The study of climates from the past and oceanic temperatures can give clues as to how future climate changes will unfold. An international team of researchers, led by the members of the Institut de Ciència i Tecnologia Ambientals (ICTA) at the Universitat Autònoma de Barcelona (UAB), has studied the evolution of Northern Pacific and Southern Atlantic sea surface temperatures, dating from the Pliocene Era; some 3.65 million years ago. The results indicate that the regions closer to the poles of both oceans have played a fundamental role in climate evolution in the tropics.
Some High Points:
- During the Pliocene epoch, the global average temperature was 5-7°F higher than today with global sea levels being about 80 feet higher and with a reduced northern hemisphere ice sheet. Towards he end of the era global cooling occurred.
- A permanent El Niño state existed in the early mid Pliocene, warmer temperature in the eastern equatorial Pacific increased a water vapor greenhouse effect and reduced the area covered by highly reflective stratus clouds thus decreasing the albedo of the planet.
- The ambient water temperature in which the organisms dwelt can be estimated from ratio of their unsaturated alkenones (C37-C39).
- The formation of an Arctic ice cap was started as indicated by an abrupt shift in oxygen isotope ratios in the North Atlantic and North Pacific ocean beds. Mid-latitude glaciation was probably underway before the end of the epoch. The global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas.