More than 10% of all trees in the Amazon rainforest have been removed since the 1960s, scientists from the University of Edinburgh say. This has contributed to an increase in the amount of CO2 in the atmosphere, which in turn raises the potential impact of climate change.
Jean-François Exbrayat and Mathew Williams, who work at the University’s School of GeoSciences and National Centre for Earth Observation, wrote in the journal Geophysical Research Letters that Amazon deforestation accounted for about 1.5% of the increase in CO2 (carbon dioxide) levels since the middle of the 19th century.
This raised the total carbon amount in the atmosphere only marginally compared to fossil fuel emissions, which account for most of the increase.
The Amazon rainforest would be 12% greener than it is today if deforestation due to human activity had not occurred. (Image: knowledge.wharton.upenn.edu)
Carbon storage
According to the authors, theirs is the first study to show the extent of deforestation in the Amazon by determining what impact human activity has had on its ability to store carbon.
Had deforestation not occurred, the rainforest would today have 12% more vegetation, and would cover a considerably greater area.
Trees need CO2 in order to grow, i.e. they absorb carbon dioxide from the atmosphere in large quantities. This helps offset the impact of fossil fuel emissions and reduces the rate of climate change.
Modelling deforestation
Exbrayat, Williams and colleagues made maps to show how big the Amazon rainforest would be today if human activity had not deforested large areas of it.
High-resolution satellite photographs have been available only since 2000, so the researchers made virtual models to calculate how the rainforest had changed in earlier decades.
They used these models to study how the loss of trees reduced the Amazon’s ability to absorb carbon.
Trees consume carbon dioxide and help reduce the rate of human-induced global warming. (Image: fs.fed.us)
Widespread destruction
Destruction of vast areas of the Amazon rainforest affects its biodiversity and could lead to the loss of several animal and plant species.
“Our study indicates that the impact of large-scale deforestation on the Amazon carbon balance has been partially offset by ongoing regrowth of vegetation, despite sustained human activity.”
The study was funded by the Natural Environment Research Council.
Citation: “Quantifying the net contribution of the historical Amazonian deforestation to climate change,” Jean-François Exbrayat and Mathew Williams. Geophysical Research Letter. Publised 19 April, 2015. DOI: 10.1002/2015GL063497.
