Speaking of major tipping points and their consequences, while climate scientists forecast a drier future for regions in the United States, and while China lays claim to largest carbon emitter in the world, the World Wildlife Fund worries about something as BASIC: the Amazon Rain Forest. And, with good reason.
Die back of the Amazon rain forest is one of the major tipping points. Global warming and deforestation reduce rainfall and lengthen the dry season. It becomes more difficult for the forest to re-establish.
Nick Sundt reports, “The Amazon region is experiencing the third extreme drought in a dozen years — and it may turn out to be the worst on record.”
The drought results from a combination of above normal temperatures over much of the region combined with low precipitation.
Source: University College London
Drought in the Amazon (1 month assessment period, through 16 October 2010).
Exceptional droughts normally occur no more than a couple of times in a century. Yet, as Brazil’s Amazon Environmental Research Institute (Instituto de Pesquisa Ambiental da Amazônia or IPAM) reports there have been 3 in the past 12 years: in 2010, 2005, and 1998.
The drought of 2010 still hasn’t ended in the Amazon and could surpass that of 2005 as the region’s worst during the past four decades.
In the Western Amazon, the Solimões River reached its lowest level in recorded history. In Manaus, the level of the Rio Negro (Black River) is approaching that of 1963 – the lowest in a century. Even if this doesn’t occur, the forest will have already experienced three extreme dry spells in just 12 years, two of which occurred during the past five years: 1998, 2005 and 2010.
And, this is not including the drought of 2007, which affected only the Southeastern Amazon and left 10 thousand sq. km. of forest scorched in the region…
The Amazon that had wet seasons so well-defined that you could set your calendar to them – that Amazon is gone…
Source: NOAA.
Most of the Amazon region received less than 75% of normal rainfall between 1 July and 30 September, 2010. Large areas have received far less precipitation, often less than 25% of normal.
The 2005 Drought
Just 5 years ago — in 2005 — the Amazon experienced an extreme drought that prompted the government of Brazil to declare a state of emergency in most of the region. In The Drought of Amazonia in 2005 (by José A. Marengo, Carlos A. Nobre, Javier Tomasella in the Journal of Climate, February 2008), researchers said:
In 2005, large sections of southwestern Amazonia experienced one of the most intense droughts of the last hundred years. The drought severely affected human population along the main channel of the Amazon River and its western and southwestern tributaries, the Solimões (also known as the Amazon River in the other Amazon countries) and the Madeira Rivers, respectively. The river levels fell to historic low levels and navigation along these rivers had to be suspended. The drought did not affect central or eastern Amazonia, a pattern different from the El Niño–related droughts in 1926, 1983, and 1998.
Editor’s note: Kudos to the WWF article for providing extensive references.
8 Comments
Climate Progress posts the story and includes commentary by a leading expert on the Amazon.
“While two unusual droughts clearly don’t make a trend, they are consistent with some model projections made well before 2005: that higher sea surface temperatures increase drought frequency and intensity, leading later this century to substantial Amazon forest die-back.”
“Every ecosystem has it limits,” cautions Simon Lewis, “a point of where they radically change. The open question is whether such a point is being reached in some parts of the Amazon. While little is expected of the climate change talks in Cancun next week, the stakes, in terms of the fate of the Amazon are much higher than they were a year ago in Copenhagen.”
Oliver Phillips, a tropical ecology professor at the University of Leeds, who has spent decades studying how forests react to changing weather, echoes the question.
Illustration: Greg Asner, Carnegie Institution for Science
“Through photosynthesis, the rain forest absorbs 2 billion tons of atmospheric carbon dioxide each year. But the 2005 drought caused a massive die-off of trees and inverted the process. Like a vacuum cleaner expelling its dust, the Amazon released 3 billion tons of carbon dioxide in 2005. All told, the drought caused an extra 5 billion tons of heat-trapping gases to end up in the atmosphere — more than the combined annual emissions of Europe and Japan.
The 2010 Drought
Even mainstream MSNBC covers the intense months-long drought through November that drained the mighty Negro River — a tributary of the Amazon — to its lowest since records began in 1902, drying up the network of water that is the lifeblood of Brazil’s huge Amazonas state.
Devastating floods have hit Brazil. These follow fast on the heels of an extreme drought in the Amazon.
“This climate-whipsawing from mega-drought to mega-flood”, warns Joe Romm, “will become increasingly common as human emissions intensify the hydrological cycle. It’s just happened to both Australia (see here) and to this country (see “Hell and High Water hits Georgia).”
John Cook also has more about the 2010 drought compared to the one in 2005.
And, via Climate Progress, we learn about a warning, relayed by Science magazine: “Second ‘100-year’ Amazon drought in 5 years caused huge CO2 emissions. If this pattern continues, the forest would become a warming source.”