Experts: New Data Show Global Warming
- Experts: New Data Show Global Warming
Climate Researchers Say Undersea, Space Data Support Projections of
By CHARLES J. HANLEY AP Special Correspondent
The Associated Press
Apr. 29, 2005 - Climate scientists armed with new data from deep in the
ocean and far into space have found that Earth is absorbing much more
heat than it is giving off, a conclusion they say validates projections
of global warming.
Lead scientist James Hansen, a prominent NASA climatologist, described
the findings on the planet's out-of-balance energy exchange as a "smoking
gun" that should dispel doubts about forecasts of climate change. A
European climate expert called it a valuable contribution to climate
Hansen's team, reporting Thursday in the journal Science, said they also
determined that global temperatures will rise 1 degree Fahrenheit this
century even if greenhouse gases are capped tomorrow.
If carbon dioxide and other heat-trapping emissions instead continue to
grow, as expected, things could spin "out of our control," especially as
ocean levels rise from melting Greenland and Antarctic ice sheets, the
researchers said. International experts predict a 10-degree leap in
Fahrenheit readings in such a worst-case scenario.
The NASA-led researchers were able to measure Earth's energy imbalance
because of more precise ocean readings collected by 1,800
technology-packed floats deployed in seas worldwide beginning in 2000, in
an international monitoring effort called Argo. The robots regularly dive
as much as a mile undersea to take temperature and other readings.
Their measurements are supplemented by better satellite gauging of ocean
levels, which rise both from meltwater and as the sea warms and expands.
With this data, the scientists calculated the oceans' heat content and
the global energy imbalance. They found that for every square meter of
surface area, the planet is absorbing almost one watt more of the sun's
energy than it is radiating back to space as heat a historically large
imbalance. Such absorbed energy will steadily warm the atmosphere.
The 0.85-watt figure corresponds well with the energy imbalance predicted
by the researchers' supercomputer simulations of climate change, the
Those computer models factor in greenhouse gases in the atmosphere,
including carbon dioxide, methane and other gases produced by everything
from automobiles to pig farms. Those gases keep heat from escaping into
space. Significantly, greenhouse emissions have increased at a rate
consistent with the detected energy imbalance, the researchers said.
"There can no longer be genuine doubt that human-made gases are the
dominant cause of observed warming," said Hansen, director of NASA's
Goddard Institute for Space Studies at Columbia University's Earth
Institute. "This energy imbalance is the `smoking gun' that we have been
Fourteen other specialists from NASA, Columbia and the Department of
Energy co-authored the study.
Scientists have found other possible "smoking guns" on global warming in
recent years, but Klaus Hasselmann, a leading German climatologist,
praised the Hansen report for its innovative work on energy imbalance.
"This is valuable additional supporting evidence" of manmade climate
change, he told The Associated Press.
In February, scientists at San Diego's Scripps Institution of
Oceanography said their research not yet published also showed a close
correlation between climate models and the observed temperatures of
oceans, further defusing skeptics' past criticism of uncertainties in
Average atmospheric temperatures rose about 1 degree Fahrenheit in the
20th century. The Intergovernmental Panel on Climate Change, a
U.N.-organized network of scientists, says computer modeling predicts
temperatures rising between 2.5 degrees and 10.4 degrees Fahrenheit by
the year 2100.
Besides raising ocean levels, global warming is expected to intensify
storms, spread disease to new areas, and shift climate zones, possibly
making farmlands drier and deserts wetter.