From the frying pan, to the fire

We did it. NOAA agrees that 2016 was the hottest year on record [1]. Not a good race to be in, though, let alone to “win”.

I recently watched a departmental colloquium from an hydrologist in Dennis Lettinmeier’s lab detailing just how anomalous the 2016 climatologies were for the Western US. That was the “strongest” ENSO event on record. (ENSO is usually defined as an atmospheric pressure difference between Darwin, Australia, and Tahiti [the Southern Oscillation] which is caused by a strong equatorial Pacific sea surface temperature gradient [El Niño].) In the US Southwest, ENSO usually means mild, wet winters, as warm SSTs provide more convective moisture over the continent, whose mountainous topography helps wring small amounts of water from the atmosphere. (This contrasts particularly with ENSO’s sibling event, La Niña, which tends to block precipitation in the Western US with a static high pressure zone over the eastern Pacific.) There is no doubt that 2016 was warm, on land and over the oceans. But what’s amazing is how this screwed up the usual ENSO-associated precipitation over the continent. For those of us who use modern analogues to build past climate histories, this is really interesting: it means that ENSO may not be a good analogue for a warm Medieval Climate Anomaly (MCA) [2]. But it’s also intreaguing because it reveals dynamics for a warm Eastern Pacific/Southwest US that were not predicted; and I don’t yet know what could have caused it, which is exciting for a scientist!

[2]. Medieval Warm Period – Wikipedia The Medieval Warm Period (MWP), Medieval Climate Optimum, or Medieval Climatic Anomaly was a time of warm climate in the North Atlantic region that may also have been related to other climate events around the world during that time, including China and other areas, lasting from about 950 to 1250.

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