Amazon drought caused huge carbon emissions

RIO DE JANEIRO Thu Feb 3, 2011 2:15pm EST

A Brazilian crosses the muddy bottom of the Rio Negro, a major tributary to the Amazon river, in the city of Manaus, October 26, 2010. REUTERS/Euzivaldo Queiroz/A Critica

A Brazilian crosses the muddy bottom of the Rio Negro, a major tributary to the Amazon river, in the city of Manaus, October 26, 2010.

Credit: Reuters/Euzivaldo Queiroz/A Critica

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RIO DE JANEIRO (Reuters) - A widespread drought in the Amazon rain forest last year was worse than the "once-in-a-century" dry spell in 2005 and may have a bigger impact on global warming than the United States does in a year, British and Brazilian scientists said on Thursday.

More frequent severe droughts like those in 2005 and 2010 risk turning the world's largest rain forest from a sponge that absorbs carbon emissions into a source of the gases, accelerating global warming, the report found.

Trees and other vegetation in the world's forests soak up heat-trapping carbon dioxide as they grow, helping cool the planet, but release it when they die and rot.

"If events like this happen more often, the Amazon rain forest would reach a point where it shifts from being a valuable carbon sink slowing climate change to a major source of greenhouse gases that could speed it up," said lead author Simon Lewis, an ecologist at the University of Leeds.

The study, published in the journal Science, found that last year's drought caused rainfall shortages over a 1.16 million square-mile (3 million square km) expanse of the forest, compared with 734,000 square miles (1.9 million square km) in the 2005 drought.

It was also more intense, causing higher tree mortality and having three major epicenters, whereas the 2005 drought was mainly focused in the southwestern Amazon.

As a result, the study predicted the Amazon forest would not absorb its usual 1.5 billion metric tons of carbon dioxide from the atmosphere in both 2010 and 2011. In addition, the dead and dying trees would release 5 billion metric tons of the gas in the coming years, making a total impact of about 8 billion metric tons, according to the study.

In comparison, the United States emitted 5.4 billion metric tons of carbon dioxide from fossil fuel use in 2009.

The combined emissions caused by the two droughts were probably enough to have canceled out the carbon absorbed by the forest over the past 10 years, the study found.

GREATER WEATHER EXTREMES

The widespread drought last year dried up major rivers in the Amazon and isolated thousands of people who depend on boat transportation, shocking climate scientists who had billed the 2005 drought as a once-in-a-century event.

The two intense dry spells fit predictions by some climate models that the forest will face greater weather extremes this century, with more intense droughts making it more vulnerable to fires, which in turn could damage its ability to recover.

Under the more extreme scenarios, large parts of the forest could turn into a savannah-like ecosystem by the middle of the century with much lower levels of animal and plant biodiversity. Although human-caused deforestation in Brazil has fallen sharply in recent years, scientists say the forest is still vulnerable.

A crucial question is whether the droughts are being driven by higher levels of greenhouse gases or are an anomaly, Lewis said. If they are driven by global warming, a vicious cycle of warmer temperatures and droughts could conceivably lead to a large-scale transformation of the forest over a period of decades.

"You could quite rapidly move to a much drier Amazon with less forest there," Lewis told Reuters.

The research was a collaboration among scientists at the University of Leeds and the University of Sheffield in Britain and Brazil's Amazon Environmental Research Institute.

(Editing by Will Dunham)

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Comments (5)
adamstwi wrote:
“The combined emissions caused by the two droughts were probably enough to have canceled out the carbon absorbed by the forest over the past 10 years”–This is disastrous & tragic; and what makes it even more is even though you’re aware of the fact, you cannot do anything about it.

Feb 03, 2011 8:00pm EST  --  Report as abuse
SparkyVA wrote:
Actually this research was preformed by two 3rd graders and one fourth grader. Please stop calling them scientists: there is nothing in this report that required any scientific discipline. The statement that drought causes global warming causes more drought while appealing to third graders is not scientific. The weather systems of the earth are a complex heating and cooling system. More heat means more evaporation. More evaporation means more precipitation. Drought is due to uneven distribution of the precipitation. If it warms the area, that heat will be transported by one of many processes including evaporation which leads to more precipitation. No, Adamstwi, the sky is not falling, and this earth is good for a few billion more years.

My worry is that intelligent life seems to be dying off as can be shown by the rigor of this “scientific” report.

Feb 04, 2011 7:03am EST  --  Report as abuse
MrGart wrote:
‎”…the United States emitted 5.4 billion metric tons of carbon dioxide from fossil fuel use in 2009″ is just one of the shocking statements in this article.
How anyone can still believe that that doesn’t have a measurable impact on global climate, can still deny that the human factor in global warming is evident, is beyond me. You must REALLY live with your head stuck firmly up your behind, if you still deny global warming is caused by the emission of greenhouse gases by the world’s industry and fossil fuels.
I wonder why so many people remain so adamant in their denial, in ridiculing what’s painfully obvious. What’s your stake in it? Your job? Your car? The reluctance to make changes in your life to help curb carbon emission? Are you that selfish? Or do you own stock in Big Oil?
It’s like those people who keep denying that smoking causes cancer, because Aunt Bertha smoked all her life and lived to be 99.

I live in the Amazon rainforest of northern Peru. I experienced last year’s drought myself. I am happy and grateful to live in one of the most amazing and beautiful places on earth, while my heart breaks seeing it slowly die and wither away.

Feb 04, 2011 11:00am EST  --  Report as abuse
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