Rising temperatures, changes in rainfall patterns and an increase in atmospheric carbon dioxide has resulted in a burst of plant growth around the world over the last two decades, particularly in the Amazon rainforests of South America, according to new research.
A team of US scientists analysed climatic data and satellite observations between 1982 and 1999 to construct a global map of plant growth. Their findings reveal that, on average, plant productivity increased by 6 per cent, and that the Amazon region accounted for over 40 per cent of this global increase.
In the past, such boosts to tropical vegetation have been primarily attributed to an increase in carbon dioxide. But the authors of the new study — published this week in the journal Science — suggest that an increase in solar radiation, owing to less cloud cover, is the key cause.
"Our study proposes climatic changes as the leading cause for the increases in plant growth over the last two decades, with lesser contribution from carbon dioxide fertilisation and forest regrowth," says lead author Ramakrishna Nemani of the University of Montana.
The researchers stress that it is impossible to tell whether the positive impacts on plant growth are due to short-term climate cycles or longer-term global climate changes. And they point out that their study addresses only one aspect of the Earth's complex responses to climate change.
Reference: Science 300, 1560 (2003)
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