Tipping Elements

Previously discussed was the idea of tipping points – it was briefly mentioned the idea of tipping elements however I did not elaborate on this.  So briefly I will look into some of the most important tipping elements now to give you an idea of where they can be found! I will explain why each one may be a potential tipping element and its importance in the earth’s system.

Arctic Sea-Ice: simply, as sea ice melts a darker ocean surface is exposed so more radiation can be absorbed. This amplifies warming! This provides a positive feedback system on climate. (Lenton, 2008) Data shows that both summer and winter sea ice are declining at present, with large areas showing a great deal of thinning. (Stroeve, 2007) Is there a cut off point for the melting of sea-ice that will be the tipping point?!

Source: NASA
The 2010 shot of the Arctic Sea Ice. This year showed a maximum in sea ice that was unexpected from the trend of the previous years, however was still below the 30 year average. (NASA, 2010)

Greenland Ice Sheet: warming of the ice sheet at its periphery lowers the altitude of the ice and as a result increases the surface temperature. Again this leads to positive feedback, in addition there is potential that this could cause the ice sheet to disappear. (Lenton, 2008) The IPCC (2007) have put this threshold for the disappearance of the ice sheet between 1.9°C-4.6°C above pre-industrial levels – one we can all agree isn’t too far off the horizon…

Atlantic Thermohaline Circulation (THC): The THC plays a large role in the rapid climate changes that have been recorded in Greenland in its historic records.  Should a large amount of water or heat enter the North Atlantic, the North Atlantic Deep Water formation and the connected Atlantic THC will be caused to shut off. All models of this have so far showed a collapse of convection and a tipping point being crossed, thus having a large effect on climate. (Lenton, 2008) The IPCC (2007) claim this is unlikely to occur anytime before 2100 (not long in the grand scheme of things) and that any subsequent transition would take more than a century. (so maybe let’s not worry too much about this, who knows?)

It is the uncertainty in the tipping points that make them more worrying. However with increased research several tipping elements have been identified and the warning signs for approaching tipping points are becoming somewhat better understood. This does not make them any more promising for the future of the earth’s climate, there is still a quite desperate need to avoid them!