What will climate change do to our planet? - degree-by-degree guide  
email to friend  E-mail this to a Friend    Print

This is our future - famous cities are submerged, a third of the world is desert, the rest struggling for food and fresh water. Richard Girling investigates the reality behind the science of climate change

Go to see full article www.timesonline.co.uk


If global warming continues at the current rate, we could be facing extinction. So what exactly is going to happen as the Earth heats up? Here is a degree-by-degree guide

1c Increase

Ice-free sea absorbs more heat and accelerates global warming; fresh water lost from a third of the world's surface; low-lying coastlines flooded

"Most striking of all," says Lynas, "was seeing how people behaved once the veneer of civilisation had been torn away. Most victims were poor and black, left to fend for themselves as the police either joined in the looting or deserted the area. Four days into the crisis, survivors were packed into the city's Superdome, living next to overflowing toilets and rotting bodies as gangs of young men with guns seized the only food and water available. Perhaps the most memorable scene was a single military helicopter landing for just a few minutes, its crew flinging food parcels and water bottles out onto the ground before hurriedly taking off again as if from a war zone. In scenes more like a Third World refugee camp than an American urban centre, young men fought for the water as pregnant women and the elderly looked on with nothing. Don't blame them for behaving like this, I thought. It's what happens when people are desperate."

Chance of avoiding one degree of global warming: zero.

2c Increase

Europeans dying of heatstroke; forests ravaged by fire; stressed plants beginning to emit carbon rather than absorbing it; a third of all species face extinction

Not only coastal communities will suffer. As mountains lose their glaciers, so people will lose their water supplies. The entire Indian subcontinent will be fighting for survival. "As the glaciers disappear from all but the highest peaks, their runoff will cease to power the massive rivers that deliver vital freshwater to hundreds of millions. Water shortages and famine will be the result, destabilising the entire region. And this time the epicentre of the disaster won't be India, Nepal or Bangladesh, but nuclear-armed Pakistan."

Chance of avoiding two degrees of global warming: 93%, but only if emissions of greenhouse gases are reduced by 60% over the next 10 years

3c Increase

Carbon release from vegetation and soils speeds global warming; death of the Amazon rainforest; super-hurricanes hit coastal cities; starvation in Africa

As the land burns, so the sea will go on rising. Even by the most optimistic calculation, 80% of Arctic sea ice by now will be gone, and the rest will soon follow. New York will flood; the catastrophe that struck eastern England in 1953 will become an unremarkable regular event; and the map of the Netherlands will be torn up by the North Sea. Everywhere, starving people will be on the move - from Central America into Mexico and the US, and from Africa into Europe, where resurgent fascist parties will win votes by promising to keep them out.

Chance of avoiding three degrees of global warming: poor if the rise reaches two degrees and triggers carbon-cycle feedbacks from soils and plants.

4c Increase

Runaway thaw of permafrost makes global warming unstoppable; much of Britain made uninhabitable by severe flooding; Mediterranean region abandoned

One of the most dangerous of all feedbacks will now be kicking in - the runaway thaw of permafrost. Scientists believe at least 500 billion tonnes of carbon are waiting to be released from the Arctic ice, though none yet has put a figure on what it will add to global warming. One degree? Two? Three? The pointers are ominous.

Chance of avoiding four degrees of global warming: poor if the rise reaches three degrees and triggers a runaway thaw of permafrost.

5c Increase

Methane from ocean floor accelerates global warming; ice gone from both poles; humans migrate in search of food and try vainly to live like animals off the land

"Where no refuge is available," says Lynas, "civil war and a collapse into racial or communal conflict seems the likely outcome." Isolated survivalism, however, may be as impracticable as dialling for room service. "How many of us could really trap or kill enough game to feed a family? Even if large numbers of people did successfully manage to fan out into the countryside, wildlife populations would quickly dwindle under the pressure. Supporting a hunter-gatherer lifestyle takes 10 to 100 times the land per person that a settled agricultural community needs. A large-scale resort to survivalism would turn into a further disaster for biodiversity as hungry humans killed and ate anything that moved." Including, perhaps, each other. "Invaders," says Lynas, "do not take kindly to residents denying them food. History suggests that if a stockpile is discovered, the householder and his family may be tortured and killed. Look for comparison to the experience of present-day Somalia, Sudan or Burundi, where conflicts over scarce land and food are at the root of lingering tribal wars and state collapse."

Chance of avoiding five degrees of global warming: negligible if the rise reaches four degrees and releases trapped methane from the sea bed.

6c Increase

Life on Earth ends with apocalyptic storms, flash floods, hydrogen sulphide gas and methane fireballs racing across the globe with the power of atomic bombs; only fungi survive

"First, a small disturbance drives a gas-saturated parcel of water upwards. As it rises, bubbles begin to appear, as dissolved gas fizzles out with reducing pressure - just as a bottle of lemonade overflows if the top is taken off too quickly. These bubbles make the parcel of water still more buoyant, accelerating its rise through the water. As it surges upwards, reaching explosive force, it drags surrounding water ?up with it. At the surface, water is shot hundreds of metres into the air as the released gas blasts into the atmosphere. Shockwaves propagate outwards in all directions, triggering more eruptions nearby."

The eruption is more than just another positive feedback in the quickening process of global warming. Unlike CO², methane is flammable. "Even in air-methane concentrations as low as 5%," says Lynas, "the mixture could ignite from lightning or some other spark and send fireballs tearing across the sky." The effect would be much like that of the fuel-air explosives used by the US and Russian armies - so-called "vacuum bombs" that ignite fuel droplets above a target. According to the CIA, "Those near the ignition point are obliterated. Those at the fringes are likely to suffer many internal injuries, including burst eardrums, severe concussion, ruptured lungs and internal organs, and possibly blindness." Such tactical weapons, however, are squibs when set against methane-air clouds from oceanic eruptions. Scientists calculate that they could "destroy terrestrial life almost entirely" (251m years ago, only one large land animal, the pig-like lystrosaurus, survived).

It has been estimated that a large eruption in future could release energy equivalent to 108 megatonnes of TNT - 100,000 times more than the world's entire stockpile of nuclear weapons. Not even Lynas, for all his scientific propriety, can avoid the Hollywood ending. "It is not too difficult to imagine the ultimate nightmare, with oceanic methane eruptions near large population centres wiping out billions of people - perhaps in days. Imagine a 'fuel-air explosive' fireball racing towards a city - London, say, or Tokyo - the blast wave spreading out from the explosive centre with the speed and force of an atomic bomb.
Buildings are flattened, people are incinerated where they stand, or left blind and deaf by the force of the explosion. Mix Hiroshima with post-Katrina New Orleans to get some idea of what such a catastrophe might look like: burnt survivors battling over food, wandering far and wide from empty cities."

Chance of avoiding six degrees of global warming: zero if the rise passes five degrees, by which time all feedbacks will be running out of control

Go to see full article www.timesonline.co.uk

Six Degrees: Our Future on a Hotter Planet, by Mark Lynas, is published on March 19 by HarperCollins