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University of Missouri Geologist Finds Exceptions to Global Warming

Posted on: Tuesday, 12 July 2005, 18:00 CDT

Jul. 10--Global warming and cooling are not global, and some regions can buck the climate trends for several million years, a University of Missouri-Columbia geologist has discovered.

Kenneth MacLeod's findings, published in last month's edition of Geology, a journal of the Geological Society of America, indicate there will be exceptions to current global warming. Some places will be cooler and some warmer -- for several million years, he said.

"To my knowledge, we are the first ones to show a regional divergence on this time scale," MacLeod said. His findings are based on a study of 70-million-year-old fossil plankton on the Atlantic Ocean floor off the coast of northeast Florida.

MacLeod said his study cannot predict regions of exception to global warming or cooling. Nor does it mean that humans are helpless to alter the current pattern of global warming caused by fuel consumption that has raised carbon dioxide levels.

"It's not an excuse to do nothing," MacLeod said. "We know we are changing climate on a global scale."

Humans have changed the atmosphere more in the past 150 years than occurred naturally over the previous 35 million years, MacLeod said. This has exposed certain parts of the globe to warming beyond what would already be the trend, he said.

"While global climate change will occur with changing carbon dioxide levels, at any one locality the changes might be more extreme or even in the opposite direction to the average global trend," MacLeod said.

There are, however, natural warming and cooling patterns that are beyond human control, he said.

"The atmosphere and oceans are vehicles by which heat is distributed around the Earth," MacLeod said. "If you change the way the oceans and atmosphere flow, you move the heat and cold around."

In his research, MacLeod found that part of the Atlantic Ocean warmed for several million years while the rest of the planet was cooling 70 million years ago.

The ocean warming was caused by a circulation of warm ocean waters from the south northward, a process called "heat piracy," MacLeod said.

The original intent of MacLeod's research was to show that global cooling probably killed off a 6- to 8-foot-wide type of clam, the same way cooling is believed to have led to the extinction of dinosaurs at the time.

But the research found a different story in the waters of the Atlantic.

"At first we didn't believe it," MacLeod said. "The harder we looked, the more we were convinced that during this interval of time when average global temperatures were dropping, the North Atlantic basin was actually warming."

Earth began cooling about 70 million years ago when intense volcanic activity declined, which reduced the rate of carbon dioxide going into the atmosphere, MacLeod said. Temperatures dropped by up to 10 degrees over a 5-million-year period, he said.

McLeod said his study of global cooling resulted from his interest, as an early 1990s graduate student, in the extinct clams, called inoceramus. In 1997, he spent six weeks with other scientists on a drilling vessel in the Atlantic where the clams lived.

They bored into layers of sediment that contained fossil plankton.

McLeod joined MU in 1999 and spent several years analyzing the sediment to determine that the Atlantic got warmer, not cooler.

"You have some expectations and you are supposed to let the data drive you," MacLeod said. "When you find something like this that doesn't fit the pattern, it is in some ways very exciting."

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Source: The Kansas City Star (Kansas City, Missouri)

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