Human impact on the environment facts for kids

Human impact on the environment means the changes humans cause to our planet's natural world. This includes changes to ecosystems, the variety of life (biodiversity), and natural resources. When we change the environment to fit our needs, it can lead to serious problems. These problems include global warming, harm to nature (like ocean acidification), the loss of many plants and animals (mass extinction and biodiversity loss), and crises where natural systems break down.

Some human activities that harm the environment globally are population growth, too much buying and using (overconsumption), taking too much from nature (overexploitation), pollution, and cutting down forests (deforestation). Some of these issues, like global warming and losing biodiversity, are so big they could threaten human survival.

The word anthropogenic means something caused by human activity. It was first used to describe how humans affect nature. This term is often used for pollution from human activities since the start of the Agricultural Revolution. It also covers all major ways humans change the environment. Many actions that warm our planet come from burning fossil fuels. This includes using electricity, driving cars, flying planes, heating homes, making things in factories, and destroying forests.

How Humans Use Too Many Resources

Humans sometimes use more resources than the Earth can naturally replace. This is a big problem for our planet.

Using More Than We Need: Overconsumption

Overconsumption happens when we use resources faster than ecosystems can renew them. We can measure this with an "ecological footprint." This compares how much humans demand from nature with how much the planet can regrow. Experts say that humanity's current demand is 70% higher than what the Earth can regenerate. Using too much for too long harms the environment and eventually makes resources disappear.

Our total impact on Earth depends on many things, not just how many people there are. Our lifestyles, how much we buy, and the pollution we create (like our carbon footprint) are also very important. In 2008, The New York Times reported that people in rich countries use oil and metals almost 32 times faster than people in developing countries. Developing countries make up most of the world's population.

Human civilization has caused the loss of 83% of all wild mammals and half of all plants. The world's chickens now weigh three times more than all wild birds combined. Domesticated cattle and pigs outweigh all wild mammals by 14 to 1. Global meat eating is expected to more than double by 2050, possibly by 76%. This will happen as the world's population grows to over 9 billion people. This increase will cause even more biodiversity loss and more Greenhouse gas emissions.

How Population Growth Affects the Planet

Some experts and environmentalists believe that the growth of the human population is a main cause of environmental problems. In 2017, over 15,000 scientists warned humanity that fast population growth is the "primary driver" behind many threats to nature and society. A 2019 report by the United Nations also said that human population growth is a big reason for the current loss of biodiversity.

Some scientists, like Jared Diamond and E. O. Wilson, think that human population growth is very damaging to biodiversity. Wilson worried that when humans reached a population of six billion, our total weight was 100 times more than any other large land animal that had ever lived.

However, blaming environmental problems only on overpopulation is a debated topic. Forecasts show that population growth is slowing down and will likely peak in this century. Many experts believe that global resources can meet this demand. Some studies suggest that population growth and overconsumption are linked. But critics say that blaming poorer populations or oversimplifying complex issues is not fair. They often see overconsumption as a separate problem.

Some people argue that reducing birth rates should focus on wealthy and middle-class people who consume the most. Their goal is to shrink the "human enterprise" and reverse the "growthmania" that threatens biodiversity and Earth's life-support systems.

Farming and Fishing's Environmental Footprint

How we grow our food and catch fish has a big impact on the environment.

Farming's Impact

The environmental impact of farming changes a lot depending on the methods used. It also depends on things like rainfall and temperature. There are two ways to look at this impact. One is "means-based," which looks at how farmers produce food. The other is "effect-based," which looks at the actual impact on the environment. For example, the quality of groundwater can be affected by how much nitrogen is put on the soil.

Farming affects the soil, water, air, animal and plant diversity, and even the food itself. Some environmental issues linked to farming include climate change, deforestation, genetic engineering, problems with irrigation, pollution, soil degradation, and waste.

Fishing's Impact

Fishing affects the environment in two main ways. First, it impacts how many fish are available to catch, leading to overfishing. Second, it harms other parts of the environment, like catching unwanted animals (by-catch) or destroying habitats like coral reefs. A 2019 report said that overfishing is the main reason for the mass extinction of species in the oceans.

