Climate Change and the Amazon Rainforest
Global climate change is happening now. The United Nations Framework Convention on Climate Change[PP1] (UNFCCC) defines climate change as a change in climate attributable directly or indirectly to human activity, and that occurs in addition to natural processes of climate variability observed over comparable periods of time. When released into the atmosphere through the burning of fossil fuels, deforestation, and other human practices, carbon dioxide and other greenhouse gases like methane absorb infrared radiation from the sun, trapping heat in Earth's atmosphere and altering the global atmosphere. Major and immediate impacts of climate change include increased flooding, storms, drought, and food insecurity, according to a recent World Bank report.
While skeptics argue that no evidence for "anthropogenic" or human-caused climate change exists, a report [S2] released by the Intergovernmental Panel on Climate Change in 2007 – the major conclusions of which have been validated by numerous follow-up studies – maintains that there is "unequivocal" evidence that global temperatures are indeed on the rise and that this phenomenon is "very likely due to the observed increase in anthropogenic (human) greenhouse gas concentrations."
The Amazon Basin and Climate Stability
Protecting the Amazon basin, which contains the largest tropical rainforest on the planet, is critical to our planet's climate stability. The rainforest serves as one of Earth's largest reservoirs of carbon dioxide, helping regulate global climate patterns through the sequestration and storage carbon dioxide in above-ground biomass and soil. By absorbing about 20 percent of the atmospheric carbon emitted by the burning of fossil fuels, the world's tropical rainforests can help mitigate climate change substantially.
As the source of one-fifth of all fresh water on the planet, the Amazon Basin's hydrological system plays a critical function in regulating the global and regional climate. Water condensation, evaporation, and transpiration over the Amazon are key drivers of the global atmospheric circulation, affecting precipitation across South America and much of the Northern Hemisphere. Among the regions directly linked to the Amazon by a complex weather system is the Rio de la Plata basin of southeastern South America, one of the most important agricultural zones on the planet. Recent climate models indicate that deforestation has also had the effect of reducing precipitation as far afield as the lower Midwest of the United States.
The Amazon's important contributions to global weather, however, are at risk as well. The Amazon serves as a carbon sink only so long as the rainforest absorbs more carbon dioxide than it releases which could soon change if patterns continue.
Worst-case Scenario: The Amazon Tipping Point
Human-induced climate change, if left unchecked, may soon cause the Amazon to emit more carbon into the atmosphere than it absorbs. Scientists predict this change could occur as Amazonian forests become less able to absorb atmospheric carbon as climate warming slows down plant growth in the region and causes trees to die more rapidly. Such was the case in 2005, when a prolonged drought in the Amazon released close to one billion tons of carbon dioxide into the atmosphere, more than it simultaneously removed through absorption.
