Scientists have expressed concerns about the implications for the rest of the world after a heatwave in Russia's Siberia region.
On Saturday, the thermometer hit a likely record of 38C – or 100.4 degrees Fahrenheit – in the Siberian town of Verkhoyansk in Russia's Sakha Republic.
The World Meteorological Organisation said it is looking to verify the temperature reading, which would be a record for the region north of the Arctic Circle.
The increasing temperatures in Siberia have been linked to wildfires that grow bigger and more severe every year, as well as the thawing of the permafrost.
Pictures of the week: June 21 - 27
Pictures of the week: June 21 - 27
Liverpool fan Dillon Parry waves a flag outside Anfield in Liverpool. (Photo by Martin Rickett/PA Images via Getty Images)
A man clears rubbish left by beachgoers in Brighton as thunderstorms and torrential rain are forecast to sweep across the UK, bringing an end to a week of blazing sunshine and scorching temperatures.
A man jumps into a disused dock in East London as Thursday could be the UK's hottest day of the year with scorching temperatures forecast to rise even further.
Sunbathers at Richmond Bridge, London, as Thursday could be the UK's hottest day of the year with scorching temperatures forecast to rise even further.
A man wearing a face mask seen with his children at the beach on the hottest day of the year.
People head to the beach at the popular seaside resort of Skegness as England records it's hottest day of the year with temperatures at 30 degrees Celsius. (Photo by Keith Mayhew / SOPA Images/Sipa USA)
Protesters singing songs during the demonstration.
Protesters from the �Africans in the Diaspora� gather outside Christie's to demand the return of African Artifacts. Europe's museums are fighting to keep Africa's artifacts as pressure mounts from campaigners. (Photo by Thabo Jaiyesimi / SOPA Images/Sipa USA)
People play in the River Cam in Grantchester near Cambridge as Thursday could be the UK's hottest day of the year with scorching temperatures forecast to rise even further.
People in Clapham Common, south London as Thursday could be the UK's hottest day of the year with scorching temperatures forecast to rise even further.
Crowds gather on the beach in Bournemouth as Thursday could be the UK's hottest day of the year with scorching temperatures forecast to rise even further.
RICKMANSWORTH, ENGLAND - JUNE 25: Amateur Annabell Fuller hits her second shot on the 1st hole during The Rose Ladies Series at Moor Park Golf Club on June 25, 2020 in Rickmansworth, England. (Photo by Richard Heathcote/Getty Images)
Andy Meldrum, owner of the Glencoe Mountain Resort, skis on some of the remaining snow patches on the slopes of Meall a'Bhuiridh in Glencoe as Thursday could be the UK's hottest day of the year with scorching temperatures forecast to rise even further.
Cows use the River Thames to cool off in Bourne End, Bucks, as Thursday could be the UK's hottest day of the year with scorching temperatures forecast to rise even further.
LONDON, ENGLAND - JUNE 25: Kyle Edmund (R) and James Ward both leave the ball for each other during their doubles match against Joe Salisbury and Jonny O'Mara on day 3 of Schroders Battle of the Brits at the National Tennis Centre on June 25, 2020 in London, England. (Photo by Clive Brunskill/Getty Images for Battle Of The Brits)
A pair of women wearing face masks turn onto Old Quebec Street from Oxford Street in London, England, on June 23, 2020. British Prime Minister Boris Johnson announced today that the next stage of lockdown easing in England would proceed on schedule, with pubs, restaurants, hotels, hairdressers, theatres, cinemas, museums, galleries, libraries, theme parks and zoos allowed to reopen from July 4. The two-metre social distancing rule is also to be halved from the same date, with people encouraged to take additional mitigation actions, such as wearing face coverings, when close together. The change, to what is being dubbed 'one-metre plus', is seen as key to the survival of the hospitality sector. (Photo by David Cliff/NurPhoto via Getty Images)
A homeless man sleeps on Cranbourn Street in London, England, on June 23, 2020. British Prime Minister Boris Johnson announced today that the next stage of lockdown easing in England would proceed on schedule, with pubs, restaurants, hotels, hairdressers, theatres, cinemas, museums, galleries, libraries, theme parks and zoos allowed to reopen from July 4. The two-metre social distancing rule is also to be halved from the same date, with people encouraged to take additional mitigation actions, such as wearing face coverings, when close together. The change, to what is being dubbed 'one-metre plus', is seen as key to the survival of the hospitality sector. (Photo by David Cliff/NurPhoto via Getty Images)
The RAF Voyager used by the Prime Minister and the royal family taxies along the runway at Cambridge airport where it has been repainted in the colours of the Union flag at a cost of almost £1 million. (Photo by Stefan Rousseau/PA Images via Getty Images)
PERMISSION GIVEN A couple relax outside their beach hut on the beach in Bournemouth, Dorset, as Britain is braced for a June heatwave with temperatures set to climb into the mid-30s this week. (Photo by Andrew Matthews/PA Images via Getty Images)
View of a field of poppies in the summer sunshine. (Photo by Keith Mayhew / SOPA Images/Sipa USA)
People sit in prayer in the nave of Worcester Cathedral in Worcester, Worcestershire, as it opens for the first time since the UK entered lockdown to reduce the spread of coronavirus.
