The biggest global environmental issues today are climate change, air pollution, unsafe and scarce water, deforestation, biodiversity loss, plastic and waste, the decline of coral reefs and fish stocks, land degradation and fast urban growth. They are connected: the same fossil fuels that warm the planet also pollute the air, and the same land clearing that destroys forests drives species toward extinction.
Below are the 10 problems with the latest figures from the UN, WMO and other primary sources, a summary table, the areas where the world is actually making progress, and what you can do.
Top 10 Global Environmental Issues
1. Climate Change
The planet is now about 1.4°C warmer than before industrialization. The World Meteorological Organization (WMO) puts 2025 at 1.44°C (±0.13°C) above the 1850–1900 average, the second or third warmest year on record, and says the eleven years from 2015 to 2025 are the eleven warmest ever measured. 2024 was the warmest, at about 1.55°C, and likely the first calendar year above 1.5°C.
The main cause is carbon dioxide from burning coal, oil and gas. CO2 in the atmosphere reached 423.9 parts per million in 2024, and it rose by 3.5 ppm in a single year, the largest increase since 1957. According to the UN Environment Programme’s Emissions Gap Report 2025, current policies point to about 2.8°C of warming this century, and 2.3–2.5°C even if countries meet all their climate pledges.
2. Air Pollution
Almost everyone breathes polluted air. The World Health Organization says 99% of the global population lives where fine-particle (PM2.5) levels exceed its guideline. Outdoor and household air pollution together cause about 7 million premature deaths every year, 4.2 million of them linked to outdoor air.
Most of this pollution comes from the same sources as greenhouse gases: power plants, vehicles, industry and, in poorer countries, cooking and heating with wood, coal or kerosene indoors.
3. Unsafe Water and Water Scarcity
One in four people, or 2.1 billion, still lack safely managed drinking water, and 3.4 billion lack safely managed sanitation, according to the WHO/UNICEF Joint Monitoring Programme’s 2025 report. At the same time, roughly half of the world’s population experiences severe water scarcity for at least part of the year, the UN World Water Development Report notes. Agriculture uses about 70% of all freshwater withdrawals, so droughts quickly become food problems.
4. Deforestation
Forests cover 4.14 billion hectares, or 32% of the world’s land. The UN Food and Agriculture Organization’s Global Forest Resources Assessment 2025 estimates that 10.9 million hectares (about 27 million acres) were deforested each year in 2015–2025. Because some land regrows or is replanted, the net loss is smaller, 4.12 million hectares a year, down from 10.7 million in the 1990s.
Tropical rainforests are the biggest concern. The world lost a record 6.7 million hectares of tropical primary forest in 2024, much of it to fire. In 2025 the figure fell to 4.3 million hectares, down 36%, according to the World Resources Institute and Global Forest Watch. Much of that improvement came from Brazil; see our guide to environmental issues in Brazil.
5. Biodiversity Loss
About 1 million animal and plant species face extinction, many within decades, according to the 2019 global assessment by IPBES, the UN’s science panel on biodiversity. The IUCN Red List now counts 49,505 threatened species out of 175,909 assessed (July 2026 update).
The wildlife that remains is thinning out. The Living Planet Report 2024 by WWF and the Zoological Society of London found a 73% average decline in monitored wildlife populations between 1970 and 2020, and an 85% decline for freshwater species. The main drivers are habitat loss from farming, overexploitation, climate change, pollution and invasive species.
6. Plastic Pollution and Waste
The world produces about 400 million tonnes of plastic waste a year, and only about 9% is recycled, the UN Environment Programme reports; the OECD projects plastic waste could nearly triple to 1 billion tonnes by 2060. Municipal solid waste of all kinds is expected to grow from 2.3 billion tonnes in 2023 to 3.8 billion tonnes by 2050 (UNEP Global Waste Management Outlook 2024).
Countries have been negotiating a global plastics treaty since 2022. The August 2025 round in Geneva ended without an agreed text, and a short session in February 2026 only elected a new chair. No date for the next negotiating round had been announced as of October 2026.
7. Coral Reef Bleaching and Ocean Acidification
Oceans absorb much of the extra heat and carbon dioxide that humans add to the atmosphere, so the water is getting warmer and more acidic. During the fourth global coral bleaching event, from early 2023 to mid-2025, bleaching-level heat stress hit 84% of the world’s coral reef area in at least 83 countries and territories, according to NOAA.
The chemistry is changing too: the pH of surface ocean water has fallen by 0.1 units since the Industrial Revolution, which is about a 30% increase in acidity. That makes it harder for corals, oysters and some plankton to build shells and skeletons.
8. Overfishing
The FAO’s most detailed assessment of marine fish stocks to date (June 2025) found that 35.5% of stocks are overfished. The good news in the same report: 77.2% of the fish actually landed come from sustainably fished stocks, because the largest fisheries tend to be the best managed. Overfishing is worst where monitoring is weak.
9. Land Degradation and Desertification
Up to 40% of the world’s land is degraded, and about 1 million km² of healthy land becomes degraded every year, affecting more than 3 billion people, according to the UN Convention to Combat Desertification (UNCCD). Degraded soil holds less water and grows less food, which makes droughts worse and pushes farming into new forest land, linking this issue to deforestation.
