According to the Food and Agriculture Organization of the United Nations, forests cover 31% of the world’s land area. That’s over 4 billion hectares of an incredibly biodiverse, precious ecosystem. Over half of the world’s forests are in just five countries – Brazil, Canada, the United States, China, and the Russian Federation. Since 1990, around 420 million hectares of forest have been lost, and while deforestation has decreased in the past decades, it remains a serious problem. Why? Here are ten negative effects deforestation has on humans and the planet:
#1. Deforestation harms biomass and worsens climate change
A recent paper in Nature Communications used climate models and satellite data to measure the climate impact of tropical deforestation on the forests left behind. They found that after deforestation in one patch of the Amazon, the resulting climate changes led to another 5.1% loss of total biomass (roots, branches, leaves, etc) for the Amazon basin. This matters because a tree’s biomass stores carbon. Since 2010, deforestation has removed 1 petagram (1 trillion kilograms) of carbon every year. That carbon goes into the atmosphere and drives climate change. Understanding how deforestation affects other forests is essential to measuring its impact and figuring out solutions.
#2. Deforestation makes air pollution worse
Forests are essential to clean air. Through photosynthesis, the leaves of trees take in carbon dioxide and water. Combined with the sun’s energy, they convert these materials into nutrients. A by-product of this process? Oxygen. One large tree can produce as much as a day’s supply of oxygen for four people. Trees also reduce the effects of PM, which are particles of different chemicals that can cause lung and heart disease. This makes trees especially valuable in cities where pollution is higher. They also store carbon dioxide and keep it out of the atmosphere. healthy forests are essentially large air filters. Deforestation has the opposite effect. It removes an essential source of cleaner air and releases the stored carbon, worsening the air quality. Bad air has serious consequences. According to the World Health Organization, around 4.2 million people die every year as a result of outdoor air pollution. Those who don’t die are at risk for a score of lung and heart diseases.
#3. Deforestation increases the risk for more pandemics
Deforestation makes pandemics more likely. Why? Many viral diseases (like COVID-19 and Ebola) come from animals living in tropical forests. As tropical forests are destroyed, the animals that carry these diseases come into closer and closer contact with humans, giving the pathogens prime opportunities to evolve and make the jump to other species. Several studies link deforestation to malaria epidemics in South America as forest clearing helps mosquitoes, which are major vectors of human diseases. Experts have been warning about the health consequences of deforestation for decades. In an article from Nature, epidemiologist Ibrahima Socé Fall is quoted, “If we continue to have this level of deforestation, disorganized mining and unplanned development, we are going to have more outbreaks.”
#4. Deforestation threatens the creation of medicines
Forests not only shield humans from dangerous pathogens. They’re a source of medicine and medical supplies. According to the UN, forest products play a huge role in public health systems, especially during COVID-19. Things like paper towels, ethanol for hand sanitizers, toilet paper, and more all come from forest products. PPE like masks and clothing for medical workers also use forest products like wood pulp. Many medications have forest origins, too. Around 120 prescription drugs and ⅔ of all medicine with cancer-fighting properties come from rainforest plants. Compounds found in these plants have been used to treat everything from heart disease to diabetes to malaria. Only a small fraction of plants have been tested for their medicinal properties, so it’s essential to protect forests and research what else they can offer humanity.
#5. Deforestation leads to greater soil erosion
Soil erosion has devastating effects on the environment, including the loss of fertile land and crops. Areas with high soil erosion are also more vulnerable to flooding, mudslides, dust storms, and water pollution. Erosion usually occurs when soil is exposed to moving water, hard rain, and strong winds. With their roots, fallen leaves, and branches, forests shield the topsoil from these harmful elements. When trees are cut down, the soil is left exposed. Soil erosion can also worsen climate change because soil holds high volumes of carbon dioxide. When soil is degraded through deforestation, the carbon is released into the atmosphere. The ocean holds significantly more carbon, but with proper land and forest management, healthy soil is a vital tool in the fight against climate change.
