Europe could suffer a SEVEN-FOLD increase in the number of extreme droughts by 2100 if greenhouse gas emissions are not curbed, study warns
- The last such two-year drought struck Central Europe between 2018–2019
- It was the region’s largest-scale and most impactful drought in the records
- Researchers used climate models to predict the future rate of extreme droughts
- They found their frequency could be halved under a moderate emissions future
Europe could suffer a seven-fold increase in the number of record-breaking droughts by the year 2100 if greenhouse gas emissions are not curbed, a study has warned.
One such extreme episode struck Central Europe across the summers of 2018–2019 — which negatively affected around a fifth of crop-growing land.
Researchers led from Germany used climate models to determine how many two-year-long droughts would occur under different future emissions scenarios.
They found that the risk of two-year-long droughts could be halved if emissions are constrained to moderate levels — reducing the scale of affected land by 37 per cent.
Europe could suffer a seven-fold increase in the number of record-breaking droughts by the year 2100 if greenhouse gas emissions are not curbed, a study has warned (stock image)
In their study, environmental expert Vittal Hari from the UFZ-Helmholtz Centre for Environmental Research in Germany and colleagues began their study by comparing the the 2018–2019 Central European drought with conditions going back to 1766.
They found that both summers during the episode were drier than the average — and, moreover, were two of the top three warmest summers in the study period.
More than half of Central Europe suffered severe drought conditions across those two years — making it the largest-scale and most impactful drought in the record.
In contrast, the second-largest drought stuck Europe between 1949–1950 but, the researchers noted, affected an area that was around only two-thirds of the size.
In the second part of their study, the team used global climate models to predict the effect that different levels of future greenhouse emissions will have on the frequency of two-year-long droughts across Europe.
The team found that in the worst-case, high-emission scenario, the second half of the century will see an alarming seven-fold increase in the number of such prolonged droughts.
Furthermore, they estimated that this future would see the extent of croplands affected by such droughts double in comparison with the 2018–20418 drought, to incorporate more than 40 million hectares of cultivated land.
The team used global climate models to predict the effect that different levels of future greenhouse emissions will have on the frequency of two-year-long droughts across Europe. Pictured, the extent of past and predicted future European droughts — with high (purple), medium (yellow) and low (orange) emission scenarios for the latter
In contrast, the researchers found that the number of two-year-long droughts could be halved if greenhouse gas emissions are constrained to moderate levels — and reduced by ten under a best-case, low-emissions scenario.
Similarly, compared with the worst-case scenario, the extent of drought-prone areas could be reduced by 37 and 60 per cent respectively in a moderate- and low-emissions future.
The full findings of the study were published in the journal Scientific Reports
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 UK.
‘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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