Equestrian statue of the Duke of Cambridge in Whitehall is being cleaned after it was graffitied with a slogan BLM. Clean up of historical statues after fourth consecutive week of Black Lives Matter protests in London. (Photo by Thabo Jaiyesimi / SOPA Images/Sipa USA)
Police officers congregate outside a cordoned off block of flats where the suspect of a multiple stabbing incident lived in Reading, west of London, on June 23, 2020. - British counter-terrorism police have been given until June 27 to question a suspect widely identified as Libyan Khairi Saadallah in an attack which saw three people stabbed to death in a park, officers said. (Photo by Ben STANSALL / AFP) (Photo by BEN STANSALL/AFP via Getty Images)
People visit the beach in Boscombe, as Britain is braced for a June heatwave as temperatures are set to climb into the mid-30s this week. (Photo by Andrew Matthews/PA Images via Getty Images)
BEVERLEY, ENGLAND - JUNE 23: Jockey Danny Tudhope riding Le Chiffre approach the finish line to win the William Hill Lengthen #yourodds Handicap (Div I) at Beverley Racecourse on June 23, 2020 in Beverley, England. (Photo by Hannah Ali/Pool via Getty Images)
Twilight at dawn at New Brighton lighthouse during low tide on the River Mersey ahead of the chance that Britain could bask in the hottest day of the year so far this week. (Photo by Peter Byrne/PA Images via Getty Images)
The Statue Robert Clive is boarded up following vandalism from previous demonstration in the City. Clive, the 1st Baron Clive better know as Clive of India, who established British rule in India stands outside the Foreign Office. Clive was first Governor of Bengal Presidency under the East India Company. Authorities boarded monuments and statues in London most due to their past linkage to slavery in anticipation of possible vandalism with far-right organisations and Black Lives Matter demonstration scheduled for this weekend. (Photo by David Mbiyu / SOPA Images/Sipa USA)
Black lives matter protester holds a placard during the demonstration.
Protests continue in London and elsewhere in the UK for the fourth consecutive week amid growing calls for reform in police forces. (Photo by Thabo Jaiyesimi / SOPA Images/Sipa USA)
People camp under a bivouac during showers next to a closed Stonehenge as people gather to celebrate the dawn of the longest day in the UK.
READING , June 21, 2020 -- A police officer stands behind a police cordon at an entrance to Forbury Gardens where stabbings took place in Reading, Britain, on June 21, 2020. Britain's counter-terrorism police said Sunday that the stabbing incident taking place in southern England's town of Reading on Saturday night "has now been declared a terrorist incident."(Photo by Tim Ireland/Xinhua via Getty) (Xinhua/ via Getty Images)
LIVERPOOL, ENGLAND - JUNE 21: Liverpool fan Emily Farley poses outside her home which is decorated in club flags, banners and paraphernalia before the Premier League match between Everton FC and Liverpool FC at Goodison Park on June 21, 2020 in Liverpool, United Kingdom. (Photo by Simon Stacpoole/Offside/Offside via Getty Images)
BLM demonstrators march through Oxford Street during the demonstration.
