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Globe Just Experienced its Third Hottest April on Record

According to reports from NASA GISS, the world just experienced its third hottest April on record. Topping out at 0.86 degrees Celsius above NASA’s 20th Century baseline, April of 2018 edged out 2010 as third in the record books despite the ongoing natural variability based cooling influence of La Nina.

(Analysis of present global temperature anomalies with information provided by NASA, NOAA and Earth Nullschool.)

The warmest regions of the world included large sections of the lower Arctic — encompassing Eastern Siberia, the East Siberian Sea, and the Chukchi Sea. In addition, Central Europe experienced much warmer than normal conditions. Notable cool pools included North-Central North America, the High Arctic, and the Weddell Sea region of Antarctica.

A seasonal reinforcement of the Jet Stream helped to keep cold air sequestered in the High Arctic during April. However, this sequestration appears to be weaker compared to recent April-through-June periods as record warm spikes returned to the High Arctic during early May. The result of strong south-to-north heat transfer through various ridge zones in the Jet Stream.

(Third warmest April on record despite La Nina. Image source: NASA.)

La Nina remained the prominent natural variability related feature during April. And the cooling influence of La Nina has tamped global temperatures down a bit following the recent record hot year of 2016. Overall, it appears that global temperatures are on track to average between 1.04 C and 1.08 C above 1880s averages during 2018. These rather high excessions are, of course, caused by atmospheric greenhouse gasses peaking in the range of 410 ppm CO2 (around 491 ppm CO2e) during April, May and June. Representing the greatest concentration of heat trapping gasses on Earth in about 15 million years.

With La Nina fading, its cooling influence is likely to become less acute and global temperatures may again begin to ramp higher by mid to late 2018. NOAA has indicated a 50 percent chance for El Nino formation during late 2018. If 2018-2019 does see an El Nino emerge, global temperatures will likely again exceed the 1.15 C threshold and potentially challenge 1.2 C.

(A warm Kelvin Wave crossing beneath the Equatorial Pacific brings with it the potential for El Nino formation during 2018-2019. If El Nino does form, and with atmospheric greenhouse gas concentrations so high, it is likely that we would see temperatures comparable to the record global warmth of 2016 re-emerge. Image source: NOAA.)

However, it is unlikely that the weaker predicted El Nino, if it does emerge, will force temperatures considerably higher than levels achieved during the strong El Nino of 2016. For that, we will likely have to wait until the early 2020s. But with carbon emissions continuing near record high ranges, temperatures are bound to rise — with the 1.5 C threshold likely to be breached by the late 2020s or early 2030s.

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