In the fall and winter of 2015/2016, the North Pacific experienced an incredible marine heatwave. Nicknamed "the Blob," this catastrophic event brought devastation, including the death of over 1 million birds and a huge loss to marine life. Researchers of a new study in Science now say the occurrence of these events is dramatically linked to the climate crisis.
The team from the University of Bern in Switzerland tracked marine heatwaves around the globe from September 1981 to December 2017 and found a 20 times increase in the occurrence of these heatwaves. The strongest heatwave used to happen once every hundreds to thousands of years, yet as we approach the fateful increase of 1.5°C (2.7°F) warming, heatwaves will begin to occur every 10 to 100 years.
The situation is even bleaker if the Paris Climate Agreement goal to keep the average global temperature increase below 2°C (3.6°F) above the pre-industrial average is not met. The team's models show that if we were to cross the 3°C (5.4°F) threshold, marine heatwaves (MHWs) would occur every few years if not annually.
“Our study highlights the strong human influence on the occurrence probabilities of all recent large and severe MHWs, and it illustrates the substantially reduced return periods these extreme heat events will have under further global warming,” wrote the researchers in the paper. “Recent MHWs have had severe impacts on marine ecosystems, and these systems have required a long time to recover in the aftermath – if they have recovered at all.”
The team suggests that a forecasting system could act as an early warning system. This could be used to protect ecosystems by putting preventative measures in place. One example they suggest is a drastic reduction in fishing pressure. However, this is only a minor fix and doesn’t stop the underlying cause. If the climate crisis is not addressed, marine ecosystems will be stressed beyond salvation and might end up irretrievably lost.
"To maintain the existence of resilient and productive marine ecosystems and to prevent many oceanic regions from reaching a continuous, severe heatwave state, global warming needs to be severely limited," they concluded.