Ocean Warming

Warmer Tropical Waters portend Climate Change
ENN News, August 7, 2000

Since 1984, tropical waters in the Northern Hemisphere have warmed at a rate of about 1 degree Fahrenheit per decade, according to data compiled” by NOAA. This figure is 10 times the global rate, a harbinger of climate change. "If temperatures continue to increase in the tropical North Atlantic, many of the coral reefs there (and their ecosystems) may be affected by bleaching. Also, since hurricane development does depend on sea surface temperatures, the conditions necessary for hurricanes to form may be accentuated," said Edward Kearns of the Rosenstiel School of Marine and Atmospheric Science. Kearns and a team of scientists led by Alan Strong of NOAA's National Environmental Satellite, Data and Information Service analyzed sea surface temperature data from the agency's polar-orbiting satellites from 1984 through 1996. Analyses of the Atlantic, Pacific and Indian oceans show a significant warming trend in tropical areas of the Northern Hemisphere, close to what is known as the thermal equator. "The most troubling finding is the marked increase in the tropical waters off the Northern Hemisphere centered around the globe at a latitude of roughly 5 degrees north," said Strong. "If this trend were to continue, implications for our coral reefs throughout these waters would be bleak."

Many coral reefs are found within the region of increasing temperatures, and most of the reefs within these latitudes have experienced bleaching over the past 10 years. Bleaching damages corals and is a sign that marine life is stressed by a number of factors. These factors include high water temperatures, pollution, sedimentation, high light levels, reduced water levels and changes in salinity. "The oceans store an enormous amount of heat energy, and they act to buffer any rapid climate change," said Kearns. "If there is any significant change in the amount of heat stored by the oceans, this would effect global temperatures." Data also showed a warming in the equatorial Pacific, cooling in the central North Pacific and general cooling the Southern Hemisphere. "The oceans are not cooling or warming uniformly; there appears to be a great deal of geographic variability," said Kearns. "When people usually speak of global warming, they think of the entire ocean warming up or cooling down. We don't have the accuracy yet to determine the magnitude of the average global trend, but we at least are trying to point out the signs of these trends." "If these trends are real ... the extensive bleachings that our reefs have experienced in the past two years would likely become commonplace," said Strong.