Australia’s ocean temperatures are the warmest on record for this time of year.

Ocean temperatures around the world have been rising for weeks, and the Earth's mean sea surface temperature (SST) has been around 0.7℃ above the 1982-2011 average. 

According to preliminary satellite data from the National Oceanic and Atmospheric Administration (NOAA), the global mean ocean surface temperature peaked at 21.1℃ in early April, surpassing the previous record of 21.0℃ set in March 2016. The data covers the majority of the world's ice-free oceans.

The warmest waters compared to normal are currently off the west coast of South America, sitting about 5℃ above the April average. 

Waters surrounding Australia have also been warmer than usual off almost every coastline this year, at times 3℃ above normal. 

According to Bureau of Meteorology climate scientist Blair Trewin; “Sea surface temperatures for March were 0.66C above the 1961-1990 average, equal fourth warmest on record… but the only area where March was the highest on record was a small area off the Pilbara coast”.

The recent record-breaking temperatures continue the climate change-induced warming seen across the majority of Earth’s oceans during the past few decades. 

The joint Bureau of Meteorologist and CSIRO State of the Climate report in 2022 reported a 1.05℃ increase in SSTs in the Australian region since 1900, with eight of the 10 warmest years recorded since 2010. 

Dr Chris Chapman, an oceanographer from the CSIRO Environment research, says there is “clear and unambiguous evidence” of rising water temperatures, and almost the entire near-surface ocean will be affected by rising temperatures in the coming decades.

The possible emergence of El Niño in 2023 could boost ocean temperatures even further over the next year. 

According to the CSIRO, El Niño tends to increase globally averaged SSTs and raise sea-levels, a La Niña does the opposite. 

Dr Chapman said that while El-Niño, or La-Nina, might make warmer oceans temperatures more likely, it is a combination of factors such as the “flavour, strength, and timing” of the phase that help determine this rise. 

“Along with what else is going on in the climate system at the time, will all play a role in what eventually occurs,” Dr Chapman said.

The warming oceans could have a significant impact on marine ecosystems and the industries that rely on them. Fisheries could be affected, and rising sea levels could threaten coastal communities. 

Additionally, warmer waters could lead to more intense and frequent storms and hurricanes. 

While the Earth's average SST has dropped slightly in recent days, it is still 0.1℃ above the old April record, with further daily and monthly records possible in the near future.