This summer, a vast area of the eastern Atlantic Ocean has warmed and then cooled at an unprecedented rate, leaving scientists baffled.
The sea surface temperature in the eastern equatorial Atlantic reached its highest levels in February and March this year, exceeding 30 degrees Celsius. These were the warmest months recorded since 1982. By June, temperatures began to mysteriously drop sharply, reaching a low of 25 degrees Celsius by the end of July. Although this cold region is returning to normal temperatures, scientists remain puzzled about the cause of the sudden drop, as reported by Live Science on August 28.
The Atlantic Ocean near the Bahamas, captured from the International Space Station (ISS) in July 2024. (Photo: NASA/JSC).
The eastern equatorial Atlantic typically experiences cycles of cold and warm phases every few years, but the rate of decline from record highs to lows this time is truly unprecedented, according to Franz Tuchen, a postdoctoral researcher at the University of Miami.
Forecasts suggest that this cooling event could develop into an Atlantic Nina, a regional climate pattern that tends to increase rainfall in West Africa while decreasing rainfall in Northeast Brazil and surrounding countries in the Gulf of Guinea, such as Ghana, Nigeria, and Cameroon. This phenomenon is not as strong as the similar La Nina event in the Pacific and has not occurred since 2013.
Scientists will declare the emergence of an Atlantic Nina if colder temperatures persist below average for three months until the end of August. However, the cold waters have warmed in recent weeks, making it almost certain that it will not be classified as an Atlantic Nina, Tuchen stated.
Understanding the cause of this sudden temperature drop will enable scientists to gain deeper insights into the peculiarities of Earth’s climate, leading to more accurate weather predictions. Colder surface waters are often associated with stronger trade winds. Trade winds blow near the equator and are the most influential factor on Nina because they push warm surface waters away and allow colder, deeper waters to surface. However, this year’s cold region has been accompanied by weaker winds in the southeastern equatorial zone.
Michael McPhaden, a scientist at the National Oceanic and Atmospheric Administration (NOAA), noted that some unusual strong winds developed in the western cold area in May, which may have contributed to the record rapid temperature drop, but these winds did not strengthen to the same extent as the temperature drop. “Something else is going on,” McPhaden remarked.
Despite being unprecedented, the temperature drop in the eastern equatorial Atlantic is unlikely to be caused by human-induced climate change. “I cannot rule that out. But at first glance, this appears to be just natural variability in the climate system of the equatorial Atlantic region,” McPhaden stated.
Using data from satellites, buoys, and other meteorological instruments, climate scientists are closely monitoring this cold region and any potential impacts it may have on surrounding continents. This could take months to fully reveal. “We just need to observe and see what happens,” McPhaden concluded.
