Last week climate scientists from around the world met in Paris for the largest scientific gathering in advance of the U.N.-sponsored climate talks that will be held in the French capital in December. During the conference I was able to sit down for a one-on-one interview with conference chair Jean Jouzel, who also currently serves as the vice chair of the Working Group I panel of the International Panel on Climate Change, which was awarded the Nobel Peace Prize in 2007.

Sixty-eight years old and white haired, Jouzel came from a farming family in Brittany, then left the countryside to study engineering at the Ecole SupÃ©rieure de Chimie Physique Electronique de Lyon, and later went on to earn a PhD in the physical sciences. His specialty is paleo-climatology: that is, he studies ice cores to understand the planet’s past climates. Jouzel has co-authored nearly 400 scientific papers, and in 2012 he was awarded the Vetlesen Prize for studies that resulted in a clearer understanding of Earth. The prize is considered the earth sciences equivalent of the Nobel Prize and is delivered every four years since 1959 by the American Foundation of the same name.

Jouzel’s courtly manners didn’t disguise his frustration with the sluggish pace of political action to reduce greenhouse gas emissions. He complained that many countries still have not released their climate commitments — or “Intended Nationally Determined Contributions” (INDCs) in U.N. parlance — and he made a strong case that developing nations should play a leading role in forming a Paris climate agreement. Still, he remains optimistic. “It is not too late,” he said, “but it is really urgent.”

What do you expect to get out of this scientific meeting five months before 2015 Paris Climate Conference?

As a member of the French scientific community we thought this meeting could be useful for COP21 in December. Paris will be as special as Kyoto and Copenhagen were. In Copenhagen we had an agreement for the second phase of the Kyoto Protocol and the main result was the shift from a qualitative convention without real objectives toward a 2°C target. Right now we hope COP21 will result in an agreement for beyond 2020. We feel that a scientific conference with a broader view would be useful. The last IPCC report was released with data from 2012. We have a collective expertise that gathered three more years of updated research. We want now to look for solutions that came up in the past few years.

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Calendar of activities leading up to COP21 in Paris in December (image: Network of Regional Governments for Sustainable Development)

What are the major concerns from the scientific community regarding a Paris deal?

It is a challenge to align [national] objectives for the coming decades. It is clear that climate warming continues. There are many topics science still needs to discover. We still have uncertainties in aspects such as sea level rise and how it is going to be by the end of the century.

In your opinion, have climate scientists won the battle of ideas against climate change deniers?

There is still a conflict nowadays against deniers, but we have good arguments. We want to show that there is a large consensus within the climate community. When we look at the U.S. discussion, climate change has shifted to a political debate. Republicans are not deniers themselves, but they are skeptical and don’t want to take action. This is not based on real, scientific arguments, but simply on the fact that the battle against climate change is not in line with [economic neo-] liberalism at some points. If you accept climate change, you accept the idea that you are supposed to have solidarity at the international level. But politically that may not be the case.

Is science still disconnected with political decision?

Yes. As a member of IPCC, our position is that we need to have policy relevance. We should have direct connection with politicians. We are scientific advisors and express the wish of wanting to bring scientific evidence into the political discussion. I hope this helps lead to the success of the Paris agreement. I will do all my best.

Should policy makers really pay more attention to scientific community?

For the last 15 years in France the government has been inviting us to join their political decisions. In 2013 the IPCC group was invited to Ã‰lysÃ©e Palace [the official residence of the French president] to present scientific reports. And the president said government acts should be based on the IPCC [findings] and scientific evidence. In countries like China, scientists are very active. However in India it is more difficult to have a voice [as a scientist]. Also, the climate [science] community in Russia has not been very active.

Many countries have not yet released their INDCs [Intended Nationally Determined Contributions]. What role should developing nations have in the negotiations? Were they supposed to be at the forefront of the discussion?

One of the countries that supports the idea that nations should have differentiated levels of responsibility is Brazil, and I partially understand its position. They say we should keep in my mind what has been emitted by different countries throughout the past, since the beginning of Anthropogenic era [200 years ago when the industrial revolution began increasing CO2 levels]. Even if those countries stopped their emissions today, we would still be going to reach a temperature beyond 2°C by the end of this century. Right now we are in the same boat. Differentiation of nations’ responsibility is clearly important.This is the spirit of Paris agreement. This is what Paris stands for. Brazil, however, hasn’t yet released its INDC. I hope it will announce soon its intended national contributions with some ambition.

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This figure shows the observed average global temperatures from 1900 to 2000 (black line) along with the temperature ranges predicted by climate models. (image: EPA)

It seems countries are waiting until the last moment to release their pledges.

Yes, this is how I see it. There are nations pushing until the last minute. At some point I am worried, but I am still optimistic to get some ambition from those countries that have delayed the release of their INDCs.

What would you ideally want to see included in the Paris deal?

I feel that the Green Climate Fund should be enhanced. There was a promise from developed countries for $100 billion a year. I hope it will be achieved by 2020. It shouldn’t be only addressed to help adaptation. We see that most countries are investing only in adaptation, and very few on mitigation. We are focusing too much on adaptation because it is easier. Mitigation doesn’t seem to be a priority for developing countries. They should also address mitigation to change their energy systems and convert to non-hydro renewables. That would be the case for Brazil and some oil-dependent countries.

We need to be clear at this point: if we want to keep the temperature to 2°C [average global increase] we have to leave 80 percent of fossil fuels that are easily accessed where they are — that means, in the ground. It seems difficult for countries like Brazil that happened to find recently a lot of oil under the pre-salt layer. That is not the way to go in the next 20 years. People will not accept the idea to go far beyond the 2°C temperature. We are talking about a 2°C target because it is the only way we can still adapt ourselves. At this temperature we still have the possibility of adaptation. Therefore we should leave fossil fuels on the ground. This is the key message, although it is not going to be so easy for developing countries. Energy matrix shouldn’t be built on fossil fuel energy — this is clear for scientists.

Do climate change scientists think a Paris agreement will indeed stop global warming?

It will never stop — but there is some hope. It is important to have in mind this urgency. It would have been much easier to deal with this issue if we had started 25 years ago. The scientific community agrees on a common message: it is not too late, but it is really urgent. We have to do it now and that is why the Paris Conference is so important. We should act now and we should be ambitious for post-2020 — decreasing the use of fossil fuels emissions and following a carbon neutral target by the end of the century if we wish to keep global warming at no more than 2°C. I hope we are not heading to 4°C; 2°C is still possible. We have to abandon the development based on fossil fuels.

This interview has been edited for clarity.

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