A degree by degree explanation of Global Warming
Even if greenhouse emissions stopped overnight 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.
The effect of one-degree warming, therefore, requires no great feat of imagination.
Want to read what it will be like under 2 degrees, or six? Click here.
“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. It has beencalculated 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. There was 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 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. 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 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.
Want to read what it will be like under 2 degrees, or six? Click here.