Return of 'ancient heatwaves' could see average global temperatures soar 'at least 14C' by the end of the century, climate experts warn

[Matrix]

• Eocene saw temperatures reach up to 14°C higher than they are now, on average 
• Build up of carbon dioxide in the atmosphere is now artificially replicating this
• Will eradicate and temperature difference between the poles and other region 

The planet could be heading for soaring temperatures comparable to an incredibly warm period of ancient heatwaves 50 million years ago. 

Researchers say that during this period, temperatures were more than 14°C warmer than they are now, on average, and warn history could repeat itself. 

The build up of carbon dioxide in the atmosphere is artificially replicating what happened naturally during the Eocene and will see year-round scorching temperatures by 2100, researchers warn. 

It will also almost destroy any difference in temperature from the equatorial regions to the poles and the world swelters.  

Researchers at the University of Michigan and the University of Arizona used a state-of-the-art climate model to successfully simulate the Early Eocene Period. 

It is widely considered to be an analogue for Earth's future climate due to the release of CO2.  

The research, published in the journal Science Advances, found that the rate of warming increased dramatically as carbon dioxide levels rose.

The researchers put the warming down to an 'increased sensitivity' of the planet to the greenhouse gas. 

'We were surprised that the climate sensitivity increased as much as it did with increasing carbon dioxide levels,' said first author Jiang Zhu, a postdoctoral researcher at the University of Michigan.  

'It is a scary finding because it indicates that the temperature response to an increase in carbon dioxide in the future might be larger than the response to the same increase in CO2 now. This is not good news for us.'

Cloud formation as a result of carbon dioxide in the atmosphere is the root cause of the phenomenal increase in temperature, they reveal.  

Complex computer models and simulations reveal that in the Early Eocene, and likely in the near future, there is a reduction in cloud coverage and opacity that amplified CO2-induced warming.  

The Early Eocene (roughly 48 million to 56 million years ago) was the warmest period of the past 66 million years, since the mass extinction of the dinosaurs.   

Geological evidence suggests that atmospheric carbon dioxide levels reached 1,000 parts per million, more than twice the present-day level of 412 ppm.

Scientists are already predicting that if emissions are not stunted, this level of CO2 could once again be a reality.    

But the CESM1.2 model was able to simulate both the warm conditions and the low equator-to-pole temperature gradient seen in the geological records.

'For the first time, a climate model matches the geological evidence out of the box--that is, without deliberate tweaks made to the model. It's a breakthrough for our understanding of past warm climates,' Tierney said. 

WHY WAS EUROPE IN THE GRIP OF A HEATWAVE IN SUMMER 2019?

WHAT CAUSED THE HEATWAVE?

The heatwave was triggered by the build-up of high pressures over Europe over the past few days, leading to the northward movement of warm air from Europe over the UK.
'At this time of year southerly winds will always lead to above average temperatures,' said University of Reading meteorologist Peter Inness. 
'Air from continental Europe, the Mediterranean and even North Africa is brought over the UK.'
'The eastward passage of weather fronts and low pressures from the North Atlantic are currently being blocked by the high pressure over Europe,' added University of Reading climate scientist Len Shaffrey. 

WAS IT RELATED TO THE US HEATWAVE?

The US's recent warm weather was caused by a high-pressure dome building up over much of the country, trapping the summer heat.
This has wider-reaching effects.
'Heatwave conditions in the U.S Midwest and the East coast have strengthened the jet stream,' explained environmental scientist Kate Sambrook of the University of Leeds.
'The resulting thunderstorms occurring on the continent have helped the jet stream to meander and move to the north of the U.K.'
'As a result of this shift, hot air has been drawn up from Europe causing the high temperatures we are experiencing this week.'

The US's warm weather had been caused by a high-pressure dome building up over much of the country, trapping the summer heat

HOW LONG WILL THE HEAT LAST?

'Although there is some uncertainty in the forecast, it looks like it will become cooler on Friday as the high pressure over Europe moves slowly towards the east,' said Dr Shaffrey.
'This will allow weather fronts to move over the UK, bringing cooler air and possibly some rain,' Professor Shaffrey added,

HOW HOT WILL IT GET?

Meteorologists are predicting high temperatures reaching up to 100°F (38°C) over central and Eastern England on Thursday.
Although different forecasts are anticipating slightly different details, 'the broad message of all the forecasts is the same,' said Dr Inness.
'It will be hot, with high temperatures persisting through the night time periods, and there is the risk of some thunderstorms over the UK.'
These will continue through Wednesday. 
'If conditions continue, it is likely that we could experience the hottest July on record,' said Dr Sambrook.
'However, the outcome is uncertain as conditions are expected to change early next week.' 
University of Oxford climate scientist Karsten Haustein added that 'there is a 40–50 per cent chance that this will be the warmest July on record.'
The final estimate depends on which observational dataset is used, he noted.
While agreeing that the next week's weather will determine this July's place in the record books, Dr Inness noted that 2019 did bring us the warmest June known since the year 1880.
'In fact, 9 of the 10 warmest Junes in the global record have happened since 2000', he said. 
In Europe, he noted, this June was also the warmest on record, reaching almost a whole degree Celsius above the previous number one back in 2003.
'Weather records are not normally broken by such large margins — a few tenths of a degree would be more likely.'
The present conditions may turn out to be record-breaking, but they are also part of a recent trend towards warmer UK summers.
'2018 was the joint hottest [year] on record with highest temperature measured at around 35°C, similar to temperatures expected this week,' said University of Leeds climatologist Declan Finney. 
The likelihood of experiencing such hot summers has risen from a less than 10 per cent chance in the 1980s to as high as a 25 per chance today, he added.

IS CLIMATE CHANGE CAUSING HEATWAVES?

'The fact that so many recent years have had very high summer temperatures both globally and across Europe is very much in line with what we expect from man-made global warming,' said Dr Inness.
'Changes in the intensity and likelihood of extreme weather is how climate change manifests,' said environmental scientist Friederike Otto of the University of Oxford.
'That doesn’t mean every extreme event is more intense because of it, but a lot are. For example, every heatwave occurring in Europe today is made more likely and more intense by human-induced climate change.'
However, local factors also play a role, with each extreme weather event being influenced by the location, season, intensity and duration.
The present heatwave is not the only notable indicator of climate change, experts note, with ongoing droughts — such as those being experienced in many parts of Germany — also being in line with scientific predictions.
Research into the 2003 European heatwave suggested at the time that human activity had more than doubled the risk of such warm summers — and that annual heatwaves like we are experiencing now could become commonplace by around the middle of the century.
'It has been estimated that about 35,000 people died as a result of the European heatwave in 2003, so this is not a trivial issue,' said Dr Inness.
'With further climate change there could be a 50% chance of having hot summers in the future,' agreed Dr Finney.
'That's similar to saying that a normal summer in future will be as hot as our hottest summers to date,' he added.

 

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