Green House Gas concentrations in the earth's atmosphere have now reached a level higher than ever in the past half million years. The escalation started with the industrial revolution, around the year 1880, and is mainly due to increasing emissions of CO2 and methane resulting from human activity. If we do not take action, this upward trend will continue.
A very large majority of the experts observing and studying these phenomena have a clear message: barring a reduction of our emissions, in particular those of carbon dioxide, by a factor of at least 2 by 2050, the mean temperature on our planet will increase by several degrees during this century. Such an increase, similar in magnitude to what happened after the ice ages, but happening in a much shorter time frame, will have a major impact on the climate. Consequences on health, on vegetation and agricultural output, on sea level, on living species, etc. in many parts of the world will be significant. Irreversible evolution is likely. The world will be revolutionarily different. Faced with this dangerous climate warming, what are we waiting for to take action? We must limit our greenhouse gas emissions by all possible means without, however, precluding sustainable development for humanity.
While significant energy savings are possible and desirable in developed countries, similar efforts cannot be demanded from developing countries. Barring a major recession and catastrophic economic downturn, the global energy consumption will continue to increase. It is essential, then, whenever possible, to resort to energy production techniques that do not use fossil fuels. Such means are available for the centralized production of electricity: nuclear, hydro and wind energy. Solar photovoltaic is well suited for isolated regions and for countries with poorly developed electricity grids. Solar thermal, geothermal energy, well managed biomass, heat pumps, should take a larger share of the heating of buildings and hot water. Research should be directed to develop efficient storage technologies to facilitate a larger penetration of variable renewable sources in a national or regional grid. Transportation will continue for some time to rely on fossil fuels; it is all the more necessary to prepare the alternatives: more public transportation, more electric vehicles powered by decarbonized electricity, more hydrogen-powered vehicles, provided the hydrogen is produced by low carbon processes.
The time has come to decarbonize society by massively reducing dependence on fossil fuels. The only way of achieving this goal is by using all the tools we have that are technologically proven, economically viable, and safe, including renewables, hydro and nuclear. We therefore call on all policy makers and citizens to engage in a balanced energy policy, built on energy savings, and a mix of these decarbonized technologies. Only such a policy may have a chance to secure an acceptable and predictable climate to our and to future generations.