Cutting down trees is one of the major drivers of global warming. Agriculture, forestry, and other land use account for roughly 21% of total global greenhouse gas emissions, with deforestation being a significant chunk of that figure. The connection is straightforward: living trees pull carbon dioxide out of the atmosphere, and removing them both stops that process and releases stored carbon back into the air. But the full picture involves more than just carbon.
How Trees Keep Carbon Out of the Atmosphere
Trees absorb carbon dioxide during photosynthesis and convert it into sugars. They burn some of those sugars to keep their cells alive, releasing a portion of carbon back through respiration. The rest gets locked into wood, branches, roots, and leaves. This is why forests act as carbon “sinks,” pulling more carbon in than they release.
The scale of this process is enormous. Trees in the United States alone sequester about 800 million metric tons of carbon dioxide every year. Globally, tropical forests do the heaviest lifting because they grow year-round and produce dense biomass. The Amazon rainforest stores between 150 and 200 billion tons of carbon above and below ground. When you cut a tree down and it decays or is burned, that stored carbon goes right back into the atmosphere as CO2.
What Happens Underground
The carbon locked in tree trunks is only part of the story. In U.S. forests, about 50% of the total stored carbon sits in the soil itself, bound up in organic matter built from decades or centuries of fallen leaves, decomposed roots, and microbial activity. Under normal conditions, soil carbon is remarkably stable and doesn’t change quickly even when trees above are harvested.
The exception is when soils are seriously disturbed. Tilling cleared forest land for agriculture, erosion on exposed hillsides, and extreme fire events can unlock that underground carbon reservoir. Converting forest to cropland is one of the most common triggers, and it means the climate damage from deforestation goes well beyond the trees themselves.
The Cooling Power of a Living Forest
Trees don’t just store carbon. They actively cool their surroundings through evapotranspiration, the process of pulling water from the soil and releasing it as vapor through their leaves. This works like a natural air conditioner. Research published in Nature Communications found that during summer, forests cool the land surface by an average of about 2.1°C during the daytime compared to non-forest areas. Nighttime temperatures are only slightly warmer (about 0.25°C), so the net effect across a full day is significant cooling of roughly 0.75°C.
In warm, wet tropical regions, this cooling effect is especially strong because trees have plenty of water to work with. Forests also promote rainfall in downwind areas, meaning their removal can reduce precipitation across entire regions. Cut the forest, and you lose this cooling and moisture cycle on top of releasing stored carbon.
The Scale of Current Forest Loss
Global deforestation is accelerating, not slowing. In 2024, total tree cover loss reached 30 million hectares worldwide, an area the size of Italy and a 5% increase over 2023. Tropical primary forests were hit hardest, losing 6.7 million hectares, nearly double the previous year’s figure. That’s the equivalent of 18 soccer fields disappearing every minute.
Most of this clearing happens to make way for agriculture: cattle ranching, soy production, palm oil plantations, and rice paddies. Each of these land uses brings its own greenhouse gas problems beyond the initial carbon release from felling trees.
Secondary Emissions From Cleared Land
Once forest is converted to farmland or pasture, the land itself starts producing additional greenhouse gases. Research comparing emissions from forest reserves and agricultural land in West Africa illustrates this clearly. Intact forest actually absorbed methane from the atmosphere, acting as a net methane sink. Rainfed rice fields on cleared land, by contrast, emitted substantial methane, roughly 0.7 to 0.8 kg of carbon per hectare each growing season.
Nitrous oxide, a greenhouse gas about 270 times more potent than CO2 over a century, also increased dramatically. The rice fields produced roughly 16 times more nitrous oxide than the forest floor. Livestock grazing on cleared land adds yet another layer of methane emissions from animal digestion. So deforestation doesn’t just release a one-time burst of carbon. It replaces a carbon-absorbing ecosystem with one that continuously generates warming gases.
The Amazon’s Troubling Shift
The Amazon offers a real-time case study of what happens when deforestation and climate change reinforce each other. Parts of the Amazon have already flipped from absorbing carbon to releasing it. Droughts appear to be a key driver: as the forest dries out, trees die, fires spread, and the carbon stored in biomass escapes. Meanwhile, deforestation has significantly increased surface air temperatures and reduced rainfall during the Amazon’s dry season, making droughts worse.
This creates a feedback loop. Less forest means less rain, which means more drought stress, which kills more trees, which means even less forest. CO2 concentrations over the Amazon have risen by approximately 87 parts per million in recent decades. The concern among climate scientists is that the Amazon could cross a tipping point where large sections permanently convert from dense rainforest to degraded savanna, releasing a massive share of those 150 to 200 billion tons of stored carbon.
The Exception: Northern Forests
Not all deforestation has the same warming effect. In the far north, cutting trees can actually produce a net cooling of surface temperatures, a finding that surprises many people. A study led by researchers at Yale, analyzing temperature data from Florida to Manitoba, found that in regions above 45 degrees latitude (roughly north of Minnesota), deforested areas were an average of 1.5°F cooler than adjacent forests.
The reason is albedo, or surface reflectivity. Dark evergreen forests in snowy regions absorb solar radiation that snow-covered open ground would reflect back to space. Remove the trees, and the bright snow bounces more sunlight away, cooling the surface. This effect is linear with latitude: the farther north, the stronger the cooling. Below about 35 degrees latitude (roughly North Carolina), the pattern reverses and deforestation causes local warming. In the tropics, where the carbon storage and evapotranspiration benefits are greatest, cutting trees is unambiguously warming.
This doesn’t mean northern deforestation is harmless for the climate. The carbon released from boreal forests still enters the atmosphere and contributes to global CO2 levels regardless of local surface temperature changes. But it does mean the relationship between tree loss and warming is more complex than a single rule applied everywhere on Earth.
Why the Impact Keeps Growing
Deforestation’s contribution to global warming compounds over time. Every hectare of forest cleared represents both a one-time release of stored carbon and the permanent loss of future carbon absorption. A mature forest doesn’t just hold carbon; it continuously pulls more from the atmosphere year after year. Losing that ongoing absorption capacity means the remaining forests and oceans have to work harder to offset human emissions, and they’re already struggling to keep up.
With 30 million hectares lost in 2024 alone, deforestation remains one of the largest and most preventable sources of greenhouse gas emissions on the planet. The 21% of global emissions tied to agriculture and land use is comparable to the entire global transportation sector. Unlike fossil fuel emissions, which require complex technological transitions to reduce, the climate impact of deforestation can be addressed by simply leaving forests standing.