There's a growing problem: we want to catch more fish, but there are fewer fish available. This gets worse as the world's population grows. Sometimes, there's a conflict between fishermen who need to fish for their living and scientists who know that we must reduce fishing in some areas to protect fish for the future.

A study in 2006 predicted that, if current trends continued, we would run out of wild-caught seafood by 2048. The scientists said this was due to overfishing, pollution, and other factors harming fish populations and their homes. However, this prediction has been debated. Many countries and international groups are now working to manage marine resources better.

The UN's Food and Agriculture Organization (FAO) reported in 2018 that the amount of fish caught from the wild has stayed the same for 20 years. But unsustainable overfishing has increased to affect 33% of the world's fisheries. They also noted that aquaculture (farmed fish) has grown a lot.

Populations of ocean sharks and rays have dropped by 71% since 1970, mostly because of overfishing. More than three-quarters of these species are now at risk of extinction.

Watering Crops: Irrigation's Effects

Irrigation is when we supply water to crops. While it helps plants grow, it can also change the amount and quality of soil and water. This then affects natural and social conditions nearby.

Irrigation often takes water from rivers and spreads it over farmland. This means less water flows downstream in the river. More water also evaporates from the irrigated area. The groundwater levels can rise, and drainage flow increases. These are direct effects.

Indirect effects include changes to soil and water quality, which can be complex. Sometimes, this leads to waterlogging (too much water in the soil) and soil salinization (too much salt in the soil). However, irrigation can also help remove excess salts from the soil if done with proper drainage.

Irrigation can also use groundwater from (tube)wells. This causes the water table to drop. This can lead to water mining (using water faster than it's refilled), land sinking (subsidence), and, near coasts, saltwater intrusion into freshwater.

While irrigation projects can be very helpful, their negative side effects are often not fully considered. Technologies like powerful pumps and dams use huge amounts of fresh water from aquifers, lakes, and rivers. This massive water diversion causes lakes, rivers, and creeks to dry up. This severely harms surrounding ecosystems and contributes to the extinction of many aquatic species.

Losing Farmland

Experts estimate that 12 million hectares (about 30 million acres) of farmland are lost each year due to degradation and abandonment. This loss comes from soil erosion, too much salt, loss of nutrients, acidification, compaction, waterlogging, and land sinking. Human-caused land degradation is especially bad in dry areas.

Despite these losses, the amount of land used for growing crops globally actually increased by about 9% from 1961 to 2012.

Soil erosion rates are generally high, especially on traditional farmlands. In the US, soil loss on cropland was estimated at 10.7 tons per hectare per year in 2010. However, this rate has been reduced by about 34% since 1982, thanks to practices like "no-till" farming. No-till farming, where the soil is not plowed, causes much less erosion and could help make agriculture more sustainable.

Land degradation is when the value of the natural environment is harmed by human activities. It's seen as any change that is damaging or unwanted. This is a major issue in the 21st century because it affects how much food we can grow, the environment, and food security. It's estimated that up to 40% of the world's farmland is seriously degraded.

The Environmental Cost of Meat Production

Making meat uses a lot of fossil energy, water, and land. It also creates greenhouse gas emissions. In some cases, it leads to cutting down rainforests, water pollution, and putting species at risk. The FAO estimated that 18% of global greenhouse gas emissions come from livestock production.

Livestock, especially cows, produce a lot of methane, a powerful greenhouse gas. Other emissions come from burning fossil fuels to grow and transport animal feed, and from fertilizers used for crops.

Meat production uses a lot of water, mostly for growing the plants that animals eat. For example, 94% of the water used for beef production is "green water," which is rainwater stored in the soil.

Animal waste can pollute water, especially where many animals are raised in one place. In the US, the livestock industry has a good record of following environmental rules, but pollution can be serious when rules are broken.

Changes in how meat is produced can reduce its environmental impact. For example, US beef production in 2007 used less fossil fuel, produced fewer greenhouse gases, and used less water and land per pound of beef than in 1977.

