Earth gained 2.24 million square kilometers of tree cover in 35 years

Overview

For decades, the dominant narrative held that global forest cover was declining. A 2018 study in Nature upended that assumption: satellite data from 1982 to 2016 showed the world's tree canopy grew by 2.24 million square kilometers—an area larger than Mexico. The net gain of 7.1% came despite ongoing tropical deforestation, with expansion in Russia, China, Europe, and the United States more than offsetting losses in the Amazon, Congo, and Southeast Asia.

The finding reflects two distinct forces reshaping Earth's land surface. In the temperate and boreal zones, agricultural abandonment (especially after the Soviet collapse) and massive tree-planting programs (especially in China) allowed forests to reclaim former farmland. In the tropics, however, cattle ranching, palm oil, and subsistence farming continue to clear primary forest—destroying irreplaceable biodiversity even as tree cover expands elsewhere. Whether the global gain represents ecological progress or a misleading metric depends on what's being counted and what's being lost.

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Key Indicators

+2.24M km²

Net tree cover gain

Total increase in global tree canopy from 1982 to 2016

+7.1%

Relative increase

Tree cover grew from 31 to 33 million km², relative to 1982 baseline

-927,000 km²

Tropical tree loss

Net loss in the tropics, offset by gains in higher latitudes

60%

Human-driven change

Share of land cover change attributed to direct human activity

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People Involved

Xiao-Peng Song

Assistant Professor, UMD Department of Geographical Sciences

Matthew C. Hansen

Professor and principal investigator at GLAD Lab

Organizations Involved

Global Land Analysis and Discovery (GLAD) Lab

Research Laboratory

Primary producer of global forest monitoring data

UMD research lab that produces satellite-based global forest change datasets used by governments, NGOs, and international organizations.

Food and Agriculture Organization of the United Nations

UN Agency

Primary source of government-reported forest statistics

UN agency that compiles national forest statistics and maintains a different definition of 'forest' than satellite-based tree cover measurements.

Timeline

Nature study reveals 35-year net tree cover gain
Research

University of Maryland researchers report that global tree canopy increased by 2.24 million km² from 1982 to 2016, a 7.1% gain that contradicts prevailing assumptions of net forest decline.
August 8th, 2018
NASA confirms CO2 fertilization driving global greening
Research

A study in Nature Climate Change attributes 70% of observed global greening to carbon dioxide fertilization, with nitrogen deposition and climate change as secondary factors.
April 25th, 2016
First high-resolution global forest maps published
Research

Hansen et al. publish 30-meter resolution global forest change data in Science, showing tree cover loss and gain from 2000-2012.
November 15th, 2013
Soviet Union dissolves
Geopolitical

The collapse triggers massive agricultural abandonment across Russia and Eastern Europe. About 31 million hectares of cropland are eventually abandoned, allowing forest regrowth.
December 26th, 1991
Satellite monitoring baseline established
Research

NOAA's AVHRR satellite begins providing consistent global vegetation data, enabling long-term land cover analysis.
January 1st, 1982
China launches Three-North Shelter Forest Program
Policy

China begins what will become the world's largest afforestation project, aimed at halting desertification. By 2018, over 66 billion trees had been planted.
November 25th, 1978

Scenarios

Predict which scenario wins. Contrarian picks score more — points lock in when the scenario resolves.

Predictions leaderboard

Temperate Gains Continue, Tropical Losses Slow

If current trends persist, tree cover expansion in China, Russia, and Europe continues while improved enforcement in Brazil and Indonesia reduces tropical deforestation. The net global gain accelerates, though biodiversity losses in primary forests remain a concern. This scenario depends on sustained political will for forest protection in tropical nations and continued afforestation investment in temperate zones.

