Why the Amazon Is Called the Lungs of the Earth: Facts

Why the Amazon is called the lungs of the Earth, and what is true

People call the Amazon the lungs of the Earth because its trees take in carbon dioxide and give out oxygen. The oxygen part of the nickname is the weak part, but the carbon part is real: the forest takes up large amounts of carbon dioxide and stores the carbon in wood, roots and soil. The often-repeated claim that the Amazon makes 20% of the world’s oxygen is wrong, and the forest uses almost all of the oxygen it produces, according to FactCheck.org. The nickname still points at something real: the Amazon stores carbon, moves water and shapes rainfall for farms across South America.

This page sorts the claims into what the sources support and what they do not. It also has a carbon calculator, so you can estimate how much carbon dioxide a cleared patch of forest puts into the air.

Does the Amazon really make 20% of the world’s oxygen

No. Plants make oxygen by photosynthesis, but plants and soil microbes use almost all of it again when they breathe and when dead plant matter rots. Oxford ecologist Yadvinder Malhi explains that about half of the oxygen is used by the plant itself and the other half by microbes and insects that break down plant material. The net oxygen produced by land ecosystems is close to zero.

The gross figures are also well below 20%. National Geographic reports Malhi’s estimate that the Amazon makes about 16% of the oxygen produced on land and 9% once ocean plankton are counted. Climate scientist Jonathan Foley arrived at about 6%. FactCheck.org gives the range as 6 to 9%, and notes that the Amazon uses nearly all of it.

Nor is the air at risk. The oxygen level has stayed near 21% of the atmosphere for a very long time, and Malhi’s note says the oxygen reservoir built up over millions of years, and National Geographic adds that today’s photosynthesis does not set it. Cutting forest does not make us run out of air. It does release carbon, change rainfall and destroy habitat, and those are the real reasons to care.

What the numbers say about oxygen

The chart below puts the viral claim next to the published estimates. These are gross production shares, not net supply.

Chart

Amazon share of Earth’s oxygen: claim vs estimates

% of oxygen produced (gross, not net). The 20% bar is the viral claim; the others are published estimates

How much carbon does the Amazon hold

Scientists agree that the Amazon holds a very large store of carbon, but they do not agree on the exact amount. A published comparison of ground plots and satellite maps lists basin-wide estimates from 58 to 134 billion tonnes of carbon (Pg C). Three mid-range estimates, from 2006 to 2010, sit between 86 and 93 Pg C. These figures count carbon in living vegetation, not soil. A single number such as “about 100 billion tonnes” hides the uncertainty, so the range is a better guide.

For scale, one tonne of carbon is 3.67 tonnes of carbon dioxide once it is released. So the carbon in living vegetation is equal to hundreds of billions of tonnes of carbon dioxide, which is why a forest that turns from sink to source matters for the climate.

The sink is weakening

Intact tropical forests took up about half of the carbon absorbed by land in the 1990s and early 2000s, removing about 15% of human carbon dioxide emissions, as Hubau and colleagues report in Nature. Their plot data show a long-term decline of the Amazon sink, driven mainly by more tree deaths.

Aircraft measurements tell a similar story. A study in Nature measured carbon dioxide and carbon monoxide above four sites in Amazonia from 2010 to 2018. It found that south-eastern Amazonia acts as a net carbon source to the atmosphere, linked to deforestation, fire and a harsher dry season. The paper reports higher emissions in eastern than in western Amazonia, with the south-east the clearest net source.

Chart

Published estimates of Amazon forest carbon

billion tonnes of carbon (Pg C) in living vegetation, whole-basin estimates from different studies

The Amazon and the water cycle

Water is the other half of the nickname that holds up. NASA reports that the Amazon basin holds about 38% of the world’s river water and discharges 6,789 cubic kilometres per year, which is 18% of global river discharge to the ocean (1980 to 2009 average).

Trees also return water to the air through their leaves. That moisture helps form clouds and rain. Scientists warn that heavy clearing, a hotter climate and more fire can tip parts of the forest into a drier state. One analysis put the tipping point for the eastern, southern and central Amazon at 20 to 25% deforestation (Lovejoy and Nobre, 2018). A newer Nature paper, reported by Mongabay in May 2026, models a shift when 22 to 28% of the forest is lost together with 1.5 to 1.9 degrees C of global warming, as early as the 2040s. Mongabay (May 2026) says roughly 17 to 18% of the Amazon had already been deforested. These are model results, not a date on a calendar.

What the Amazon gives, claim by claim

The table below lists each benefit with only what we could check against a source.

We give no percentage for medicines, people fed or export value because we could not match one to a source we opened. If you need a figure for biodiversity or trade, take it from the national statistics office or a UN agency and note the year.

How fast is the forest being cleared

Brazil measures clearing in its part of the Amazon by satellite. INPE’s PRODES system reported 5,731 square kilometres of clearing in the Legal Amazon from August 2024 to July 2025. That is 12% lower than the 6,518 km² of the year before, which was itself 28% below 9,064 km² in 2023.

The fall is real, but it is a fall from a high level. The World Resources Institute reports that Brazil’s primary forest loss fell 42% in 2025, yet Brazil still lost the largest area of tropical rainforest of any country because its forests are so large.

Chart

Clearing in Brazil’s Legal Amazon

km² per PRODES year (August to July); selected years, 2021 and 2022 not shown

Calculator: how much carbon dioxide does clearing release

Use the calculator to turn a cleared area into tonnes of carbon dioxide and a comparison with cars. The inputs are yours, so replace the example values with the forest type and the share of carbon you expect to be released.

Try the numbers for your own farm below.

