The report concludes that overwelming evidence can be found on land, in the oceans and in the air that human activity is driving up global temperatures and that changes observed in the last 60 years are ‘unprecedented’ over the last few thousand years.
It adds that significant cuts in carbon emissions are required immediately to avert a 2°C temperature rise as by 2011, 531 billion tonnes of carbon had been released this century out of a maximum quota of 840 billion tonnes which humanity must stick to if climate change is to be kept to ‘safe’ levels.
Trade body RenewableUK has greeted the report as a strong reminder of the need to increase deployment of renewable technologies. Deputy chief executive, Maf Smith, said: “The scientific community is sending a clear and unequivocal message to policymakers that urgent action is needed to reduce our carbon emissions and set in place paths to create a future of clean, carbon reducing sources of energy if we are to reduce our negative impacts on our environment.
“Wind has a vital role to play in this, given that as a result of wind power deployment in the UK we are reducing by 10 million tonnes every year the amount of carbon that we pump in to the atmosphere. This report shows that we cannot rest on our laurels though, we have to make sure that we hit our 2020 carbon reduction targets as well as looking beyond 2020 so we can create a decarbonised economy fit for the future.”
Greenpeace chief scientist, Doug Parr, said: “This report is about what kind of future we want. We either compound climate change by continuing to dig up and burn fossil fuels, then suffer the consequences, or we take a different path.
“Dangerous levels of warming of two degrees or more can be avoided, but this requires countries like the UK accepting the folly of grasping for yet more oil and gas in the Arctic, the tar sands and the Home Counties, and instead taking strong and rapid action on renewables.”
Energy secretary, Ed Davey, said: “The message of this report is clear – the Earth’s climate has warmed over the last century and man-made greenhouse gases have caused much of that global warming. The gases emitted now are accumulating in the atmosphere and so the solutions must be set in motion today. The risks and costs of doing nothing today are so great, only a deeply irresponsible government would be so negligent.
“Without urgent action to cut greenhouse gas emissions this warming will continue, with potentially dangerous impacts upon our societies and economy. This strengthens the case for international leaders to work for an ambitious, legally binding global agreement in 2015 to cut carbon emissions.
“This report is the most authoritative, credible analysis of climate change science ever. It represents a huge amount of work by over 250 unpaid scientific experts drawn from universities and research institutes in 39 different countries around the world. We owe them our gratitude because this report makes clear what is at stake if we don’t act.”