Could Ennis, Farah, Bolt, Higgs and Nasa help sort our climate tipping points problem?

Mike Childs

13 August 2012

I'm pretty optimistic about human's ability to do great things.

Feats like landing a one tonne robot on Mars; the discovery of the Higgs boson; and even Jessica Ennis, Mo Farah and Usain Bolt at the Olympics all demonstrate human brilliance and determination.

So should I really worry about climate change? Surely we'll sort this problem out, even if it is at the last moment?

Let's hope that's the case. But there could be a stumbling block - climate change tipping points.

Climate tipping points occur when you suddenly pass a point of no return. There are a number of climate tipping points we need to be concerned about. These are reviewed in a paper produced for Friends of the Earth by James Price. The two tipping points to be most immediately worried about are:

• Arctic summer sea ice - sea ice melt increases the expanse of darker sea which is then warmed by absorbing the sun's energy and this melts more sea ice. The tipping point for Arctic summer sea ice is thought to lie somewhere between 1 to 2.5 degrees of global warming above pre-industrial levels. After this tipping point is crossed an ice free Arctic sea will become a norm during summer. We are already committed to around 1.5 degrees of warming. Melting Arctic ice may already be the cause of the recent freezing cold winters experienced in the UK and other northern countries which suggests that if we cross this tipping point these cold winters could also become the norm.
• The Greenland Ice sheet - the melting of the Greenland ice sheet contributes to sea level rise and if it completely melts it could raise sea levels by a massive 7 metres. Recent work has suggested that a best guess of the likely tipping point to the irreversible melting of the ice may be 1.6 degrees warming above pre-industrial levels, although with a range of possibilities spanning 0.8 to 5.1 degrees. If we cross this tipping point we commit future generations to a very changed world, even though the melting may take hundreds or thousands of years.

But there are also a number of climate tipping points that emerge if global temperatures go 3.5 degrees higher than pre-industrial levels - and we're currently on track for 4 degrees of warming. These include replacements of forests globally with other ecosystems due to forest dieback, irreversible ice sheet melting of the West Antarctic Ice Sheet, a shift in the West African monsoon, and changes to the sea currents, such as the Gulf Stream that keeps Western and Northern Europe warm for its latitude.

All this suggests we need apply human brilliance and determination in reducing climate emissions extremely fast if we want to avoid the complete loss of the summer Arctic sea ice and irreversible melting of the Greenland ice sheet. If we want to avoid the other tipping points we also need to cut emissions far far quicker than current plans.

It isn't too late to stop dangerous climate change as our new briefing explains but I wonder whether Ennis, Farrah, Bolt, Higgs and NASA would mind lending us a helping hand?

This blog was written by James Price and reviewed by Tim Lenton's team of experts on climate tipping points at Exeter University.