NB : this article has been published in the paper 20 minutes dated june 24, 2002.
It is now established that, since 1750, man accumulates some gases in the atmosphere : carbon dioxide, methane and nitrous protoxyde for the main part. Coming from the use of coal, oil and gas, from agriculture, from fertilizer use, from deforestation, etc, these gases significantly -and most of all very quickly – reinforce the natural greenhouse effect, that models the climate system. From there we will get an increase of the average surface temperature, but also, most likely, an increase of the phenomena “out of the norm” or inexpected : unusually mild winters, unusually intense rainfalls, summer droughts, violent winds are some examples. An average temperature gaining several degrees in a century would constitue a true “climate shock”, and one has hard times to imagine how it could radically modify our environment.
Among the consequences, massive destruction of ecosystems, starvations, breakouts and conflicts are perfectly possible, and more generally we will considerably increase the pressure on a world already fragilized by some of our other behaviours, nobody being able to guarantee that there will be some sanctuaries. Because of the very long lifetime of greenhouse gases above our heads (one century or more), the dice are already thrown for part of the future evolution : whatever we do tomorrow, the climate will be modified because of us for the centuries to come (and sea will rise for millenaries).
However the brutality of the ongoing evolution still heavily depends on our emissions of the decades to come. At what level shoudl we act ? To stop enriching the atmosphere in greenhouse gases, we should divide the world emissions by 2 at least. If every earth resident has the same “right to emit”, it then represents a division by 4 of the present emissions for a country like France, and by 12 for the US. Well, the Kyoto protocol only asks for a 5% decrease of the emisssions of the sole industrialized countries : even if we manage to meet this objective, we are very far from being out of trouble for such. Decreasing our emissions is not compatible, for example, with the development of air trafic and the number of cars in the world, with housing always more spacious, an important meat consumption, and more generally wwith the development of material consumption. If prolongating the trends perhaps leads us to a catastropha, mitigating efficiently climate change would in no case be a marginal correction in a globally unchanged world : it is a diffficult choice, that concerns all of us as consumers.