Alarm bells have been rung at the UN agency in particular because of an “unprecedented peak” in sea surface temperatures in the North Atlantic.

“The first week of July…could be considered as the warmest period or the warmest week ever recorded”, with a global average temperature close to 17.24 degrees Celsius on 7 July, said Omar Baddour, Chief of Climate Monitoring at WMO.

Unprecedented is new normal

The WMO expert added that daily June temperatures in the North Atlantic had been “dramatically high” compared to usual readings, while Antarctic sea ice levels reached their lowest extent for June since satellite observations began.

At a shocking 17 per cent below average, this year’s readings broke the June 2022 record by a substantial margin and represented “a really dramatic drop in the sea ice extent in the Antarctica” – some 2.6 million square kilometers of lost sea ice.

Michael Sparrow, Chief of WMO’s World Climate Research Programme, highlighted that “it really is completely unprecedented" seeing this kind of reduction in sea ice around the Antarctic.

“The Antarctic region is normally thought of being relatively stable; it is much colder than the Arctic. We’re used to seeing these big reductions in the sea ice in the Arctic, but not in the Antarctic.”

A marine heatwave

Beyond Antarctica, the UN agency warned that the “marine heatwave” would also impact fisheries distribution and ocean ecosystems, with knock-on effects on the climate.

It is not only the surface temperature of the water, but the whole ocean is becoming warmer and absorbing energy that will remain there for hundreds of years, explained WMO.

“When you have a tropical cyclone, everything is affected in the shores, including fisheries, but also including inland,” said Mr. Baddour. “With heavy precipitation that could lead to casualties, displacement of populations, and so on. So, if we say that it is a dramatic change, that also means a dramatic likelihood of extreme weather and climate events.”

El Niño effect

Just last week, WMO announced the onset of El Niño, characterized by a warming of the Pacific Ocean. Combined with the human-induced greenhouse gas effect, the weather pattern is expected to make one of the next five years the warmest on record.

The WMO officials told journalists in Geneva that “we are in uncharted territory, and we can expect more records to fall as El Niño develops further”, with impacts extending into 2024.

“During an El Niño year, you get higher temperatures in the atmosphere as well because heat is moving from the oceans to the atmosphere,” said Mr. Sparrow.

“We are actually at the beginning of that process, so El Niño hasn’t had as much of an effect as it is going to later in the year. So, we’re seeing these high temperatures in the North Atlantic…despite the fact that El Niño hasn’t really got going yet.”

According to the WMO’s Mr. Baddour, the warmest year is expected to be post-2023, when El Niño is expected to pick up. A record year in 2024 is likely, if the strength of El Niño continues to develop in line with forecasts.