Those of us who follow the climate debate are well aware of targets - often expressed as a percentage of 1990 emissions. Now it would be nice to believe that they choose 1990 as being the year that I started work in the sector, but it's really just a convenient baseline, roughly matching the break up of the Soviet empire and a couple of years before the seminal Earth Summit in Rio. So we have ended up with an abacus of number - 20% improvements in energy efficiency by 2020, 30% cuts in CO2, the main gas causing climate change, by 2030 and 80% cuts by 2050. So just when you are wondering whether we will meet any of those targets, here's a new one: full decarbonisation by 2100. Suddenly the goalposts have moved from 35 years to 85. Is 85 the new 35 - and does it matter?
"The benchmark is the two-degree ceiling on global warming. The impacts of climate change will only be controllable to any degree if we manage to keep global temperature rise down to no more than 2° Celsius as compared to the pre-industrial period"Merkel explained. French President François Hollande, who will be hosting the Paris conference marking 20 years from Kyoto on climate change this autumn, stressed that the national emission reduction targets announced so far fall well short of what is needed to keep global warming under the two-degree ceiling and noted that so far only 40 of the 194 countries planned to attend have published targets.
Merkel and Hollande jointly called on the international community to completely renounce the use of oil, gas and coal over by 2100.
"All energy needs should be met using renewable sources. We must decarbonise our economies in the 21st century,"added the German Chancellor.
So will it happen, or will the cynics be proved right? I am hopeful that it can, and believe that it is quite helpful to have a very long term goal - not least to give us a point against which to recalibrate if we slip, as I fear we inevitably will, on some of the intermediate ones. And is it achievable? With political will - which must include the USA, China, Russia and key developing countries as well as Britain and other EU countries - yes. 85 years is still a long way away, although young children alive today in developed countries will probably live to see it.