image credit: NASA/Goddard Scientific Visualization Studio; image source; larger image

NASA Finds Thickest Parts of Arctic Ice Cap Melting Faster

The bright white region near the center of the image shows the year-round Arctic ice in 2012. To see the startling decrease since 1980, visit NASA Finds Thickest Parts of Arctic Ice Cap Melting Faster and slide the white line in the middle of the image to the right.

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PhET Simulation: The Greenhouse Effect

Security note:
Once you have clicked on the "simulation" link below, be sure to read the Java Security Advisory before running the simulation: To do that, click the "Read now" button on the yellow band near the top of the PhET page.

Investigate climate change with this PhET simulation. You'll see how greenhouse gases keep Earth much warmer than it would be without them.

(This feature was updated on May 3, 2013.)

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image credit: Robert Rhode (Wikimedia Commons); image source; larger image

Greenhouse Effect

This is the famous "Keeling curve" of carbon dioxide concentration in the atmosphere versus time, from about 1958 to about 2007, measured in Hawaii. Notice that the rate of warming (indicated by the slope of the blue line) increases slowly but steadily over time.

Carbon dioxide is an important greenhouse gas. Greenhouse gases absorb the infrared radiation given off by Earth. This absorbed radiation is promptly re-emitted in all directions; much of it returns to Earth, raising the temperature of its surface by a substantial 33°C.

Carbon dioxide is produced by burning fossil fuels. As more countries industrialize, the use of fossil fuels increases, as does the amount of carbon dioxide in the atmosphere

The inset in the graph shows the annual cycle: For six months, plant photosynthesis absorbs carbon dioxide from the atmosphere, and the curve goes down; then, for the next six months, the decay of dead plants returns carbon dioxide to the atmosphere, and the curve goes up.

To learn more, visit Greenhouse Effect and also this UCAR page.

Ice over the Poles

Visit Ice over the Poles for an interesting article on ice at the Poles--both sea ice at the North Pole, and land ice on Antarctica. Be sure to see the explanation of how melting of ice sheets or glaciers can provide "positive feedback" and increase the rate of warming.