#6. Deforestation affects biodiversity
Biodiversity is the variety of life found on earth, including plants, animals, and microorganisms. It measures variations in genetics, species, and ecosystems. Biodiversity comes with a range of benefits, such as healthier soil, cleaner water, healthier plants and animals, and better food security. Every ecosystem’s delicate balance is a little bit different, but experts agree that biodiversity is important for every ecosystem. A piece on The Conversation summarizes what researchers found when they examined five million records stretching over 150 years. They discovered many things, including how changes in biodiversity affect species differently depending on their lifespan. Deforestation also harms biodiversity more in “pristine forests” than in forests more accustomed to disturbances. How significant the forest loss is matters, too. If forests are destroyed, animals and plants could go completely extinct if they can’t adapt fast enough.
#7. Deforestation throws off the water cycle
Trees play an important role in the water cycle. Moisture falls on the ground through rain, snow, and fog. The soil and streams absorb a lot of water but some seeps deeper into underground aquifers or gets evaporated into vapor. The forest’s roots drink in water from the soil, moving it through the tree in a process called transpiration. The water then evaporates from the leaves or needles of the tree and returns to the atmosphere. A study in 2019 found that on a local scale, the forest canopy can regulate the rate of moisture and energy returning to the atmosphere. This impacts water retention and forest ecosystems. The bigger the forest, the bigger its impact. When forests are destroyed, the water cycle is disrupted, which can impact how much rain an area gets, the air temperature, and the health of the surrounding plant, animal, and human communities.
#8. Deforestation harms forest watersheds
Speaking of water, forest watersheds are also vital to humanity and the planet. In the United States alone, forest watersheds are a source of clean water for over 180 million people. When forests are healthy, they filter water, regulate rainfall, manage groundwater tables, and protect communities from droughts and floods. On the coast, forests are essential for marine life. Deforestation causes harm in a variety of ways. Forests are unable to filter properly or regulate the water supply. The risk for floods, erosion, and landslides increases. In 2016, Global Forest Watch released a report showing the world’s watersheds lost 6% of their tree cover between 2000 and 2014. Forest loss, fire, and erosion were common threats. The watershed in Sumatra, Indonesia, lost more than 22% of its forest cover from logging, agricultural expansion, and infrastructure. The effects? More water pollution, landslides, fires, and floods.
#9. Deforestation makes outdoor work dangerous
Millions of people work outdoors in industries like construction and agriculture. When forests are healthy, they block the sun’s radiation, offer shade, and cool down the air. When trees in places like the Amazon are cut down, the temperature shoots up. According to 2021 a study in One Earth, nearly 5 million people working in tropical areas over the past 15 years lost around 30 minutes of safe work time per day because of deforestation. In other tropical areas, around 100,000 people (90% of whom live in Asia) lost more than 2 hours of safe work time. Losing safe work time forces many to continue working in unsafe conditions where high temperatures cause heat strain and heat stroke, which can be fatal. The study’s lead author said: “Our findings highlight the vital role tropical forests play in effectively providing natural air-conditioning services for populations vulnerable to climate change – given these are typically regions where outdoor work tends to be the only option for many, and where workers don’t have the luxury of retiring to air-conditioned offices whenever the temperature rises to intolerable levels.”
#10. Deforestation has a huge economic impact
Forests are a crucial economy. Everywhere in the world, communities living in forests depend on their biodiversity. Around 86 million green jobs involve forests while 880 million people collect wood for fuel or produce charcoal. People of all income levels use forests, but 90% of those living in extreme poverty depend on them for at least part of their livelihood. Many forms of recreation and tourism also rely on forests. Based on some estimates, the economic value of the forest’s ecosystem services could be as high as $16.2 trillion every year. The total value could be much higher. According to an analysis by the Boston Consulting Group, which attempted to measure value based on climate regulatory function, environmental benefits, social value, and commercial output, the world’s forests could be worth as much as $150 trillion. As much as 90% of the value comes from forests’ ability to store carbon. The analysis pointed to land-use changes and rising global temperatures as the biggest threats to that value.
