Archives par mot-clé : AMOC

Understanding Abrupt Climate Change in the Late Quaternary

by R.S. Bradley & H.F. Diaz, Nov18,  2021 in Eos

Between about 75,000 and 10,000 years ago, there was a series of sudden and dramatic changes in rainfall patterns in tropical regions likely triggered by changes in ocean water circulation. A recent article in Reviews of Geophysics examines the evidence of these “Tropical Hydroclimatic Events” and explores the potential causes. Here, one of the authors explains more about these abrupt climate change events of the past and suggests how it can inform our understanding of potential future climate change.

What are “Tropical Hydroclimatic Events” (THEs)? When and where did they occur?

When we look back at past climate variations in continental regions of the Tropics and sub-Tropics (~30ºN-30ºS), it is abundantly clear that there were times when climate abruptly changed, causing some areas that were formerly wet to become quite dry, and areas that were formerly dry to become much wetter, disrupting plant and animal communities, as well as people living in the region. We call those changes “Tropical Hydroclimatic Events (THEs).” The changes affected vast areas (and lasted for centuries in some cases_ before the climate shifted back to the former conditions. There were at least half a dozen of these THEs between about 10,000 and 75,000 years ago.

Yet Another Model-Based Claim Of Anthropogenic Climate Forcing Collapses

by K. Richard, Feb 25 2021 in NoTricksZone

High-resolution climate models have projected a “decline of the Atlantic Meridional Overturning Circulation (AMOC) under the influence of anthropogenic warming” for decades (Lobelle et al., 2020). New research that assesses changes in the deeper layers of the ocean (instead of “ignoring” these layers like past models have) shows instead that the AMOC hasn’t declined for over 30 years.

The North Atlantic has been rapidly cooling in recent decades (Bryden et al., 2020, Fröb et al., 2019). A cooling of “more than 2°C” in just 8 years (2008-2016) and a cooling rate of -0.78°C per decade between 2004 and 2017 has been reported for nearly the entire ocean region just south of Iceland. The cooling persists year-round and extends from the “surface down to 800 m depth”