In this temperature
range, both poles are certain to melt, bringing an eventual sea
level rise of 50 metres.
of the most dangerous of all feedback loops will now be starting
– runaway thawing of permafrost. Scientists estimate somewhere
in the region of 500 billion tons of carbon are stored in the arctic
ice, waiting to be released.
the death of the Amazon and runaway carbon feedback at 3C, stabilising
global temperatures at 4C may not be possible – 3C will lead
inexorably to 4C, will lead inexorably to 5C.