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Amazon: Largest rainforest on earth becomes a source of carbon dioxide

2021-07-15T11:33:46.009Z


The plants in the Amazon rainforest store enormous amounts of carbon. However, due to climate change, deforestation and fires, larger amounts of the substance are now being released in the region than the vegetation can absorb.


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Fire in the Amazon rainforest in August 2020: In the event of a fire, the carbon stored in the plants is released as CO₂

Photo:

CARL DE SOUZA / AFP

According to a study, the Amazon region now releases more carbon into the earth's atmosphere than it absorbs.

This is the result of a study by Brazilian experts published on Wednesday in the journal Nature.

Accordingly, the eastern part of the region in particular emerges significantly more of the material than it binds - especially in the dry season.

The carbon emitted by fires, for example, is found in the atmosphere as the greenhouse gas CO₂.

For decades, the largest rainforest on the planet withdrew large amounts of carbon dioxide (CO₂) from the earth's air envelope through photosynthesis, thereby dampening climate change.

That has changed, reports Luciana Gatti's team from the Brazilian National Institute for Space Research (Inpe).

The bottom line is that around 290 million tons of carbon were released into the atmosphere from the area from 2010 to 2018, mainly because of the many fires.

According to the analysis, these released 410 million tons of carbon annually, with 120 million tons of the vegetation only removing a fraction of this amount from the air.

Almost three quarters (72 percent) of the emissions were caused by the eastern regions, although these account for just under a quarter of the total area of ​​the Amazon (24 percent).

Measurements from the airplane

In order to determine the carbon budget in the Amazon, Gatti's team measured the carbon concentrations from 2010 to 2018 from an airplane.

During a total of 590 flights in four different regions, they determined the values ​​of, among other things, carbon dioxide (CO₂) and carbon monoxide (CO) up to an altitude of 4.8 kilometers.

From this, they calculated the carbon balances of the four sub-regions, taking into account the air currents.

They therefore depend heavily on land use: In the past few decades, around a sixth (17 percent) of the entire rainforest has been destroyed: in the western Amazonia it was around 11 percent, in the eastern, smaller part, at around 27 percent, significantly more.

Most of the land has been converted to pastures and arable land.

According to the research team, a mix of climate change, deforestation and fires is responsible for the poor carbon balance.

"The intensification of the dry season and an increase in deforestation seem to increase the stress on the ecosystem in the eastern Amazon region, lead to more fires and increase carbon emissions."

Data from the previous fire years are missing

This is bad news for the development of the world climate, explains Scott Denning from Colorado State University in Fort Collins in a "Nature" comment. It is questionable whether the tropical rainforests will be able to store large amounts of CO₂ in the future. "I'm not surprised that the Amazon region is now a source of carbon," said Martin Heimann, director emeritus at the Max Planck Institute for Biogeochemistry in Jena. "Man's influence is considerable."

Rico Fischer from the Leipzig Helmholtz Center for Environmental Research sees a few weaknesses in the analysis. In view of the complex air currents at different heights, conclusions about the origin of the measured CO₂ are associated with considerable uncertainties. Many studies have confirmed that the Amazon's ability to absorb CO2 is declining. Whether the region is actually already a carbon source is still subject to change.

At the same time, data from previous years was missing from the analysis. The tremendous number of fires of the past two years - Inpe registered more than 100,000 fires in 2020 alone - were no longer included in the analysis. "The fire areas have increased in the last two years," says Fischer. “As a result, the carbon emissions are possibly even higher than the level shown in the study. In addition, large areas of forest are lost «- and with it their potential for carbon storage.

The increasing concentrations of greenhouse gases - especially CO₂ - in the atmosphere are the cause of climate change.

Every year humans release around eleven gigatons (billion tons) of carbon into the earth's atmosphere - primarily through fossil fuels, as researchers recently wrote in the journal "Earth System Science Data".

Of this, the vegetation absorbs 3.4 gigatons through photosynthesis, the oceans another 2.4 gigatons.

This leaves a good five gigatons of carbon that accumulates in the atmosphere year after year.

Plants remove carbon dioxide from the air through photosynthesis and absorb the carbon it contains.

Gatti's team estimates that around 123 gigatons (123 billion tons) of carbon are bound in the form of biomass in the Amazon region.

jme / AFP / dpa

Source: spiegel

All tech articles on 2021-07-15

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