Global ocean temperatures in 2023 point to a potential new normal if warming trends continue toward 3.0°C above pre-industrial levels. A recent scientific study reveals that the extraordinary conditions observed last year could become standard under sustained higher emissions.
Starting in March 2023, the North Atlantic recorded exceptionally high temperatures, surpassing levels seen over the previous four decades. By August 2023, the North Atlantic ran about 1.4°C warmer than the 1982-2011 average, marking a striking anomaly in regional heat content.
Model-based analyses indicate that last year’s oceanic extremes resemble what would be expected if global warming reached a 3°C increase over pre-industrial times, underscoring the close link between greenhouse gas emissions and ocean heat uptake.
Currently, global temperatures have risen roughly 1.2°C above pre-industrial levels, and the trajectory remains uncertain unless emissions are dramatically reduced.
New research published in the Bulletin of the American Meteorological Society investigates the drivers behind the record ocean temperatures observed in 2023.
Till Kuhlbrodt, of the University of Reading, led the study and commented that the extraordinary North Atlantic heat and the lack of sea ice in the Southern Ocean signal that the oceans are sending clear warnings. The researchers emphasize the need to understand why these regions are warming so rapidly and what factors are pushing the Atlantic and Southern Oceans into this unusual territory.
energy imbalance
The study highlights Earth’s energy imbalance as a major contributor to extreme ocean temperatures. The planet currently absorbs more solar energy than it emits, at a rate of about 1.9 watts per square meter, which becomes heat stored in the climate system.
This excess energy is immense, roughly equivalent to 300 times the Earth’s annual global electrical energy consumption when viewed over a single year.
The imbalance has intensified in recent years, driven largely by heat-trapping gases from human activities that trap and store heat within the atmosphere and oceans.
Oceans absorb almost all of the warming
As the energy surplus grows, the oceans take in most of the excess heat. More than 90% of the extra energy accumulated by the planet ends up in the ocean, driving long-term changes in marine environments.
Since 2016, the upper 100 meters of the Atlantic Ocean have warmed at a faster pace than any other basin, signaling a pronounced regional response to the global energy imbalance.
Researchers suggest that the additional warming in the Atlantic may be linked to a record decline in sea ice in the Southern Ocean. This rapid warming and ice loss contribute to broader sea level rise and shifts in global climate patterns.
The winter sea ice extent around Antarctica in 2023 reached the lowest levels recorded since satellite monitoring began in the 1970s, underscoring the rapid, interconnected changes occurring in polar regions.
Researchers stress the importance of measuring ocean temperature and sea ice with high accuracy to allow climate models to predict extreme events more reliably. Such measurements will support policy decisions aimed at mitigation and resilience on a global scale in the future.
Kuhlbrodt added that more Atlantic data are needed to conclusively link warming trends and ice melt to shifts in ocean currents, but the evidence points to hidden climate connections between the poles.
Reference work: 10.1175/BAMS-D-23-0209.1
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