Deforestation: Facts, causes & effects

Aerial view of trucks removing trees from a forest.
Experts estimate that a chunk of forest the size of a soccer field is lost every second to deforestation. (Image credit: Shutterstock)

Deforestation is the permanent removal of trees from a forest. Deforestation can include clearing the land for farming or livestock, or using the timber for fuel, construction or manufacturing.  

Forests cover more than 30% of  Earth's land surface, according to the World Wildlife Fund (WWF). These forested areas produce oxygen and absorb carbon dioxide (CO2), and are home to an estimated 80% of Earth's terrestrial species. Forests also are a source of  food, medicine and fuel for more than a billion people. Worldwide, forests provide 13.4 million people with jobs in the forest sector, and another 41 million people have jobs related to forests. 

Forests are an important natural resource, but humans have destroyed substantial quantities of forested land. In North America, about half the forests in the eastern part of the continent were cut down for timber and farming between the 1600s and late 1800s, according to National Geographic

Today, most deforestation is happening in the tropics. Areas that were inaccessible in the past are now within reach as people build new roads through the dense forests. The world has lost about 10% of its tropical tree cover since 2000, and nearly 47,000 square miles (121,000 square kilometers) were destroyed in 2019 alone, The New York Times reported in 2020.

The World Bank estimates that about 3.9 million square miles (10 million square km) of forest have been lost since the beginning of the 20th century. In the past 25 years, forests shrank by 502,000 square miles (1.3 million square km) — an area bigger than the size of South Africa.

Why do people destroy forests?

Often, deforestation occurs when people cut or clear forested area to make way for agriculture or grazing. The Union of Concerned Scientists (UCS) reports that just four commodities are mostly responsible for the vast majority of tropical deforestation: beef, soy, palm oil and wood products. UCS estimates that an area the size of Switzerland (14,800 square miles, or 38,300 square km) is lost to deforestation every year. 

People often light fires to clear land for agricultural use. First, workers harvest valuable timber, then burn the remaining vegetation to make way for crops like soy, or for cattle grazing. In 2019, the number of human-lit fires in Brazil skyrocketed. As of August 2019, more than 80,000 fires burned in the Amazon, an increase of almost 80% from 2018, National Geographic reported

Many forests are cleared to make way for palm oil plantations. Palm oil is the most commonly produced vegetable oil and is found in half of all supermarket products. Growing the trees that produce the oil requires the leveling of native forest and the destruction of local peatlands — which doubles the harmful effect on the ecosystem., The global palm oil market was valued at $36.71 billion in 2019 and has been "witnessing unprecedented growth," according to a 2020 report published by Business Wire

Aerial view of a palm tree farm planted where a rainforest once stood.  (Image credit: Shutterstock)

What are the effects of deforestation?

Forests can be found from the tropics to high-latitude areas and contain a wide array of trees, plants, animals, fungi and microbes, according to WWF. Some places are especially diverse — the tropical forests of New Guinea, for example, contain more than 6% of the world's species of plants and animals. 

When forests are destroyed, complex ecosystems are disrupted or perish. Human communities that depend on forests also suffer the consequences of widespread deforestation. In countries like Uganda, people rely on trees for firewood, timber and charcoal. From 2000 to 2020, , Uganda lost more than 3,500 square miles (9,200 square kilometers) of its forest cover, Global Forest Watch reported. Families send children — primarily girls — to collect firewood, and kids have to trek farther and farther to get to the trees, Ugandan entrepreneur Sanga Moses told the website Good Black News (GBN) Collecting enough wood often takes all day, so the children miss school, GBN reported. 

According to the United Nation's 2020 State of the World's Forests report, three-quarters of Earth’s freshwater comes from forested watersheds, and the loss of trees can worsen water quality. The report also found that over half the global population relies on forested watersheds for their drinking water as well as water used for agriculture and industry.

Deforestation in tropical regions can also affect the way water vapor forms over the canopy, which can reduce rainfall. A 2019 study published in the journal Ecohydrology showed that parts of the Amazon rainforest that were converted to agricultural land had higher soil and air temperatures, which can exacerbate drought conditions. In comparison, forested land had rates of evapotranspiration that were about three times higher, adding more water vapor to the air. 

Trees also absorb carbon dioxide, mitigating the emission of greenhouse gases produced by human activity. As climate change continues, trees play an important role in carbon sequestration, or the capture and storage of excess carbon dioxide. Tropical trees alone are estimated to provide about 23% of the climate mitigation that's needed to offset climate change, according to the World Resources Institute, a nonprofit global research institute.