Some impacts of livestock can even be good for the environment. Animals can turn leftover crops into food, control weeds, and their manure can be used as fertilizer instead of synthetic ones. Grazing can also improve wildlife habitats and help store carbon in the soil. However, many studies show that the growing demand for meat is a big reason for biodiversity loss. This is because it leads to deforestation and habitat destruction. A 2006 UN report found that about 26% of the Earth's land is used for grazing livestock.

The Problem with Palm Oil

Palm oil is a type of vegetable oil from oil palm trees. It's used in many foods, cosmetics, and other products worldwide. Over one-third of all vegetable oil used globally is palm oil.

Losing Animal Homes: Habitat Loss

Because palm oil is in such high demand, more and more oil palm plantations are created. This means cutting down natural forests to make space. This deforestation has happened in Asia, Latin America, and West Africa. Malaysia and Indonesia have 90% of the world's oil palm trees. These forests are home to many different species, including many endangered animals like birds, rhinos, and tigers. Since 2000, 47% of deforestation has been for oil palm plantations, affecting about 877,000 acres each year.

Impact on the Variety of Life: Biodiversity

Natural forests have a huge variety of life, with many different organisms living there. But oil palm plantations are the opposite. Studies show that these plantations have less than 1% of the plant diversity found in natural forests. They also have 47–90% less mammal diversity. This isn't because of the oil palm tree itself, but because the plantations usually only grow one type of plant. This is called a monoculture. Natural forests, however, have many different plants and animals, making them very diverse.

One way to make palm oil more sustainable is through agroforestry. This means growing multiple types of plants, like coffee or cocoa, alongside oil palms. While these are more diverse than monoculture plantations, they are still not as good as natural forests. Also, agroforestry might not bring as many economic benefits to workers and local communities.

Making Palm Oil Sustainable: RSPO

The Roundtable on Sustainable Palm Oil (RSPO) is a group that sets rules for producing, sourcing, and using sustainable palm oil. As of 2018, over 4,000 members follow these rules. Currently, 19% of global palm oil is certified as sustainable by the RSPO.

The RSPO rules say that oil palm plantations cannot be grown where there are forests, endangered species, fragile ecosystems, or areas important to local communities. They also call for less use of pesticides and fewer fires. Plus, there are rules to ensure the well-being of workers and local communities.

Effects on Ecosystems

Human activities are causing harm to our planet's natural systems.

Harming the Environment: Environmental Degradation

Environmental degradation is when the environment gets worse. This happens through using up resources like air, water, and soil. It also includes destroying ecosystems, losing animal homes, the extinction of wildlife, and pollution. It's any change to the environment that is seen as harmful or unwanted. This harm is caused by a combination of a large and growing human population, increasing wealth and resource use per person, and using technologies that use up resources and pollute.

A 2021 study found that only about 3% of the Earth's land is still ecologically healthy. This means these areas have healthy populations of native animals and very little human impact. Many of these untouched ecosystems were in areas where indigenous peoples live.

Breaking Up Habitats: Habitat Fragmentation

A 2018 study found that 87% of the oceans and 77% of land (not including Antarctica) have been changed by human activity. Only 23% of the planet's land remains as wilderness.

Habitat fragmentation means that large areas where animals live are broken up into smaller pieces, leading to habitat loss. This fragmentation and loss are considered the main reasons for the loss of biodiversity and harm to ecosystems worldwide. Human actions are largely responsible for this, as they change how connected and healthy habitats are. Understanding these effects is important for protecting biodiversity and helping ecosystems work properly.

Many plants and animals, including those we eat, depend on pollination for reproduction. When habitats are destroyed, pollination is reduced, and crop yields suffer. Many plants also rely on animals, especially those that eat fruit, to spread their seeds. So, destroying animal habitats severely affects all the plant species that depend on them.

Losing Species: Mass Extinction

Biodiversity means the variety of life on Earth. Since humans appeared, we have been causing the extinction of entire species at an alarming rate. This happens directly (like through hunting) or indirectly (like by destroying homes). Humans are causing the current mass extinction, called the Holocene extinction. We are driving extinctions 100 to 1000 times faster than the normal rate.

