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Wednesday, October 14, 2009

Joseph Romm: NASA reports hottest June to September on record*; NOAA says “weak” El Niño “expected to strengthen and last through” winter

NASA reports hottest June to September on record*; NOAA says “weak” El Niño “expected to strengthen and last through” winter

by Joseph Romm, Climate Progress blog, October 13, 2009
Fast on the heels of the second warmest August on record and warmest June-July-August for the oceans, NASA’s Goddard Institute for Space Studies reports that this was the second hottest September on record.
Unlike NOAA, which will announce its September global analysis in a few days, NASA just quietly updates its data set (here).  So you have to do a little math to see that for the June through September period, 2009 now tops both 2005 and 1998.  I put the asterisk in the headline since these four months in 2009 are only slightly warmer than those in 1998.

I’m not cherry-picking these last four months, but rather ENSO-picking them.  The reason 1998 was so anomalously warm even beyond the human-caused trend was the uber-El Niño.  Back in January, NASA had predicted:  “Given our expectation of the next El Niño beginning in 2009 or 2010, it still seems likely that a new global temperature record will be set within the next 1-2 years, despite the moderate negative effect of the reduced solar irradiance.”

Then, back in early June NOAA put out “El Niño Watch,” which I noted meant that “record temperatures are coming and this will be the hottest decade on record.”  So here we are.

What makes these record temps especially impressive is that we’re at “the deepest solar minimum in nearly a century,” according to NASA.  It’s just hard to stop the march of anthropogenic global warming, well, other than by reducing GHG emissions, that is.

Another thing that makes these record temps impressive is that we’re only in a “weak El Niño,” according to the latest monthly “El Niño/Southern oscillation (ENSO) Diagnostic Discussion” of the Climate Prediction Center of NOAA’s National Weather Service:

Synopsis: El Niño is expected to strengthen and last through the Northern Hemisphere winter 2009-2010.

A weak El Niño continued during September 2009, as sea surface temperature (SST) anomalies remained nearly unchanged across much of the equatorial Pacific Ocean (Figs. 1 & 2). Since the transition to El Niño conditions during June, the weekly values of the Niño-3.4 index have remained between +0.7°C and +0.9°C (Fig. 2). Subsurface oceanic heat content (average temperatures in the upper 300m of the ocean, Fig. 3) anomalies continued to reflect a deep layer of anomalous warmth between the ocean surface and the thermocline, particularly in the central and east-central Pacific (Fig. 4)….  These oceanic and atmospheric anomalies reflect an ongoing weak El Niño.
A majority of the model forecasts for the Niño-3.4 SST index (Fig. 6) suggest that El Niño will reach at least moderate strength during the Northern Hemisphere fall (3-month Niño-3.4 SST index of +1.0°C or greater). Many model forecasts even suggest a strong El Niño (3-month Niño-3.4 SST index in excess of +1.5°C) during the fall and winter, but in recent months some models, including the NCEP CFS, have over-predicted the degree of warming observed so far in the Niño-3.4 region (Fig. 7). Based on the model forecasts, the seasonality of El Niño, and the continuation of westerly wind bursts, El Niño is expected to strengthen and most likely peak at moderate strength.
ENSO 9-09
What is particularly interesting to me is the prediction that, while his is not going to be a blockbuster El Niño in terms of amplitude, as we saw in 1997-1998, it may turn out to be a pretty long one.  If it lasts through June 2010, then that year seems poised to be the hottest on record.
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