Deforestation not only eliminates vegetation that is important for removing carbon dioxide from the air, but the act of clearing the forests also produces greenhouse gas emissions. The Food and Agriculture Organization of the United Nations says that deforestation is the second-leading cause of climate change. (The first is the burning of fossil fuels.) In fact, deforestation accounts for nearly 20% of greenhouse gas emissions.

Deforestation not only removes trees that sequester greenhouse gases; it also produces a significant amount of greenhouse gases in the process.  (Image credit: Shutterstock)

Are there solutions to deforestation?

Developing alternatives to deforestation can help decrease the need for tree clearing. For example, the desire to expand the amount of land used for agriculture is a compelling economic reason to deforest an area. But if people adopted sustainable farming practices or employed new farming technologies and crops, the need for more land might be diminished, according to the UN's Sustainable Forest Management Toolbox. 

Forests can also be restored, through replanting trees in cleared areas or simply allowing the forest ecosystem to regenerate over time. The goal of restoration is to return the forest to its original state, before it was cleared, according to the U.S. Forest Service. The sooner a cleared area is reforested, the quicker the ecosystem can start to repair itself. Afterward, wildlife will return, water systems will reestablish, carbon will be sequestered and soils will be replenished. 

Everyone can do their part to curb deforestation. We can buy certified wood products — made from wood that has been sustainably harvested — go paperless, limit our consumption of products that use palm oil and plant a tree when possible. However, deforestation is a global problem that won't be overcome by individual actions, and will require large-scale efforts by nations' leaders to change course and reduce forest destruction. 

In 2020, more than 100 countries pledged to end and reverse deforestation by 2030, signing an agreement at the 26th annual United Nations Climate Change Conference (COP26) in Glasgow. A dozen countries that signed the pledge promised to provide $12 billion between 2022 and 2025 to mitigate the damage to forests from wildfires, to restore land and to assist Indigenous communities, The Guardian reported on Jan. 3. Other donors in the private sector pledged $7.2 billion, to support the development of agriculture strategies that do not rely on deforestation.

Additional resources

Check out this animation of deforestation in the Amazon made with images from NASA's Landsat 5 and 7 satellites. You can learn more about forest conservation efforts from the Yale School of Forestry & Environmental Studies. Read more about the problems caused by deforestation according to the International Union for the Conservation of Nature. 


World Wildlife Fund, “Deforestation and Forest Degradation”.

National Geographic Society Resource Library, “Deforestation”.

The New York Times, "'Going in the Wrong Direction': More Tropical Forest Loss in 2019,"  June 2, 2020.

World Bank Blogs, "Five forest figures for the International Day of Forests," March 21, 2016.

Global Forest Watch, "2017 Was the Second-Worst Year on Record for Tropical Tree Cover Loss," June 27, 2018.

The Guardian, "One football pitch of forest lost every second in 2017, data reveals," June 27, 2018.

National Geographic, "The Amazon is burning at record rates—and deforestation is to blame," August 21, 2019

Rainforest Rescue, "Palm oil – deforestation for everyday products".

Union of Concerned Scientists, "What's Driving Deforestation?" Feb 8, 2016.

Business Wire, "Global Palm Oil Market (2020 to 2025) - Drivers, Restraints & Trends," April 07, 2020.

Global Forest Watch, "Uganda Deforestation Rates & Statistics"

Good Black News, "Uganda Native Sanga Moses Awarded $1 Million to Boost his Innovative Energy Business, Eco-Fuel Africa," April 23, 2015.

Food and Agriculture Organization of the United Nations, "The State of the World's Forests: 2020".

Oliveira et al. "Effects of land‐cover changes on the partitioning of surface energy and water fluxes in Amazonia using high‐resolution satellite imagery," Ecohydrology, 2019.

World Resources Institute, "By the Numbers: The Value of Tropical Forests in the Climate Change Equation," October 4, 2018.

United Nations, "Sustainable Forest Management (SFM) Toolbox."

U.S. Forest Service, "Reforestation"

Sarah Derouin
Live Science Contributor

Sarah Derouin is a science journalist based in Michigan. She has a doctorate in geology from the University of Cincinnati and is a graduate of the University of California-Santa Cruz Science Communication program. Her work has appeared in Eos, Mongabay, Scientific American, and other news outlets. She is also an assistant producer on Big Picture Science radio show and podcast.