Act now to limit climate change says climate expert at Grantham Annual Lecture

Professor Thomas Stocker speaking at the 2013 Grantham Annual Lecture at Imperial College London.

The chance to keep global warming below the safe level of a 2°C increase is rapidly disappearing said Professor Thomas Stocker.

The professor of climate and environmental physics at the University of Bern in Switzerland, was speaking at the 2013 Grantham Annual Lecture on 26 November at Imperial College London.

In his talk on ‘Anthropocene: The Closing Doors of Climate Targets’, he presented an overview of how human activities since 1870 have changed the climate system and the need to reduce CO₂ emissions rapidly to limit mean global warming to a safe level.

Professor Stocker told the audience that the influence of humans on the climate system is so great that we have now entered a new geological epoch, the Anthropocene. A period that he said would be recognised in the future by the significant increase in the amount of CO₂ in the atmosphere compared to the previous 800,000 years.

As co-chair of the Intergovernmental Panel on Climate Change (IPCC) Working Group I, Professor Stocker led a group of over 600 scientists, which published its fifth assessment report on the current understanding of physical science basis of climate change on 27 September.

In his talk, he said that there were three key messages to take from the 2,000 page report:

• Observation of warming of the climate system is now unequivocal
• Human influence on the climate system is clear
• Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions

A warming of 2°C above pre-industrial global temperature is the level of safe climate change agreed by the international community. Professor Stocker said this has already become an ambitious target and that the chance of keeping to it is rapidly disappearing as the rate of CO₂ emissions from human activity continues to increase.

Professor Stocker finished his talk with the message that the international community has to act now and that any further delay in reducing emissions could “close the door on limiting global mean warming, and consequent impacts, permanently”.