This extinction event continues, with meat eating, overfishing, ocean acidification, and the decline of amphibians being examples of a widespread loss of biodiversity. Human overpopulation and overconsumption, especially by very wealthy people, are seen as the main reasons for this rapid decline. A 2017 warning from scientists stated that this sixth extinction event caused by humanity could wipe out many current life forms by the end of this century. A 2022 scientific review confirmed that a biodiversity loss crisis, described as a sixth mass extinction event, is happening now because of human activity.

A June 2020 study argued that the current extinction crisis "may be the most serious environmental threat to the persistence of civilization." It said that this crisis is irreversible and will speed up because of the fast growth in human numbers and consumption.

The Decline in Biodiversity

It's estimated that from 1970 to 2016, 68% of the world's wildlife has been destroyed by human activity. In South America, there's believed to be a 70% loss. A May 2018 study found that 83% of wild mammals, 80% of marine mammals, 50% of plants, and 15% of fish have been lost since human civilization began. Currently, livestock make up 60% of all mammal weight on Earth, followed by humans (36%) and wild mammals (4%). According to a 2019 global assessment, human civilization has pushed one million species of plants and animals to the edge of extinction, with many expected to disappear in the next few decades.

When plant biodiversity declines, the remaining plants produce less. Loss of biodiversity threatens how well ecosystems work and the services they provide, like food, fresh water, raw materials, and medicines.

A 2019 report looked at 28,000 plant species and found that almost half of them were at risk of extinction. Not noticing and appreciating plants is called "plant blindness," and it's a worrying trend because it puts more plants at risk than animals. Our increased farming has come at a higher cost to plant biodiversity, as half of the Earth's habitable land is used for agriculture. This is one of the main reasons behind the plant extinction crisis.

Defaunation is the loss of animals from natural communities.

Species That Don't Belong: Invasive Species

Invasive species are plants or animals that are not native to a specific area. Their presence is likely to harm humans or the animals already living there.

When non-native species are brought into new areas, they can cause big and lasting changes to the environment. For example, rats, cats, and goats have greatly changed the biodiversity on many islands. These new species can also breed with native animals, causing genetic changes.

Cats as Invasive Species

Domestic and wild cats are known for harming native birds and other animals worldwide. In Australia, over two-thirds of mammal extinctions are blamed on domestic and wild cats. They also cause over 1.5 billion deaths of native animals each year. Because pet cats are fed by their owners, they can keep hunting even when their prey populations decline. This is a big problem in areas with many lizards, birds, snakes, and mice. Outdoor cats can also spread harmful diseases like rabies and toxoplasmosis to wild animals.

The Burmese Python

Another example of a destructive invasive species is the Burmese Python. These snakes are from Southeast Asia. They have had a huge impact in the Southern Florida Everglades in the United States. After a breeding facility was flooded in 1992 and some snake owners released unwanted pythons, the python population exploded in Florida's warm climate. This has greatly affected the Everglades. A 2012 study found that raccoon populations dropped by 99.3%, opossums by 98.9%, and rabbit and fox populations almost disappeared.

Hybrid Boars

In the 1980s, Canadian pig farmers brought wild boars from the UK to breed them, creating a hybrid with more meat. But when the pork market crashed in 2001, many of these hybrids were released into the wild. Now, about 62,000 of these hybrids are thriving in the Canadian prairies. They have adapted to harsh winters with thick fur and long legs, and their sharp tusks help them dig for food. They cause a lot of damage to farms, and even big efforts to reduce their numbers aren't enough. These boars are now moving into northern US states, raising worries about crop damage and the spread of diseases like African swine flu, which could seriously harm the pork industry.

Coral Reefs in Danger

Human activities are causing coral reefs to decline.

Polluting Our Water

Wastewater from homes, factories, and farms can be treated in treatment plants before being released into rivers and oceans. Even treated wastewater still has chemicals and biological contaminants that can affect nearby ecosystems.

