Hottest day ever recorded as northern hemisphere swelters and sea ice melts

Monday marked the world’s hottest-recorded day.

The average global temperature breached 17 degrees for the first time since records began in the 1800s.

The record eclipses the previous high average daily temperature of 16.92°C in August 2016, during the last El Niño period declared by nations in both the western and eastern Pacific Ocean.

The WMO yesterday confirmed El Niño was underway, joining the US-based NOAA forecast, although Australia’s Bureau of Meteorology remains at ‘El Niño Alert.’

The record hot day peaked at 17.01°C according to data from the National Centers for Environmental Prediction, a branch of NOAA.

At the same time, data from the European Union’s Copernicus Climate Change Service indicated the first days of June exceeded 1.5°C higher than pre-industrial temperatures. 1.5°C is the aspirational target laid out in the Paris Climate Agreement from 2015.

These threshold breaches come amid temperature records tumbling across parts of the northern hemisphere.

This June was the hottest on record for the UK, described by the nation’s Met Office as a “Fingerprint of climate change”. The average mean temperature was 15.8°C – nearly a full degree hotter than the previous record of 14.9°C recorded in 1940 and 1976.

Depending on how quickly carbon emissions are brought down by governments, the UK could exceed the previous average high, “every other year” by 2050, according to the Met Office’s climate extremes chief meteorologist Paul Davies.

Alarm at the other end of the globe

In Antarctica, a persistent and concerning trend of record-low sea ice has scientists urgently searching for answers.

On February 21, Antarctic sea ice hit its record low – at least since the start of satellite records in 1979. Sea ice decline has accelerated since 2016. But the reasons for this are not clear.

This trend comes on the back of 2022’s record minimum levels, which are on track to be lower again in 2023.

Image 1
On this NSIDC chart, 2022’s record Antarctic sea ice extent is indicated by the dotted red line. 2023’s current sea ice extent – including record lows in February – is indicated by the solid blue line. Credit: National Snow and Ice Data Centre, University of Boulder Colorado.

While the reasons for the sudden drop in sea ice extent are not fully understood, increased global temperatures will play a part.

“Sea ice is affected by the ocean, but it’s also affected by the atmosphere,” says Dr Ariaan Purich, a climate scientist specialising in Antarctic research from Monash University.

Purich points out that for more than three decades of satellite records, Antarctic sea ice remained relatively stable, while Arctic ice coverage has witnessed a downward trend.

The reason for this stability, she says, “was linked with changing winds in particular”, but also other processes.

“And then in 2016 sea ice declined really dramatically, and has been low since. It’s incredibly low at the moment. I guess the question is: has the warming caught up with these dynamic processes?

“Changes in winds have been leading to this increase [in ice] previously, but ultimately you get to some kind of temperature threshold where the winds can no longer offset the temperature increase.”

Purich says while Antarctic researchers like herself don’t fully understand potential changes in the dynamic processes at play in south polar regions, there is an expectation that if atmospheric and ocean temperatures continue to increase, a decline in sea ice should be expected.

“Couldn’t be more timely”: new data record shows marked decline in sea ice

The knock-on effects of this continuing downward trend in sea ice would likely be severe locally and globally: not only removing crucial habitat for marine life, and slowing ocean circulation but also reducing the bright, reflective shield Antarctica provides to reduce the ocean’s heat absorption.

“That’s going to be a positive feedback. The ocean Is going to warm faster because there’s less sea ice.”

Warnings of El Niño for Australia

A recent report by Australia’s Climate Council – an independent not-for-profit advocating for climate policy – warns that record sea surface temperatures, sea ice reduction in the north and south of the planet and slowing ocean currents puts the planet on track for a record hot year.

June saw temperatures well above average in parts of Australia’s north – in places like Longreach and Charleville temperatures were five degrees above the average. Queensland’s June temperatures were the highest on average, while swathes of the state broke records.

Southern parts of Western Australia, on the other hand, saw their lowest recorded June, according to reports.

Parts of Queensland experienced record June temperatures and higher June temperatures on average. Credit: Bureau of Meteorology.

While Australia’s weather bureau is yet to declare El Niño, Climate Council research director Dr Simon Bradshaw is concerned the trends overseas will be experienced in Australia once the southern hemisphere summer rolls around.

“We have indeed seen a harrowing run of extreme weather through the northern hemisphere summer, and we’ve obviously been watching closely and with very heavy hearts the fire season in Canada and the extreme heatwaves across South and Southeast Asia,” Bradshaw says.

“It really does highlight the very real, very human, very brutal impact of climate change and the prospect of an El Niño event and more severe heat waves [in Australia] is certainly something we’re concerned about.

“Everything we do to drive down emissions, every tonne of carbon left in the ground, is reducing the severity of these extremes that we would see in the future.”

Subscribe to ultramarine from riaus

Do you care about the oceans? Are you interested in scientific developments that affect them? Then our new email newsletter Ultramarine, launching soon, is for you. Click here to become an inaugural subscriber.

Please login to favourite this article.