The harshness of this winter should not make us forget the reality of global warming. The American president seems to want to make his country a leader in the fight against greenhouse gas emissions.

A new wind has invaded American and global politics with the inauguration of Barack Obama last January 20th, while a bad wind blew in the southwest of France four days later. We will try to connect these two high profile events.

The first temptation when faced with the violence of Hurricane Klaus which hit on January 24th in northern Spain and south-western France, and the desolation that it left behind it in the vast pine forests of the Landes, is to relate this event to global warming.

Another temptation, this time that of climate skeptics, is to try to show that the coldest winter that we have had in Switzerland since 1987 is proof that global warming doesn’t exist. Which, in fact, confuses a lot of people.

In terms of the current winter in Switzerland, it was said numerous times that global warming is evident in the long term and on a continental scale, not on the basis of a season confined to one part of Europe. The tendency to warming has shown itself for more than a century and has accelerated since the 1990s in conformance with predictions. This does not prevent us from seeing one or several particularly cold seasons return, which doesn’t do anything other than momentarily flex the increase in atmospheric temperatures. This is what one would call “natural variability” of the climate, or in other words the combination of numerous mechanisms that make the climate fluctuate around a certain norm. It could be that we are currently in a conjunction of climatic patterns that favor a series of cold winters, but sooner or later the warming will continue.

In terms of the storm on January 24th, it is no longer possible to relate it with global warming because, if there were a direct relationship of cause and effect between a level of a particular temperature of the atmosphere and the frequency or intensity of storms, one could logically have, not once in a decade but several times per year, a flood of these disturbances.

The temperature of the atmosphere, as a source of energy, certainly represents a necessary condition for this type of storm, but it is an insufficient condition. In fact, winter storms like Lothar at the end of 1999 or like the very recent Klaus are generated by complex hydrodynamic mechanisms, notably the surface temperatures, the latent energy freed by the formation of clouds, or even kinetic energy provided by the behavior of the wind in terms of altitude. In certain conditions, a little disturbance arising, for example, off of the U.S. cost can grow to reach the same intensity as that which destroyed around 60 percent of Finnish forests in several hours. Very happily, only a tiny fraction of the atmospheric disturbances develop to reach the degree of intensity of Klaus and one therefore sees that the extreme storms occur independently of the tendency to warming. Furthermore, the future projections of climate models do not seem to indicate an increase in the number of storms (in the regions recently hit by Klaus or those devastated in Switzerland by Lothar almost 10 years ago, in any case). Maybe because there will be a certain compensation between the mechanisms responsible for the increase in these storms? What is sure, however, is that other types of meteorological and climatic extremes will increase in frequency and in intensity, in particular heatwaves, extreme rain and droughts….

And Barack Obama in all these problems? The hopes raised by his election after eight years of a reign of sad results make him number one in the press, whether it be in regards to social (health, education) economic (the recovery plan) technological (energy), ethical, or environmental issues. It is undeniable that the new president has surrounded himself with a team whose collective and individual competencies have rarely been equaled in Washington. The enthusiasm and the eloquence of Obama give people the desire to believe in him.

In appointing John Holdren to the position of “Mr. Climate” in the United States, Barack Obama has definitively turned the page of the Bush era and seems to be beginning a series of reform projects concerning energy and mobility, sources of a large part of greenhouse gas emissions. America finally returns to the negotiation table with a proactive attitude in a pivotal year where it is going to be necessary to agree on the implementation of the post-Kyoto in the ministerial conference that will be held in Copenhagen in December. If what we see since January 20th in Washington follows the same rhythm, the United States could even become (again) the world leader in the fight against global warming. There isn’t really European leadership that would pave the way for the rest of the planet, even if since one or two years ago Europe has made propositions with interesting measures to reduce greenhouse gas emissions, propositions that were ratified at the end of 2008 by the 27. On the cutting edge of the environment 10 to 15 years ago, Switzerland is happy today with aligning itself with European positions, which is not a bad thing in and of itself but which well illustrates the lack of leadership.

Barack Obama has reason to act quickly and to make up the lost time. A recent study that appeared in the journal Nature indicates that the inertia of the climate system is such that, having passed a certain threshold of temperature, we will have to wait until the year 3000 before the climate finds its real level, whatever the measures of protection taken may be. If the atmosphere was the only element of the climate in jeopardy, the inertia would be much less important (a few months to several years). However, the atmosphere that is warming communicates its heat to the ocean, which, in turn, stores it in its surface layers, the polar ice shrinks, accelerating the warming of cold regions. If later atmospheric temperatures were to stabilize, the heat stored in the ocean would be slowly but surely restored to the atmosphere. The new thermal conditions of the poles would no longer permit the atmosphere to get colder. One could compare this ocean inertia to the electric plate on a stove that warms up in several seconds, but requires many minutes to cool down – continuing to defuse its heat in the air.

Before such a pessimistic conclusion, one can ask oneself if it is worth it to take on costly measures now if one will have to wait a millennium before the climate calms down. The response is clearly yes. We find ourselves perhaps in a position where, if we take appropriate measures, it is still possible to curb global warming by a few decades rather than by centuries. The challenge that Obama seems to want to pick up is to break another inertia, that of the political world faced with the necessity of making important decisions.