Consequences of Deforestation: Effects With Data

The main consequences of deforestation are lost habitat, eroded soil, muddier rivers, higher flood and water-supply risk, stored carbon released into the air, hotter and drier local weather, more disease and lost livelihoods for people who live in or near the forest. Some show within a year or two of clearing. Others build over decades. FAO counts 489 million hectares of forest lost to deforestation between 1990 and 2025, and 88% of it was in the tropics (FAO Global Forest Resources Assessment 2025).

This guide covers the short-term effects first, then the longer ones. The main effects have a dated number from a named source. It also has three charts and a calculator that turns a clearing area into tonnes of CO2. For ways to stop the loss, we link to our guides on Amazon deforestation solutions and on what the Amazon does for the climate, so we do not repeat them here.

Effects of deforestation at a glance

Deforestation means forest is cleared and the land is put to another use, such as crops, pasture, mining, roads or towns. The table lists the main effects and where each was measured.

How much forest is being lost

The world is losing forest more slowly than 30 years ago, but the loss is still large. FAO reports that deforestation fell to 10.9 million hectares a year in 2015-2025, from 17.6 million a year in 1990-2000. Forests still cover 4.14 billion hectares, about one third of the land.

The picture differs by region. In FAO’s data, South America had the highest deforestation rate in 2015-2025, at 4.22 million hectares a year, almost half its 1990-2000 rate. Africa’s rate was 3.45 million hectares a year. Europe’s was 145,000 hectares a year.

Satellite data from the University of Maryland, shown on Global Forest Watch, tell a similar story for the wettest forests. The world lost 4.3 million hectares of tropical primary forest in 2025. That is 36% less than the fire-driven record of 2024 but 46% more than a decade earlier (WRI, April 2026). Brazil, Bolivia and the Democratic Republic of the Congo were among the countries with the most loss.

Two different measures are in use. FAO counts forest that is converted to another land use. Global Forest Watch counts tree cover loss from any cause, including fire and tree harvest, and it can regrow. Do not mix the two numbers.

Chart

Deforestation rate by period

Million hectares a year; world, tropics and Africa

Habitat and biodiversity loss

Clearing removes the shelter, food and breeding sites of forest species.

Forests that are cut into pieces suffer even if some trees remain. A global study found that more than 70% of the world’s forest is within 1 km of an edge, and a synthesis of experiments over 35 years found that fragmentation reduces biodiversity by 13 to 75% (Haddad et al., Science Advances, 2015). The effects were largest in the smallest, most isolated patches, and they grew with time. So the damage does not stop when the bulldozers leave.

Soil erosion and silted rivers

Tree canopy breaks the force of heavy rain. Roots and leaf litter hold soil in place and let water soak in. When they go, rain hits bare ground, runs off faster and carries topsoil with it. Topsoil carries the nutrients and organic matter that crops use, so its loss can mean lower fertility and higher fertilizer bills.

Rivers show the change. A 2024 study of Amazon rivers used satellite data for 2001-2020. It found that in heavily cleared eastern basins the sediment response came within a year, while in less disturbed western basins it took one to two years. The study also found that clearing had to be substantial to show up: in 69% of the major tributary basins with an immediate response, more than 5% of the basin had been cleared.

On a farm, the same process shows up as rills, gullies and silt-laden ponds after the first big storms on newly cleared slopes. Keeping a strip of trees or grass along streams and across slopes slows this. Check local rules on buffer strips and clearing permits before you act, as they differ by country and state.

Floods and water supply

Forests soak up rain and release it slowly. FAO notes that forests can reduce the risks and impacts of drought, desertification, soil erosion, landslides and floods. Once the cover is gone, more rain runs off quickly. Very large floods depend on many other factors, so do not expect forest alone to prevent them.

Water quality follows. Silt, nutrients and farm chemicals reach streams faster, and towns downstream pay to clean the water. FAO says that at least one third of the world’s biggest cities draw a significant share of their drinking water from forested areas, including New York, Singapore, Rio de Janeiro and Cape Town (FAO, 2011).

The cost can be put in numbers. A US Forest Service assessment of watersheds in the southern United States estimates that each 1% of forest lost upstream could raise drinking water treatment costs by 1.7%. That is an estimate for one region, not a law for every river, but it shows why water utilities pay to protect forest.

Carbon release and the climate

Trees and forest soil store carbon. Clearing, and especially burning, sends it back to the air as CO2. The Global Carbon Budget 2025 puts emissions from deforestation at around 1.9 billion tonnes of carbon a year over 2015-2024. Forest regrowth and tree planting took up about 1.3 billion tonnes, which offsets two thirds of that. Wood harvest, peat drainage and peat fire add smaller amounts. Net emissions from land use averaged 1.4 billion tonnes of carbon a year, which is 5.0 billion tonnes of CO2.

Chart

Carbon flows from land use

Billion tonnes of carbon a year, average 2015-2024

Fire is a growing part of the story. In 2025, fire caused 42% of the 25.5 million hectares of global tree cover loss, according to WRI’s Global Forest Watch analysis. Much of that was boreal forest in Canada, where wildfire caused 5.3 million hectares of tree cover loss. This is tree cover loss, not all of it permanent deforestation, but it shows how much stored carbon can leave a forest quickly.

Estimate the CO2 from clearing your own land

The calculator below uses your numbers: the area, the carbon stored per hectare and the share that is released. Forest carbon stocks vary a lot with forest type, age and soil, so use a figure from your local forest inventory or advisor.

Try the numbers for your own farm below.

