When climate change or global warming is discussed, carbon dioxide immediately comes to mind. This greenhouse gas is often associated with automobiles and industrial activities, and can also be produced from burning oil, coal and natural gas in the generation of electricity. While carbon dioxide is the most prominent greenhouse gas associated with global warming, others include methane and nitrous oxide.

Carbon dioxide is also a naturally occurring greenhouse gas. In fact, greenhouse gases are essential to life on Earth. Natural processes such as volcanic eruptions and animal respiration emit carbon dioxide into the atmosphere. Plants use carbon dioxide for photosynthesis and the atmosphere uses it to warm the surface of the Earth. Greenhouse gases, in natural concentrations, keep the earth’s average temperature at about 60 degrees Fahrenheit to sustain plant and animal life. Without these gases, the earth would be a chilly zero degrees – too cold to sustain life.

The greenhouse effect is a process in which gases, such as carbon dioxide, create a blanket in the upper atmosphere. That layer allows heat from the sun to pass through earth’s atmosphere and warm the surface on which we live. The atmosphere, comprised of a variety of gases, acts like the sides and roof of a greenhouse. At the surface of the earth, some of the heat and energy from the sun is absorbed by the oceans and land. The heat and energy that is not absorbed bounces back into the atmosphere. While some of the energy makes it back through to outer space, much of it remains trapped in the atmosphere, causing the Earth to heat up – much like a greenhouse.

If the greenhouse effect becomes too strong, or if there is an abundance of gases in the atmosphere, heat that would normally escape back through Earth’s atmosphere becomes trapped. This causes global warming, or an increase in the average temperature of the Earth.

In the last 100 years, the Earth’s temperature has risen one degree Fahrenheit. While it sounds like a small amount, it’s actually quite significant. At the peak of the planet’s last ice age – about 18,000 years ago – glaciers covered much of North America. The average global temperature at that time was only seven degrees colder than it is today.

Scientists have taken a historical look at the concentration of carbon dioxide in Earth’s atmosphere over the years to determine the causes of increasing average temperature. Humans have released 2.3 trillion tons of carbon dioxide in the last 200 years. Since the Industrial Revolution in 1750, the concentration of carbon dioxide in our atmosphere has increased 30 percent.