In order for the concentration of greenhouse gases (GHG) in the atmosphere to diminish, global emissions must be reduced by at least one-half or two-thirds, as soon as possible. If this amount of reduction is equitably shared out on a world scale, the emissions of a resident of France should be reduced by three-quarters or four-fifths. With this in mind the French Energy Programme Law of 2005 set the objective of cutting emissions by 75% in France by 2050. This is a major challenge, and to date few stakeholders and citizens have measured its scope.
All of humankind together emits more than twice as much CO2 as can be absorbed by natural ecosystems such a forests, prairies and oceans at the present time. Methane and nitrous oxide require smaller reductions, but fluorinated gases must be completely eliminated. Holding the temperature increase down to a “manageable” level (and this notion opens another debate) means that the concentration of GHGs must necessarily be stabilised. For CO2 this means cutting global emissions in half, as quickly as possible. In accounting terms, this means in theory that in 2008 each inhabitant of the Earth has the right to emit less than 2 tonnes CO2-equivalent, at the very most, each year (and undoubtedly less in coming years if emissions and the world population continue to grow).
The target of 2 tonnes CO2-equivalent is a major challenge. In the current state of technology, this “emission quota” is rapidly attained. Just one of the following actions suffices:
driving 5 000 to 7 000 km in urban areas in a small car
a few months of natural gas heating for an average house
a few months of purchases at the electronic goods store and the supermarket
a round-trip plane trip from Paris to New York (as an order of magnitude).
It must be kept in mind that as hydrocarbon reserves are finite, reductions on this scale will have to be made “one day or another” (see the web page on future oil, gas and coal production). Greenhouse gas emissions (and CO2 in particular) will fall someday, well before the end of this century. It remains to be seen whether we want to control this contraction, or submit to it. The first option involves small drawbacks in the short-term, in order to avoid big trouble later on. The second option allows us to maintain our current life style for a few more years, but at a prohibitive cost. If we change nothing the youngest members of the population, and all those to come, will pay a tremendous price, bearing the brunt of an energy crisis and major climate change that will in all likelihood put an end to the golden age in which we have lived for the past 60 years and which has given us peace, prosperity, democracy, health, abundant food and education for all.
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