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Sea surface temperatures soared to record levels globally between April 2023 and March 2024, surpassing the previous record by almost 0.25°C, intriguing scientists worldwide.
Ocean heat can have devastating long-term effects. (Representative image)
The record-breaking sea surface temperatures in 2023-24 were a one-in-512-year extreme event, which would not have been possible without global warming, according to a new study investigating the unusual event that caused intense marine heatwaves.
While ocean temperatures have been steadily rising over the years due to climate change, there was a stark and highly unusual jump from April 2023 to March 2024. During this period, the average sea surface temperatures—excluding the largely sea-ice-covered polar regions—surpassed the previous record from 2015–2016 by nearly 0.25°C.
This is particularly concerning because prolonged ocean heat can have devastating long-term effects. It not only triggers intense marine heatwaves, leading to mass die-offs of fish, birds, and marine mammals and accelerating coral bleaching—all of which have socioeconomic consequences—but also disrupts regional climate patterns. For instance, marine heatwaves in the Indian Ocean can influence monsoon winds and precipitation over India, affecting water and food security. Additionally, they can intensify tropical cyclones, making them more destructive.
This sudden increase in sea surface temperatures from April 2023 onwards, along with its unprecedented intensity, raised concerns among scientists about whether global warming might have accelerated. It also sparked worries over whether current climate models are capable of accurately simulating such record-breaking jumps in ocean temperatures.
Now, a team of researchers from the University of Bern, Switzerland, led by Jens Terhaar, has used observation-based statistical models to analyse the phenomenon. Their study, published in the peer-reviewed journal Nature found that the temperature spike was, in fact, a one-in-512-year extreme event under current long-term warming trends. Such a dramatic increase would have been virtually impossible without the ongoing impact of global warming and is likely driven by human-induced climate change.
Although “unlikely,” the researchers emphasised that this warming was not “entirely unexpected” when assessed using climate models. By analysing 270 simulations from a wide range of fully coupled climate models, they demonstrated that these models successfully capture such extreme jumps in global ocean temperatures and predict that they will eventually revert to the expected long-term warming trend. They reassured that current climate models remain fit for purpose.
This essentially means that global warming may not have accelerated unexpectedly, as initially feared, and that the observed spike still aligns with our current understanding of climate patterns.
According to current projections, temperatures are expected to revert to the long-term warming trend after such spikes, with this adjustment predicted to occur by September 2025. Since mid-July 2024, sea surface temperatures have remained warmer than in any year before the 2023 spike, though they are no longer “record-breaking”.
