Wednesday, August 28, 2019

Amazon Tropical Forest ‘Dieback’ As Hydrological Cycle Disrupted

“The rain in the rainforest is not an accident of geography or meteorology. The towering trees of the Amazon play important parts in the orchestra of the region’s water system.

The trees take in rainwater through their roots, move it up into the canopy, and release it into the air, a process called evapotranspiration. The trees also release volatile organic compounds that react to form tiny particles. These particles serve as nucleation points to form clouds and eventually lead to more rainfall. 

Multiply this pattern by the hundreds of billions of trees in the rainforest and you get a powerful mechanism for recycling water and generating rainfall that keeps even the thirstiest of trees quaffed in hot tropical weather.

This rainfall pattern helps sustain agriculture throughout Brazil and top up reservoirs that hydrate major cities, feeding and quenching the thirst of millions.
But these trees are rapidly disappearing, along with the shrubs, grasses, fungi, and soil bacteria that work alongside them to circulate moisture. The rate of deforestation in the Amazon has picked up again after years of decline, with roughly a soccer field-size area lost every minute.

Once the rainforest loses a certain amount of area, this orchestra will fall out of tune. There will not be enough remaining tropical woodlands to continually evaporate and condense moisture through the forest. Without this cycling of rainfall, downwind vegetation will not get enough water. That flora in turn will weaken and move less moisture through the air, resulting in less rainfall for the forested areas even further downwind. These parched trees will become more vulnerable to pests and fire. The mighty stalwarts of the Amazon will shrivel up, and a wave of death will start at the periphery and propagate throughout as much of it degrades from a dense tropical forest into a sparse savanna. The cycle will continue without our input. And there will be little we can do to stop it.
This is a scenario known as a forest dieback.”

Note: The soil in the Amazon tropical rainforest is the poorest and most infertile in the world. If one cuts down the forest, it is irretrievably lost. The humus layer is quickly washed out. Hence, the destruction of the Amazon will have been exponentially evil.

What If We Cleared the Amazon? 
(8 minutes):

Note: Lost forests are usually replaced by agriculture, which produces its own emissions. Add in these impacts and the real contribution of deforestation to global climate warming since 1850 is as much as 40 percent. At that rate, tropical deforestation could add 1.5 degrees Celsius (2.7°Fahrenheit) to global temperatures by 2100 – even if we shut down fossil fuel emissions tomorrow.

Amazon Soil: Poorest In The World