(From The New York Times, 4/25/89, p. C4) WARMING OF OCEANS SPURS CONCERN OVER SHIFT IN CL
(From The New York Times, 4/25/89, p. C4)
WARMING OF OCEANS SPURS CONCERN OVER SHIFT IN CLIMATE
By William K. Stevens
Government scientists, employing satellites and advanced methods
of measurement, have found that the average surface temperature
of the world's oceans rose more than 1 degree Fahrenheit from
1982 to 1988.
By comparison, the earth's surface has warmed about 9 degrees
since the end of the last Ice Age 12,000 years ago. A 1-degree
increase in less than a decade is considered extremely large,
climatologists said, and it would be alarming if it were to
continue at that rate for a long time.
Scientists believe that the greenhouse effect, in which
increasing levels of carbon dioxide and other gases combine with
moisture to trap heat inside the earth's atmosphere, will cause a
further rise of 2 to 9 degrees in the global temperature by the
middle of the next century. The result, they say, could be
serious dislocations of the earth's climate.
No one contends that the increases in ocean temperature detected
in the 1980's are caused by the greenhouse effect for sure. And
some scientists believe that the readings were skewed because a
Mexican volcano, El Chichon, erupted in 1982. But climatologists
said that while the findings did not prove global warming, they
were consistent with it.
"It's too soon to tell" whether the new readings say anything
about climatic trends, said A. E. Strong of the National Oceanic
and Atmospheric Administration, who reported them in the current
issue of the British journal Nature.
"If this trend continues at the same rate for another six or
eight years, we're going to be concerned that a significant
portion of this is a result of global warming," he said. "But it
could easily cool off, and we could see just a short-term cycle."
Dust from a Volcano
The measurements were made by infrared sensors aboard NOAA
satellites that take readings at 2.5 million to 3 million points
in the ocean. This compares with some 50,000 conventional
thermometer readings taken aboard ships and buoys. In this
respect, he said, the satellite coverage is superior.
But the eruption of El Chichon in 1982 sent so much dust into the
air that it would have distorted the satellite readings and
produced lower temperatures, said Dick Reynolds, who analyzes
satellite and ship readings for the National Weather Services
Climate Analysis Center. This, climatologists say, would have
guaranteed a rise after 1982, as the dust cleared. Mr. Reynolds
said that data from ships and buoys showed almost no trend during
Dr. Strong said that from 1984 on, dust from El Chichon was not a
factor, and that the trend after that, as measured by satellite,
was essentially the same as for the entire 6.5 years. Over the
whole period, he said, the average temperature of the ocean
outside the polar regions rose to 36.8 degrees, from 35.5
Insofar as the satellite readings are accurate, a six-year trend
"is really very short compared with the ups and downs we've seen"
over the long term, said Kirk Bryan, a climatologist at the
Geophysical Fluid Dynamics Laboratory at Princeton University.
He noted in particular a dramatic warming trend in the 1930's in
the Northern Hemisphere and a cooling trend in the 1960's.
"We still haven't explained why those events occurred," he said.
In the Northern Hemisphere, the 1930's were about 1 degree warmer
than the 1960's.
Dr. Strong holds that ocean measurements are a more accurate
gauge of temperature change on a global scale because cities are
"heat islands" and distort land measurements.
Before 1982, he said, sensing instruments aboard satellites were
unable to deal with the distorting effect of temperature
measurements of moisture in the earth's atmosphere. The latest
instruments, he said, are able to do that.
The sea-level readings from buoys are still used, he said, not
least to help calibrate the satellite-borne sensors. And in any
case, he said, the satellites have put climatologists and
meteorologists in a much better position to assess change as it
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