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“The recent run of 11 consecutive record global average temperatures is hard to comprehend,” said Michael Rawlins at the Climate System Research Center at the University of Massachusetts Amherst. “It means that we may not fully understand how the various factors are contributing to the sharp uptick in heat in recent years.”
With May’s data now on the books, this year could out rank 2023 as the hottest year ever on Earth since global records began in 1850. Specifically, May 2023 ended up being the third warmest for that month.
But now global year-to-date temperatures for 2024 are currently outpacing 2023’s unprecedented year.
Last year was 1.18 C (2.12 F) above the 20th-century temperature average of 13.9 C (57 F) and 2.43 degrees F warmer than pre-industrial (1850 to 1900) levels. The year 2023 was also 0.27 F warmer than the previous record set in 2016, according to NOAA data.
In fact, scientists said, the 10 warmest years in the 174-year record have all occurred during the last decade, 2014–2023. Both 2015 and 2016 experienced record global monthly temperatures, in which 15 consecutive months set record feats.
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“These records just keep on breaking each month, with no sign of slowing down,” said Jared Rennie, research meteorologist with NOAA’s National Centers for Environmental Information (NCEI). “Right now, there’s a 61% chance 2024 will be the warmest year on record, and it’s all but certain it will be a Top 5 year.”
The May breakdown
You can see in the chart below May 2024′s readings compared to the previous Top 3 record-setting warm years of 2020 (blue), 2016 (yellow), and 2023 (red) — with the 1991-2020 average represented by the gray dashes.
Human-caused climate change paired with an aggressive El Niño climate pattern earlier this year have been major drivers behind this warming streak, according to climate scientists.
How does New England stack up?
Temperatures have been pacing well above average since the start of the year across New England.
“Looks like spring will be a Top 5 warmest spring on record for New England,” Rawlins said, “and year to date we’re seeing one of the warmest years on record — currently ranking 2nd warmest at Hartford and 3rd warmest at Worcester.”
There will also likely be a few Top 5 or 10 finishes for ‘warmest May on record’ for Boston and other locations as well, based on NOAA’s historical data (dating back 174 years).
Most notably, the recent surge of warm weather has pushed May average temperatures 1 to 6 degrees above normal across parts of New England.
Here’s a look at some of the temperature differences for May in various cities:
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- Boston — +1.2 degrees
- Providence — +0.6 degrees
- Worcester — +3.9 degrees
- Springfield — +4.1 degrees
- Hartford — +5.5 degrees
- Concord, N.H. — +3.5 degrees
- Portland, Maine — +1.2 degrees
- Manchester, N.H. — +3.6 degrees
- Burlington, Vt. — +5.2 degrees
Monthly global temperature departures (essentially how far away temperatures are registering from the norm) have averaged 0.1 to 0.15 C above previous record-setting years in 2016, 2020, and 2023 — with May being the warmest by the widest margin of around 0.20 C.
How does June look?
La Niña will further develop in June with the upwelling of cooler water across the equatorial Pacific Ocean’s surface. These cooler sea surface temperatures typically help cool the Earth’s atmosphere and this can possibly neutralize the streak of excessive global air temperatures.
“I think June is more likely than not at this point to also be the warmest June on record, though it’s far from certain,” Hausfather said.
Air temperatures this high right before summer have never been seen in the Northern Hemisphere. Usually, La Niña gradually brings down global air temperatures — which means the streak of record territory may have to wait until mid- to late-summer to ease up. That’s when La Ninã is set to fully take hold.
“The influence of a transition from El Nino to La Nina typically has a lagged influence on global average temperatures,” Rawlins said. “In fact, the anomalous heat usually emerges toward the end of the El Nino, not at the beginning like it did last year.”
The United States, however, may continue its warming trend. “Looking forward into the summer, a good chunk of the US will experience warmer-than-normal temperatures ... especially out west,” Rennie said.
New England, and the rest of the country, looks to start June above average.
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There remains some hope that temperatures may taper as La Nina strengthens, although aggressive climate change may negate La Nina’s contribution to curb Earth’s warming atmosphere.
Warming ocean temperatures continue to break records, too
It’s not just air temperatures setting monthly records — sea surface temperatures around the globe have also been setting monthly records, marking May 2024 as the warmest on record, pushing the streak of record-setting monthly highs to 14 consecutive months. Also, daily sea surface temperatures away from the poles continue to set record daily highs dating back to March 8, 2023.
Rising ocean temperatures are a critical barometer for a host of climate concerns, among them hurricanes. The warmer waters in the Atlantic can lead to a more intense hurricane season, which starts on Saturday and lasts through November. Such intense ocean temperatures can lead to more hurricane activity. Warm ocean temps directly supply energy to storms, with frequency, strength, and duration determined by the available warm water.
Ken Mahan can be reached at ken.mahan@globe.com. Follow him on Instagram @kenmahantheweatherman.
