Above: Departures from average temperature (degrees C) over land and ocean areas during April 2020. Parts of northern Europe and Asia were more than 5°C (9°F) above average, while much of central and eastern Canada and the United States were 2–4°C (4–7°F) below average. (NOAA/NCEI)
Last month ended up as one of the two warmest Aprils in global recordkeeping that goes back to 1880, according to the agencies that monitor world temperature. In its monthly global climate summary released Wednesday, NOAA placed April 2016 as the warmer of the two, with the global average temperature just 0.07°C above April 2010. Meanwhile, NASA rated April 2020 as 0.04°C warmer than April 2016, and Europe’s Copernicus Climate Change Service had the two months in close to a dead heat, with April 2016 the warmer of the two by just 0.01°C.
Such differences in rank order emerge largely from variations in how the different agencies account for data-sparse areas, such as the Arctic.
Pushing the month into top-tier status for global warmth were high temperatures throughout many of the world’s oceans, as well as intense heat for mid-spring across much of Eurasia. As we discussed in a post last week, Kyrgyzstan, China, and Mongolia each set all-time record-high temperatures for April. Readings as high as 110°F were observed in China at latitudes comparable to the northern United States, and wildfires ripped across much of eastern Siberia.
Another center of intense heat was across the southern Gulf of Mexico and adjoining land areas. Cuba had its hottest April on record by far, with the monthly temperature 2.8°C (5.0°F) above average—a huge margin for a monthly average across a large tropical island. Miami also had its hottest April by far, running 3.4°C (6.1°F) above average. Even more astounding, dozens of locations across Cuba saw their hottest temperatures on record not just for April but for any month of the year (see the full list at Dr. Jeff Masters’ global roundup). Among these cities was Havana, the capital of Cuba, which hit its highest-ever reading of 38.5°C (101.3°F) on April 12. That same day brought a new all-time national high for Cuba of 39.7°C (103.5°F), set at Veguitas; it was the third time in three days that the nation topped its previous all-time high.
What are the odds that 2020 will be the warmest year on record?
The year as a whole (January-April) is running just behind 2016 as the warmest on record globally, according to NCEI. One statistical tool maintained by the center, the Global Annual Temperature Rankings Outlook, is projecting a 69% chance that 2020 will end up as the warmest year in the global database, slightly down from the 75% chance projected a month ago. NASA's numbers are similar (see tweet from Gavin Schmidt below).
There is much higher confidence—greater than 99.9%—that 2020 will wind up among the warmest five years on record, according to NCEI. All five of those years to date have occurred since 2015.
One factor that made 2016 the warmest year in global recordkeeping was the record-strength El Niño event that peaked in late 2015 and early 2016. As it spreads warm water across the surface of the equatorial Pacific Ocean, El Niño can send vast amounts of stored oceanic heat into the atmosphere. Most of the recent record-warm spikes atop longer-term global warming from human-produced greenhouse gases have occurred during El Niño, so to get a January-to-April period this warm without El Niño in play is truly noteworthy.
By the same token, there’s an increasing chance that a new La Niña event will keep 2020 from matching or topping 2016. Sea surface temperatures across the Niño regions of the eastern tropical Pacific have dropped markedly over the past few days, and the net heat content in the upper part of the equatorial Pacific between the International Date Line and 100°W has dropped below average for this time of year. Given the recent trends in observations and seasonal models, it’s quite possible NOAA will raise the odds of an La Niña event in its monthly forecast to be issued on Thursday, May 15.
U.S. storminess dominates the global toll of billion-dollar disasters for 2020 thus far
For this year through April, the planet has seen a total of ten billion-dollar weather disasters, according to the April 2020 Catastrophe Report from insurance broker Aon. Six of those are related to severe weather in the United States, including two billion-dollar-plus severe weather episodes on April 6-9 and April 10-14.
The deadliest weather extreme on Planet Earth so far this year is flooding in East Africa associated with an unusually prolonged and extreme “long rains” season. The floods have taken at least 400 lives since March.
For more details on global heat and cold records for April and the year to date, see the in-depth post by Dr. Jeff Masters at his Eye of the Storm blog at ScientificAmerican.com.
