Poles warmed more than models expected56 million years ago marks the boundary between the Paleocene

Poles warmed more than models expected56 million years ago marks the boundary between the Paleocene and the Eocene Epochs. At that time, there was a rapid climate change on Earth, with extremely high temperatures at the planet’s poles, comparable to the tropics today (https://tmblr.co/Zyv2Js1vvz8m2). It is thought that at the Paleocene-Eocene boundary there was a rapid release of carbon trapped in the oceans and this triggered rapid climate change by increasing greenhouse gas abundances.This picture shows a shell of one foraminifera, a single-celled organism that precipitates the mineral calcite from the ocean. Scientists have developed several ways to use the chemistry of this mineral as records of the temperature in the water that they formed from, specifically by measuring the abundances of the isotopes of each isotope of oxygen in the carbonate mineral.This foram formed in the surface ocean at the North Pole during the Eocene. After it died, its shell found its way into sedimentary rocks and eventually it was measured by scientists from Yale University. They used the abundances of all 3 oxygen isotopes and the ratio of magnesium to calcium in forams like this to reconstruct the chemistry and temperature of the Eocene ocean.They found that this foram, found at the North Pole, formed in waters that were at temperatures from 30–36°C. Not only is that vastly warmer than the nearly 0°C waters found at the North Pole today, but it is several degrees warmer than even the highest temperatures predicted by climate models for the poles at this time. Scientists base those models on the physics of the atmosphere, but they have to calibrate them based on the measurements geologists can give of what the Earth did millions of years ago.These results imply that temperatures at the poles go up even more than predicted when there are huge spikes in atmospheric carbon dioxide, the poles are even more sensitive than scientists had previously predicted. This result, therefore, implies that the potential costs of increasing carbon dioxide in the atmosphere are even higher than scientists were predicting even last year.-JBBImage credit: Laura Cottonhttp://bit.ly/2E1etWgOriginal paper:http://www.pnas.org/content/early/2018/01/12/1714744115 -- source link

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