In September 2007 less sea ice covered the Arctic than at any point since the U.S. government began keeping records of its decline. All told, it covered 502,000 square miles (1.3 million square kilometers) less ocean than even the year before—a loss equal to an area the size of California and Montana combined. But what might be bad news for polar bears and other animals dependent on sea ice could be good news for the alga known as phytoplankton.
“Because these plants are photosynthetic, it’s not surprising to find that as the amount of sea ice cover declined, the amount of [photosynthesis] increased,” says biological oceanographer Kevin Arrigo of Stanford University’s School of Earth Sciences, who led an effort to use the MODIS (Moderate Resolution Imaging Spectroradiometer) devices on NASA’s Terra and Aqua satellites to determine changes in phytoplankton growth.
“If trends continue, we can expect probably a doubling of primary production,” in photosynthetic activity undertaken by millions of algae, he adds. Because these organisms are the basis of the food chain, that means more food for fish and, ultimately, the animals that feed on fish (as long as they don’t depend on sea ice to do it—like polar bears who use the ice as a hunting platform).
“Over a decade ago, NASA researchers first documented a lengthening growing season,” says terrestrial ecology program scientist Diane Wickland of NASA. “We are extending satellite observation records and deriving ever more quantitative information from them.”
