The Amazon is a vital part of Earth’s biosphere. The fires currently burning have the potential to irreversibly disrupt the carbon and water cycles.
For the last few weeks, in the wake of the news about the Amazon fires, claims have been made saying that 20% of the world’s oxygen is produced by the Amazon rainforest. This has seemingly been quoted by everyone and their grandmothers, which left me wondering if that nugget of information held any truth at all. The Amazon is indeed vital to our planet’s biosphere, but how important is it in reality? More specifically, how much does it contribute to our oxygen supply? Let’s take a closer look!
The Carbon Cycle and our Oxygen supply
The Carbon Cycle is defined as a biological process in which the element carbon is circulated through the natural world in its various forms. Carbon dioxide (CO2) is the gas taken up by plants and algae to convert carbon and water into carbohydrates through photosynthesis; following this process, the plant or algae then releases oxygen. This process removes the carbon dioxide in the air.
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It is important to note that some amount of oxygen produced during photosynthesis is also used up afterward in other normal processes by the same organisms. This is because they use oxygen to burn the carbohydrates they form to gain energy, which produces carbon dioxide.
Carbon dioxide is also produced when the organisms are burned or die and decompose; this makes the net result of all the oxygen produced roughly zero.
Given that, one may ask why there is any oxygen in the atmosphere at all, but that answer is simple.
Almost all the oxygen in the atmosphere is made by sea-dwelling microorganisms called phytoplankton. When these microorganisms die, they sink to the bottom of the ocean floor, meaning they never decompose in the atmosphere. This means that there is an excess of oxygen, as decomposition in the atmosphere converts oxygen to carbon dioxide, but that can’t happen underwater.
The excess oxygen accumulated over millennia creates a reservoir in our atmosphere which supports all life on the plant. Phytoplankton are the reason why our atmosphere is so rich in oxygen. Phytoplanktons still remain the main producer of atmospheric oxygen, even after the emergence of land-based photosynthetic life forms.
The Water Cycle and how it is affected by the density of flora
The Water Cycle is a system through which water moves in a cycle through the earth and the atmosphere. The cycle consists of several processes, the most important of which are evaporation, transpiration, condensation, precipitation, and run-off. In this article, we will mainly focus on transpiration.
Transpiration is the process through which water vapor is lost by plants, which then condenses in the atmosphere to form rain clouds. Therefore, trees are crucial to rain. The density of trees and vegetation is a key factor for the development of precipitation, especially in inland areas.
Rainfall cycles are dependent on transpiration from vegetation, especially in the rainforests of our planet. The rainfall cycles in South America are heavily dependent on the transpiration from the Amazon rainforest.
Some important conclusions and facts about this situation
This information makes it clear that we are not, in fact, dependent on the Amazon for oxygen at all, as any oxygen it produces is insignificant on the larger scale. It is, however, a critical part of the carbon and water cycles. It acts as a “sink” for carbon dioxide, removing millions of tons of the gas from the atmosphere every year and storing it as organic matter. Thus, the Amazon acts as a powerful frontier against global warming.
Rates of deforestation have rapidly increased in the last year in the Amazon as environmental laws have been loosened. Brazil’s National Space Research Institute (INPE) has reported that deforestation in the Amazon has increased by over 80% in the last year (Source).
The number of fires reported has also increased in correlation. In June (the start of the dry season), there was an increase of 25% over last year in Brazil alone (Source). It’s important to note that October is when the dry season is expected to end. The full extent of the impact of these massive fires will only be determined then.
Another important term in this issue is the “tipping point”. This refers to the point when the Amazon has lost around 20-25% (Source) of its flora and is considered by many to be the point at which it will be almost impossible for the Amazon to recover. Given the current rate of destruction, we are expected to reach this devastating point by the end of this year. After this, the Amazon will lose its ability to recover from the damage it has suffered and will rapidly start to disappear.
How is this information relevant to the current problem?
The function of the rainforest as a buffer against global warming is being seriously threatened as thousands of miles of the Amazon burn, producing tons of carbon dioxide and carbon monoxide (which is far more toxic). CAMS estimates that 228 megatons of carbon dioxide has been released in this year alone due to fire activity in the Amazon forests, more than any year since 2010 (Source).
Wildfires are not unusual in the rainforest during its dry season, but the intensity and widespread nature of the fires this year is incredibly worrying. The excessive amount of carbon dioxide being released into the atmosphere is expected to rapidly speed up global warming.
Moving on to the water cycle, the large expanses of the Amazon define the rain pattern for the entire continent. Brian D. Farrell, a Harvard biologist, has conducted research in the Amazon for decades. He has stated that if the destruction of the Amazon reaches the tipping point, it has the potential to change the climate and ecosystems of South America completely.
The lower levels of water vapor being released into the atmosphere, due to the lower density of vegetation, will dry up the rain cycle in the South American continent. This will lead to a shift in vegetation and climate, from a rainforest to a grassland. This kind of shift can persist for thousands of years, mimicking previous instances of this occurrence in prehistoric times.
These kinds of shifts will spell disaster for the ecological and economic systems of the continent and the rest of the planet. The Amazon is home to thousands of species that are uniquely found there. Moreover, it is the home and source of livelihood for several indigenous peoples.
The fires and rampant deforestation in the Amazon basin must be brought under control, lest we lose some of the most important resources on our planet.