[00:08] What is the greenhouse effect? What can a greenhouse like this one tell us about how our planet is changing?

[00:14] Simply put, energy from the sun warms Earth's surface and atmosphere. In turn, our planet's surface cools naturally by radiating some of the heat back into the atmosphere and space.

[00:24] On a planet like Venus, a thick atmosphere of carbon dioxide and other gases trap nearly all heat energy. In fact, Venus has what's called a runaway greenhouse effect with a surface temperature of over 900 degrees Fahrenheit. That's hot enough to melt lead.

[00:39] Like Venus, certain gases in Earth's atmosphere absorb heat. But like this greenhouse, Earth's atmosphere holds just enough heat to allow life to flourish. If we alter the gases in our atmosphere, we can change the temperature as well.

[00:54] Most greenhouse gas on Earth is simple water vapor. But other gases include CO2 and methane, which are produced by both natural and manmade sources.

[01:02] Even though greenhouse gases are found in much smaller amounts than water vapor, because of their properties, trace gases have a big effect on the insulating capacity of our atmosphere.

[01:11] Right now atmospheric carbon dioxide is rising sharply. Planetary warming is underway too. So we humans must ask the question, do we want the future we're in the process of creating?

[01:23] To learn more about Our Changing Planet visit us on the web at www.umac.org/ocp.