It’s looking increasingly likely we’ll see an El Niño starting this summer. If so, next year will almost certainly be the hottest year on record.
The silver lining is that climatologist Kevin Trenberth says an El Niño would probably be a change “for the better” for the U.S. “in the short term” since it might mean a weaker hurricane season and some relief for the devastating drought that is slamming the Southwest.
The latest U.S. Drought Monitor shows just how widespread the drought is:
So what’s coming? NOAA’s’s Climate Prediction Center says in its monthly “El Niño Southern Oscillation (ENSO) Diagnostic Discussion“:
ENSO Alert System Status: El Niño Watch
Synopsis: Chances increase for El Niño beginning in July-September 2012.
Let’s look at the global and national implications.
Globally, as I discussed last month, NASA said that the development of an El Niño this year would lead to “rapid warming.” That’s because the supposedly slow rate of recent global warming was actually due to the deepest solar minimum in a century combined with that the fact that “the cool La Niña phase of the cyclically variable Southern Oscillation of tropical temperatures has been dominant in the past three years.”
With global warming continuing unabated and the sun coming out of that atypical minimum, an El Niño would make a new global record all but inevitable. After all, we just had the warmest La Niña year on record:
Global average surface temperatures during El Niño and La Niña years.
As NASA wrote in its January analysis, “Global Temperature in 2011, Trends, and Prospects”:
We conclude that the slowdown of warming is likely to prove illusory, with more rapid warming appearing over the next few years.
At a national level, an El Niño this summer may be a good thing, at least for a while. Kevin E. Trenberth, senior scientist at the National Center for Atmospheric Research, explained what an El Niño would mean for us:
The developing El Nino is apt to change weather patterns across the United States and perhaps in the short term, for the better. The hot dry pattern that has prevailed has the potential to be changed as the North American monsoon kicks in in July to provide some relief in the Southwest. It also acts to shift hurricane activity to the Pacific, making for a less active Atlantic hurricane season. The strongest effects are in the winter half year, however. Look for higher global mean temperatures over the next year.
Certainly we need relief from the drought — and a less active hurricane season is always a good thing.
El Niño and La Niña are typically defined as sustained sea surface temperature anomalies (positive and negative respectively) greater than 0.5°C across the central tropical Pacific Ocean (the so-called Nino3.4 region). You can read the basics about ENSO here.
Right now, the Australian government’s Bureau of Meteorology reports, the Nino3.4 sea surface temperature index just shot up to 0.7°C — a 0.3°C jump in the last two weeks:
If the index were to merely stay at this level for a few months, that would be sufficient for an El Niño.
NOAA’s National Center for Environmental Prediction Climate Forecast System (version 2), however, projects a pretty sizable El Niño by year’s end:
Stay tuned. The heat is on.
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