I'd say the chances of stabilizing with a 3 degree increase are not real good.
UP TO ONE DEGREE OF WARMING
Even if greenhouse emissions stopped overnight - of which there is about as much chance as Tony Blair holidaying in Skegness - the concentrations already in the atmosphere would still mean a global rise of between 0.5 and 1C. A shift of a single degree is barely perceptible to human skin, but it's not human skin we're talking about. It's the planet; and an average increase of one degree across its entire surface means huge changes in climatic extremes.
Six thousand years ago, when the world was one degree warmer than it is now, the American agricultural heartland around Nebraska was desert. It suffered a short reprise during the dust- bowl years of the 1930s, when the topsoil blew away and hundreds of thousands of refugees trailed through the dust to an uncertain welcome further west. The effect of one-degree warming, therefore, requires no great feat of imagination.
"The western United States once again could suffer perennial droughts, far worse than the 1930s. Deserts will reappear particularly in Nebraska, but also in eastern Montana, Wyoming and Arizona, northern Texas and Oklahoma. As dust and sandstorms turn day into night across thousands of miles of former prairie, farmsteads, roads and even entire towns will be engulfed by sand."
What's bad for America will be worse for poorer countries closer to the equator. The Hadley centre calculates that a one-degree increase would eliminate fresh water from a third of the world's land surface by 2100. Again we have seen what this means. Lynas describes an incident in the summer of 2005: "One tributary fell so low that miles of exposed riverbank dried out into sand dunes, with winds whipping up thick sandstorms. As desperate villagers looked out onto baking mud instead of flowing water, the army was drafted in to ferry precious drinking water up the river - by helicopter, since most of the river was too low to be navigable by boat." The river in question was not some small, insignificant trickle in Sussex. It was the Amazon.
While tropical lands teeter on the brink, the Arctic already may have passed the point of no return. Warming near the pole is much faster than the global average, with the result that Arctic icecaps and glaciers have lost 400 cubic kilometres of ice in 40 years. Permafrost - ground that has lain frozen for thousands of years - is dissolving into mud and lakes, "destabilising whole areas as the ground collapses beneath buildings, roads and pipelines". As polar bears and Inuits are being pushed off the top of the planet, previous predictions are starting to look optimistic. "Earlier snowmelt," says Lynas, "means more summer heat goes into the air and ground rather than into melting snow, raising temperatures in a positive feedback effect. More dark shrubs and forest on formerly bleak tundra means still more heat is absorbed by vegetation."
Out at sea the pace is even faster. "Whilst snow-covered ice reflects more than 80% of the sun's heat, the darker ocean absorbs up to 95% of solar radiation. Once sea ice begins to melt, in other words, the process becomes self-reinforcing. More ocean surface is revealed, absorbing solar heat, raising temperatures and making it unlikelier that ice will re-form next winter. The disappearance of 720,000 square kilometres of supposedly permanent ice in a single year testifies to the rapidity of planetary change. If you have ever wondered what it will feel like when the Earth crosses a tipping point, savour the moment."
Mountains, too, are starting to come apart. In the Alps, most ground above 3,000 metres is stabilised by permafrost. In the summer of 2003, however, the melt zone climbed right up to 4,600 metres, higher than the summit of the Matterhorn and nearly as high as Mont Blanc. With the glue of millennia melting away, rocks showered down and 50 climbers died. As temperatures go on edging upwards, it won't just be mountaineers who flee. "Whole towns and villages will be at risk," says Lynas. "Some towns, like Pontresina in eastern Switzerland, have already begun building bulwarks against landslides."
At the opposite end of the scale, low-lying atoll countries such as the Maldives will be preparing for extinction as sea levels rise, and mainland coasts - in particular the eastern US and Gulf of Mexico, the Caribbean and Pacific islands and the Bay of Bengal - will be hit by stronger and stronger hurricanes as the water warms. Hurricane Katrina, which in 2005 hit New Orleans with the combined impacts of earthquake and flood, was a nightmare precursor of what the future holds.
"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.
