The global sea surface temperatures for both April and May were the highest on record for those calendar months in a series stretching back to 1850, according to the UK’s Met Office.
With the expected continued warming of the eastern tropical Pacific because of the emerging El Niño, it is likely that global sea surface temperatures will challenge more records this year.
The temperature in the North Atlantic in May was the highest on record for the month since 1850, with temperatures around 1.25°C above the average over the reference period of 1961 to 1990.
Professor Albert Klein Tank, head of the Met Office Hadley Centre, said, “Typically, airborne dust from the Sahara helps to cool this region by blocking and reflecting some of the sun’s energy; but weaker than average winds have reduced the extent of dust in the region’s atmosphere potentially leading to higher temperatures. Additionally, lighter-than-usual trade winds could be playing a role.
“All of these elements are part of natural variation within the climate system which are coming together to elevate sea surface temperatures to higher levels. It is not believed that these factors represent a climate-change-induced tipping point that produces runaway temperatures. However, they will add to climate and weather impacts this year.”
Climate scientists are also reviewing several other factors including: the warm phase of the Atlantic Multi-decadal Oscillation since 2020; reduced emissions from shipping; and a persistent weather pattern with easterly winds from the continent warming the sea surface.
What impacts will stem from elevated Atlantic sea surface temperatures? The eastern tropical Atlantic is the principal spawning ground for North Atlantic hurricanes. Meteorological records show that during periods influenced by El Niño that the development of hurricanes is suppressed in the north Atlantic because wind shear – winds crossing at different heights – tend to blow fledgling hurricanes apart. However, forecasters have had to take into account the rise in sea surface temperature as tropical cyclones derive their energy from warmer waters. The forecast this year from the Met Office suggests an above average season for the number of tropical storms and cyclones in the North Atlantic basin.
Julian Heming, a tropical cyclone expert with the Met Office, said, “We are getting indications from models of an Atlantic tropical storm development east of the Caribbean by the middle of next week. This would be highly unusual in this area so early in the season. June storms normally form further west in the Caribbean or Gulf of Mexico. The high sea surface temperatures in the tropical Atlantic would likely be one of the main factors if this development did happen next week.”