Warming pool in Pacific blamed on human activities

A long-term, increasingly warming pool of water in the northeast Pacific has been discovered by a team of researchers from the University of Hamburg. The pool measures three million square kilometres and results from increased anthropogenic greenhouse-gas emissions. This means that the warming pool is not the result of natural climatic variations – but of human influences instead.

“This warming pool will continue to increase the water temperature in the future, increasing both the frequency and intensity of local marine heatwaves,” says Dr. Armineh Barkhordarian an expert on atmospheric science.

“The sharp increase in average water temperature is pushing ecosystems to their limits.”

Barkhordarian says the long-term warming pool has promoted local marine heatwaves in the past. One of these gained notoriety as the deadly ‘Pacific Ocean Blob’, which had devastating consequences between 2014 and 2015: marine productivity faltered, toxic blooms formed, and seabirds and marine mammals died in droves. In addition, the event led to severe droughts on the west coast of the USA.

The most recent marine heatwave has continued for three years, from 2019 to 2021, producing water temperatures up to six degrees Celsius above average. Barkhordarian’s team says the probability of such a heatwave arising without human influences is less than one per cent; there is a 99 per cent probability that increased greenhouse-gas emissions were also required.

“More frequent and extreme marine heatwaves are a serious burden for affected ecosystems. This not only poses a tremendous threat to biodiversity; it can also push these marine ecosystems past a tipping point, after which they can no longer recover,” says Barkhordarian.

“The discovery of the long-term warming pool will now provide us with crucial information on the likelihood of such extreme events in the future.”