WASHINGTON - A sobering new report warns that the
oceans face a "fundamental and irreversible ecological transformation"
not seen in millions of years as greenhouse gases and climate change
already have affected temperature, acidity, sea and oxygen levels, the
food chain and possibly major currents that could alter global weather.
The report, in Science magazine, brings together
dozens of studies that collectively paint a dismal picture of
deteriorating ocean health.
"This is further evidence we are well
on our way to the next great extinction event," said Ove Hoegh-Guldberg,
the director of the Global Change Institute at the University of
Queensland in Australia and a co-author of the report.
John Bruno, an associate professor of marine sciences at the
University of North Carolina at Chapel Hill and the report's other
co-author, isn't quite as alarmist, but he's equally concerned.
are becoming increasingly certain that the world's marine ecosystems
are reaching tipping points," Bruno said, adding, "We really have no
power or model to foresee" the impact.
The oceans, which cover 71
percent of the Earth's surface, have played a dominant role in
regulating the planet's climate. However, even as the understanding of
what's happening to terrestrial ecosystems as a result of climate change
has grown, studies of marine ecosystems have lagged, the report says.
The oceans are acting as a heat sink for rising temperatures and have
absorbed about one-third of the carbon dioxide produced by human
Among other things, the report notes:
- The average temperature of the upper level of the
oceans has increased more than 1 degree Fahrenheit over the past 100
years, and global ocean surface temperatures in January were the second
warmest ever recorded for that month.
- Though the
increase in acidity is slight, it represents a "major departure" from
the geochemical conditions that have existed in the oceans for hundred
of thousands if not millions of years.
"ocean deserts" in the Pacific and Atlantic oceans grew by 15 percent,
or roughly 2.5 million square miles, from 1998 to 2006.
Oxygen concentrations have been dropping off the Northwest U.S. coast
and the coast of southern Africa, where dead zones are appearing
regularly. There is paleontological evidence that declining oxygen
levels in the oceans played a major role in at least four or five mass
- Since the early 1980s, the production of
phytoplankton, a crucial creature at the lower end of the food chain,
has declined 6 percent, with 70 percent of the decline found in the
northern parts of the oceans. Scientists also have found that
phytoplankton are becoming smaller.
Volcanic activity and large meteorite strikes in the past have
"resulted in hostile conditions that have increased extinction rates and
driven ecosystem collapse," the report says. "There is now overwhelming
evidence human activities are driving rapid changes on a scale similar
to these past events.
"Many of these changes are already occurring
within the world's oceans with serious consequences likely over the
One of the consequences could be a disruption of
major ocean currents, particularly those flowing north and south,
circulating warm water from the equator to polar regions and cold water
from the poles back to the equator. Higher temperatures in polar regions
and a decrease in the salinity of surface water due to melting ice
sheets could interrupt such circulation, the report says.
change in currents could further affect such climate phenomena as the El
Nino-Southern Oscillation, the Pacific Decadal Oscillation and the
North Atlantic Oscillation. Scientists just now are starting to
understand how these phenomena affect global weather patterns.
our comprehension of how this variability will change over the coming
decades remains uncertain, the steady increase in heat content in the
ocean and atmosphere are likely to have profound influences on the
strength, direction and behavior of the world's major current systems,"
the report says.
Kelp forests such as those off the Northwest U.S.
coast, along with corals, sea grasses, mangroves and salt marsh
grasses, are threatened by the changes the oceans are undergoing, the
report says. All of them provide habitat for thousands of species.
polar bear isn't the only polar mammal that faces an escalating risk of
extinction, the report says; penguin and seal populations also are
"It's a lot worse than the public thinks," said Nate
Mantua, an associate research professor at the University of
Washington's Climate Impacts Group.
Mantua, who's read the report,
said it was clear what was causing the oceans' problems: greenhouse
gases. "It is not a mystery," he said.
There's growing concern
about low-oxygen or no-oxygen zones appearing more and more regularly
off the Northwest coast, Mantua said. Scientists are studying the
California Current along the West Coast to determine whether it could be
affected, he added.
Richard Feely, a senior scientist with the
National Oceanic and Atmospheric Administration's Pacific Marine
Environmental Laboratory in Seattle, said the report in Science seemed
so direct because one of the authors was Australian.
come at you full-bore and lay it on the line," Feely said.
so, he said, the condition of the oceans is indeed deteriorating.
combination of these impacts are tending to show they are additive," he
said. "They combine to make things worse."
Asked what the oceans
will be like in 50 years if trends aren't reversed, Bruno, the UNC
professor, said that all the problems would have accelerated and there'd
be new ones. For instance, he said tens of thousands of species found
only in the Pacific might migrate across the top of North America as the
sea ice melts and enter the Atlantic, where they've never been.
said a 50-year time frame to consider changes in the ocean was way too
"I am a lot more worried about 200 to 300 years
out," he said.