Ocean warming in 2023 raises alarms for future climate extremes

Researchers have revealed the implications of record-high ocean temperatures observed in 2023

Dr. Till Kuhlbrodt led a study from the University of Reading, published this month in the Bulletin of the American Meteorological Society; warning that if global warming reaches 3.0°C above pre-industrial levels, the extreme ocean conditions witnessed last year could become the new normal.

2023 record high heats

The North Atlantic, in particular, experienced an extraordinary heatwave from March 2023 onwards, exceeding anything seen in the past four decades.

By August 2023, the North Atlantic was approximately 1.4°C warmer than the 1982-2011 average. Climate model projections indicate that last year’s extreme ocean conditions align closely with what scientists anticipate as the average scenario under 3°C of global warming.

Dr. Kuhlbrodt emphasises that the oceans are sounding an alarm and urges a deeper understanding of why specific regions are warming rapidly.

Earth’s energy imbalance

The study emphasises Earth’s energy imbalance as a key driver, with the planet currently absorbing over 1.9 watts per square meter more solar energy than it radiates back to space as heat.

This energy surplus, escalating rapidly in recent decades due to heat-trapping gases from human activities, has channelled more than 90% of the excess energy into the oceans.

Since 2016, the Atlantic Ocean has accelerated warming compared to other ocean basins in the top 100 meters.

Atlantic warming

A crucial aspect highlighted in the research is the potential link between the enhanced Atlantic warming and the record-low sea ice levels in the Southern Ocean. The study points to a significant decline in sea ice cover surrounding Antarctica in 2023, reaching the lowest extent since satellite monitoring began in the late 1970s.

“We urgently need to understand exactly why parts of the ocean are warming rapidly so we can prepare for more frequent weather disruption across the planet. How often we get hit by more of these extremes hangs on figuring out what’s driving the Atlantic and Southern Oceans into uncharted territory,” Dr. Kuhlbrodt stressed.

The researchers stress the importance of quantifying the impact of rapid Atlantic warming on sea ice cover. Accurately attributing oceanic and sea ice extremes is crucial for refining climate models, enabling them to predict future extremes more accurately. This, in time, will inform mitigation policies and resilience measures globally.