that was very successful and that people got to understand the link between climate change and some of these extreme events. We hope we can build on that in the fifth assessment report. 

– What do you expect of the public discussions when the fifth report comes out? 

– I’m sure there will be lots of discussions. It’s very difficult to predict, but I hope it is an informed, objective and dispassionate discussion.

– Will adaptation be even more important in a scenario where the reductions of emissions are far from good enough to avoid dangerous climate change?

– Adaptation is important, but neither adaptation nor mitigation alone will be able to meet the challenge.  They need to complement each other. We also said very clearly in our special report on extreme events that you could reach thresholds or benchmarks, tipping points where both ecosystems as well as social systems might find it very challenging to deal with adaptation beyond that.   

– Do you think it will be more difficult to deal with the challenges of climate change in a situation of recession and economic crisis?

– Not really, the current situation might also provide an opportunity to bring about change. You can revive the economy and do it in a way that can be good for the climate.

There are a number of organisations that are looking at the employment and economic implications of more efficient use of energy, greater use of renewable energy and there is a growing amount of literature in this area which I hope will be assessed in the Fifth Assessment Report. 

– You are now 72 years old and recent years have been stormy, and there has also been quite a lot of focus on you as a person. Did you ever think that you shouldn’t have taken this job, and that you wanted to quit?

– Never, I’ve never had a moment’s regret. I took this job with my eyes open. It’s an occupational responsibility. It’s a 24 hour routine. This Saturday I played a cricket match in New Delhi at a temperature of 40 degrees out in the hot sun.

– I’m very proud of being a part of the IPCC. When the InterAcademy Council assessed our activities they clearly stated that this was a social innovation. The IPCC is historically an innovation that has no parallel. And what could I want more out of life than to be associated with the IPCC.

–  And since you have asked this question, you know that I was personally attacked way back in December 2009.  There was an article published about me in the Sunday Telegraph, which I may say had a lot of false allegations. I wrote to them, I tried every reasonable argument to make them withdraw the article and make them accept that what they had written was false and not right. I had to contact a law firm in London that agreed to take up my case on a no win no fee basis. They initiated proceedings and that was when the Sunday Telegraph decided to withdraw the article, pay that law firm 53,000 pounds in legal expenses and the newspaper issued an apology to me. I’m prepared to stand up and fight for my convictions and integrity.

– But after the next report you are done as the chair of IPCC ?

– I have lots of other plans. There are so many things to do in life. By the time I finish I would have been the chair of IPCC for 13 years which is almost half the life of the IPCC. I think someone else should take over.

– What will you do when you retire? Play cricket?

– If you ask me what I will do when I retire I would say that I will never retire. I will work till the day I die.  What I really want to do is work with youth on these questions; they are dedicated to them.

(A shorter version of this interview has been published in Norwegian in Teknisk Ukeblad, who kindly permitted the publishing of the original.)