What science tells us about future temperature rises

If greenhouse gas emissions continue to rise at current rates, then global temperatures could rise by more than 6 °C over this century. This will lead to increasingly dangerous effects on society. To avoid the worst effects it has been proposed that temperature rises are limited to 2 °C.

However, the latest climate projections from the Met Office Hadley Centre show just how challenging this target is. This was brought into sharp focus in results presented to policymakers at CoP in Poznan last December, and in calculations produced for the UK Committee on Climate Change.

Dr Vicky Pope, Head of Climate Change Advice at the Met Office states: “Even with drastic cuts in emissions in the next 10 years, our results project that there will only be around a 50% chance of keeping global temperatures rises below 2 °C.

“This idealised emissions scenario is based on emissions peaking in 2015 and quickly changing from an increase of 2–3% per year to a decrease of 3% per year. For every 10 years we delay action another 0.5 °C will be added to the most likely temperature rise.”

The Met Office produced these scenarios, and similar ones used by the Committee on Climate Change, looking at a number of possibilities to help guide policymakers’ negotiations. All the scenarios confirm what many others will also be reporting at a high-profile science meeting in Copenhagen in March — that limiting the temperature rise to 2 °C is looking increasingly challenging.

Dr Jason Lowe, Head of Climate Mitigation advice at the Met Office says: “The results also highlight that if global warming continues unabated then the risks of even greater warming are increased, making climate change even more dangerous.”

And Dr Pope warns: “The science tells us that we should continue to work to reduce the chances of global temperature rises going above 2 °C. However, if the world fails to make the required reductions, it will be faced with adapting not just to a 2 °C rise in temperature but to 4 °C or more by the end of the century.”