Extreme heat is the ocean’s ‘new normal’

More than half of world’s ocean annually exceeds extreme heat thresholds, compared to 2% at the turn of the 20th Century. 

Monterey Bay Aquarium has taken a leading role in a five year study first published in PLOS Climate. The results of which paint a worrying picture of how prevalent rising sea temperatures are across the planet. 

150 years of ocean surface temperatures were mapped for the study, allowing scientists to identify a fixed historical benchmark for marine heat extremes. 2014 was the first year in which more than half of the world’s oceans experienced extreme temperatures, and the trend has continued since then, peaking at 57% in 2019. Crucially, though, this is when research stopped, suggesting the problem is likely to have grown worse since then. 

This compares to just 2% of oceans being affected at the end of the 19th Century. Ecosystems vital for marine life to survive are directly threatened by extreme heat, including coral reefs, seagrass meadows, and kelp forests. It’s also important to note a number of these have a role to play in carbon reduction efforts needed to stabilise the climate crisis. As such, their destruction could negate current projections as to how much and the type of work this will involve. 

‘Climate change is not a future event. ‘The reality is that it’s been affecting us for a while. Our research shows that for the last seven years more than half of the ocean has experienced extreme heat,’ said Dr. Kyle Van Houtan, who headed the research team during while employed as chief scientist at Monterey Bay Aquarium. ‘These dramatic changes we’ve recorded in the ocean are yet another piece of evidence that should be a wake-up call to act on climate change… We are experiencing it now, and it is speeding up.’

Last year, Environment Journal published a feature written by Dr Carol Turley, Dr Phil Williamson and Professor Ric Williams, looking at climate extremes impacting oceans. 

Image credit: Photo by SGR