dpa | The world’s oceans could be heading toward new heat records. “The development resembles the situation in spring 2023, when global sea temperatures began to surpass the highs of earlier years by an ever-widening margin,” said Helge Gößling, a climate physicist at the Alfred Wegener Institute (AWI) in Bremerhaven, to the German Press Agency.
“Currently the temperatures are already noticeably above the values of 2023 and on par with the previous records of 2024, which were associated with the El Niño event of 2023/24.”
According to data from the Climate Reanalyzer platform, the global mean surface temperature in March and April already on several days exceeded the high values from 2024. The University of Maine platform has been recording daily global and regional values for about four decades, relying in part on satellite measurements.
Influence of El Niño has so far played little role
Similar to spring 2023, the emerging natural climate phenomenon El Niño is currently not yet having a clear influence on global temperatures, Gößling explained. The spatial patterns, however, differed from those three years ago: the North Pacific is affected much more strongly, the North Atlantic shows no extraordinary heat anomalies. “That was different in 2023, when weak trade winds in the North Atlantic led to a lack of evaporative cooling.” The Pacific off the coast of California and Mexico is currently heating up particularly strongly.
It should also be noted that global warming has continued to progress over the past three years. “That the oceans overall staying above the long-term average is absolutely to be expected,” emphasized Gößling. The current development shows that the 2023/24 records were not an absolute outlier followed by a supposed warming pause. “Rather, we are on a steady warming path for the foreseeable future.”
Total Temperature to Depth Continues to Rise
Mojib Latif of GEOMAR Helmholtz Centre for Ocean Research Kiel noted that, given fluctuations in sea surface temperature, one should not forget that the total temperature of the oceans in the course of the climate crisis is steadily reaching record levels. The seas have for decades acted as a massive heat reservoir: they absorb around 90 percent of the heat that accumulates due to the rise in greenhouse gases in the atmosphere, Latif explained.
This is expected to continue and will help temporarily buffer atmospheric temperatures, the climate scientist explained. In the long term, however, part of the heat will also be released again. This lag of the gigantic ocean heat store is a physical reason why warming beyond two degrees is hardly avoidable. Added to this is socio-economic inertia: global greenhouse gas emissions cannot be suddenly reduced to zero, but only over decades. Moreover, the long-lived gases already released will continue to have an effect.
Increasingly Severe El Niño Impacts
How rising ocean temperatures influence the frequency and strength of El Niño events is still unclear, Latif explained. But it is clear that El Niño effects are stronger in a warmer world. “There is more energy in the system, storms and rainfall are, on average, stronger.” This means not only more suffering, damage and problems in the regions directly affected by El Niño’s consequences. “Ultimately, it has global economic effects — for example through lost crops.”
Signs of an imminent strong El Niño are, according to the World Meteorological Organization (WMO), becoming more evident. The weather phenomenon occurs roughly every two to seven years and lasts about a year each time. During these phases, regionally more heat from the Pacific is released into the atmosphere, with altered weather patterns as a consequence. It can bring heavy rainfall in parts of Africa or South America, but also droughts in places like Australia or Indonesia.
Whether a strong El Niño event is currently developing cannot yet be said with certainty, Gößling said. “In the summer we should have a clearer view of whether an event will actually occur that brings new global records.”
