Policy relevant....

So here is a map of potential policy-relevant tipping elements in the climate system. It's been updated from Schellnhuber and Held (2002) and overlain on global population density (Lenton et. al., 2007). Subsystems indicated could exhibit threshold-type behaviour in response to anthropogenic climate forcing.These could be triggered this century and would undergo a qualitative change within this millennium, i.e. something man would defiantly notice!  

Exclude from the map systems are any thresholds which appear inaccessible this century (e.g., East Antarctic Ice Sheet) or the qualitative change would appear beyond this millennium (e.g., marine methane hydrates). 

A question mark indicates systems whose status as tipping elements is particularly uncertain.

I like to think that all these issues are being seriously considered by the higher ups and debated, especially at this year's climate summit. Here's hoping....

References

1. 1. Lenton, T.M. Held, H. Kriegler, E. Hall, J.W. Lucht, W. Rahmstorf, S. Schellnhuber, H.J. (2008)
      Tipping elements in the Earth’s climate system. Proc. Natl Acad. Sci. USA 105, 1786–1793.
   
   
   Schellnhuber, H-J. , 
2. Held, H. 

(2002) in Managing the Earth: The Eleventh Linacre Lectures, edsBriden J , Downing T (Oxford Univ Press, Oxford), pp 5–34.