Earth 'will heat up by 4C' by the year 2100, scientists predict

Rise is twice that considered dangerous by climate scientists

The Earth’s temperature could increase by 4C by 2100, scientists have warned.

Temperature rises resulting from unchecked climate change might be at the severe end of the scale of current predicitions, according to a new scientific study.

The author of the study, professor Steven Sherwood, said that unless emissions of greenhouse gases were reduced, the planet would heat up by a minimum of 4C by 2100, twice the level regarded as dangerous by climate scientists.

The research, based on a new climate model taking greater account of cloud changes, shows that as the planet gets warmer, fewer clouds will form. This means that less sunlight is reflected back into space, driving temperatures up further still.

Professor Sherwood, of the University of New South Wales in Australia, told The Guardian: "This study breaks new ground twice: first by identifying what is controlling the cloud changes and second by strongly discounting the lowest estimates of future global warming in favour of the higher and more damaging estimates.

"4C would likely be catastrophic rather than simply dangerous," Sherwood said. "For example, it would make life difficult, if not impossible, in much of the tropics, and would guarantee the eventual melting of the Greenland ice sheet and some of the Antarctic ice sheet" - causing sea levels to rise by many metres as a result.

The research, which is published in the journal Nature, is described as a “big advance” in terms of alleviating uncertainty about the true impact of global warming. Hideo Shiogama and Tomoo Ogura, at Japan's National Institute for Environmental Studies, said the explanation of how fewer clouds form as the world warms was "convincing", and agreed this indicated future climate would be greater than expected. But they said more research was needed to narrow down the projections of future temperatures.

Scientists measure the impact of greenhouse gases on the Earth’s climate by estimating the temperature rise that would be caused by a doubling of carbon dioxide in the atmosphere compared with pre-industrial levels, which is likely to happen within 50 years according to current trends. 

Despite decades of research attempting to narrow uncertainties, these estimates have previously spanned roughly 1.5 to five degrees, but the new research estimated a narrower window between 3C and 5C by focusing on an area of uncertainty: cloud formation.

Researchers worked to ensure that computer climate models accurately represented the way clouds form in the real world. When water evaporates from the oceans, the vapour can either rise over nine miles to form rain clouds that reflect sunlight, or it can drift back down without forming clouds. Climate models that incorporated both of these potentialities predicted significantly higher future temperatures than those only including the nine-mile-high clouds.

"Climate sceptics like to criticise climate models for getting things wrong, and we are the first to admit they are not perfect," Sherwood told The Guardian. "But what we are finding is that the mistakes are being made by the models which predict less warming, not those that predict more."

He added: "Sceptics may also point to the 'hiatus' of temperatures since the end of the 20th Century, but there is increasing evidence that this inaptly named hiatus is not seen in other measures of the climate system, and is almost certainly temporary."

However, Sherwood also told The Guardian that his team’s cannot conclusively rule out the fact that future temperature rises may lay at the lower end of projections. "But," he said, for that to be the case, "one would need to invoke some new dimension to the problem involving a major missing ingredient for which we currently have no evidence. Such a thing is not out of the question but requires a lot of faith."

He added: "Rises in global average temperatures of [at least 4C by 2100] will have profound impacts on the world and the economies of many countries if we don't urgently start to curb our emissions."

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksA special investigation by Andy McSmith
News
Andy Davidhazy at the beginning (left) and end (right) of his hike
video
News
Taylor Swift is applying to trademark song lyrics from 1989
people
Voices
The popularity of TV shows such as The Liver Birds encouraged Liverpudlians to exaggerate their Scouse accent
voicesWe exaggerate regional traits and turn them into jokes - and those on the receiving end are in on it too, says DJ Taylor
Life and Style
Parker says: 'I once had a taster use the phrase 'smells like the sex glands of a lemming'. Who in the world can relate to that?'
food + drinkRobert Parker's 100-point scale is a benchmark of achievement for wine-makers everywhere
News
i100
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Junior Web Designer - Client Liaison

£6 per hour: Recruitment Genius: This is an exciting opportunity to join a gro...

Recruitment Genius: Service Delivery Manager

Negotiable: Recruitment Genius: A Service Delivery Manager is required to join...

Recruitment Genius: Massage Therapist / Sports Therapist

£12000 - £24000 per annum: Recruitment Genius: A opportunity has arisen for a ...

Ashdown Group: Practice Accountant - Bournemouth - £38,000

£32000 - £38000 per annum: Ashdown Group: A successful accountancy practice in...

Day In a Page

Election 2015: How many of the Government's coalition agreement promises have been kept?

Promises, promises

But how many coalition agreement pledges have been kept?
The Gaza fisherman who built his own reef - and was shot dead there by an Israeli gunboat

The death of a Gaza fisherman

He built his own reef, and was fatally shot there by an Israeli gunboat
Saudi Arabia's airstrikes in Yemen are fuelling the Gulf's fire

Saudi airstrikes are fuelling the Gulf's fire

Arab intervention in Yemen risks entrenching Sunni-Shia divide and handing a victory to Isis, says Patrick Cockburn
Zayn Malik's departure from One Direction shows the perils of fame in the age of social media

The only direction Zayn could go

We wince at the anguish of One Direction's fans, but Malik's departure shows the perils of fame in the age of social media
Young Magician of the Year 2015: Meet the schoolgirl from Newcastle who has her heart set on being the competition's first female winner

Spells like teen spirit

A 16-year-old from Newcastle has set her heart on being the first female to win Young Magician of the Year. Jonathan Owen meets her
Jonathan Anderson: If fashion is a cycle, this young man knows just how to ride it

If fashion is a cycle, this young man knows just how to ride it

British designer Jonathan Anderson is putting his stamp on venerable house Loewe
Number plates scheme could provide a licence to offend in the land of the free

Licence to offend in the land of the free

Cash-strapped states have hit on a way of making money out of drivers that may be in collision with the First Amendment, says Rupert Cornwell
From farm to fork: Meet the Cornish fishermen, vegetable-growers and butchers causing a stir in London's top restaurants

From farm to fork in Cornwall

One man is bringing together Cornwall's most accomplished growers, fishermen and butchers with London's best chefs to put the finest, freshest produce on the plates of some of the country’s best restaurants
Robert Parker interview: The world's top wine critic on tasting 10,000 bottles a year, absurd drinking notes and New World wannabes

Robert Parker interview

The world's top wine critic on tasting 10,000 bottles a year, absurd drinking notes and New World wannabes
Don't believe the stereotype - or should you?

Don't believe the stereotype - or should you?

We exaggerate regional traits and turn them into jokes - and those on the receiving end are in on it too, says DJ Taylor
How to make your own Easter egg: Willie Harcourt-Cooze shares his chocolate recipes

How to make your own Easter egg

Willie Harcourt-Cooze talks about his love affair with 'cacao' - and creates an Easter egg especially for The Independent on Sunday
Bill Granger recipes: Our chef declares barbecue season open with his twist on a tradtional Easter Sunday lamb lunch

Bill Granger's twist on Easter Sunday lunch

Next weekend, our chef plans to return to his Aussie roots by firing up the barbecue
Joe Marler: 'It's the way I think the game should be played'

Joe Marler: 'It's the way I think the game should be played'

The England prop relives the highs and lows of last Saturday's remarkable afternoon of Six Nations rugby
Cricket World Cup 2015: Has the success of the tournament spelt the end for Test matches?

Cricket World Cup 2015

Has the success of the tournament spelt the end for Test matches?
The Last Word: Justin Gatlin knows the price of everything, the value of nothing

Michael Calvin's Last Word

Justin Gatlin knows the price of everything, the value of nothing