Discussed by: World Resources Institute, Global Forest Watch analysts

Consensus —

Tropical Deforestation Accelerates, Erasing Net Gains

Political shifts in Brazil, Indonesia, or the Democratic Republic of Congo weaken forest protections. Agricultural commodity prices rise, intensifying pressure to clear land for cattle, soy, and palm oil. Tropical losses overwhelm temperate gains, returning global tree cover to net decline. Fire seasons intensify under climate change, compounding the effect.

Discussed by: Mongabay, Carbon Brief, environmental researchers

Consensus —

Quality vs. Quantity Debate Reshapes Policy

Policymakers increasingly distinguish between natural forest restoration and monoculture plantations. International climate commitments shift from raw tree cover targets to ecosystem quality metrics. Tree-planting programs (like China's Great Green Wall) face scrutiny over biodiversity, water use, and survival rates. The headline 'tree cover gain' becomes less relevant than measures of forest health and carbon storage.

Discussed by: Stanford researchers, conservation biologists, Science journal

Consensus —

Climate Feedbacks Reshape Forest Geography

Warming temperatures push boreal forests northward into tundra, but southern edges die back from heat, fire, and drought faster than northern expansion can compensate. The net effect on global tree cover becomes negative as boreal forests shrink. Meanwhile, CO2 fertilization effects plateau, reducing the growth boost that drove earlier greening.

Discussed by: Nature, Arctic Focus, boreal forest researchers

Consensus —

Historical Context

U.S. Eastern Forest Recovery (1920s-Present)

1920-present

What Happened

By 1920, over two-thirds of American forests had been logged at least once. Eastern forest cover hit its nadir. Then the Great Depression and urbanization pulled farmers off marginal land. The Civilian Conservation Corps planted millions of trees. Abandoned fields reverted to forest naturally.

Outcome

Short Term

Forest cover in the eastern U.S. increased from roughly 10% in 1930 to nearly 40% by 2000.

Long Term

The U.S. became a model of 'forest transition'—the pattern where industrializing nations first deforest, then reforest as agriculture concentrates on productive land and marginal land is abandoned.

Why It's Relevant Today

The global tree cover gain documented in 2018 reflects this same pattern playing out across Russia, China, and Europe—economic development and agricultural concentration allowing forests to reclaim former farmland.

Post-Soviet Agricultural Collapse (1991-2012)

1991-2012

What Happened

When the Soviet Union dissolved, subsidies to collective farms vanished. About 34% of Russian cropland was abandoned. In the Kirov region and across Eastern Europe, young forests grew up in empty fields. Forest cover across the former Soviet bloc increased by 4.7% from 1985 to 2012.

Outcome

Short Term

Abandoned farmlands began sequestering an estimated 42.6 million tonnes of carbon annually—roughly 10% of Russia's fossil fuel emissions.

Long Term

The region became a significant global carbon sink. However, only 14% of abandoned land has converted to forest so far, suggesting substantial future sequestration potential.

Why It's Relevant Today

Russia contributed the single largest national gain in tree cover (+790,000 km²) in the 1982-2016 study period. This unintentional 'rewilding' demonstrates how economic disruption can produce environmental recovery.

China's Great Green Wall (1978-2050)

1978-present

What Happened

Facing advancing deserts, China launched the Three-North Shelter Forest Program in 1978—the largest afforestation effort in history. The government invested over $100 billion and planted more than 66 billion trees along the northern border. By 2024, a forest belt fully encircled the Taklamakan Desert.

Outcome

Short Term

China's tree cover increased 34% from 1982 to 2016, adding 324,000 km² of canopy. NASA attributed about 25% of global greening to Chinese forest expansion.

Long Term

Critics note high tree mortality rates, monoculture vulnerabilities (a billion poplars died to one pathogen in 2000), and water stress in arid regions. The program's long-term sustainability remains uncertain.

Why It's Relevant Today

China's state-directed reforestation represents the 'active' counterpart to Russia's 'passive' forest recovery. Together they illustrate the two pathways—planned planting and natural regrowth—driving global tree cover expansion.