Climate change - Ocean temperatures without daily records again for the first time
The oceans have set new heat records for over 15 months in a row - now, these constant record highs may finally come to an end. According to preliminary data from the US platform "Climate Reanalyzer," the global surface temperature has not exceeded the daily values of the previous year. It is expected that the global sea temperature in the second half of the year will be rather below the extreme records of 2023, explained Helge Goessling, climate physicist at the Alfred Wegener Institute (AWI) in Bremerhaven.
The oceans have been unusually warm since March of the previous year. Every single day since then, the ocean surfaces have shown the highest temperature since recording began approximately 40 years ago, often with a significant distance from the previous daily record. The temperature is still significantly above the average of 1982 to 2011.
Human-induced warming
The primary cause of the increase is believed to be human-induced greenhouse gases. Over 90 percent of the resulting warming effect is reportedly absorbed by the oceans. Even a change of just one tenth of a degree means the warming of enormous water masses.
Additionally, there have been other effects in addition to steady human-induced warming. For instance, El Nino has been pumping heat from the deep Pacific waters to the surface. "The influence of El Nino on the global mean temperature is becoming noticeably weaker," explained Goessling. The transition to its counterpart La Nina - also a natural, regularly occurring climate phenomenon - could lead to a decrease in the global temperature. "However, it is still unclear how much cooling we can actually expect."
Unanswered questions about temperature rise
The AWI researcher refers to analyses indicating that El Nino's influence on the records was not particularly large. Experts name other factors for the unusually strong fluctuations. These could include the reduction of sulfur emissions in shipping and the eruption of an underwater volcano.
"Overall, these contributions seem too small to explain the recent temperature rise," Goessling concluded. Wherever the rest comes from - the cause is crucial in the question of whether temperatures will continue to rise as expected or take a different path into the stratosphere.
The record value of daily ocean surface temperatures, surpassed nearly every day since March, was set approximately 40 years ago at the Alfred Wegener Institute (AWI) in Berlin. The maximum value of global sea temperature in 2023 was significantly high, influenced not only by human-induced warming but also by natural phenomena like El Niño. Despite El Niño's weakening influence and the upcoming shift to La Nina, it remains uncertain how much cooling will occur. The International scientific community continues to explore unanswered questions about the temperature rise, as factors such as sulfur emissions reduction and underwater volcanic eruptions may contribute, yet not sufficiently to explain the recent temperature rise. Helge Goeßling, a climate physicist at AWI in Bremerhaven, emphasizes the importance of further research to determine the cause and predict future climate trends.