Hotter, drier local weather and effects on crops

Forests return water to the air through their leaves, which helps keep the air cool and moist. Cleared land loses that effect. A review in Nature Climate Change found that tropical deforestation results in warmer, drier conditions at the local scale. It also described thresholds: beyond a certain amount of clearing, rainfall declines, although small clearings can sometimes enhance it locally (Lawrence and Vandecar, 2015).

The effect on rain may reach farms far from the forest. A satellite study in Nature found that over more than 60% of the tropical land surface, air that had passed over extensive vegetation produced at least twice as much rain as air that had passed over little vegetation. The authors combined this with deforestation trends and estimated rainfall reductions of 12% in the wet season and 21% in the dry season across the Amazon basin by 2050 (Spracklen et al., 2012). That is a projection, not a measurement, and models differ.

For a farmer, the risk is a drier, hotter growing season on land that was cleared for crops. Where erosion removes topsoil and organic matter drops, yields may fall and inputs may have to rise to hold output.

Chart

Projected Amazon basin rainfall loss by 2050

Percent reduction, from observed rain-vegetation link and deforestation trends (a projection)

Health: malaria, smoke and heat

Clearing changes where mosquitoes breed and where people live and work. A study of 795 municipalities in the Brazilian Amazon from 2003 to 2015 found that a 10% increase in deforestation led to a 3.27% increase in malaria incidence. For 2008, the midpoint of the study, that equalled about 1,567 more square kilometres cleared and about 9,980 more cases (MacDonald and Mordecai, PNAS, 2019). The same paper found a feedback: high malaria burden was linked to less clearing.

This is one region and one disease, so it does not show the same size of effect everywhere. Burning also fills the air with smoke that harms lungs, and workers clearing land face heat and dust. As an example of smoke harm from a boreal wildfire (not tropical deforestation), the 2025 Canadian wildfire season forced the evacuation of more than 80,000 people and sent smoke into populated parts of the United States and Canada (WRI, 2026).

Social consequences of deforestation

The people hit first live in or next to the forest. Wild foods, firewood, timber, fibre and medicinal plants matter to forest households. When the trees go, they must buy these things or go without.

WRI notes that drivers of forest loss include agricultural expansion, mining, fire and local reliance on forests for food and fuel, so the people who clear the land and the people who bear the costs can be different groups.

Downstream communities lose too. Silted rivers raise water treatment costs, and floods and eroded soils can reduce yields on farms outside the cleared area.

Economic impacts of deforestation

Clearing brings income at the start: timber sales, a new farm, a mine or a road. The costs come later and are spread across many people. They include extra water treatment, more disease, lost soil fertility, flood damage and lost forest products. The USDA estimate that each 1% of upstream forest lost could raise treatment costs by 1.7% (southern United States), and the modelled 9,980 extra malaria cases in Brazil in 2008, are two examples that can be counted.

What helps after clearing

Land that is already cleared can still be made safer. Planting trees among crops (agroforestry), growing cover crops, farming along the contour and restoring streamside buffers all cut runoff and erosion. Certified low-impact logging and secure land rights help where forest is still harvested. For the policy side, see the guides linked at the top.

Clearing rules, permits and carbon-credit rules differ by country and state. Check your local rules and get professional advice before you clear, replant or sell credits.

▶ Regenerative practices such as cover crops, agroforestry and carbon farming that protect soil on land that is already cleared. · 10:25

Watching land change from space

Satellites let you check the effects above on your own land or supply chain. Sentinel-2 images are public and show new bare soil, tree cover change and vegetation recovery every few days where skies are clear. Farmonaut Satellite + AI Farm Monitoring System draws vegetation index maps for fields and forest areas you outline. Satellite images show that vegetation has changed. They do not show the cause, so check with a visit on the ground.

▶ How to read satellite vegetation maps in a web app. · 10:16

FAQ

What are the main consequences of deforestation?

The main effects are habitat and biodiversity loss, soil erosion, silted rivers, floods and higher water treatment costs, carbon emissions, hotter and drier local weather, more malaria in some regions, and lost food, fuel and income for forest communities.

What are the short-term effects of deforestation?

Within a year or two, the clearest effects are lost habitat, runoff and erosion, silted rivers and carbon release. In the Amazon, river sediment responded within a year in heavily cleared basins (ESurf, 2024).

How does deforestation affect humans?

It removes food, fuel and income for forest households, can raise disease such as malaria, worsens smoke and heat, and raises the cost of clean water. In Brazil, a 10% rise in clearing was linked to a 3.27% rise in malaria incidence (PNAS, 2019).

Which are the five main consequences of deforestation, with examples?

Five with examples: biodiversity loss (fragmentation cut biodiversity by 13-75% in experiments); soil erosion (Amazon rivers silting); carbon release (1.9 billion tonnes of carbon a year); water impacts (an estimated 1.7% higher treatment cost per 1% upstream loss, southern US); and social harm (lost food, fuel and land rights).

Does deforestation cause climate change?

It adds CO2 to the air and, at local scale, makes land warmer and drier. Global net emissions from land use were 1.4 billion tonnes of carbon a year over 2015-2024, with deforestation the main source of gross emissions (Global Carbon Budget 2025).

Is deforestation getting better or worse?

Both. FAO says the global rate has fallen since the 1990s, to 10.9 million hectares a year, yet WRI, using a different measure, reports that tropical primary forest loss in 2025 was still 46% above a decade earlier.

Related pages on our site: carbon footprint tracking, supply chain traceability, farm fleet management, large-scale farm management, satellite weather data API, satellite data API and the Farmonaut app.