Water pollution happens when harmful substances contaminate bodies of water like rivers, lakes, and oceans. This can come from many sources, including industrial waste, agricultural runoff (fertilizers and pesticides), and untreated sewage. These pollutants can harm aquatic life, make water unsafe for drinking, and disrupt entire ecosystems.

Climate Change: A Global Challenge

Today's climate change is happening because of more greenhouse gases in the atmosphere. This is mainly caused by burning fossil fuels (coal, oil, natural gas), cutting down forests, changing how land is used, and making cement. These huge changes to the global carbon cycle have been possible because of advanced technologies. These technologies help us find, extract, transport, refine, and burn fossil fuels, and also support modern farming.

Livestock farming contributes to climate change by producing greenhouse gases and by destroying "carbon sinks" like rainforests. A 2006 UN report said that 18% of all greenhouse gas emissions come from livestock. Raising animals and growing their food has led to millions of acres of rainforest being destroyed. As the world eats more meat, the demand for land will also rise. Ninety-one percent of all rainforest land cut down since 1970 is now used for livestock.

The effects of climate change are widespread and serious. They include rising global temperatures, more frequent and intense heatwaves, changes in rainfall patterns leading to more droughts or floods, and rising sea levels. These changes can harm ecosystems, affect food production, and increase the risk of natural disasters.

Air Pollution and Its Effects

Acid Rain

Pollutants released from burning fossil fuels often return to Earth as acid rain. Acid rain is precipitation (like rain, fog, or snow) that contains high levels of sulfuric and nitric acids. Acid rain harms streams, lakes, wetlands, and other water environments. It damages forests, removes important nutrients from the soil, and releases aluminium into the soil. This makes it hard for local plants to absorb water.

Scientists have found that kelp, eelgrass, and other aquatic plants absorb carbon dioxide, which helps reduce ocean acidity. Growing these plants could help lessen the damaging effects of acidification on marine life.

Ozone Layer Depletion

Ozone depletion means the thinning of the ozone layer in Earth's atmosphere. The ozone layer protects us from harmful ultraviolet (UV) radiation from the sun. Chemicals like chlorofluorocarbons (CFCs), once used in aerosols and refrigerators, were a major cause of this depletion. While international efforts have helped reduce these chemicals, the ozone layer is still recovering.

Disturbing the Nitrogen Cycle

Nitrogen is a key element for life, and humans have greatly changed its natural cycle. A big concern is N₂O (nitrous oxide), which stays in the atmosphere for over 100 years and is 300 times more effective at trapping heat than CO₂. Nitrogen oxides (NO_x) from factories, cars, and farm fertilizers, along with ammonia (NH₃) from soils and livestock, travel through the air. They affect how nitrogen moves through nature and how nutrients are lost.

Six main effects of NO_x and NH₃ emissions are:

• Less clear air due to tiny particles.
• Higher ozone levels.
• Ozone and particles harming human health (like breathing problems and cancer).
• Increasing global warming.
• Lower crop yields due to ozone.
• Making ecosystems more acidic and causing too many nutrients (eutrophication).

Technology's Environmental Effects

Technology often has environmental impacts that are hard to avoid or predict. These impacts are measured by how many resources are used or how much pollution is created for each unit of economic output. Technologies are designed to use, control, or "improve" nature for human benefit. However, nature's processes are very finely tuned by evolution, so any disturbance by technology can lead to negative environmental results. Also, basic laws of physics mean that when we move or change materials and energy with technology, there will always be environmental consequences. Creating "order" in our economy (like buildings and factories) often means increasing "disorder" in the environment.

Mining's Impact on the Environment

Mining affects the environment in many ways. It causes erosion, creates sinkholes, leads to biodiversity loss, and pollutes soil, groundwater, and surface water with chemicals. Sometimes, forests are cut down near mines to make more space for waste and soil.

Even though plants need some heavy metals to grow, too much of these metals is toxic to them. Plants polluted with heavy metals often grow less, produce less, and don't perform well. Heavy metal pollution also reduces the organic matter in soil, leading to fewer nutrients and harming plant growth, or even killing plants.

