It’s Winter. Sections of Brazil are experiencing their worst drought in 84 years. Sao Paulo, a city of 9 million, has 97 days of water supply left. And, again, the Great Rainforest is burning.
Over the past few decades a combination of insults including clear cutting, slash and burn agriculture, and rising instances of heatwaves and drought driven by human-caused climate change has resulted in increasingly severe impacts to forested regions around and within the Amazon. Major fires, which were once almost unheard of in the damp, wet regions of the great Amazon delta first cropped up in the late 1980s and early 1990s but have since become more widespread.
(Wildfire outbreak in the Amazon on August 13, 2014. For reference bottom edge of frame is 180 miles. Image source: LANCE MODIS.)
Now, a combination of basement burning of root systems in the Amazon, heat, and drought are resulting in a kind of existential crisis for a region that has been described by scientists as ‘the Earth’s lungs.’ It is a situation that brings with it the ever-increasing risk of major fire outbreaks. And as of 2012 and 2013, after a period of ever-increasing burning, dry equatorial winters have brought with them extraordinarily severe fires that have torn through forested zones and threatened infrastructure. In one such instance during 2013, a major region-wide blackout was set off by a fire originating in Brazil’s rainforest.
And now the burning has begun anew.
For as of August 13 of this year, large wildfires were erupting within the Amazon near regions of cleared forest and deep within the forest interior. Over the past week, these fires expanded and became more widespread. Now, much of Brazil is under a pall of smoke from wildfires that have expanded to range over a very broad rainforest region.
(Smoke from wildfires covering almost all of the Amazon on August 20, 2014. For reference, bottom edge of frame is 1,000 miles and the Amazon River flows from middle left until it terminates at upper right into the South Atlantic. Image source: LANCE MODIS.)
News media and public reporting of fire instances within Brazil are sketchy. But the satellite picture doesn’t lie. Observational estimates place these fires in the range of 500,000 to 1,500,000 acres initially. But given the fire intensity, they are likely to burn on for weeks to months.
Conditions in Context: 3 Percent of the Amazon Lost To Fire From 1999-2010
The new fires originated in a region now known to harbor ongoing understory fires. These fires burn beneath the interlaced root systems of the Amazon and have been discovered to continue to smolder year-round. During times of intense heat and drought, these fires can break through to the surface and more intensely burn through large swaths of forestland. After burning, they sink back into the understory, waiting for another heat/drought trigger.
Last year, NASA published a study which found that fully 3 percent of the Amazon had likely been lost to fires during the period of 1999-2010. A primary culprit for these losses was found to be understory fires, which NASA identified as a significant threat to the Amazon forest system.
(3 percent or 33,500 square miles of a 1.2 million square mile area under investigation burned from 1999-2010 according to a 2013 NASA study. Location of fires indicated in orange.)
Perhaps most significantly, the NASA study implicated climate change as the primary cause for these fires, finding that drought and heatwaves related to increases in human heat trapping gasses had depleted ground moisture levels, resulting in a greatly increased instance of fires.
Post 2010, the satellite record indicates that these fires have continued to grow in intensity. And so the risk to the Amazon expands.
Overall, the Amazon currently stores about 120 gigatons of carbon. It represents about 10% of the global uptake of carbon from the atmosphere through forest tree and plant respiration. But as the Amazon burns and becomes deforested, it shifts from being a carbon absorber to a carbon emitter. Currently, depleted and burning areas of the Amazon are estimated to emit 500 megatons of CO2 each year. And though this has not yet tipped the balance to make the Amazon a net carbon emitter, human climate change and deforestation is driving the world’s largest rainforest rapidly in that direction.
Under human driven climate change and deforestation, the heat and drought situation will only worsen for Brazil. Even without clear cutting, the fires will expand and, eventually, the rainforest will be consumed. Without substantial mitigation action by humans, it is bound to happen. The vast carbon store that is the rainforest will almost certainly begin adding to the already rapacious human heating effect. A process that will continue for decades and will only end once the rainforest is gone entirely.
Hat tip to Bernard