Another Sign of Global Warming? Underwater Deserts Expand Alarmingly Fast

Author:  Charley Wang

Institution:  University of Toronto
Date:  February 2008

Anyone who has tried to cross a desert will tell you that the lack of water is the biggest challenge you will face. But for some deserts, the problem isn't a lack of water: it's an abundance of water. According to images taken from the SeaStar spacecraft, the world's underwater deserts are expanding alarmingly fast.

These deserts are located in subtropical gyres – enormous vortices buried deep within the world's ocean basins. The gyres are regions of water cut off from the rest of the ocean by strong, circulating ocean currents that can trap enormous quantities of material in the gyres. The same currents that trap junk within the gyre also prevent nutrients stored in deeper waters from rising to higher layers where most organisms live. As a result, the gyres comprise the least biologically productive parts of the ocean – hence the term biological desert.'

In the past, these gyres have garnered some attention as a potential environmental concern because they trap a lot of the garbage thrown into the ocean. In fact, unconfirmed reports estimate that there is a continent of trash nearly twice the size of Texas floating in the North Pacific Gyre. But researchers have now noticed another problem with the gyres: they are growing. Since 2006, the gyres appear to have expanded by 15 percent, or 6.6 million acres - 33 times the size of New York City.

According to Jeffrey Polovina, an oceanographer at the U.S. National Marine Fisheries Service in Hawaii, "we're seeing this pattern in each of the four ocean basins." Polovina further suggests that global warming could be causing this rapid expansion, possibly by slowing ocean currents. However, scientists also note that it is difficult to rule out the possibility that expansion is simply part of a reversible natural cycle.

One thing is for sure – with the vast quantities of non-degradable trash currently trapped by the gyres, their destruction could cause major environmental damage and seriously pollute the world's oceans. Further study is being conducted, however, and researchers hope to determine the cause and, perhaps, the treatment for this phenomenon.

Written by Charley Wang

Reviewed by Elizabeth Ng, David Metcalfe.

Published by Pooja Ghatalia.