Besides harming the environment, chemical leaks from mining also affect the health of local people. In some countries, mining companies must follow environmental rules to return the mined area to a state close to its original condition. Some mining methods can have serious environmental and public health effects. Heavy metals are toxic to soil organisms, affecting their processes and reducing their numbers and activity. Even low levels of heavy metals can stop plants from working normally.

Energy Industry's Environmental Footprint

How we get and use energy has many different environmental impacts. Recently, there's been a growing trend towards using more renewable energy sources.

Using fossil fuels leads to global warming and climate change. But in many parts of the world, not enough is changing. If the idea that oil production will peak and then decline is true, exploring other energy sources that are better for the environment could become more important.

New technologies are rapidly helping us change how we generate energy, manage water and waste, and produce food. These changes can lead to better environmental and energy use practices.

Biodiesel's Environmental Impact

Biodiesel is a type of fuel made from plants. Its environmental impact includes energy use, greenhouse gas emissions, and other types of pollution. A study found that using 100% biodiesel in buses instead of petroleum diesel reduced petroleum use by 95%. Biodiesel also cut carbon dioxide emissions by 78.45%. In city buses, biodiesel reduced particle emissions by 32%, carbon monoxide by 35%, and sulfur oxides by 8%. However, hydrocarbon emissions were 35% higher, and nitrogen oxide emissions were 13.5% higher with biodiesel. Biodiesel from vegetable oils (like canola or soybean oil) breaks down easily in the environment compared to petroleum diesel.

Coal Mining and Burning

Coal mining and burning have many environmental impacts. Surface coal mining, which involves drilling and blasting, releases large amounts of airborne particles into the air. These particles contain harmful toxins like ammonia, carbon monoxide, and nitrogen oxides. These toxins can cause serious health problems, including respiratory and cardiovascular diseases. Even though coal is the most used energy source globally, burning it releases poisonous toxins that lead to various health issues like skin, blood, and lung diseases, and different types of cancer. It also contributes to global warming. Modern mining technology has led to more mine waste, causing more pollution problems. Studies in countries like India show that coal mining severely affects plants and soil, leading to fewer plant populations in mining areas.

Nuclear Power's Environmental Impact

Nuclear power affects the environment through its entire process, including mining, processing, transporting, and storing fuel and radioactive waste. When radioisotopes are released, they can be dangerous to humans, animals, and plants as these radioactive particles enter living things.

Radiation can cause cancer and has many effects on living organisms. The environmental impacts of nuclear power plant disasters, like Chernobyl and Fukushima, can last for a very long time. These events were also made worse by poor management and natural disasters. The time it takes for radioactive particles to decay varies greatly. For example, radioactive Plutonium-244 has a half-life of 80.8 million years, meaning it takes that long for half of it to decay. However, very little plutonium-244 is produced in the nuclear fuel cycle, and materials with shorter half-lives are less dangerous because they give off less radiation.

Oil Shale Industry's Impact

The oil shale industry affects the environment through land use, waste management, and water and air pollution. Surface mining of oil shale causes the usual environmental impacts of open-pit mining. Also, burning and processing oil shale create waste material that needs to be disposed of, and harmful air emissions, including carbon dioxide, a major greenhouse gas. New technologies might reduce some of these concerns in the future, but they could also create new problems, like groundwater pollution.

Petroleum's Environmental Impact

Petroleum, which includes oil and natural gas, often has a negative environmental impact because it is toxic to most forms of life. Petroleum is essential for almost all parts of modern society, especially for transportation and heating homes and businesses.

Reservoirs and Their Effects

The environmental impact of reservoirs (artificial lakes created by dams) is being looked at more closely as the world needs more water and energy.

Dams and reservoirs can provide drinking water, generate hydroelectric power, increase water for irrigation, offer recreation, and control floods. However, they can also have negative environmental and social impacts during and after construction. Common problems include stopping fish from reaching their breeding grounds, less water downstream, and smaller catches for fishing communities. While technology offers solutions to many negative impacts, these are often not used unless required by law. Whether reservoirs are ultimately good or bad for the environment and people has been debated for a long time.

