40% of Amazon Will Disappear Despite Climate Change Efforts

Fourty percent or more of the Amazon rainforest will be “decimated” by the middle of the next century even if we cut all CO2 emissions by 2050, said the UK Met Office. The finding was presented this past month in Copenhagen, which is preparing to host the UN Climate Change Conference in December.

In this satellite image of deforestation in Brazil, tropical rainforest appears bright red, while pale red and brown areas represent cleared land. Black and gray areas have probably been recently burned.

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Human-driven deforestation (measured by a net decrease in tree density) will occur even in the absence of a 3° Celsius or more increase in global, average temperature, which is what many scientists believe to be necessary for rain forest loss to pass a “tipping point”.

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Tropical rain forests promote ‘evapotranspiration’ clouds which trap moisture near the surface, and help maintain relatively cooler, lower atmospheric temperatures (preventing much direct sunlight from reaching the ground). This cloud cover creates a “protective zone” between the ground and itself, which in turn, promotes more rain forest growth (and more CO2 absorption). The rain forest and its evapotranspirative cloud covering are “structurally coupled” (mutually dependent and reinforcing). But rain forest loss cuts into this protective and self-perpetuating activity, increasing local temperatures and the rate of evaporation (which is related to the amount of vapor pressure, which increases with temperature), causing a net loss in surface moisture (denying the forest’s ability to reconstitute), and can lead to an increase in detrimental effects like desertification. Many climate scientists have held that as long as temperatures remained below 3° Celsius, this forest decimation trend could be mitigated, and thus the impact on the global climate would not be as severe.

But this most recent climate model, if it is validated through follow up studies, may be an indication that the Amazonian Rain Forest is already locked into an irreversible trend, regardless of what humans do now to mitigate it. Critics say that the model fails to reproduce the current climate exactly, but supporters argue that the model closely replicates 20th Century Rain forest patterns.

Presiding over this month’s Copenhagen meeting was the Danish Prime Minister Anders Rasmussen who took an active part in the proceeding by asking key climate questions of conference panel scientists. Many questions left unanswered by the last IPCC (the UN sponsored Intergovernmental Panel on Climate Change) report of April, 2007 were addressed at the conference, chief of which was the question of whether or not the Greenland and the Antarctic ice sheets were experiencing a net loss of ice mass. The last IPCC report left this issue unresolved due to a lack (at the time) of hard data on glacial movement.

Other ‘Worst Case’ Climate Change Scenarios Being Realized

Since 2007, recently completed global research projects such as the International Polar Year (see my recent article: Major Studies Reveal State of the Poles), have produced far more compelling evidence that there is, in fact, a net loss of ice mass occurring in these regions. Using this data, recent climate models produced by University of Bristol (UK) researchers show that although a complete disintegration of the Greenland ice mass would require a warming of at least 6° Celsius, a mere 15% loss of ice mass would be sufficient to raise sea levels by 1 meter–a “horrendous prospect” according to lead scientist Jonathan Bamber.

Other issues discussed at the conference included: calculating the risk of massive CO2 release due to the loss or destruction of natural carbon storage “sinks”, such as permafrost, soils, and plants. According to the most recent calculations, the sub-arctic permafrost is preventing 1.7 trillion tons of stored carbon–double the 2007 IPCC estimate–from being released into the atmosphere. Computer modeling of this effect is still quite tenuous and tricky (due to many interacting factors), but this possibility only adds to the challenge of controlling CO2 emissions. Climate scientists are especially concerned about certain types of soil components known as yedoma sediments which are high in methane (30%), a potent greenhouse gas, which, in the upper atmosphere, also destroys ozone (O3). Researchers also tackled theoretical speculation regarding increased CO2 absorption by forests and plants.

“The worst case IPCC projections, or even worse, are being realized,” said Katherine Richardson, oceanographer and Copenhagen Climate Conference co-chair in a March 26 Science Magazine news report.

Climate researchers also cited a lack of evidence supporting the theory that forests respond naturally to increase atmospheric CO2 by increasing their photosynthetic uptake of the gas. Last month’s Copenhagen meeting was convened by 11universities from the UK, Australia, the U.S. and  Europe. While there was no complete consensus on each and every issue, participating scientists were generally in accord on certain questions (such as  ice mass loss) and the need to for dramatic caps on CO2 emissions. The aim of the conference was to get a firmer grip on the science constituting climate science before delegates meet in Copenhagen again this December (COP15) to work on a follow-up to the 1997 Kyoto Accords.

About the photo: Extensive deforestation and fragmentation are visible in this satellite image, acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on August 24, 2000, of the state of Rondonia, Brazil, along the Jiparaná River. Tropical rainforest appears bright red, while pale red and brown areas represent cleared land. Black and gray areas have probably been recently burned. The Jiparaná River appears blue. Photo credit: NASA and the U.S./Japan ASTER Science Team via Visible Earth.

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