Amazon: sailed?




As the length of the (6400 km) might argue that perhaps the Nile or the Yangtze. And by affluent can be compared no river on Earth. It accounts for one fifth of all fresh water that pours into the oceans of the large and small streams. Amazon delivers annually in the Atlantic 7000 cu. miles of water - more than three times larger than the average annual runoff of the Yenisei, Lena, Ob, Amur and Volga together. Amazon basin is about 7 million square feet. km, and during the spill, its width in the lower reaches as high as 80 km. One would think that could happen to such a mighty river?
In 1999, hydrologists noted that the amount of water in the Amazon has steadily decreased. According to their calculations, from 1999 to 2003, consumption of water in the river fell from 267 000 to 226 000 cubic meters per second. And two years later, disaster struck. In the summer and in the autumn the strongest drought has burst: water level dropped to its lowest level in 30 years - so long carried out scientific observations.
In places where the flow depth was typically 15 m in 2005, it was less than meters. Great River could go wading.
The first consequence of the cataclysm was the cessation of navigation on a large part of the area. Many areas were completely cut off from the world, because the land covered by forest roads in the Amazon is not always paved, passengers and cargo are transported mainly by river. But the vessels which have got to a trap is there was only a beginning.
With shoaling of the river most of its living creatures deprived of their natural habitat and began to die. Coast and the shoaled channels have been covered by the dead fish poisoning remained water. In the cities located near the river there was a danger of epidemics. Iquitos in Peru (population 500 000 people) suffered from thirst in a few weeks. In the area of drought killed a fifth of the cattle. In the 16 municipalities of the Brazilian state of Amazonas emergency was declared.
What happened? On this account, there are several versions. As have established the US-Brazilian expedition, who investigated the Amazon in 1985-1987, the river is mainly fed from two sources. Half the volume of water brought rain clouds, which are formed by evaporation of moisture from the Amazonian forests, extending in an area of 5.5 million sq. km. But rainfall is steadily declining due to unsustainable harvesting of trees. In June and August 2005, the first in the Amazon has fallen two-thirds of normal rainfall in July - only a third.
The other half of the volume of water give the glaciers in the Andes, where are the sources of rivers. But as a result of global warming, glaciers are retreating: in 30 years melted 11 billion cubic meters of ice - the area of glaciers has decreased by 20 percent.
There is another version, pointing to global warming. But the mechanism of drought explained otherwise. According to some scholars, it has caused an excessive increase in water temperature in the North Atlantic. Over the ocean surface began to form the ascending air currents in the Amazon - downward. As a result, the clouds are not formed and no precipitation.
British scientists who conducted the study forests of the Amazon, came to a sad conclusion: global warming, apparently, lead to the loss of tropical forests. According to their calculations, it can happen in a hundred years. Under the more pessimistic forecasts, they may disappear as early as 2050, and destroy them is not warming, but the people themselves involved in clearings in the Amazon. The rate of forest harvesting in the tropics only grow. If nothing changes, then in 5-10 years, the process of disappearance of the Amazon rainforest could be irreversible.
Do we understand this threat in the Amazon itself? A few months ago in the Brazilian state of Pará irreparable banned felling of trees and the conversion of forests into agricultural land. The area of protected forests in the pair now be 16.4 million hectares. Such solutions offer hope for a favorable outcome. According to the established view, the Amazon forests play a vital role in the climatic equilibrium of the planet: they absorb the lion's share of carbon dioxide emitted into the atmosphere. Second such river humanity does not exist.