As the Earth warms from the buildup of carbon dioxide in its atmosphere,
the oceans that cover 70 percent of its surface are warming too.
This warming will likely benefit some marine species at the expense of others.
A study in the May 20 issue of the journal Nature confirmed that there
has been a warming trend in the world's oceans since 1993, as the waters
have absorbed much of the excess energy in the planet's atmosphere.
The warming that has already occurred, and is expected to continue in the
coming decades, will likely spell bad news for many ocean species, such as
corals and species that dwell in the cold waters of the planet's poles.
But some creatures beneath the ocean surface might actually have an
advantage in the newly warmed waters.
A 2008 study, for example, revealed that a warming of just a few degrees
Fahrenheit in Antarctic waters could make them hospitable to sharks, which
haven't lived in the area for about 40 million years.
It's easier for sharks to maintain their high metabolism in warmer waters.
If sharks do migrate into the area, they could wreak havoc on the existing
ecosystems of the oceans around Antarctica.
A study of starfish found these iconic ocean dwellers grew faster in water at
warmer temperatures and higher carbon dioxide levels (another result of all
the extra greenhouse gas in the atmosphere) than at normal conditions â€”
which is bad news for the clams, mussels and other bivalves they prey on.
Work by Jeremy Jackson, a professor of oceanography at Scripps Institution
of Oceanography at the University of California at San Diego, suggests that
ocean warming â€” along with other threats such as overfishing and habitat
destruction â€” could convert once complex ocean ecosystems into ones that
favor simpler species, such as microbes, toxic algal blooms and jellyfish.