A four degree world? You really don't want to go there...

A A A

If Earth heats by four degrees Celsius -- some seven degrees Fahrenheit -- the planet we call home would become a very unwelcoming place.

(AFP) -

If Earth heats by four degrees Celsius - some seven degrees Fahrenheit - the planet we call home would become a very unwelcoming place.

Even as some world leaders tamp down expectations for the December 7-18 UN climate conference, experts say the threat of a 4C (7.2 F) warming over pre-industrial times is all too plausible.

Once that threshold is crossed, what might a four-degree world look like?

Brace yourself.

Oceans have risen by at least a metre (3.25 feet), drowning several island nations and driving hundreds of millions of people in Bangladesh, Thailand and Vietnam and other delta nations to scramble for higher ground.

Polar bears are a folk memory, starved to extinction in an Arctic where temperatures have soared by 15 C (27 F), nearly four-fold the global average.

Australia is routinely swept by white-hot fires of the kind that claimed 170 lives last February.

A third - perhaps more - of the Amazon forest has been reduced to desolate shrubland, its treasure chest of flora and fauna decimated.

Asia's eternal fountain, the Himalayan glaciers, are running dry.

South Asia's precious monsoon, once reliable as clockwork, has become fickle, dumping too little or too much rain.

A quarter of the planet's mammals are on a downward spiral toward extinction.

"A 4.0 C increase in global mean temperatures has the potential to threaten human security and quality of life in a manner unprecedented in recent history," says Arizona State University professor Pamela McElwee.

Francois Gemmene, a researcher at France's Institute for Sustainable Development and International Relations (IDDRI), adds: "At 4.0 C, climate-driven migration redraws the map of population distribution across the surface of the globe."

Science fiction? If only.

On November 16, an international team of scientists, the Global Carbon Project, said carbon emissions had surged by 29 percent from 2000 to 2008.

This places Earth on track with the worst-case warming scenario put forward by the UN's Nobel-winning Intergovernmental Panel on Climate Change (IPCC), it said.

Under its so-called "business-as-usual" forecast, voracious use of coal and other fossil fuels would see planetary warming of 4.0-to-6.4 C (7.2-to-11.5 F) by 2100 compared with 2000.

To that, add another 0.74 C of warming that has occurred since the Industrial Revolution.

This would spell disaster for Earth's population, 6.7 billion today, on course for nine billion in 2050.

"The carrying capacity of the planet could fall to one billion people or less," said John Schellnhuber, director of the Potsdam Institute for Climate Impact Research in Germany.

In September, Britain's Met Office, a leading centre on climate change, said the 4.0 degree rendezvous could come as early as 2060 - in time for you or your children to experience it first-hand.

Crossing that threshold, they conclude, would send the misery index into unchartered territory.

In 2080, three billion people would struggle to find adequate water.

Yields of the major crops that feed most of the planet today would shrink, some dramatically, resulting in chronic hunger for tens, possibly hundreds, of millions. Africa, where so many teeter today at or below subsistence levels, would be hit especially hard.

For biodiversity, already on the cusp of the sixth major extinction in Earth's history, "a four degree world would be mayhem," said Pavan Sukhdev, a leading expert on the economics of ecosystems.

"Even two degrees, if you break it down, would create regional catastrophes in many places," he told AFP.

The loss of coral reefs - which may be a foregone conclusion even at current levels of warming - will leave half a billion people without livelihood.

The good news, virtually all of these experts said, is that there is still time to halt the slide if greenhouse-gas emissions peak soon enough and fall thereafter.

But the window of opportunity is narrowing rapidly.

PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Tradewind Recruitment: Phase Co-ordinator for Foundation and Key Stage 1

Negotiable: Tradewind Recruitment: Phase Co-ordinator for Foundation and Key S...

Tradewind Recruitment: SEN Teacher

Negotiable: Tradewind Recruitment: SEN Teacher We have a fantastic special n...

Tradewind Recruitment: History Teacher

Negotiable: Tradewind Recruitment: My client is an 11-18 all ability co-educat...

Tradewind Recruitment: Year 6 Teacher

£100 - £150 per day: Tradewind Recruitment: Year 6 Teacher Birmingham Jan 2015...

Day In a Page

Isis hostage crisis: The prisoner swap has only one purpose for the militants - recognition its Islamic State exists and that foreign nations acknowledge its power

Isis hostage crisis

The prisoner swap has only one purpose for the militants - recognition its Islamic State exists and that foreign nations acknowledge its power, says Robert Fisk
Missing salvage expert who found $50m of sunken treasure before disappearing, tracked down at last

The runaway buccaneers and the ship full of gold

Salvage expert Tommy Thompson found sunken treasure worth millions. Then he vanished... until now
Homeless Veterans appeal: ‘If you’re hard on the world you are hard on yourself’

Homeless Veterans appeal: ‘If you’re hard on the world you are hard on yourself’

Maverick artist Grayson Perry backs our campaign
Assisted Dying Bill: I want to be able to decide about my own death - I want to have control of my life

Assisted Dying Bill: 'I want control of my life'

This week the Assisted Dying Bill is debated in the Lords. Virginia Ironside, who has already made plans for her own self-deliverance, argues that it's time we allowed people a humane, compassionate death
Move over, kale - cabbage is the new rising star

Cabbage is king again

Sophie Morris banishes thoughts of soggy school dinners and turns over a new leaf
11 best winter skin treats

Give your moisturiser a helping hand: 11 best winter skin treats

Get an extra boost of nourishment from one of these hard-working products
Paul Scholes column: The more Jose Mourinho attempts to influence match officials, the more they are likely to ignore him

Paul Scholes column

The more Jose Mourinho attempts to influence match officials, the more they are likely to ignore him
Frank Warren column: No cigar, but pots of money: here come the Cubans

Frank Warren's Ringside

No cigar, but pots of money: here come the Cubans
Isis hostage crisis: Militant group stands strong as its numerous enemies fail to find a common plan to defeat it

Isis stands strong as its numerous enemies fail to find a common plan to defeat it

The jihadis are being squeezed militarily and economically, but there is no sign of an implosion, says Patrick Cockburn
Virtual reality thrusts viewers into the frontline of global events - and puts film-goers at the heart of the action

Virtual reality: Seeing is believing

Virtual reality thrusts viewers into the frontline of global events - and puts film-goers at the heart of the action
Homeless Veterans appeal: MP says Coalition ‘not doing enough’

Homeless Veterans appeal

MP says Coalition ‘not doing enough’ to help
Larry David, Steve Coogan and other comedians share stories of depression in new documentary

Comedians share stories of depression

The director of the new documentary, Kevin Pollak, tells Jessica Barrett how he got them to talk
Has The Archers lost the plot with it's spicy storylines?

Has The Archers lost the plot?

A growing number of listeners are voicing their discontent over the rural soap's spicy storylines; so loudly that even the BBC's director-general seems worried, says Simon Kelner
English Heritage adds 14 post-war office buildings to its protected lists

14 office buildings added to protected lists

Christopher Beanland explores the underrated appeal of these palaces of pen-pushing
Human skull discovery in Israel proves humans lived side-by-side with Neanderthals

Human skull discovery in Israel proves humans lived side-by-side with Neanderthals

Scientists unearthed the cranial fragments from Manot Cave in West Galilee