Tuesday, July 10, 2012

Natural Climate Shifts stopped Coral Reef growth for 2500 years



My heading above reflects what was actually found.  The original screeching headline was "Natural Climate Shifts Drove Coral Reefs to a Total Ecosystem Collapse Lasting 2,500 Years"

The authors go on to speculate that man-made global warming could have similar effects but we will worry about that when we actually see some of that fabled man-made global warming  -- or any global warming at all, for that matter


Climate change drove coral reefs to a total ecosystem collapse lasting thousands of years, according to a paper published this week in Science. The paper shows how natural climatic shifts stopped reef growth in the eastern Pacific for 2,500 years.

The reef shutdown, which began 4,000 years ago, corresponds to a period of dramatic swings in the El Niño-Southern Oscillation (ENSO).

Doctoral student Lauren Toth and Aronson, her adviser at Florida Tech, led the study of how past episodes of climate change influenced tropical reefs of the eastern Pacific. Toth, Aronson and a multi-institutional research team drove 17-foot, small-bore aluminum pipes deep into the dead frameworks of coral reefs along the Pacific coast of Panama and pulled out cross-sections of the reefs. By analyzing the corals in the cores, they were able to reconstruct the history of the reefs over the past 6,000 years.

"We were shocked to find that 2,500 years of reef growth were missing from the frameworks," said Toth. "That gap represents the collapse of reef ecosystems for 40 percent of their total history." When Toth and Aronson examined reef records from other studies across the Pacific, they discovered the same gap in reefs as far away as Australia and Japan.

Toth linked the coral-reef collapse to changes in ENSO. ENSO is the climate cycle responsible for the weather conditions every few years known as El Niño and La Niña events. The timing of the shutdown in reef growth corresponds to a period of wild swings in ENSO. "Coral reefs are resilient ecosystems," said Toth. "For Pacific reefs to have collapsed for such a long time and over such a large geographic scale, they must have experienced a major climatic disturbance. That disturbance was an intensified ENSO regime."

SOURCE


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