Shop Windows to the Universe

The Spring 2011 issue of The Earth Scientist is focused on modernizing seismology education. Thanks to IRIS, you can download this issue for free as a pdf. Print copies are available in our online store.
This sea ice in the Beaufort Sea is light in color compared with the dark ocean water. The sea ice reflects most of the sunlight that hits it. The ocean water absorbs most of the sunlight that hits it.
NASA

Ice-Albedo Feedback: How Melting Ice Causes More Ice to Melt

The sea ice that floats on the Arctic Ocean is covered with snow all winter. The snow-covered ice is bright white so it absorbs very little of the solar energy that gets to it. And during the Arctic winter, very little solar energy gets to it anyway. The Sun stays low on the horizon, days are short, and above the Arctic Circle there is at least one day of winter when the Sun does not make an appearance at all.

Summer is warmer than winter but it becomes even warmer as the ice changes and melts. How does this happen? As summer approaches, the Sun climbs higher in the sky each day and the weather gets a little warmer. Warmer temperatures melt the snow, exposing the bare sea ice. Pools of melt water form on the ice and cracks called leads break the ice into pieces like a puzzle. The exposed ice is darker in color than the snow. The pools and cracks are also darker. And where the ice has melted, dark ocean water is exposed. Because all these changes make the surface darker, the albedo is lower, more solar energy is absorbed, and less is reflected. Holding onto the energy causes more ice to melt, which, in turn, lowers the albedo, causes more energy to be absorbed and more warming.

This is a normal seasonal process, called a positive feedback. However it is changing as Earth’s climate changes.

Because Earth’s temperature is climbing as more greenhouse gases are released into the atmosphere, the snow on top of the ice melts earlier in the spring. A little later each autumn, temperatures drop to the chilly levels needed for sea ice to again form. There is more time during the summer for the compounding cycle of melting ice, lowering albedo, trapping of more solar energy, and more ice melt. And there is less time in the winter for ice to reform.

This process of a little warming causing more warming is called the ice-albedo feedback. The ice-albedo feedback can turn a small climate change into a big climate change. The sea ice is melting rapidly in the Arctic Ocean. According to climate models that pace of ice melt will speed up even more, so much that that there may be no more summer sea ice within the next few decades.

Last modified July 18, 2007 by Lisa Gardiner.

Shop Windows to the Universe Science Store!

Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Sea Ice in the Arctic and Antarctic

Sea ice is frozen seawater. It can be several meters thick and it moves over time. Although the salts in the seawater do not freeze, pockets of concentrated salty water become trapped in the sea ice when...more

Albedo

This picture of the Earth surface was taken from high above the planet in the International Space Station. In this view from above, we can see that there are lots of different things that cover the Earth....more

Effects of Climate Change Today

Over 100 years ago, people worldwide began burning more coal and oil for homes, factories, and transportation. Burning these fossil fuels releases carbon dioxide and other greenhouse gases into the atmosphere....more

Earth's Greenhouse Gases

Even though only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases, they have a huge effect on climate. There are several different types of greenhouse gases. The major ones are carbon...more

Black Carbon

The burning of fossil fuels like coal, gas and oil releases particles into the atmosphere.  When fossil fuels are not burned completely, they produce black carbon -- otherwise known as soot.  Soot looks...more

Content for Climate Change Education Courses

Looking for online content that can be used for a climate change education course or module? Pages linked below can be used to support an introductory climate change education for either a unit or a full...more

Exploration of the Poles of the Earth

Polar exploration includes the physical exploration of the Arctic and the Antarctica. The Arctic is the area around the Earth's north pole and includes parts of Canada, Greenland, Russia, the United States...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA