… and not about oxygen at all! Over the past few weeks satellite images released by Brazil’s space agency have shown the shocking deforestation by blazing fires, but misconceptions are spreading just as quickly as the fires. Although losing the Amazon would be an unspeakable tragedy, we should be all be concerned for reasons other than fear of impending suffocation.
It is clear that the fires in the Amazon are horrific and have rightfully sparked outrage, but how accurate is the current claims regarding oxygen production, and what should we be more worried about?
1. “The Amazon produces 20% of the worlds oxygen”
Over the past few weeks this factoid has been bounced around and is nearly ubiquitous in reports, exacerbated by saying that “the Earths lungs are burning”. While this brings up a very visceral mental image, inspiring strong emotions and engaging the general public, this is not entirely accurate.
Tropical forests do produce approximately a quarter to a third of all photosynthesis ON LAND, the Amazon makes up around half of all tropical forests so it alone produces 12-16% of all LAND photosynthesis. A bit of neat rounding then ends you up at 20%, but this still only takes into account photosynthesis occurring on land. Around half off all photosynthesis comes from our oceans, thereby halving the initial Amazon figure to 6-9%.
So now we have a more accurate figure for how much oxygen the Amazon actually produces, how much of this oxygen will actually make its way into humans lungs? The short answer is very little, if any at all. The Amazon ends up consuming nearly all of the oxygen it has produced via photosynthesis in a few ways:
It is important to understand that plant do not simply make oxygen through photosynthesis, they also respire and produce CO2. During respiration, plants actually use half or more of the oxygen they have produced so they can break down carbohydrates and continue to survive when there is no sunlight aka at night time.
The remaining oxygen that the trees and plants have produced is the consumed by other creatures that live in the forest, from the large animals such as sloths wildcats, down to microorganisms and bacteria. Therefore, the net contribution of the Amazon to the earths oxygen level is, as Malhi says, “effectively zero”.
2. The amazon hosts incredible biodiversity
The amazon rainforest is the largest remaining tropical rainforest on Earth, and has unparalleled biodiversity hosting at least 10% of the world’s species. As our knowledge increases and our scientific understanding progresses, we may be closer to being able to comprehend just how valuable the Amazon truly is.
Between 2014 and 2015 381 new types of plants or animals were discovered, that’s more than 1 every other day. On the 10th of September a paper published in the Smithsonian illustrated this beautifully by reporting two entirely new species of electric eel in the Amazon basin. For over 250 years researchers had thought there was only one species of electric eel, only to find through DNA analysis that as well as the known Electrophorus electricus, two further species Electrophorus voltai and Electrophorus varii exist. If this wasn’t incredible enough, they found E. voltai can deliver 860 volts of electricity making it “the strongest living bioelectricity generator” known.
If not purely for the wondrous marvel of discovering the as yet undiscovered, then surely for the technology these species could inspire or the cures for human diseases they could harbour. After all, E. electricus inspired the design of Volta’s first electric battery, advanced hydrogel batteries used to power medial implants and even inspired treatments for neurodegenerative disease, just imagine what could be waiting in the Amazonian basin.
3. Carbon sink and release
Although the rainforest does not act as “the earths lungs”, this does not mean that the environmental benefit of photosynthesis is nullified – while the forest may not be adding oxygen, it is certainly storing carbon.
6CO2 + 6H2O + Light energy → C6H12O6 (sugar) + 6O2
Top level, through the process of photosynthesis plants take in carbon dioxide, strip the carbon away to make carbohydrates and release the oxygen.
The amount of CO2 removed from the atmosphere by trees is a hotly debated topic, with scientists debating whether any tropical forest is even capable of “breathing in more than it breathes out” and reducing global CO2 levels, so if the trees aren’t reducing CO2 levels why are we bothered? Although the levels are being visibly reduced, carbon is being stored either way.
The amazon has locked down an estimated 150-200 billion tons of carbon in its biomass and soil, making it one of the largest carbon pools on earth. When trees and other flora are burned this carbon is released into the atmosphere mostly as CO2. Some estimate that if the entire forest were to burn down it could raise CO2 concentrations by nearly 25%.
It is well established that increasing CO2 levels increases the rate of photosynthesis so fuels the growth in plants, this is called the CO2 fertilization effect. Increasing CO2 levels can increase photosynthesis up to a point where another factor is limiting growth – this is often Nitrogen. If nitrogen is in short supply this then becomes the primary controller of biomass production and therefore carbon sequestering.
Don’t cheer for high CO2 levels though, growing food at elevated CO2 levels makes it become less nutritious. The crops lose iron, zinc, protein etc, meaning it loses enough key nutrients to cause deficiencies.
