Burning coal, oil and gas

Burning coal, oil, and gas—also known as fossil fuels—is how we generate much of the world’s energy. This process is central to powering homes, cars, factories, and many other parts of daily life. But while fossil fuels have driven industrial growth and given us reliable access to energy, their use also creates significant environmental problems. To understand why, it’s helpful to look at both how burning these fuels works and what happens as a result.

When fossil fuels like coal, oil, and natural gas are burned, what’s really happening is a chemical reaction between the fuel and oxygen from the air. All these fuels contain carbon and hydrogen atoms. During burning (which scientists call “combustion”), these atoms combine with oxygen, breaking their old molecular bonds and making new ones. Specifically, the carbon in the fuel combines with oxygen to form carbon dioxide, and the hydrogen forms water vapor.

For example, coal is made mostly of carbon. When burned, it releases a lot of carbon dioxide into the air. Oil and natural gas have a higher share of hydrogen, but they still produce plenty of carbon dioxide. The energy from this reaction is used to heat water and produce steam, which in turn spins turbines to create electricity in power plants. In cars, the explosions from burning gasoline push pistons, running the engine. Heating systems for buildings also burn gas or oil for warmth. The process is similar in all these cases: fuel plus oxygen equals energy, carbon dioxide, and water.

Why is this a problem? The biggest issue is the sheer volume of carbon dioxide released. Carbon dioxide is a greenhouse gas, which means it traps heat in the atmosphere. Normally, greenhouse gases are essential because they keep the Earth warm enough for life. But over the last century and a half, burning fossil fuels has added billions of tons of carbon dioxide to the atmosphere—much more than natural processes can remove. This builds up and leads to global warming.

Global warming refers to the gradual increase in the Earth’s average temperature. Even small rises—just a degree or two Celsius—can cause big changes. Ice at the poles melts, sea levels rise, and weather becomes more unpredictable. Some places see more droughts, others more floods. All these changes disrupt agriculture, freshwater supplies, and the homes of both humans and wildlife.

Carbon dioxide isn’t the only problem, though. Burning coal, oil, and gas releases a mix of other pollutants. When coal is burned, it doesn’t just make carbon dioxide and water—it also produces small particles, sulfur dioxide, nitrogen oxides, mercury, and heavy metals. These pollutants have more immediate health impacts. Small particles and gases can irritate lungs and worsen respiratory diseases like asthma. Sulfur dioxide and nitrogen oxides combine with moisture in the air to form acid rain, which can damage forests, lakes, and soil. Acid rain can make lakes too acidic for fish and can stunt or kill trees.

Some pollutants released are harmful even in tiny amounts. For example, when coal is burned, trace amounts of mercury are released into the air. Mercury eventually settles into water bodies and accumulates in fish, traveling up the food chain and posing risks to people—especially young children and pregnant women—who eat contaminated seafood.

Oil refineries and gas extraction sites also present hazards. Oil spills, whether from drilling accidents or leaking pipelines, can devastate marine life and coastlines. Extracting coal often means stripping away forests and topsoil to get at seams close to the surface—a process known as strip mining. This not only destroys wildlife habitat but also leads to erosion and water pollution when rain washes exposed soil and residue into nearby rivers.

Natural gas is often seen as "cleaner" because it produces less carbon dioxide for the same amount of energy compared to coal and oil. But it has its own problems. Methane, the main component of natural gas, is itself a potent greenhouse gas—much more so than carbon dioxide in the short term. If methane leaks from wells or pipelines during extraction and transport, it goes straight into the atmosphere, worsening global warming.

Another issue is that the infrastructure needed for fossil fuel extraction and use—mines, oil rigs, pipelines, refineries, and power plants—can harm ecosystems directly by fragmenting habitats, polluting water, and making noise that disturbs wildlife. Some fossil fuel sites are located near or within communities that already face economic and health challenges, adding to the burden of disease and social inequality.

While technology has made burning fossil fuels more efficient and has reduced some pollutants through filters and cleaner-burning engines, the central problem remains: every fossil fuel burned emits carbon dioxide and, often, other pollutants. Tackling the environmental challenges tied to fossil fuel use means either capturing and storing these emissions—something that’s technically complex and still expensive—or transitioning to alternative sources of energy like wind, solar, hydropower, and geothermal. These alternatives don’t create the same air pollutants or greenhouse gases when generating energy.

In summary, burning coal, oil, and gas breaks chemical bonds to release energy, but it also produces carbon dioxide and a range of other pollutants. These emissions drive climate change, pollute the air, damage natural environments, and cause health problems for people. The extensive use of fossil fuels over the last century has led to huge benefits for society, but managing and reducing their environmental impact is one of the biggest challenges we face today.