'No solution' found in more trees
BBCNews.com, Nov. 28, 2003
Planting trees in the Amazon to curb global warming is unlikely to work.
Brazilian and US scientists have found the rainforest emits more of the greenhouse gas carbon dioxide than it absorbs when conditions are very wet.
Their report, published in the journal Science, comes just three days before the latest United Nations negotiations on climate change take place in Milan.
The researchers say previous studies have almost certainly over-estimated how much CO2 the Amazon can take in.
The study by Scott Saleska, from Harvard University in Cambridge, Massachusetts, is pertinent because the idea of using forests to curb global warming forms a central plank of the Kyoto Protocol.
The treaty allows countries to plant new trees and conserve old forests rather then cut the amount of greenhouse gases they produce.
But this latest research undertaken over three years in the Amazon provides graphic new evidence that the relationship between trees and carbon dioxide is a complex one.
Saleska's study of old-growth Amazonian rainforest shows clearly that drought or other disturbances that kill trees can lead to higher levels of carbon dioxide release.
These increases in carbon loss occur during wet seasons when the dead wood breaks down, not during the dry season as has been generally found.
Many environmentalists believe that politicians have run ahead of scientific understanding in giving forestry such prominence in the Kyoto Protocol.
They argue tree planting has been seized on not because it is good science, but because it is politically expedient.