Independent on Sunday, 18 October 2015:
It may be reassuring to learn that Professor Rockstrom is cautiously optimistic, but the reality is rather different (“Climate change measures paying off, says scientist”, 11 October). The 1992 Rio declaration committed all nations to the “stabilisation of greenhouse gas concentrations in the atmosphere” and the prevention of “dangerous anthropogenic interference with the climate system”. Since then, annual emissions of carbon dioxide have risen by 60 per cent, atmospheric levels have passed 400 parts per million, and our current trajectory will use our entire remaining carbon budget by 2040. Renewable energy represents only 2 per cent of global primary energy production.
Anything agreed at Paris will not become operative until 2020 and will be voluntary. Professor Rockstrom points to the banning of CFCs as an exemplar of how to solve an environmental problem. But they were replaced by HCFCs and HFCs, which are powerful greenhouse gases. I pointed this out in an editorial for The Lancetin 1989. Sadly they are still in widespread use.
Dr Robin Russell-Jones
Stoke Poges, Buckinghamshire