Global Warming Can Trigger Extreme Ocean, Climate Changes, Scripps-led Study Reveals
: "The global warming of 55 million years ago, known as the Paleocene/Eocene Thermal Maximum (PETM), emerged in less than 5,000 years, an instantaneous blip on geological time scales (the researchers indicate that 5,000 years can be considered an upper limit and they believe the warming could have unfolded much more quickly than geological records can show them). The PETM set in motion a host of important changes around the globe, including a mass extinction of deep-sea bottom-dwelling marine life. Fossil records indicate key migrations of terrestrial mammal species during this time—including evidence of the first horses and primates in North America and Europe—likely allowed by warm conditions that opened travel routes not possible under previously colder climates.
In the Nature study, the scientists (Flávia Nunes and Richard Norris) analyzed foraminifera called Nuttalides truempyi from 14 sites around the world in deep-sea sediment cores maintained by the Integrated Ocean Drilling Program. The isotopes were used as nutrient "tracers" to reconstruct changes in deep-ocean circulation through the PETM period. Nutrient levels tell the researchers how long a sample has been near or isolated from the sea surface, thus giving them a way to track the age and flow path of deep sea water. "
Scripps Institution of Oceanography: scripps.ucsd.edu