a rise of 2 degrees

Like most climate scientists, Sir Nicholas [Stern] seems to believe that if we want to avoid dangerous climate change, we should seek to prevent the global teamperature from rising by 2 degrees centigrade above its pre-industrial level. If we fail to do so, he says,'0.7 to 4.4 billion people' could suffer 'growing water shortages'. There is a high chance of 'falling crop yields in many developing regions'. The Amazon rainforest 'could be significantly, and possibly irrevocably, damaged'; 15-40% of the world's species face extinction; 'small mountain glaciers disappear worldwide', threatening water supplies; and there is the 'potential for the Greenland ice sheet to begin melting irreversibly, accelerating sea level rise and committing the world to an eventual 7 metre sea level rise'.