Earth keeps getting warmer. Scientists believe this is caused by an increase in something called greenhouse gases.
Greenhouse gases collect in Earth's atmosphere. The atmosphere is a layer of gases that surround Earth. Carbon dioxide (CO2), methane (CH4), and ozone (O3), are kinds of greenhouse gases.
The greenhouse gases allow the sun's light to shine onto Earth's surface. Some of that heat gets reflected. It bounces from the surface of Earth. Then, the gases trap the heat inside Earth. The gases act like the glass walls of a greenhouse. In other words, they are warming.
Animals and Plants Contribute to Greenhouse Gases
Without the greenhouse effect, Earth's average temperature would drop. Now, it is about 57 degrees Fahrenheit (14 degrees Celsius). It could drop to as low as 0 degrees Fahrenheit (minus 18 degrees Celsius). The weather would go from mild to very cold.
Some greenhouse gases come from nature. Animals and plants release carbon dioxide when they breathe. Methane is another greenhouse gas. It is released when soil and living things break down. Volcanoes also release greenhouse gases.
Factories and Vehicles Can also Be Blamed
The Industrial Revolution happened in the late 1700s and early 1800s. This led to more factories and machines being built. The factories burned fuel and released more greenhouse gases into the atmosphere.
Greenhouse gases almost doubled between 1970 and 2004.
The amount of CO2 in the atmosphere is growing. There is more CO2 now than Earth has seen over the last 650,000 years.
Much of the CO2 comes from burning fossil fuels. Cars, trains and planes all burn fossil fuels, such as gasoline. Many electric power plants do as well.
More Gases Lead to Global Warming
Humans also release CO2 into the atmosphere when they cut down forests. Trees contain large amounts of carbon.
People add methane to the atmosphere through farming of livestock such as cows. It also happens when we mine for coal.
Fluorinated gases are also greenhouse gases. Chlorofluorocarbons (CFCs) are one example of these. CFCs are used in refrigerators, air conditioners and aerosol cans.
As greenhouse gases increase, so does Earth's temperature. This rise caused by humans is known as global warming.
The Greenhouse Effect and Climate Change
Even small increases in temperatures can have huge effects.
Perhaps the biggest effect is that glaciers and ice caps melt faster than usual. The meltwater drains into the oceans. This causes sea levels to rise.
Glaciers and ice caps cover about one-tenth of the world's land. If all this ice melted, sea levels would rise about 70 meters (230 feet).
Climate scientists say that the world's sea level has risen.
Rising sea levels cause flooding in coastal cities. This could force millions of people in lower-lying areas out of their homes.
Millions of more people in countries depend on water from melted glaciers. They use it for drinking and watering crops. Losing these glaciers would greatly hurt those countries.
Greenhouse gases also cause changes in rain and snow.
In the 1900s, rain and snow increased in eastern parts of North and South America. It also increased in Northern Europe, and northern and Central Asia. However, it decreased in parts of Africa and southern Asia.
As climates change, so do environments. Animals that are used to a certain climate could become threatened.
Many humans depend on predictable rain patterns. This helps them to grow specific crops. If the climate of an area changes, the people there may no longer be able to grow anything. Some of them depend on farming for survival.
What Can We Do?
- Drive less. Use public transportation, carpool, walk, or ride a bike.
- Fly less. Airplanes produce huge amounts of greenhouse gas emissions.
- Reduce, reuse, and recycle.
- Plant a tree. Trees absorb carbon dioxide, keeping it out of the atmosphere.
- Use less electricity.
- Eat less meat. Cows are one of the biggest methane producers.
- Support alternative energy sources that don’t burn fossil fuels.