BETWEEN ONE AND TWO DEGREES OF WARMING
At this level, expected within 40 years, the hot European summer of 2003 will be the annual norm. Anything that could be called a heatwave thereafter will be of Saharan intensity. Even in average years, people will die of heat stress.
"The first symptoms," says Lynas, "may be minor. A person will feel slightly nauseous, dizzy and irritable. It needn't be an emergency: an hour or so lying down in a cooler area, sipping water, will cure it. But in Paris, August 2003, there were no cooler areas, especially for elderly people.
"Once body temperature reaches 41C (104F) its thermoregulatory system begins to break down. Sweating ceases and breathing becomes shallow and rapid. The pulse quickens, and the victim may lapse into a coma. Unless drastic measures are taken to reduce the body's core temperature, the brain is starved of oxygen and vital organs begin to fail. Death will be only minutes away unless the emergency services can quickly get the victim into intensive care.
"These emergency services failed to save more than 10,000 French in the summer of 2003. Mortuaries ran out of space as hundreds of dead bodies were brought in each night." Across Europe as a whole, the heatwave is believed to have cost between 22,000 and 35,000 lives. Agriculture, too, was devastated. Farmers lost $12 billion worth of crops, and Portugal alone suffered $12 billion of forest-fire damage. The flows of the River Po in Italy, Rhine in Germany and Loire in France all shrank to historic lows. Barges ran aground, and there was not enough water for irrigation and hydroelectricity. Melt rates in the Alps, where some glaciers lost 10% of their mass, were not just a record - they doubled the previous record of 1998. According to the Hadley centre, more than half the European summers by 2040 will be hotter than this. Extreme summers will take a much heavier toll of human life, with body counts likely to reach hundreds of thousands. Crops will bake in the fields, and forests will die off and burn. Even so, the short-term effects may not be the worst:
"From the beech forests of northern Europe to the evergreen oaks of the Mediterranean, plant growth across the whole landmass in 2003 slowed and then stopped. Instead of absorbing carbon dioxide, the stressed plants began to emit it. Around half a billion tonnes of carbon was added to the atmosphere from European plants, equivalent to a twelfth of global emissions from fossil fuels. This is a positive feedback of critical importance, because it suggests that, as temperatures rise, carbon emissions from forests and soils will also rise. If these land-based emissions are sustained over long periods, global warming could spiral out of control."
In the two-degree world, nobody will think of taking Mediterranean holidays. "The movement of people from northern Europe to the Mediterranean is likely to reverse, switching eventually into a mass scramble as Saharan heatwaves sweep across the Med." People everywhere will think twice about moving to the coast. When temperatures were last between 1 and 2C higher than they are now, 125,000 years ago, sea levels were five or six metres higher too. All this "lost" water is in the polar ice that is now melting. Forecasters predict that the "tipping point" for Greenland won't arrive until average temperatures have risen by 2.7C. The snag is that Greenland is warming much faster than the rest of the world - 2.2 times the global average. "Divide one figure by the other," says Lynas, "and the result should ring alarm bells across the world. Greenland will tip into irreversible melt once global temperatures rise past a mere 1.2C." The ensuing sea-level ?rise will be far more than the half-metre that ?the IPCC has predicted for the end of the century. Scientists point out that sea levels at the end of the last ice age shot up by a metre every 20 years for four centuries, and that Greenland's ice, in the words of one glaciologist, is now "thinning like mad and flowing much faster ?than [it] ought to". Its biggest outflow glacier, Jakobshavn Isbrae, has thinned by 15 metres every year since 1997, and its speed of flow has doubled. "At this rate," says Lynas, "the whole Greenland ice sheet would vanish within 140 years. Miami would disappear, as would most of Manhattan. Central London would be flooded. Bangkok, Bombay and Shanghai would lose most of their area. In all, half of humanity would have to move to higher ground."
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."
Everywhere, ecosystems will unravel as species either migrate or fall out of synch with each other. By the time global temperatures reach two degrees of warming in 2050, more than a third of all living species will face extinction.
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.
BETWEEN TWO AND THREE DEGREES OF WARMING
Up to this point, assuming that governments have planned carefully and farmers have converted to more appropriate crops, not too many people outside subtropical Africa need have starved. Beyond two degrees, however, preventing mass starvation will be as easy as halting the cycles of the moon. "First millions, then billions, of people will face an increasingly tough battle to survive," says Lynas.
