(Climate News Network, 7 Jul 2021) More carbon dioxide could parch the rainforest as effectively as the woodman’s axe or farmer’s torch. Both are on the cards.
Brazilian scientists have identified a new way to take the rain out of the rainforest. All the world has to do is to make sure more carbon dioxide reaches the trees − half as much again as today.
The effect will be stark: it will be roughly the same as if Brazil’s business leaders, politicians and farmers cleared the entire Amazon rainforest and replaced it with cattle pasture.
As climate scientists have been pointing out for years, both processes seem to be happening anyway. The region is already experiencing fire and drought as greenhouse gas emissions continue to rise. And great tracts of the forest are being destroyed, degraded or felled in pursuit of land for soya or beef. What is new is the confirmation that extra carbon dioxide can itself affect the levels of rainfall on the canopy.
That is because most of the rain that in the right season sweeps almost daily over the inland Amazon is not freshly evaporated water from the Atlantic, but condensed from vapour transpired from the forest foliage. As the forest extends inland, most of the rainfall is recycled, again and again. In effect, a great rainforest powers its own repeating sprinkler system. And more carbon dioxide in the atmosphere could limit the flow.