85 per cent of Amazonian rainforest at risk of destruction, researchers warn

The Times
March 12, 2009

Lewis Smith, Environment Reporter, Copenhagen

The Amazonian rainforest is likely to suffer catastrophic damage, even with the lowest temperature rises forecast under climate change, researchers have decided.
The damage will be so severe that it will cause irreversible changes to the world’s weather patterns, which is expected to bring more storms, floods and heat waves to Britain.
Up to 40 per cent of the rainforest will be lost if temperature rises are restricted to 2C, which most climatologists regard as the least that can be expected by 2050.
Climate change researchers issued the assessment of the forest’s fragility after discovering a time-lag in the effects of temperature rises on the forest.

It had previously been thought that the trees and other vegetation, and the vast range of animals living among them, would be safe if temperatures rose no more than 2C. Researchers have now found that even 2C will destroy large tracts of the forest but that the die-back is slow and will take up to a century to have its full effect.
A 3C rise is likely to result in 75 per cent of the forest disappearing and a 4C rise, regarded as the most likely increase this century unless greenhouse gas emissions are greatly reduced, will kill off 85 per cent of the forest.
Chris Jones, of the Met Office Hadley Centre in Exeter, told a scientific conference in Copenhagen that the time delay had masked the full impact of temperature rises. He led a team of researchers who calculated that 20 to 40 per cent of the forest will be killed off by 2050 if there is a 2C rise.
“We are committed to losing a fair degree of the forest,” Dr Jones told scientists. “Everything above 1C commits us to some forest loss.”
Until Dr Jones presented his findings it had been assumed that the Amazonian rainforest was safe from severe climate-related loss until temperatures rose more than 3C. However, the slowness of forests to respond to change hid the likely real impact.
A 1C temperature rise is expected to be reached in the 2020s. Temperatures have already risen 0.75C above pre-industrial levels and so much greenhouse gas is in the atmosphere that a further 0.6C is already guaranteed.
Vicky Pope, the head of climate change advice at the Met Office Hadley Centre, said the findings showed that the threat to the forest was much higher than expected.
“Impacts could be much worse than previously thought,” Dr Pope said in Copenhagen, where scientists have been meeting to discuss the latest research into climate change and its effects. “Even if temperature rises are limited to 2C above pre-industrial levels, as much as 20 to 40 per cent of the Amazonian rainforest could be lost if this temperature is sustained for 100 years or more.”
Trees will be lost to the rise in temperatures because as forests warm up, evaporation rates increase and they begin to dry out. Over several decades the drier conditions will kill off the trees.
Other research presented at the conference showed that there is a significant chance that even if greenhouse gas emissions are reduced, temperatures may not start falling for at least a century.
Peter Cox, of the University of Exeter, said of the finding that at least a fifth of the Amazonian rainforest was almost certainly doomed. “Ecologically it would be a catastrophe and it would be taking a huge chance with our own climate. The tropics are drivers of the world’s weather systems and killing the Amazon is likely to change them for ever. We don’t know exactly what would happen but we could expect more extreme weather,” Professor Cox said.
Destroying the Amazonian rainforest would also turn what was now a significant carbon sink into a significant source of carbon, he said. “It would amplify global warming significantly. Just as an example, at the moment deforestation adds about a fifth of the world’s carbon to the atmosphere.”