10. Population Growth and Urban Expansion
The world had 8.2 billion people in 2024, and the UN expects the population to peak at about 10.3 billion in the mid-2080s. Growth itself is slowing, so the bigger environmental question is how and where people live and consume. Cities are now home to 45% of the global population, and the number of megacities has grown from 8 in 1975 to 33 in 2025 (UN World Urbanization Prospects 2025). Unplanned sprawl paves over farmland, forests and wetlands, so how cities grow matters as much as how fast.
Global Environmental Issues at a Glance
| Issue | Key figure | Source | Trend |
|---|---|---|---|
| Climate change | 2025: +1.44°C vs 1850–1900; CO2 423.9 ppm (2024) | WMO | Worsening |
| Air pollution | 99% breathe air above WHO guideline; ~7 million deaths/yr | WHO | Slow progress |
| Drinking water | 2.1 billion lack safely managed water | WHO/UNICEF | Slow progress |
| Deforestation | 10.9 million ha/yr (2015–2025) | FAO | Slowing |
| Biodiversity | 49,505 threatened species on the Red List | IUCN | Worsening |
| Plastic | ~400 million t/yr, ~9% recycled | UNEP | Worsening |
| Coral reefs | 84% of reef area hit by bleaching heat (2023–2025) | NOAA | Worsening |
| Overfishing | 35.5% of stocks overfished | FAO | Stable |
| Land degradation | ~1 million km² degraded per year | UNCCD | Worsening |
| Urban growth | 45% of people live in cities | UN DESA | Growing |
Which Environmental Problems Are Getting Better?
Global problems can be solved when countries act together, and two older issues prove it.
- The ozone layer. After the 1987 Montreal Protocol banned ozone-depleting chemicals, nearly 99% of them were phased out. The ozone layer is on track to recover to 1980 levels by about 2066 over Antarctica, by 2045 over the Arctic and by 2040 elsewhere. The 2025 ozone hole was the fifth smallest since 1992.
- Acid rain. Acid rain was one of the headline environmental issues of the 1980s. In the U.S., the EPA’s Acid Rain Program has cut power plant sulfur dioxide emissions by more than 95% and nitrogen oxides by more than 89%.
- Clean energy. The world added a record 692 GW of renewable power capacity in 2025, 510 GW of it solar, according to IRENA. Wind and hydropower are part of that growth; see our guides to wind energy pros and cons and whether hydropower is renewable.
Older lists of environmental issues often include acid rain and the ozone hole as current threats. Both still need monitoring, but their trends are now positive, which is why they are not in our top 10.
What Is Being Done
- Climate: under the Paris Agreement, countries submit national climate targets (NDCs) every five years. The latest round, due in 2025, still falls short of 1.5°C, according to UNEP’s Emissions Gap Report.
- Nature: in the 2022 Kunming-Montreal Global Biodiversity Framework, countries agreed to conserve at least 30% of land and sea by 2030 and restore 30% of degraded ecosystems. A UN review in October 2026 found current pledges falling well short of the 30% goal.
- Plastic: treaty talks continue under the UN, while many countries and U.S. states restrict single-use bags and packaging.
- Water, air and land: most progress happens through national laws, such as clean air standards, wastewater treatment and land restoration programs supported by the UNCCD.
What You Can Do
Individual actions matter most where they cut energy use or change what gets produced:
- Cut home energy use first. Heating, cooling and electricity are a large part of a typical household’s footprint; efficiency upgrades and clean power reduce both CO2 and air pollution. Start by measuring your ecological footprint.
- Drive less or drive electric where it is practical, and combine trips.
- Buy less single-use plastic and recycle correctly. Our guide to easy ways to recycle at home covers the basics.
- Eat with forests in mind. Beef, soy, palm oil, cocoa and coffee are linked to tropical deforestation; certified products reduce that risk.
- Support local action. Many of these issues are decided by city and state rules on land use, transit and waste.
For a school report, pick one issue, give one global figure and one local example. Human-environment interaction is a useful frame: see our human-environment interaction guide for how people depend on, adapt to and modify the environment.
Frequently Asked Questions
What is the biggest environmental issue in the world?
Most scientists and the UN treat climate change as the biggest because it makes many other problems worse, including droughts, coral bleaching, wildfires and species loss. In terms of direct deaths, air pollution is the largest, at about 7 million premature deaths a year according to the WHO.
What are 5 examples of global environmental issues?
Climate change, air pollution, deforestation, biodiversity loss and plastic pollution. Other major examples are unsafe water, ocean acidification, overfishing and land degradation.
What is the main cause of today's environmental problems?
Most trace back to how people produce energy, food and goods. Burning fossil fuels drives climate change and air pollution, while expanding farmland drives deforestation, land degradation and habitat loss.
Are any global environmental problems improving?
Yes. The ozone layer is recovering after the Montreal Protocol, acid rain has dropped sharply in the U.S. and Europe, deforestation is slowing compared with the 1990s, and renewable energy capacity is growing at a record pace.