To find anything comparable we have to go back to the Pliocene - last epoch of the Tertiary period, 3m years ago. There were no continental glaciers in the northern hemisphere (trees grew in the Arctic), and sea levels were 25 metres higher than today's. In this kind of heat, the death of the Amazon is as inevitable as the melting of Greenland. The paper spelling it out is the very one whose apocalyptic ?message so shocked Lynas in 2000. Scientists at the Hadley centre feared that earlier climate models, which showed global warming as a straightforward linear progression, were too simplistic in their assumption that land and the oceans would remain inert as their temperatures rose. Correctly as it would turn out, they predicted positive feedback.
"Warmer seas," explains Lynas, "absorb carbon dioxide, leaving more to accumulate in the atmosphere and intensify global warming. On land, matters would be even worse. Huge amounts of carbon are stored in the soil, the half-rotted remains of dead vegetation. The generally accepted estimate is that the soil carbon reservoir contains some 1600 gigatonnes, more than double the entire carbon content of the atmosphere. As soil warms, bacteria accelerate the breakdown of this stored carbon, releasing it into the atmosphere."
The Hadley team factored this new feedback into their climate model, with results that fully explain Lynas's black-comic note to himself: The end of the world is nigh. A three-degree increase in global temperature - possible as early as 2050 - would throw the carbon cycle into reverse. "Instead of absorbing carbon dioxide," says Lynas, "vegetation and soils start to release it. So much carbon pours into the atmosphere that it pumps up atmospheric concentrations by 250 parts per million by 2100, boosting global warming by another 1.5C. In other words, the Hadley team had discovered that carbon-cycle feedbacks could tip the planet into runaway global warming by the middle of this century - much earlier than anyone had expected."
Confirmation came from the land itself. Climate models are routinely tested against historical data. In this case, scientists checked 25 years' worth of soil samples from 6,000 sites across the UK. The result was another black joke. "As temperatures gradually rose," says Lynas, "the scientists found that huge amounts of carbon had been released naturally from the soils. They totted it all up and discovered - irony of ironies - that the 13m tonnes of carbon British soils were emitting annually was enough to wipe out all the country's efforts to comply with the Kyoto Protocol." All soils will be affected by the rising heat, but none as badly as the Amazon's. "Catastrophe" is almost too small a word for the loss of the rainforest. Its 7m square kilometres produce 10% of the world's entire photosynthetic output from plants. Drought and heat will cripple it; fire will finish it off. In human terms, the effect on the planet will be like cutting off oxygen during an asthma attack.
In the US and Australia, people will curse the climate-denying governments of Bush and Howard. No matter what later administrations may do, it will not be enough to keep the mercury down. With new "super-hurricanes" growing from the warming sea, Houston could be destroyed by 2045, and Australia will be a death trap. "Farming and food production will tip into irreversible decline. Salt water will creep up the stricken rivers, poisoning ground water. Higher temperatures mean greater evaporation, further drying out vegetation and soils, and causing huge losses from reservoirs." In state capitals, heat every year is likely to kill between 8,000 and 15,000 mainly elderly people.
It is all too easy to visualise what will happen in Africa. In Central America, too, tens of ?millions will have little to put on their tables. Even a moderate drought there in 2001 meant hundreds of thousands had to rely on food aid. This won't be an option when world supplies ?are stretched to breaking point (grain yields decline by 10% for every degree of heat above 30C, and at 40C they are zero). Nobody need look to the US, which will have problems of its own. As the mountains lose their snow, so cities and farms in the west will lose their water and dried-out forests and grasslands will perish at the first spark.
The Indian subcontinent meanwhile will be choking on dust. "All of human history," says Lynas, "shows that, given the choice between starving in situ and moving, people move. In the latter part of the century tens of millions of Pakistani citizens may be facing this choice. Pakistan may find itself joining the growing list of failed states, as civil administration collapses and armed gangs seize what little food is left."
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.
timesplus.co.uk |
