The growing human population has dramatically altered Earth’s ecosystems, transforming forests, grasslands, and other wilderness into farms, pasture, timberland, mines, and settlements. People are now using close to 75% of Earth’s ice-free land area directly and are indirectly affecting the rest of the globe through pollution and climate change. Tallied together, global agricultural systems, land use, and forestry contribute close to 20% of all human-caused greenhouse gas emissions.
Trees and other plants take in carbon dioxide during photosynthesis, making them key actors for ecosystem health and climate regulation. Yet human changes to landscapes, especially deforestation, have released carbon back into the atmosphere for centuries. In fact, forest loss prior to 1850 continues to affect atmospheric carbon dioxide concentrations, and thus the global climate, today.
According to the Food and Agriculture Organization of the United Nations (FAO), the world lost around 10 million hectares (25 million acres) of forest each year between 2015 and 2020, an area equal to the size of South Korea. The pandemic did little to reduce forest loss despite widespread economic shocks: An area larger than the United Kingdom was deforested in 2020, including more than 4.2 million hectares of primary tropical forests.
Data from Global Forest Watch reveal that tropical deforestation currently accounts for 8% of the world’s annual carbon dioxide emissions. This means that if tropical deforestation were a country, it would be the world’s largest greenhouse gas emitter, following China and the United States.
The leading cause of global deforestation is agriculture. While agriculture practices vary around the world and therefore affect regional environments differently, the main drivers of forest clearing are livestock grazing, commercial crops such as palm oil and soybeans, and small scale farming—also known as shifting agriculture—in which farmers work on small plots of land for short periods and then move to other plots once the soil has been depleted of nutrients. Expanding industrial agriculture—indicative of large-scale farms and livestock operations—disproportionately contributes to soil degradation, unsustainable water use, biodiversity loss, and waste production. Climate-changing greenhouse gas emissions from the agricultural sector are roughly split between emissions from land clearing and emissions from food production practices. About half of those production emissions come from ruminant livestock, namely cattle, sheep, and goats.
Current farming methods can degrade soil more than 100 times faster than new soil is formed. Over plowing and overgrazing turn fertile land into wasteland, which in turn increases both food insecurity and climate vulnerability, especially for the over 500 million people already living in areas that have recently experienced desertification. Far more people live in populous and arid regions where land degradation poses a risk to food production.
As emerging economies continue to grow, so too will the demand for resource-intensive foods—namely, animal products. The demand for ruminant meat (beef, lamb, and goat) is projected to increase 88% between 2010 and 2050. This poses challenges to curbing agricultural greenhouse gas emissions and preventing the conversion of remaining forests to farmland. Feeding the additional 2 billion people projected to be added to the planet by 2050 will require rebalancing food supply and demand. Innovations in agricultural production are paramount to addressing food security and climate change.
Some of the most effective interventions to reduce future food demand and thus agriculture-related greenhouse gas emissions are those that facilitate slower population growth. This is especially true for the regions in which population growth is expected to occur the fastest. Stabilizing population involves increasing educational opportunities for girls, expanding access to high quality reproductive health services, and reducing infant and child mortality rates through improved health services.
Producing beef, the most common of the ruminant meats, requires more than 20 times more land and creates more than 20 times more greenhouse gases per calorie of edible protein compared to plant proteins like beans or lentils. These animals are major sources of methane pollution, a greenhouse gas roughly 30 times more potent than carbon dioxide.
Recent analysis from the United Nations, the World Bank, and the World Resources Institute concluded that without major increases in agricultural productivity, the land area required to feed the world’s growing population could wipe out most of the world’s forests and woodlands by mid-century—further accelerating the impacts of climate change.
Forest restoration is integral for maintaining biodiversity and mitigating species extinction. It also provides a variety of social and economic benefits. Forest restoration aids climate mitigation and adaptation, improves water security, and increases nature’s carbon storage capacity—in turn strengthening biodiversity and enhancing ecological services like air and water purification, soil stabilization, and storm buffering.
The future of food security will depend on the development of new and sustainable food systems that facilitate equitable production and consumption, reduce degradation, prevent biodiversity loss, and build climate resilience.
Human Impacts on the Environment Info Brief
Download this info brief for detailed information on the ways in which human population growth and activities intersect with and exacerbate the world’s most pressing environmental challenges, including climate change.
Human Impacts Slide Deck
This slide deck offers a detailed look into some of humanity’s most environmentally destructive practices and showcases several possibilities for macro-level solutions to global environmental pressures and climate change.
Browse literature on the connections between global population growth, industrialization, and mounting environmental pressures made worse by climate change. This resource also includes solution-oriented sources outlining potential paths toward a global transition to renewable energy, sustainable land use practices, and responsible consumption patterns.