The world's average temperature has reached a new high for the third time in a week, unofficial records show.
Data analysed by a group of US scientists shows the global average temperature on Thursday was 17.23C.
It breaks the 17.01C record set on Monday, surpassed just a day later when the average temperature reached 17.18C.
The temperatures are being driven by human-induced climate change and the naturally-occurring weather pattern known as El Niño, scientists say.
The El Niño Southern Oscillation, or ENSO as it is also called, is the most powerful fluctuation in the climate system anywhere on Earth. It happens every three to seven years, and in the warming phase, warmer waters come to the surface of the tropical Pacific and push heat into the atmosphere.
"Climate scientists aren't surprised about the global daily temperature record being broken, but we are very concerned," Friederike Otto, senior lecturer in climate science at Imperial College London, said.
It "should be a wake-up call for anyone who thinks the world needs more oil and gas," she added.
Before this week, the last time the record was broken was in August 2016.
Experts warn that many societies have not yet adapted to more extreme heat and the impacts it has on people and the environment.
The temperature readings come from a tool called Climate Reanalyzer. Scientists at the University of Maine use a combination of readings from surface, air balloon and satellite observations as well as computer modelling to assess average global temperatures.
The readings are not an official government record, but they are closely watched as an indicator of how temperatures are fluctuating.
On Thursday the US weather service National Oceanic and Atmospheric Administration (NOAA) said it could not confirm records that come partly from computer simulations, according to Associated Press.
"But we recognize that we are in a warm period due to climate change," NOAA said.
Scientists warn that it is uncommonly hot and it is likely the records will continue to be broken this summer.
"El Niño hasn't peaked yet and summer is still in full swing in the Northern Hemisphere, so it wouldn't be surprising if the daily temperature record is broken again and again in 2023," Dr Paulo Ceppi, lecturer in climate science at Imperial College London, said.
Higher global temperatures are likely to make heatwaves even hotter and wildfires more severe, he added.
Last month was the hottest June on record, the EU's climate monitoring service Copernicus said on Thursday.
In the UK, record-high June temperatures saw "unprecedented" fish deaths and threatened the survival of insects as plants they feed from wilted, warned environment groups.
A study by the UK Met Office concluded that climate change made the June heat more than twice as likely.
Scorching heat is continuing to hit parts of the world, with North Africa seeing temperatures of near 50C and parts of China suffering under 40C.
Southern Europe could see more than 60 days this summer when conditions are dangerous for humans, the European Environment Agency warned in June.
Higher-than-average heat also affects crops and raises the risk of wildfires.
Heat increases in seas have also been detected in recent weeks, including a marine heatwave in the UK and Ireland.
And Antarctic sea ice reached its lowest extent for June - 17% below average - since satellite observations began.
Governments globally are committed to reducing their carbon emissions to reach net zero - the point when humans will stop adding greenhouse gases to the atmosphere.
Global temperatures will only start to approximately stabilise once the world reaches net zero, Dr Ceppi explains, BBC reports.