Farming, forests and the Amazon

Pasture and crops sit next to the forest edge. For farmers and food buyers, the practical question is how to grow food without clearing more forest. Four things are on the table: raising output on land that is already cleared, keeping trees on farms, checking supply chains for clearing, and watching the land from space so problems are seen early.

Satellites help because the Amazon is too big to patrol on the ground. INPE maps clearing from Sentinel-1 radar and Sentinel-2 images, as its own technical note says. Radar matters in the wet season, because it can see through cloud. Sentinel images are public, and you can read more in our guide to precision farming techniques and our list of farm tools.

Cloud is the main limit for optical satellites in rainforest regions. The short video below explains why radar images fill the gap.

▶ Why optical satellite pictures fail under cloud and how radar fills the gap. · 2:37

Carbon on farms and in supply chains

A farm can lock carbon in soil and trees, and it can also lose carbon. Tools for carbon footprinting estimate the emissions of a farm or a product. Tools for product traceability record where a commodity came from. Neither tool proves a supply chain is clear of deforestation on its own; the claim needs satellite checks and records that an outside party can audit.

Farmonaut Satellite + AI Farm Monitoring System shows satellite vegetation maps for fields you draw, on web, Android and iOS, and has an API for developers: see the satellite and weather API docs. Our pages on crop loan and insurance verification and the large-scale farm management app cover related uses. For an example of drone and satellite work in the United States, see our post on precision farming in California.

Check product labels, local rules and a qualified adviser before changing fertilizer, pesticide or land-use practice, and get legal or financial advice before signing any carbon or credit contract.

▶ A guide to carbon farming and how it stores carbon in soil. · 5:30

Risks and what helps

WRI says lower or stable forest loss in Brazil, Colombia, Indonesia and Malaysia in 2025 was associated with policy changes, better law enforcement and voluntary company action. Our post on solutions to Amazon deforestation in Brazil covers more options.

Carbon storage is not guaranteed even in standing forest. Because the Amazon sink is weakening in the plot data, protecting forest and cutting emissions elsewhere both matter.

How to read a claim about the Amazon

Many numbers about the Amazon float around without a source. Four checks catch most mistakes.

• Gross or net. Oxygen made by photosynthesis is a gross figure. What matters for the air is the net figure after respiration and decay, and that is close to zero.
• Forest or basin. The basin is the land that drains to the river. The forest is the trees. Water numbers such as NASA’s 18% describe the basin; carbon numbers describe forest biomass.
• Estimate or measurement. Basin carbon is an estimate built from plots and satellite maps, which is why published values run from 58 to 134 billion tonnes of carbon.
• Which year. Clearing rates change from year to year. PRODES counts August to July, not the calendar year.

When a page gives a round number with no source and no year, treat it as a guess. The table above shows where we have no figure we can stand behind.

What the sink data mean for climate maths

A forest that is a sink offsets a little of the carbon dioxide we emit. A forest that is a source adds to it. The size of the Amazon makes the difference large. If one hectare of tree biomass holds 100 tonnes of carbon, the calculator above shows that clearing 1,000 hectares and releasing most of it equals the yearly emissions of tens of thousands of US cars. That is one patch. It is the sum of many patches, plus fire and drought, that decides whether a region tips from sink to source.

The plots and aircraft data agree on direction but not on a single number, and the regions differ. The Nature aircraft study reports more clearing, warming and dry-season stress in the east than the west, with the south-east the part that is a net source. For a farmer or buyer, the point is that where the carbon sits and what happens at the edge of the forest matter as much as the basin-wide total.

Watching land from space

A farm beside a forest edge can use vegetation maps to spot stress early and to keep a record of land cover over the years. The video below shows how NDVI maps work.

▶ How satellite NDVI maps show crop stress before you can see it. · 4:09

How we checked the numbers

We checked each figure against the page or paper named next to it, and we use the date and the basis the source gives (gross or net, estimate or measured, forest or basin). Carbon values come from a published comparison of studies, the water figures from NASA, clearing data from INPE’s technical notes, the tipping-point range from the authors’ own paper and a May 2026 news report on a newer one. The vehicle comparison uses the US Environmental Protection Agency’s per-vehicle figure for 2022 data. Where we could not find a source, we did not print a number.

FAQ

Why is the Amazon rainforest often called the lungs of the Earth?

Because its trees take up carbon dioxide and make oxygen by photosynthesis, so people compare it to a lung. Scientists say the comparison is only partly right: the forest stores carbon, but it uses nearly all the oxygen it makes (Oxford, National Geographic, FactCheck.org).

Does the Amazon produce 20% of the world’s oxygen?

No. Estimates of gross production range from about 6 to 9% of the global total, and the net supply to the air is close to zero.

How much carbon is stored in the Amazon?

Estimates range from 58 to 134 billion tonnes of carbon, with three mid-range estimates (2006 to 2010) near 86 to 93. The spread reflects how hard it is to measure forest carbon over such a large area.

Is the Amazon still a carbon sink?

Intact forest still absorbs carbon, but the sink has weakened in plot data, and aircraft measurements show south-eastern Amazonia acting as a net source from 2010 to 2018.

Which share of river flow comes from the Amazon?

NASA’s analysis puts the Amazon basin at 18% of global river discharge to the ocean, using the 1980 to 2009 average.

Can satellite monitoring help protect the forest?

Yes. INPE maps clearing from Sentinel satellites each year, and fast alerts can support enforcement. Satellites show where the vegetation changed, but they do not by themselves show the cause.

Related pages on our site

See also EUDR deforestation monitoring and deforestation in Australia.