Comments gathered from our colleagues at the Science Media Centre in London
Dr Chris Huntingford, Centre for Ecology and Hydrology, said:
“As more key countries, including the superpowers, sign up to major emissions reductions, there emerges the real chance that we can provide a safe and stable climate for future generations.
“All current knowledge of how the climate system operates suggests that to prevent dangerous future levels of global warming, emissions must both peak in the very near future followed by dramatic reductions in fossil fuel use over the next few decades. That is why these pre-Copenhagen announcements are monumental in aiding future protection of our global environmental.
“Although there does remain some uncertainty in the exact magnitude of response of the climate system to human intervention, what is not controversial is that if emissions grow at the current rate, then there will be irreversible and dangerous change. Major alterations of the climate system could affect river flows and crop yields. Hence these announcements to decrease future emissions rates have major and welcome implications for ensuring future food and water security for all.
“It is encouraging for the climate change researchers to see that their predictions of what is needed to avoid dangerous climate change now appearing in international policy. This places a heavy responsibility on the climate change scientists to be absolutely correct. There is very compelling evidence the current changes we are witnessing are not a natural cycle, and that computer predictions of major future warming without emissions reductions can be trusted.
“Climate change research can be given credibility in that multiple independent teams have analysed existing temperature measurements. All these independent groups conclude that rapid global warming is happening, it is a serious threat, and to prevent this reaching dangerous levels implies a massive switch by society away from burning fossil fuels.
“There is compelling evidence from measurements and climate model simulations that global warming exists, and the rate of warming seen during the last century is not a natural cycle. As we move onwards, climate research and policy will need to iterate to determine the precise emission reductions needed to avoid dangerous climate change. However all indications are that around 80% reductions will eventually be needed, and it is heartening to see such numbers in statements by the US. If applied globally, there is strong evidence that we will achieve a safe and stable future climate, and as such the recent announcements are very welcome news indeed.”
Robert Bell, Chief Technical Officer at AEA, advisors to the UK government on climate change, said:
“China had previously said it would announce a ‘notable’ carbon intensity reduction target. A 45% reduction relative to 2005 matches that description. Obviously it means absolute emissions will still rise, perhaps even doubling by 2020, but no-one believes China is in a position to offer an absolute reduction. As with the US offer of a 17% absolute reduction relative to 2005, which is only a 3% reduction relative to 1990, the important issue is that both targets could help get initiatives on the ground moving. That is what is urgently needed. A 55% reduction offer from China would have been more in keeping with the requirements of climate science, but 45% is a good step. It will itself require a continuation of China’s recent strong policies.”