The counterattack of global warming on Amazon
The counterattack of global warming on Amazon
Amazon is also victim of global warming. Ever more frequent extreme events cause damage that linger for years in the forest. Photo: Disclosure
Manaus, AM-effects of global warming have been devastating to the Amazon rainforest. Droughts and storms, increasingly frequent, have killed trees and leaving scars be healed. Recently published studies demonstrate that the damage caused by these extreme events, related to climate change, can last for years and result in the emission of millions and even tons of greenhouse gases.
The year 2005 was tragically striking for the forest. Devastating storms earlier this year caused the death of millions of trees throughout the region. In the following months, came a great drought, with a peak in October, which reached 30% of the Amazon basin, or the equivalent of 1.7 million square kilometers, leaving damage which continued to be observed long after.
In extreme droughts, trees can lose branches and die slowly. For the atmosphere, means the release of greenhouse gases that fuel global warming. Carbon emissions caused by the drought of 2005 are estimated between 1.2 and 1.6 billion tons. For comparison, the historical average emissions from deforestation in the Amazon since 1975 is close to 200 million tons per year.
But scientists still seek tools to understand the damage caused by the string of extreme events on the region. They fear, for example, that major recurring droughts may change the structure and functioning of the Amazon ecosystem. An article published by NASA, on January 22, the magazine of the United States National Academy of Sciences, PNAS, demonstrates that the concern is well founded. The American researchers found that the forest had not yet recovered from the damage of 2005, when a new great drought came, five years later. Before, the researchers believed in the ability of the forest to recover in just a year. But according to the study, an area of approximately 800 thousand square kilometers, the equivalent of little more than half of the State of Amazonas, continued to suffer the effects of drought for years. In 2010, the drought reached half of the Amazon basin, causing emissions that may have gotten more than three billion tons of carbon.
Phenomenon known as blowdown is able to pluck trees from the ground. Photo: Disclosure.
If frequent and severe droughts are bad news, cheer for much rain also does not help. According to Forester Niro Higuchi, of the Instituto Nacional de Pesquisas da Amazônia (INPA), with headquarters in Manaus, in January 2005, gust of winds up to 140 kilometers per hour hit an area of 180 miles wide and 1,000 miles long in the Brazilian Amazon, causing the death of 500 million trees.
Effects like the blowdown, storms that sweep the ground literally destroying what lies ahead, they are able to wreak havoc as large as the deforestation caused by man. These phenomena are well known and called by bordering “wind farm”, but still there was no method to measure the size of the damage they do.
A u.s. team led by Jeffrey Chambers, of the laboratory of Berkeley, United States, with the participation of five researchers linked to the graduate program of tropical forest Science INPA, have developed a tool to measure the damage from major storms throughout the Amazon region.
The method named Tree Tropical Ecosystem and Community Simulator (GADGETS) is described and applied in an article published in the January 28 issue of the same Journal PNAS.
With satellite imagery, the researchers were able to assess the effects of storms on the forest, which is not limited to downed trees, but also to damage in those who remained standing. Combining the information with data obtained in the field, it was possible to do a map of tree mortality in the chosen area. “Some areas have had 80 percent of trees felled, other 15 percent,” says Chambers.
The model found that between 9.1 and 16.9% of the mortality of trees is omitted in conventional analyses, based only on forest inventories. This means that millions of dead trees do not enter the carbon account for the Amazon forest. In 2005, emissions caused by tree mortality due to storms reach 200 million tons.
Storms cause extensive damage to the forest. Map produced from satellite images and field information indicates gradual destruction in the area next to Manaus, in 2005. Photo: Disclosure.
“The fall of trees is very violent, you always have the desraização of trees and others are damaged and will be extremely compromised in terms of survival”, says Niro Higuchi, who participated in the study. “We don’t know how long it will last the effect on these trees and if they will recover. Therefore, the estimate is conservative. ”
The new tool can be used to mediate the mortality in other forest types. Chambers and colleagues published in Science in 2007 that Hurricane Katrina killed or caused severe damage at about 320 million trees. The carbon emitted by decaying trees are equivalent to all carbon absorbed by forests of the United States in a year.
According to Chambers, the forest growth absorbs an important share of carbon from the atmosphere, but we must also consider the increased mortality of trees associated with global warming. “So, which of these processes will win in a long period: growth or mortality?” asks. The studies published this week, according to him, offer tools to observe and respond to the effects of climate change in the coming years.