Hervé Le Treut, scientist and member of IPCC, talks about 20 years of climate science.
Since the first Rio summit, what changes have occurred climate-wise?
In 1992, scientific results that indicated global warming were based on physical models that were still simple. These results were confirmed by many more precise studies and the climate itself is now evolving perfectly in line with the forecasts. But the outlook is bleak: the 2°C temperature rise the international community has pledged not to exceed could be reached by 2050.
How do you explain that in spite of the accumulated scientific proof, there are still so many people who doubt climate change?
Of course, there are lobbies linked to economic or political players who regard this scientific diagnosis as a barrier to their activities. There are also a lot of people who are frightened by these expected changes, those who don’t want to be blamed and those who fall into both categories: they prefer to ignore warnings and listen to messages that allay their fears. Anyway, we must avoid unnecessary debates in favour of necessary ones. As regards the evolution of climate change, there are certainties as well as uncertainties; we are thus faced with difficult choices. China is now the world’s biggest polluter.
What effect will this have on the planet?
The rapid growth of emerging countries has given a new twist to the problem. Admittedly, a Chinese pollutes half as much as a European and an Indian pollutes it even less: how can we deprive them of the growth we ourselves have attained with little hindrance? But they are collectively leading to a new wave of increased greenhouse gas emissions even though these emissions need to be reduced. In the face of inevitable climate change, we shall have to develop adaptation strategies.
Do you have any particular expectations for the Rio + 20 summit?
I think that a certain form of enthusiasm and innocence has disappeared in the 20 years since Rio. How can we separate the climate problem from political and social demands, energy constraints, the will to protect biodiversity and feeding the planet? Will Rio + 20 help in producing a new form of governance adapted to such complex challenges ? Without firm answers to these questions, we may face more disappointments.
What are the challenges for RIO+40 in the next 20 years?
By the time Rio + 40 comes round, we will most likely have already faced new crisis situations. In terms of the climate – heat waves, droughts, melting ice – but also in other related areas such as the increased cost of energy. The challenge in the coming decades will be to react to these crises peacefully and democratically.
Interview by Olivier Blond
Extrait du livre « 20 ans après… la Terre Le bilan du développement durable » rédigé par la rédaction de GoodPlanet. Ce livre sort à l’occasion du 20e anniversaire du Sommet de la Terre de Rio et disponible dès le 14 juin2012 aux éditions de la Martinière. Soutenez-nous en achetant cet ouvrage.