Wednesday, April 23, 2014

Does El Niño Plus Global Warming Equal Global Temperature Records in 2014 and 2015?

Chart of global temperature since 1950, also showing the phase of the El Niño-La Niña cycle. (Credit: NASA) Click to enlarge.
An El Niño appears increasingly likely this year, according to the National Oceanic and Atmospheric Administration (NOAA) and Australia’s Bureau of Meteorology (BOM).  If it starts relatively quickly, then 2014 could well be the hottest year on record, but if it is a strong El Niño, as many currently expect, then 2015 would likely break all previous global records.

When the El Niño forms and then peaks is crucial to whether 2014 or 2015 (or both) will be the hottest year on record.  A 2010 NASA study found the 12-month running-mean global temperature tends to lag the temperature in the key Niño 3.4 region of the equatorial Pacific “by 4 months.”

Because 1997/1998 was a “super El Niño,” and because we haven’t had one of those since — or indeed any El Niño at all since 2010 — it can appear as if global warming has slowed (if you cherry-pick a relatively recent start year).  But in fact several recent studies have confirmed that planetary warming continues apace everywhere you look, especially the ocean.

Recent research finds that one reason the rate of surface warming has the slowed down is that trade winds have sped up in an unprecedented fashion, mixing more heat deeper into the oceans, while bringing cooler water up to the surface.  Remember, more than 90 percent of human-induced planetary warming goes into the oceans, while only 2 percent goes into the atmosphere, so small changes in ocean uptake can have huge impact on surface temperatures.  The lead author of this study explained when that process ends “as it inevitably will –- our research suggests heat will quickly accumulate in the atmosphere.  So global temperatures look set to rise rapidly.”

As meteorologist Eric Holthaus notes on Slate, a major El Niño could in fact be the triggering event to the return of the rapid phase of warming surface air temperatures.

Does El Niño Plus Global Warming Equal Global Temperature Records in 2014 and 2015?

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