Our Record Warmth: Pointing out the Obvious
Our Record Warmth: Pointing out the Obvious
Well, this is the start of the next phase of my blogging life. I expect to do about a blog per month on Wunderground. At the risk of overcommitting, something alien to me, I also intend to revive the climatepolicy.org blog for the American Meteorological Society.
I have not been writing about our months of record warmth – one right after another. Many others have been doing an excellent job (Masters and Henson, 2015; Masters and Henson, 2016). Plus, I am taking the long view; it might look tedious in 20 years to have 240 more monthly blogs on record heat.
I have, however, been thinking about how to frame our string of record heat. Once again, a brief definition of El Niño. El Niño and La Niña are names given to recurring patterns of oceanic and atmospheric variations that are concentrated in the tropical Pacific Ocean. When there is an El Niño, the globe is warmer and when there is a La Niña, the globe is cooler. Starting in 2015, and extending into 2016, there was a strong El Niño. A La Niña often follows an El Niño; they are like the up and down portions of a wave.
If you take the warming trend associated with carbon dioxide warming and add the El Niño warmth, it is reasonable to expect record high global temperatures. If there were going to be a significant break in the record, the cooling related to La Niña would be a likely cause of such a break. Back in the late spring, the El Niño ended, and we went into an El Niño-neutral time. The streak of record warm months continued. We have been flirting with the ocean and atmosphere moving towards La Niña, and for a while a La Niña was predicted. If you read the current (September-October) summaries from the seasonal prediction centers listed below, they are, now, predicting El Niño-neutral conditions as the most likely pattern at year’s end. The take away message, the impact on global temperatures associated with El Niño and La Niña variability should be close to zero. Not too warm, not too cold.
I want to do a little bit of a comparison. To do that, I start with three figures of monthly averaged global temperature, expressed as percentile differences from the 20th-century average. These are for July 2016, August 2015, and August 2016.
Figure 1: July 2016 Blended Land and Sea Surface Temperature Percentiles. Differences from 20th-century average. Based on global temperature data from 1880 to current (137 years).
In my previous blog, I commented on the July 2016 observations (Figure 1). In particular, I noted that the blue areas, all at northern or southern extremes, were few and small. In a world without a strong warming trend, then we would expect the warm (reds) and cool (blues) areas to, more or less, balance. This is not the case. The warming trend, which increases the average global temperature is now large enough that regions cooler than average are rare. This figure for July 2016 is a month where we are El Niño-neutral, flirting perhaps with a weak La Niña. That is, during the summer of 2016, the variability associated with the El Niño and La Niña cycle is tending more towards cooler. Given that fact, and the temperature observations, global warming is, in fact, moving to be a dominant factor in our weather.
Now look at August 2015 compared with August 2016.
Figure 2: August 2015 Blended Land and Sea Surface Temperature Percentiles. Differences from 20th-century average. Based on global temperature data from 1880 to current (136 years).
Figure 3: August 2016 Blended Land and Sea Surface Temperature Percentiles. Differences from 20th-century average. Based on global temperature data from 1880 to current (137 years).
In 2016, the areas of “much cooler than average” are smaller than in 2015. August 2015 variability is in the realm of El Niño, which is typified, especially, by the bright red of the equatorial Pacific Ocean. August 2016 is in the realm of La Niña, which is typified by the cool areas in the equatorial Pacific Ocean. In this case, however, the cool, blue, areas are quite small. There are also large differences between the two years in the Indian Ocean. When the temperatures are all added up and averaged, 2016 is warmer than 2015. The strength of the 2015 El Niño and the presence of the 2016 weak La Niña temperature structure, and the fact that August 2016 is warmer, suggest that we are at the start of a time of accelerating temperature increase.
I introduce one more figure, which is one of my favorites. I like this figure because it separates out the El Niño and La Niña cycle, which is the largest source of global variability on a year-to-year basis. The figure reveals trends in concert with the variability. It highlights the extraordinary scale of the 1997-98 El Niño, the only year of similar warmth to all of the years since 2002.
Annual Global Temperature Anomalies 1950-2015 (for 2015, January to October)
Figure 4: Global annual average temperatures anomalies (relative to 1961-1990) based on an average of three global temperature data sets (HadCRUT.18.104.22.168, GISTEMP and NOAAGlobalTemp) from 1950 to 2014. The 2015 average is based on data from January to October. Bars are colored according to whether the year was classified as an El Niño year (red), a La Niña year (blue) or an ENSO-neutral year (grey). Note uncertainty ranges are not shown, but are around 0.1°C. Source: WMO, Press Release N° 13, 25 November 2015
If you take this figure and place a line on the top of the La Niña years since 1980 (Figure 5), the direction appears, without benefit of statistical analysis, to be less variable than, for example, a similar line connecting the El Niño years. It is like the La Niña years let us see the background warming of the planet. For better or worse, that La Niña trend line suggests that the cool time of this cycle will be comparable to the 1997-98 El Niño. Again, with regard to the warming of the Earth, we have not only left the proverbial station, but we are out in the country on open track, accelerating to full speed.
Figure 5: Same as Figure 4, but with red trend arrow inserted by author.
Looking at the next few months, I will be interested in seeing how the El Niño and La Niña cycle plays out. Curious about the drought in California. Right now, however, it looks as if the Earth has warmed to the point that what is a cool phase today is comparable to what was an extraordinarily warm event less than 20 years ago. And beyond that, I really don’t have a pithy conclusion.
Forecast and Analysis Centers
Climate Prediction Center Alert System and the Climate Prediction Center Diagnostic Discussion
International Research Institute Forecast Products and the Quick Look
Japanese Meteorological Agency El Niño Monitoring and Outlook and a nice graph of historical events
Australian Bureau of Meteorology Wrapup
CLIVAR (Variability and predictability of the ocean-atmosphere system) Forecast Page
World Meteorological Updates
Pacific Marine Environmental Laboratory El Niño Theme Page Forecasts
Climate Prediction Center FAQ
NOAA’s El Niño Page and NOAA’s La Niña Page
Summaries in Blogs
NOAA’s ENSO Blog
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I'm a professor at U Michigan and lead a course on climate change problem solving. These articles often come from and contribute to the course.
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