How the Amazon Rainforest Works
The Amazon Rainforest is a vital natural wonder, stretching across nine South American countries. With its sprawling 5.5 million square kilometers, it accounts for 40% of the world's remaining rainforests and is the largest tropical rainforest on Earth.
Earth's Lungs, Heart, and Life Source
The Amazon Rainforest is Earth’s lungs, heart, and life source, producing 20% of the world’s oxygen and regulating global carbon levels through its vast canopy of 390 billion trees. Equally vital is its role in the water cycle: the rainforest generates immense amounts of water vapor through transpiration, creating "flying rivers" that influence rainfall across South America and beyond. This cycle not only sustains the Amazon’s biodiversity but also helps regulate temperatures locally and globally by reflecting sunlight, absorbing heat, and stabilizing climate systems. As a natural thermostat and water source, the Amazon is indispensable to Earth’s ecological and climatic balance.
Water Cycles in the Presence of a Rainforest
The Amazon's Hidden Cycle: How Evapotranspiration Shapes Our Climate
Ali Bin Shahid
The Amazon Rainforest, a vital cog in Earth’s climate machinery, plays a crucial role beyond its well-known capacity as a carbon sink. This article delves into the Amazon's significant yet underappreciated function in global climate regulation through evapotranspiration (ET).
Understanding Evapotranspiration
Evapotranspiration is the combination of water evaporation and plant transpiration. In the Amazon, this process significantly contributes to the global water cycle, with more than half of the precipitation over land returning to the atmosphere. The Amazon, covering 5.5 million square kilometers, exemplifies this on a grand scale, with transpiration rates among the highest globally.
The Amazon's Water Recycling Power
In the Amazon, ET plays a pivotal role in local and global climate. Sap flux measurements near Manaus indicate that during the driest part of the year, transpiration contributes up to 95% of ET. This colossal natural process cools the Earth and sustains the hydrological cycle.
The Global Impact
ET in the Amazon is essential for maintaining the regional hydrological cycle, which is conducive to tropical rainforests. Any alteration in ET, such as that caused by deforestation, has significant local and regional climatic implications.
The Threat of Deforestation
Deforestation reduces ET, ranging from 15% to 40% in the dry season. Such a decrease is alarming, as it directly affects the regional climate and, by extension, global weather patterns.
Historical Case Study: The Mini-Ice Age and the Great Dying
The study by Alexander Koch and colleagues provides a historical perspective. The Great Dying of Indigenous Peoples in the Americas led to massive land abandonment and forest regrowth, which removed 7.4 gigatonnes of carbon from the atmosphere in the 1500s. This regrowth was significant enough to impact atmospheric CO2 levels and global temperatures before the Industrial Revolution.
The Amazon's role in global climate regulation is multi-faceted and crucial. Understanding and preserving its unique ability to regulate climate through evapotranspiration is not just a regional priority but a global imperative.
The Amazon’s vast forests act as a natural “pump,” drawing moisture from the Atlantic Ocean, creating clouds, and generating rainfall that sustains not only the forest but also regional and global weather patterns. Deforestation disrupts this process, leading to reduced rainfall, prolonged droughts, and the collapse of ecosystems. By restoring degraded areas, replanting native species, and protecting the remaining forest, we can reestablish the biotic pump, enhance moisture recycling, and prevent the tipping point of a dieback.
Transpiration is the process by which plants and trees absorb water and release it as water vapor into the atmosphere through their leaves. The Amazon Rainforest plays a vital role in this process, as its vast vegetation releases around 20 billion tons of water vapor daily, driving regional rainfall and influencing global weather patterns through “flying rivers” of atmospheric moisture. This helps regulate local and global climates, supports agriculture, and sustains biodiversity. Deforestation and climate change threaten the Amazon’s ability to maintain this critical function, highlighting the urgent need for conservation to protect its role in the global water and climate cycles.
Transpiration
How Plants Cool the Planet.
The Biopic Pump: How Forests Create Rain.
Is our planet’s largest cooling organ.
Is essential to maintaining planetary health and regulating global temperatures.
Is responsible for 8% of global oxygen production (or 20% of the world's oxygen?)
Produces around 22% of global river discharge.
Has, when healthy, a cooling effect of 190 W/m² through evapotranspiration and cloud formation.
Has a total cooling effect of 4 x 10²² joules/year and offsets 134% of Earth’s energy imbalance (EEI = 2.9 x 10²² joules/year or 1.81 W/m²)
Maintains rains for food production in large parts of South America, the western and midwestern U.S., and South Africa.
Is home to over 16,000 species of trees and 390 billion individual trees.
The Amazon Rainforest
The Amazon rainforest covers 5.5 million square kilometers (2.1 million square miles) and spans nine countries, with the majority in Brazil.
Evapotranspiration in the Amazon
Bigger is Badder When it Comes to Climate Impact of Farms in the Amazon
An analysis of 20 years of satellite data shows significant temperature differences on agricultural land in the southern Amazon, with extensively deforested commercial estates up to 3 °C (5.4 °F) warmer than surrounding forests, and smaller rural farms 1.85 °C (3.3 °F) warmer than the forests.
Loss of vegetation reduces transpiration of water from plants into the atmosphere, a process that provides 50% of the rainfall in the Amazon. Large-scale commodity farms saw major reductions in this “convective” rainfall, which were not observed in the atmosphere over rural farms.
Experts have long warned that disruptions in rainfall patterns caused by deforestation in the Amazon could tip the entire biome into an irreversible transition into degraded savanna, with major knock-on effects for global climate and weather.
‘’We live on a live planet that can respond to the changes we make, either by canceling the changes or by canceling us.”
— James E. Lovelock, The Revenge of Gaia