Whats global warming? Want to know more about the greenhouse effect?

We asked the Environmental Protection Agency to help us find answers.


We know: 1-Minute Lesson on Global Warming

What's global warming?

Global warming refers to an average increase in the Earth's temperature, which in turn causes changes in climate. The Earth has warmed about 1F in the last 100 years. And the four warmest years of the 20th century all happened in the 1990s.


Periods of increased heat from the sun may have helped make the Earth warmer. But many of the world's leading climatologists think that the greenhouse gases people produce are making the Earth warmer, too.

What causes global warming?

When scientists talk about the issue of climate change, their concern is about global warming caused by human activities. Many scientists believe that the things people do that send greenhouse gases into the air are making our planet warmer.

What are greenhouse gases and the greenhouse effect?

The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun. Without these gases, heat would escape back into space and Earth's average temperature would be about 60F colder. Because of how they warm our world, these gases are referred to as greenhouse gases.

How could an increase in the Earth's temperature affect things?

A warmer Earth may lead to changes in rainfall patterns, a rise in sea level, and a wide range of impacts on plants, wildlife, and humans.

Average global temperature has increased by almost 1F over the past century; scientists expect the average global temperature to increase an additional 2 to 6F over the next one hundred years. This may not sound like much, but it could change the Earth's climate as never before. At the peak of the last ice age (18,000 years ago), the temperature was only 7F colder than it is today, and glaciers covered much of North America.

What are some of the biggest contributors to the production of greenhouse gases and the increase in global temperatures?

  • Auto emissions
  • Burning of coal and oil to produce electricity
  • Methane gas produced by the accumulation of trash at landfills

What can we do to help reduce the production of greenhouse gases?

  1. Reduce driving and use more energy efficient cars
  2. Reduce electricity use and use more efficient appliances, especially those certified with an Energy Star label
  3. Recycle
  4. Plant trees, which absorb carbon monoxide, a greenhouse gas
  5. Increase use of renewable energy sources such as solar, wind and hydro power.


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