The world is breaching a key warming threshold at a rate that has scientists concerned, a analysis has found.

The average global temperature in 2023 was at least 1.5C higher than pre-industrial levels on about a third of days.

Keeping below that marker long-term is widely considered crucial for avoiding climate change’s most damaging impacts.

Nevertheless, 2023 is on track to be the hottest year on record, and 2024 could even be hotter.

“It’s an indication that we’re reaching levels we haven’t reached before,” says Dr Melissa Lazenby.

Global temperatures recorded in September and extreme weather events dominated much of the summer have contributed to this latest finding.

Political leaders signed an agreement in Paris in December 2015 to maintain global temperatures “well below” 2C for this century, and to make every effort to keep them below 1.5C.

Global average temperatures are quoted as differing from what they were during the pre-industrial era, between 1850 and 1900, prior to the widespread use of fossil fuels.

The Paris thresholds cannot be exceeded for one day or one week, but rather over a period of 20 or 30 years.

A long-term average warming figure of 1.1C to 1.2C is currently recorded.

In the long run, however, the more often 1.5C is breached for individual days, the closer the world gets to breaking it.

In December 2015, when politicians were signing the deal on 1.5C threshold, this happened for a few days for the first time in modern history.

Several times since then, the limit has been broken, typically for short periods of time.

Around 75 days exceeded that mark in 2016, influenced by a strong El Nio event – a natural climate shift that raises global temperatures.