Friday, February 11, 2011

Mass tree deaths in Amazon


Please find below details about the impact of global warming on amazon forests

  • Forests are carbon sinks
  • Amazon forests absorb about a quarter of world’s carbon
  • But the depleting forest cover due to drought and deforestation has pushed it to the tipping point, where it will become a carbon source
  • This will cause a rapid climate change
  • The use of satellite imagery by brazil to monitor amazon forests has helped put a check on deforestation

THE 2010 drought

  • The 2005 drought was considered by many as a one in century phenomenon
  • But 2010 drought was much more severe
  • Several states announced emergencies
  • Rio negro reached its lowest levels

§ It is the largest left tributary of the Amazon and the largest black water river in the world

  • Billions of trees died leading to lesser carbon absorption
  • 8.5 bn tonnes of carbon dioxide was released

GLOBAL WARMING

  • Global warming is going to cause more frequent droughts in future
  • The growing warmth of atlantic sea is the main driving factor

Climate tipping points

  • Arctic Icecap
  • It has high albedo i.e it relfects most of sunlight back into atmosphere thus keeping the underneath ocean cold
  • If it melts, the ocean will be exposed to heat leading to more melting
  • Tundra
  • It is warming at a rapid apce
  • This may melt the permafrost which has trapped within it vast amount of carbon
  • Also there are bacterias that feed on frozen soil and generate methane
  • Hence its melting will lead to emission of carbon dioxide and methane in large amounts
  • Gas hydrates
  • Huge reserves of methane remain frozen on or just below ocean floor
  • These methane water crystals are highly unstable as they are close to their melting points
  • Any small rise in temperature could trigger huge release of methane
  • West antarctic ice sheet
  • Much of it is below sea level
  • It is vulnerable even to small amounts of warming
  • When it melts completely, sea level will rise by 6 meters

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