With new records being set for global heat and El Niño growing stronger, 2015 may represent a new "step up" in the continued rise in global temperatures. Here's why...

El Niño 2015 considered rare, aims to rewrite heat records

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Scott Sutherland

Meteorologist/Science Writer

Saturday, May 23, 2015, 8:11 AM - With new records being set for global heat and El Niño growing stronger, 2015 may represent a new "step up" in the continued rise in global temperatures. Here's why...

Even as experts declared an El Niño earlier this year, 2014 had already topped the list of hottest years (without El Niño's help), and 2015 was already setting global heat records.

So far, with only the weak El Niño Modoki declared as of March:

Now, with the El Niño strengthening into a more classic pattern - with warmer sea surface temperatures in the eastern Pacific, near Peru and Ecuador - and with projections showing that it could be a fairly significant event this year, the risk of 2015 far surpassing 2014 on the list of hottest years on record is rising.

Why?

In general, as NOAA states in their latest Global Analysis, "El Niño conditions tend to enhance global temperatures, with stronger events having generally larger impacts."

El Niño 2015 is turning into a fairly rare one. Whereas a typical El Niño develops throughout the spring, summer and fall, peaks in early winter and then dissipates early the following year, this one developed much earlier.

Even in 2014, as the ocean and atmosphere patterns "struggled" to line up, model projections were warning of a possible "super" El Niño, like the one seen in 1997/98. Now, with a weak Central Pacific El Niño (aka El Niño "Modoki") called in March, and the pattern strengthening and pushing towards the east, there's the potential for this one to both peak in the summer and persist into early 2016.

The only El Niño on record that's similar is the one that occurred between 1986-1987.

The above graph, from SkepticalScience.com, shows "The Escalator" pattern of warming since 1970 (with the overall rising trend indicated in red). Very obvious in the data are three large "steps" in global temperatures - 1977-1978, 1986-1987 and 1997-1998, and two smaller ones - 2002-2003 and 2012-2013. These represent periods when temperatures spiked in a very short time, resulting in a new temperature plateau. Even though these plateaus persisted for some time after, and some even showed a slight cooling trend, they did not affect the overall warming trend. The next spike simply drove global temperatures to an even higher level.

Other than the final step (in 2012-13), each of others occurred during an El Niño - the '76-'77 and '77-'78 weak El Niños, the '86-'87 strong El Niño, the '97-'98 "super" El Niño (which drove 1998 to the top of the list of warmest years on record, where it stayed until 2005) and the moderate '02-'03 El Niño. Even in 2012, Pacific Ocean temperatures indicated a potential El Niño, however the pattern peaked in the fall, just shy of reaching El Niño status.

The '86-'87 "step," which went up by about 0.15oC (32.27oF), is the one that's of greatest interest here, though, as the strong and unusual El Niño that developed that year is the closest "analogue" pattern to what we're seeing so far in 2015.



Global Temp Anomalies for April 1986 and April 2015. Credit: NASA GISS

As shown in the graphics above, global temperatures are already much warmer now than they were in 1986, when that "analogous" El Niño was developing.

If this year develops along the same lines, with a strong El Niño peaking this summer and persisting throughout the year, pumping a large amount of heat into the atmosphere, we could be in the middle of the next "step up" to a new, warmer plateau for the globe.

Sources: NOAA | SkepticalScience.com | NASA GISS | Golden Gate Weather Services

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