Archives par mot-clé : Ocean

Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability

by Hiroki Tokinaga et al., PNAS, May 1, 2017

Arctic amplification is a robust feature of climate response to global warming, with large impacts on ecosystems and societies. A long-standing mystery is that a pronounced Arctic warming occurred during the early 20th century when the rate of interdecadal change in radiative forcing was much weaker than at present. Here, using observations and model experiments, we show that the combined effect of internally generated Pacific and Atlantic interdecadal variabilities intensified the Arctic land warming in the early 20th century.

A paleo-perspective on ocean heat content: Lessons from the Holocene and Common Era

by Yair Rosenthal et al., January 1, 2017


Here we review proxy records of intermediate water temperatures from sediment cores in the equatorial Pacific and northeastern Atlantic Oceans, spanning 10,000 years beyond the instrumental record.

These records suggests that intermediate waters were 1.5–2 °C warmer during the Holocene Thermal Maximum than in the last century.

Intermediate water masses cooled by 0.9 °C from the Medieval Climate Anomaly to the Little Ice Age.


When will Earth lose its oceans?

by J.  Lecomte et al., CNRS, December 16, 2013

The natural increase in solar luminosity — a very slow process unrelated to current climate warming — will cause the Earth’s temperatures to rise over the next few hundred million years. This will result in the complete evaporation of the oceans. The first three-dimensional climate model able to simulate the phenomenon predicts that liquid water will disappear on Earth in approximately one billion years, extending previous estimates by several hundred million years.

Jérémy Leconte, Francois Forget, Benjamin Charnay, Robin Wordsworth, Alizée Pottier. Increased insolation threshold for runaway greenhouse processes on Earth-like planetsNature, 2013; 504 (7479): 268 DOI: 10.1038/nature12827


Atlantique Nord : le risque d’un refroidissement rapide au XXIe siècle revu à la hausse

par D. Swingedouw et al., CNRS, 15 février 2017

Dans le cadre du projet européen EMBRACE, une équipe d’océanographes a réexaminé ces 40 projections climatiques en se focalisant sur un point névralgique au nord-ouest de l’Atlantique Nord : la mer du Labrador. Cette mer est le siège d’un phénomène de convection, qui nourrit à plus grande échelle la circulation océanique de retournement. Ses eaux de surface se refroidissent fortement en hiver, deviennent plus denses que les eaux de profondeur et plongent vers le fond. La chaleur des eaux profondes est transférée vers la surface et empêche la formation de banquise