4. Its effect on the local and global climate
If being home to countless species, various tribes, and the carbon lockdown does not drive environmental efforts, then perhaps another facet of the amazon’s role in global climate may drive them.
The Amazon fuels the local climate by absorbing the water and releasing it into the atmosphere as water vapour through the process of evapotranspiration. The trees also release volatile organic compounds (VOC’s) which can act as nucleation points from which clouds and rainfall can form. Ultimately, the Amazon produces half of its own rain, with one water molecule being recycled 5-7 times before it leaves the system ether by the river or via the atmosphere.
The water recycling fuels the wet climate in the amazon itself, but it also provides water to populations further south, ironically providing water to the very farmers who are cutting it down. Scientists are concerned that soon there will come a point when the level of deforestation will tip the balance, the forest will not be able to maintain the level of water recycling required to survive and will collapse on its own without further human participation.
But it is not just the local climate that would be affected, scientific models have shown that burning the Amazon could change the global climate, changing how heat is spread and where vegetation can grow.
The Amazon’s hydrological system releases water into the atmosphere but also to the ocean by rivers influencing ocean current circulation and world climate. 20% of the worlds flowing fresh water runs through the Amazon, with the freshwater run-off influencing the current off the coast of South America in turn affecting the jet stream, causing ripples in weather patterns across the globe. Studies have shown massive deforestation could alter water supplies as far away as Africa.
As mentioned, the Amazon river carries fresh water from the Amazonian basin into the ocean, carrying with it nutrients and minerals such as nitrogen, phosphorus and silicon. The nutrients in this run-off feeds a huge algal bloom at the point where the freshwater meets the ocean.
In this bloom a single-celled algae called a diatom forms a partnership with a microbe called cyanobacteria. The cyanobacterium extracts nitrogen from the air, allowing the diatom to grow and multiply, pulling in carbon dioxide from the atmosphere.
However, the nutrient run-off is not always beneficial. From 2009, discharge from the Amazon River brought unusually high levels of nutrients into the Atlantic, caused by deforestation and fertiliser use, causing upwelling of the nutrient rich water allowing Sargassum seaweed to boom in number. Sargassum attract fish, birds, turtles and is beneficial for marine life, however this change in nutrient levels have causing populations to explode, causing thick mats of seaweed to smother coral-reefs, trap marine live and wash up on beaches along the Caribbean Sea and the Gulf of Mexico, earning the name of “the Great Atlantic Sargassum Belt”.
This belt changes the water chemistry, creating bad conditions for the corals and marine life and even trapping sea turtles preventing them from returning to the open water when they have laid their eggs.
The fewer trees there are to retain the nutrients the greater the runoff, but deforestation also causes nitrogen to leach from the soil reduces the plants ability to grow by removing a vital building block.
5. The indigenous people
While “fire in a forest” sounds bad, it is also a way of life for the indigenous tribes. It can be used in rotational farming allowing regeneration, and producing patches or burnt and unburnt forest introducing natural firebreaks. Sustainable fires can also be used to catch prey, which is how the Kayapo people hunt tortoises as they hide in the Savanna grasses, protecting sacred forests and gathering resources.
That being said, the highly destructive fires that have been reported over the last few months are not sustainable and are wreaking untold destruction on the lives of the indigenous people that live in the Amazon.
There are approximately 800,000 indigenous people live in the rainforest, speaking 274 unique languages and belonging to over 300 ethnic groups, with some tribes still making no contact with the modern world.
While attempted exploitation of tribal territories is not new, from mining to agriculture and cattle farming, the fires are an increasing pressure.
This article features a photo gallery showing the shocking reality the indigenous people are facing, while this article is a rousing message from Raoni Metuktire, an environmentalist and chief of the Kayapo people. I highly recommend reading both.
Since retired military officer Jair Bolsonaro took office in January the rate of deforestation has surged, as is evident from the satellite images, however the president insists the at reports of large parts of it being on fire “have been greatly exaggerated”.
Bolsonaro has also insisted to the UN that the amazon rainforest belongs to Brazil and is “not the heritage of mankind”. After spending a fair chunk of time reading research papers and countless articles to write this article, I can only disagree.
Under Bolsonaro’s encouragement farm owners are invading indigenous tribes’ territories, torching their land and destroying their resources. While we pursue (as Greta Thunberg eloquently said) the fairy tale of eternal economic growth, ecosystems are being destroyed, species we don’t know exist are going extinct, and global weather patterns are in danger of rapid changes.
While the Amazon may not be “the lungs of the Earth”, it is a hugely biodiverse air-conditioning unit that we simply cannot afford to lose.