Wind Power's Environmental Impact

Wind power is a clean energy source, but it also has some environmental impacts. These can include noise from the turbines, visual impact on the landscape, and potential harm to birds and bats. However, compared to fossil fuels, wind power has a much smaller carbon footprint and does not produce air pollution.

Manufacturing's Environmental Footprint

Cleaning Agents

Cleaning agents have various environmental impacts. In recent years, efforts have been made to reduce these effects. For example, some cleaning products now use more natural ingredients or are designed to be biodegradable.

Nanotechnology

Nanotechnology involves working with extremely tiny materials. Its environmental impact has two sides: it could help improve the environment, but it could also create new types of pollution if nanomaterials are released. Since it's a new field, there's a lot of discussion about how industrial use of nanomaterials will affect living things and ecosystems.

Paint

Paint has different environmental impacts. Traditional paints and painting methods can harm the environment, especially from lead and other additives. We can reduce this harm by accurately estimating how much paint we need to avoid waste. Also, using paints, coatings, and techniques that are better for the environment helps. Guidelines from organizations like the United States Environmental Protection Agency help set standards for environmentally friendly practices.

Paper

Making paper uses a lot of trees, water, and energy, and it can cause pollution. However, recycling paper helps reduce these impacts by saving trees and using less energy and water.

Plastics

Some scientists suggest that by 2050, there could be more plastic than fish in the oceans. A December 2020 study found that human-made materials, or "anthropogenic mass," now weigh more than all living biomass on Earth. Plastic alone outweighs all land and marine animals combined.

Pesticides

Pesticides are chemicals used to kill pests, but their environmental impact is often much larger than intended. Over 98% of sprayed insecticides and 95% of herbicides end up somewhere other than their target. This includes non-target species, the air, water, sediments, and food. Pesticides pollute land and water when they leak from production sites, run off from fields, are thrown away, or are sprayed from the air or into water.

How much pesticide moves from the sprayed area depends on the chemical's properties. Factors in the soil, like its texture and ability to hold water, also affect how much pesticide will leave the area. Some pesticides contribute to global warming and harm the ozone layer.

Pharmaceuticals and Personal Care Products

Pharmaceuticals (medicines) and personal care products (like soaps and cosmetics) can enter the environment through wastewater. Even after treatment, these products can contain chemicals that affect aquatic life and ecosystems. Scientists are studying how these substances impact water quality and wildlife.

Transport's Environmental Impact

Transportation has a big environmental impact because it uses a lot of energy and burns most of the world's petroleum. This creates air pollution, including nitrous oxides and small particles. It also contributes significantly to global warming by releasing carbon dioxide, which is the fastest-growing emission sector for transport. Road transport is the biggest contributor to global warming.

In developed countries, rules have reduced emissions from individual vehicles. However, this has been canceled out by more vehicles and more use of each vehicle. There are ways to greatly reduce carbon emissions from road vehicles. Environmentalists are calling for a shift from air and road travel to trains and human-powered transport (like biking). They also want more electric transport and better energy efficiency.

Other environmental impacts of transport include traffic congestion and urban sprawl (cities spreading out). This sprawl can take over natural habitats and farmland. By reducing transport emissions globally, we can greatly improve Earth's air quality, reduce acid rain and smog, and help with climate change.

The health impact of transport emissions is also a concern. Studies have linked exposure to traffic emissions to problems during pregnancy, like shorter pregnancies and possibly slower growth of babies.

Aviation's Environmental Impact

Aircraft engines create noise, particles, and gases that contribute to climate change and global dimming. Even though aircraft engines are becoming more fuel-efficient and less polluting, the rapid growth of air travel means that total pollution from aviation is increasing. In the EU, greenhouse gas emissions from aviation grew by 87% between 1990 and 2006. This is partly due to more people traveling frequently and air travel becoming very common.

There's an ongoing discussion about taxing air travel and including aviation in an emissions trading system. The goal is to make sure that the full environmental costs of aviation are considered.

Roads and Their Impact

Roads have local environmental effects like noise pollution, light pollution, water pollution, habitat destruction or disturbance, and local air quality issues. They also have wider effects, including climate change from vehicle emissions. The way roads, parking, and related facilities are designed, built, and managed, along with vehicle design and rules, can change these impacts.

