- WASHINGTON, DC (ENS)
- The oceans of the world have warmed substantially during the past 40
years, the National Oceanic and Atmospheric Administration announced Thursday.
NOAA researchers suggest that much of the heat from global warming may
have been stored in the oceans, reducing atmospheric temperature increases
but leading to potentially huge climate changes in the near future.
- Ocean warming could signal more impending global warming
(Photo courtesy Ocean-Atmosphere Carbon Exchange Study)
- Researchers from NOAA's Ocean Climate Laboratory in Silver
Spring, Maryland examined three major ocean basins - the Atlantic, Indian
- They found the greatest warming has occurred in the upper
300 meters (975 feet) of the ocean waters. This level has warmed an average
of 0.56 degrees Fahrenheit.
- The water in the upper 3,000 meters (9,750 feet) of the
world's oceans has warmed on average by 0.11 degrees Fahrenheit.
- These findings represent the first time scientists have
quantified temperature changes in all of the world's oceans from the surface
to a depth of 3,000 meters.
- "Since the 1970s, temperatures at the earth's surface
have warmed, Arctic sea ice has decreased in thickness, and now we know
that the average temperature of the world's oceans has increased during
this same time period," said NOAA Administrator D. James Baker.
- Sea ice has been shrinking over the past 40 years, perhaps
due in part to warmer ocean waters (Three photos courtesy National Aeronautic
and Space Administration)
- The ocean and atmosphere interact in complex ways to
produce Earth's climate. Owing to its large mass, the ocean acts as the
memory of the earth's climate system and can store heat for decades or
- As a result, it might become possible some day for scientists
to use ocean temperature measurements to forecast the earth's climate decades
in advance, the researchers said.
- "It is possible that ocean heat content may be an
early indicator of the warming of surface, air and sea surface temperatures
more than a decade in advance," said Sydney Levitus, who heads NOAA's
Ocean Climate Laboratory.
- "For example, we found that the increase in subsurface
ocean temperatures preceded the observed warming of surface air and sea
surface temperatures, which began in the 1970s," Levitus said.
- "Our results support climate modeling predictions
that show increasing atmospheric greenhouse gases will have a relatively
large warming influence on the earth's atmosphere," Levitus warned.
- "One criticism of the models is that they predict
more warming of the atmosphere than has been actually observed. Climate
modelers have suggested that this missing warming' was probably to be found
in the world ocean. The results of our study lend credence to this scenario,"
- The scientists determined their findings by using data
- 5.1 million temperature profiles - from sources around the world, to
quantify the variability of the heat content (mean temperature) of the
world,s oceans from the surface through 3000 meter depth for the period
1948 to 1996.
- The researchers looked at temperature changes in the
Atlantic, Indian and Pacific oceans.
- "In each ocean basin substantial temperature changes
are occurring at much deeper depths than we previously thought. This is
just one more piece of the puzzle to understanding the variability of the
earth's climate system," said Baker.
- The Pacific and Atlantic Oceans have been warming since
the 1950s, while the Indian Ocean has warmed since the 1960s. The similar
warming patterns of the Pacific and Indian Oceans suggest that the same
phenomena is causing the changes to occur in both oceans.
- The world ocean warming is likely due to a combination
of natural variability, such as the Pacific Decadal Oscillation, and human
induced effects, the researchers say. The scientists, led by Levitus, report
their findings in today,s issue of the journal "Science," in
an article titled "Warming of the World Ocean."
- The NOAA report was made possible in part by an international
ocean data management project headed by Levitus that has added more than
two million historical temperature profiles to electronic archives during
the past seven years.
- A massive iceberg that peeled off the Ross Ice Shelf
in Antarctica this week could be a symptom of warming oceans (Photo courtesy
NOAA/Space Science and Engineering Center, University of Wisconsin-Madison)
- "International cooperation in building the global
ocean databases required for understanding the role of the ocean as part
of the earth's climate system has been excellent," said Levitus.
- Contributions of subsurface ocean temperature data have
come from all countries that make oceanographic measurements including
the United States, Russia, the United Kingdom, Germany, France, Canada,
Australia, and Japan.
- Nearly all of the data were gathered by research ships,
naval ships, buoys, and merchant ships. Some merchant ships deploy instruments
that measure the temperature of the upper ocean as participants in voluntary
- Understanding the role of the ocean in climate change
and making 10 year climate forecasts will soon be greatly enhanced by observations
planned as part of an emerging international Global Ocean Observing System.
- Meanwhile, a recently completed study of climate over
the past 100 years suggests that interactions between the atmosphere, ocean
and sea ice systems may have played a prominent role in the global warming
of the early 20th century, NOAA scientists say.
- Climate is a result of interactions between many factors,
like this "cloud wake" off Guadalupe island, located in the Pacific
Ocean off the coast of Baja California
- Using climate models run on high performance supercomputers,
scientists at NOAA's Geophysical Fluid Dynamics Laboratory in Princeton,
New Jersey, conducted six experiments to explore possible causes for the
warming in the first half of the century. Their findings were also published
in today,s issue of "Science."
- They linked warming in the early part of the century
with a combination of ingredients, including increasing concentrations
of greenhouse gas and sulfate aerosols.
- The supercomputers turned up strong evidence that warming
in the latter part of the 20th century was due in large part to human generated
- "The fact that all experiments capture the warming
from 1970 on is indicative of a robust response of the climate model to
increasing concentrations of greenhouse gases," said Thomas Knutson,
a research meteorologist.
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