By Chantelle Barretto

Misty rainforest horizontal view

The Amazon Rainforest has a unique ecosystem that is complex, interconnected, and oftentimes is independent from the patterns and behaviours of the natural environment elsewhere in the world. There is a distinct Circle of Life that plays out in the Amazon, where all the life within is inextricably linked; a change in the equilibrium for any one of those myriad components has a cascading effect throughout the Circle.

Recent news from NASA’s Jet Propulsion Laboratory has provided evidence indicating that the Amazon rainforest is responsible for the timing of its own rainy season – which explains why its rainy season typically happens 2-3 months earlier that it does in most tropical regions in the Southern Hemisphere. (*1) Most of these regions experience what NASA describes as “a belt of converging trade winds that shifts depending on the seasons,” which occurs when Monsoon winds intersect in the Intertropical Convergence Zone. Although the Amazon is affected by this same phenomenon, its rainy season is governed by the transpiration of flora. (*2) NASA researchers have found that the water vapor above the Amazon contains far more heavy isotopes than does vapor that arises from large bodies of water (which are usually responsible for causing rainfall), implying that it is water emitted from the leaves of plants and trees within the rainforest that result in rainfall.

Despite the Amazon’s incredible capacity to control its own rainy and dry seasons, the balance that enables this phenomenon is thrown off when any of the factors involved are altered. What we are now seeing is that, in light of the significant and devastating amount of deforestation the rainforest has seen over the past 5 decades, there are increasingly fewer trees left to drive the requisite transpiration that maintains this weather cycle. (*3) If deforestation continues at a rate that prevents enough moisture from being released into the air, the shorter rainy seasons experienced by the Amazon in recent years will continue. Eventually, if the current course is not corrected, “the forest will no longer receive enough rain each year to keep trees alive, and the region will transition from forest to grassy plains.” (*1)

Once again, the warning signs of impending catastrophe are evident. We already know that forests are an invaluable asset in combating and mitigating the effects of climate change. We are beginning to understand the wide-ranging effects of an increase in global temperatures on the fragile ecology and flora and fauna of the world’s forests. Now our latest finding is that, with continued deforestation in the Amazon, in due course the world’s largest tropical rainforest could well become the world’s largest grassy plain.

 

1. Rasmussen, Carol. “New Study Shows the Amazon Makes Its Own Rainy Season.” NASA, NASA, 17 July 2017, www.jpl.nasa.gov/news/news.php?feature=6897.

2. Hunter-Hart on July 18, 2017, Monica. “The Amazon Makes Its Own Rainy Season — Meaning It’s Badass, and Vulnerable.” Inverse Science, Inverse, 18 July 2017, www.inverse.com/article/34303-amazon-deforestation-rainy-season-nasa.

 

3. Cooke, Lacy. “Scientists Discover the Amazon Forest Sets off Its Own Rainy Season.” Inhabitat, Inhabitat, 21 July 2017, inhabitat.com/scientists-discover-the-amazon-forest-sets-off-its-own-rainy-season/.