New science on Amazon deforestation (It's not all sad and depressing!)
Deforestation can inhibit rainfall in the forests of the Amazon, but new science also points to hope
Despite suffering deforestation over the last 70 years, the Amazon remains the largest rainforest in the world. It is so large that it creates its own weather system. Rains fall on the forest, the trees transpire the water as vapor back to the atmosphere, where it accumulates and creates more rain. This system is so great that it also sustains rains into remote areas of South America.
Scientists recently examined what would happen to this rain system if deforestation continues for the Amazon. The changes to rainfall would be complex and far-reaching, with declines in rainfall in some areas of South America far from the Amazon. The scientists published their results in the journal Climate Dynamics in May.
In our simplest understanding, deforestation occurs when trees in a forest are cut down or otherwise removed faster than they can replace themselves or be replaced as part of silviculture and controlled forestry. Logging and conversion of land for agriculture are typical reasons for deforestation.
When trees are replaced by grassland or crops, the way rain and sunlight interact with the earth and vegetation is completely changed. More sunlight reaches the ground, warming it more, leading to higher near-ground temperatures. Less evapotranspiration from trees means that fewer clouds form, too.
The researchers ran all these factors—fewer clouds, warmer air, etc.—through a computer model in which approximately 40 percent of the Amazon basin was deforested.
The scientists found that rainfall was greatly reduced throughout the piedmonts of the Andes, which is presently the area that receives the greatest amount of rain in the Amazon. Their models also found that rainfall would be reduced over the Amazon plains, with daytime precipitation declining by about 10 to 20 percent and nighttime precipitation declining by 20 to 30 percent. The scientists point out that this has large implications for the hydrology of the Amazon and the Amazon/Andes transition zone.
If the deforestation continues to the extent that the scientists modeled, rainfall and climate in general for almost all of South America could be compromised, with most areas suffering from less rainfall. Climate change would further jeopardize the climate and weather.
Driven mostly by logging, ranching, and farming, deforestation of the Amazon was recognized as a phenomenon 70 years ago.And by the late seventies the destruction of the Amazon rainforest had become a concerning problem. Starting in the eighties, and peaking in the nineties and early 21st century, the pace of forest removal increased to its greatest extent. The pace greatly slowed around ten years ago, when restrictions on deforestation were put in place. But the election of Jair Bolsanaro, who loosened restrictions on logging and ranching, brought back great destruction of the Brazilian rainforest. By 2018 it was estimated that about 17 percent of the Amazon had been converted to grasslands or farms.
All is not lost
There can, however, be some hope. Another group of scientists looked at almost 80 different tropical forests through South America, North America, and Africa that had been deforested but were allowed to regrow. They found that tropical forests recover rapidly from deforestation. In only 20 years, most forests had returned to almost 80 percent of their original tree diversity and almost 80 percent of their soil fertility and soil carbon storage. The researchers published their findings in the journal Science in December of last year.
In the United States we have a history of temperate forest restoration. The great forests of New York state were largely converted to farmlands in the early to mid 1800s, and by the 1880s, less than 25 percent of New York state was forested. Those tree covered hills and valleys through the Finger Lakes, the Adirondacks, and much of the rest of the state were pasturelands and farms growing corn, barley and other crops.
These farms were almost all entirely abandoned by the turn of the 20th century, when farmers sought better farming opportunities in the Midwest and Great Plains. New York state residents made efforts in the 1930s to reforest these areas, and their efforts proved successful. Upstate New York is now one of the most forested regions of the United States.
I doubt that the farmers of the Amazon have a Midwest of Great Plains to move to. The easiest solution to reducing deforestation in the Amazon would be to eliminate the cattle ranches, and that is only achieved if we give up our hunger for beef.
Veggie burger anyone?
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Robinson, R. ed. (2001) 'Deforestation' in Plant Sciences, New York, NY: Macmillan Reference USA, available: https://link.gale.com/apps/doc/CV2643350076/SCIC?u=sddp_main&sid=bookmark-SCIC&xid=954da737 [accessed 03 Jun 2022].
Special to The New York Times. 1952, U. S. Help To Brazil Covers Wide Area: Official And Private Agencies PARTICIPATE IN MOST PROJECTS FOR NATION'S DEVELOPMENT, New York, N.Y.
By, B.W. 1979, In the Rain Forest, a Complex and Threatened World: Rain Forests Are Endangered Age Is Hard to Determine, New York, N.Y.