Global Ocean temperature reaches a new highs

Highest-ever global ocean temperature has been recorded in past July

12/20/20232 min read

According to statistics from the EU's climate change agency, Copernicus, the highest average ocean temperature ever recorded was attained at the end of July, raising worries about the health of coral reefs and other aquatic life throughout the world.

The worldwide average sea surface temperature (SST) hit 20.96°C, shattering the previous record of 20.95°C established in 2016. This is the highest reported average SST since records started.

Much life in the ocean is temperature dependent. As most fish are cold-blooded, they are capable of surviving within a limited range of species-specific temperatures. Changing water temperatures can have both a detrimental effect on the animals’ health, and also cause them to change the area of ocean which they inhabit.

A change in the distribution of predatory fish and their prey can have a knock-on effect on the species both above and below them in the aquatic food chain, which in turn may impact the presence of plankton and algal blooms, themselves both heavily influenced by local water temperatures.

Most commonly reported is the bleaching of coral reefs, during which a rise in temperatures causes the reef-building coral polyps to eject the zooxanthellae dinoflagellates (algae) that provide them with nutrients and also colour, exposing the white stony exoskeleton secreted by the corals beneath.

Coastal communities would be the hardest hit. Hundreds of thousands of jobs in the fishing industry would be lost almost overnight. It would take 25 years for fish stocks to recover. The cost of cleanup alone would be $20 billion.

For several months, unusually high temperatures have been recorded, including a recent marine heatwave in the North Atlantic that brought average ocean temperatures close to the previous record set in 2022, and water temperatures along the UK and Mediterranean coasts reaching more than 5°C above the seasonal average in some places.

The rise in SST corresponds with the start of the latest El Nino Southern Oscillation (ENSO), a recurring sea surface temperature rise in the eastern Pacific Ocean that is one of the most powerful influences on the global climate system.

This year's El Nino is the first in seven years, and while it is still in its early stages, some experts are concerned that this year's ocean warming may continue, given the greatest average world temperatures are often reported in March, after the southern hemisphere's summer.