Black Lives Matter protests continue in The UK since the death of George Floyd at the hands of police officer in Minneapolis. (Photo by David Mbiyu / SOPA Images/Sipa USA)
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University of Michigan environmental school dean Jonathan Overpeck, a climate scientist, said: "The Arctic is figuratively and literally on fire – it's warming much faster than we thought it would in response to rising levels of carbon dioxide and other greenhouse gases in the atmosphere, and this warming is leading to a rapid meltdown and increase in wildfires.
"The record warming in Siberia is a warning sign of major proportions."
Much of Siberia had high temperatures this year that were beyond unseasonably warm.
From January through to May, the average temperature in north-central Siberia has been about 8C above average, according to the climate science non-profit organisation Berkeley Earth.
Berkeley Earth climate scientist Zeke Hausfather said: "That's much, much warmer than it's ever been over that region in that period of time."
Siberia is in the Guinness Book of World Records for its extreme temperatures. It is a place where the thermometer has swung by 106C (190 degrees Fahrenheit), from a low of minus 68C to 38C.
Such prolonged Siberian warmth has not been seen for thousands of years "and it is another sign that the Arctic amplifies global warming even more than we thought", Mr Overpeck said.
Russia's Arctic regions are among the fastest warming areas in the world.
Andrei Kiselyov, the lead scientist at the Moscow-based Voeikov Main Geophysical Observatory, said that the temperature on Earth over the past few decades has been growing, on average, by 0.18C every 10 years.
But in Russia it increases by 0.47C – and in the Russian Arctic, by 0.69C every decade.
"In that respect, we're ahead of the whole planet," Mr Kiselyov said.
Thawing permafrost is a huge problem in Siberia because buildings and pipelines are built on it. It also releases more heat-trapping gas and dries out the soil, which increases wildfires, according to Vladimir Romanovsky, who studies permafrost at the University of Alaska Fairbanks.
"In this case it's even more serious, because the previous winter was unusually warm," Mr Romanovsky said. The permafrost thaws, ice melts, the soil subsides and then it can trigger a feedback loop that worsens permafrost thawing, and "cold winters can't stop it".
A catastrophic oil spill from a collapsed storage tank last month near the Arctic city of Norilsk was partly blamed on melting permafrost.
In 2011, part of a residential building in Yakutsk, the biggest city in the Sakha Republic, collapsed due to thawing and subsidence of the ground.
Last August, more than four million hectares of forests in Siberia were on fire, according to Greenpeace.
Vladimir Chuprov, director of the project department at Greenpeace Russia, warned that this year the fires have already started raging much earlier than the usual start in July.
Katey Walter Anthony, a University of Alaska Fairbanks expert on methane release from frozen Arctic soil, said persistently warm weather, especially if coupled with wildfires, causes permafrost to thaw faster, which in turn exacerbates global warming by releasing large amounts of methane, a potent greenhouse gas 28 times stronger than carbon dioxide.
"Methane escaping from permafrost thaw sites enters the atmosphere and circulates around the globe," she said.
"Methane that originates in the Arctic does not stay in the Arctic. It has global ramifications."
What happens in the Arctic can even warp the weather in the United States and Europe.
Judah Cohen, a winter weather expert at Atmospheric Environmental Research, said that in the summer, the unusual warming lessens the temperature and pressure difference between the Arctic and lower latitudes where more people live.
That seems to weaken and sometimes even stall the jet stream, meaning weather systems such as those bringing extreme heat or rain can remain over places for days on end.
According to Russian meteorologists, a combination of factors – such as a high pressure system with a clear sky and the sun being very high, extremely long daylight hours and short warm nights – have contributed to the Siberian temperature spike.
Marina Makarova, chief meteorologist at Rosgidromet, said: "The ground surface heats up intensively. The nights are very warm, the air doesn't have time to cool and continues to heat up for several days."
She added that the temperature in Verkhoyansk remained unusually high from Friday through Monday.
Scientists agree that the spike is indicative of a much bigger global warming trend.
Freja Vamborg, senior scientist at the Copernicus Climate Change Service in the UK, said: "The key point is that the climate is changing and global temperatures are warming.
"We will be breaking more and more records as we go."