Shipping's Environmental Impact

Shipping contributes to greenhouse gas emissions and oil pollution. In 2007, carbon dioxide emissions from shipping were estimated to be 4 to 5% of the global total. The International Maritime Organization (IMO) estimated this could rise by up to 72% by 2020 if no action is taken. There's also a risk of introducing invasive species to new areas, often by attaching to a ship's hull.

The IMO is working on ways to reduce greenhouse gas emissions from international shipping.

Military Activities and the Environment

Military spending and activities have clear environmental effects. The United States military is considered one of the biggest polluters globally, with over 39,000 sites contaminated with dangerous materials. Several studies also show a strong link between higher military spending and more carbon emissions. Increased military spending has a bigger effect on carbon emissions in richer countries than in poorer ones. Military activities also use a lot of land and resources.

However, militaries don't always have negative effects. There are examples of militaries helping with land management, conservation, and making areas greener. Also, some military technologies have been very useful for conservationists and environmental scientists.

Besides the cost to human lives and society, war has a big environmental impact. "Scorched earth" methods, used during or after wars for centuries, can cause much greater devastation with modern technology. Unexploded ordnance (bombs that didn't go off) can make land unusable or dangerous to cross.

Light Pollution

Artificial light at night is one of the most obvious changes humans have made to the Earth. It's also the easiest form of pollution to see from space. The main environmental impacts of artificial light come from how light acts as an information source, not just an energy source. For example, predators that hunt by sight often become better hunters under artificial light, changing how predator and prey interact. Artificial light also affects how animals move (dispersal), find their way (orientation, migration), and their hormone levels. This can disrupt their natural daily rhythms (circadian rhythms).

Fast Fashion's Environmental Impact

Fast fashion has become a very successful industry in many countries, especially with the rise of globalization. Fast fashion means making clothes quickly and cheaply, then selling them at very low prices. Today, this industry is worth trillions of pounds.

Environmental Impacts of Fast Fashion

The fast fashion industry contributes between 4–5 billion tonnes of carbon dioxide per year. This is 8–10% of total global emissions. Carbon dioxide is a greenhouse gas, meaning it traps heat in the atmosphere, causing the Earth's temperature to rise. This is known as global warming.

Besides greenhouse gas emissions, the industry is also responsible for almost 35% of microplastic pollution in the oceans. Scientists estimate there are about 12–125 trillion tonnes of microplastic particles in the Earth's oceans. Marine organisms, including fish that humans eat, ingest these particles. Many of these fibers likely come from clothing and other textiles, either from washing or breaking down.

Textile waste is a huge environmental problem. About 2.1 billion tonnes of unsold or faulty clothing are thrown away each year. Much of this goes to landfills, but most materials used to make clothes are not biodegradable. This means they break down slowly and contaminate soil and water.

Fashion, like most other industries, uses a lot of water for production. The speed and amount of clothing produced in fast fashion mean the industry uses 79 trillion liters of water every year. This high water use has been very harmful to the environment and its ecosystems, leading to water depletion and water scarcity. This affects not only marine organisms but also human food sources, like crops. The industry is responsible for roughly one-fifth of all industrial water pollution.

Warnings from Scientists

Scientists' Warnings to Humanity

Many scientific publications have warned everyone about growing threats to sustainability, especially to "environmental sustainability". The World Scientists' Warning to Humanity in 1992 began with: "Human beings and the natural world are on a collision course." About 1,700 of the world's leading scientists, including most Nobel Prize winners in science, signed this warning letter. The letter mentioned severe damage to the atmosphere, oceans, ecosystems, soil productivity, and more. It said that if humanity wants to prevent the damage, we need to take steps. These include better use of resources, stopping the use of fossil fuels, stabilizing the human population, ending poverty, and more. More warning letters were signed in 2017 and 2019 by thousands of scientists from over 150 countries. They again called for reducing overconsumption (including eating less meat), reducing fossil fuel use, and using fewer other resources.

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