IPCC: Feeling the heat

Overall, the UK coverage of IPCC 4 has had an urgency beyond what we are seeing in the Canadian papers (who are, to be fair, much better than they used to be on this mother of all issues). From the front page of The Independent, a paper not known for its alarmism:

UN delivers definitive warning on dangers of climate change

By Michael McCarthy, Environment Editor, in Paris

Published: 03 February 2007

 

 

 

A terrifying leap in average global temperatures of 6.4C ­ with higher figures nearer the poles ­ could occur over the next century, according to the most authoritative report yet on global warming.

The rise, which would make agriculture, even life, almost impossible over much of the Earth, was the worst-case scenario envisaged by hundreds of scientists on the UN’s Intergovernmental Panel on Climate Change (IPCC). They reported yesterday on their three-year study of how temperatures are likely to rise as global warming takes hold.

The “six-degree world” might come about by 2100, the scientists said, if human society carries on with rapid economic growth and high levels of burning fossil fuels ­ coal, oil and gas ­ which emit the carbon dioxide causing the atmosphere to warm. Their worst case was worse than that suggested in the previous IPCC report, published in 2001, when the highest rise envisaged by the end of the century was 5.8C.

… Perhaps the most significant new fact in their report was the prediction ­ for the first time ­ that if CO2 were allowed to double from before the Industrial Revolution, to about 550 parts per million, the Earth’s temperature would probably rise by 3C. This, though lower than the worst case, would still, in effect, be unsupportable by society.The significance of this is that some scientists, including the Government’s chief scientific adviser, Sir David King, have been seeing the 550ppm figure as a realistic level at which (or below which) the world might aim to stabilise CO2 levels. This will hardly seem realistic now.

The report examines six scenarios of human activity and predicts temperature rises to go with each. The “best guesses” range from a rise of 1.8C at the low end to 4C at the top. Even the smallest would be greatly destabilising.

The study, the IPCC’s 4th Assessment Report or AR4, has a lower worst-case scenario for sea-level rise than its predecessor, 59cm by 2100 rather than 88cm. But qualifications made about the models used for sea-level simulation make it clear this new figure could rise considerably, ending up worse than the earlier one.

Besides the temperature rises it predicts, yesterday’s report, released in Paris in a media scrum of more than 50 television crews, is noteworthy for the higher level of confidence with which it sets out its case. It will be seen as bringing to an end a 20-year argument about whether or not global warming is happening and whether or not human activities are its cause. These doubts have been used as an excuse for inaction, in particular by George Bush’s administration. …

+2.4°: Coral reefs almost extinct

 

 

In North America, a new dust-bowl brings deserts to life in the high plains states, centred on Nebraska, but also wipes out agriculture and

cattle ranching as sand dunes appear across five US states, from Texas in the south to Montana in the north.

Rising sea levels accelerate as the Greenland ice sheet tips into irreversible melt, submerging atoll nations and low-lying deltas. In Peru, disappearing Andean glaciers mean 10 million people face water shortages. Warming seas wipe out the Great Barrier Reef and make coral reefs virtually extinct throughout the tropics. Worldwide, a third of all species on the planet face extinction

+3.4°: Rainforest turns to desert

The Amazonian rainforest burns in a firestorm of catastrophic ferocity, covering South America with ash and smoke. Once the smoke clears, the interior of Brazil has become desert, and huge amounts of extra carbon have entered the atmosphere, further boosting global warming. The entire Arctic ice-cap disappears in the summer months, leaving the North Pole ice-free for the first time in 3 million years. Polar bears, walruses and ringed seals all go extinct. Water supplies run short in California as the Sierra Nevada snowpack melts away. Tens of millions are displaced as the Kalahari desert expands across southern Africa

+4.4°: Melting ice caps displace millions

Rapidly-rising temperatures in the Arctic put Siberian permafrost in the melt zone, releasing vast quantities of methane and CO2. Global temperatures keep on rising rapidly in consequence. Melting ice-caps and sea level rises displace more than 100 million people, particularly in Bangladesh, the Nile Delta and Shanghai. Heatwaves and drought make much of the sub-tropics uninhabitable: large-scale migration even takes place within Europe, where deserts are growing in southern Spain, Italy and Greece. More than half of wild species are wiped out, in the worst mass extinction since the end of the dinosaurs. Agriculture collapses in Australia

+5.4°: Sea levels rise by five metres

The West Antarctic ice sheet breaks up, eventually adding another five metres to global sea levels. If these temperatures are sustained, the entire planet will become ice-free, and sea levels will be 70 metres higher than today. South Asian society collapses due to the disappearance of glaciers in the Himalayas, drying up the Indus river, while in east India and Bangladesh, monsoon floods threaten millions. Super-El Niños spark global weather chaos. Most of humanity begins to seek refuge away from higher temperatures closer to the poles. Tens of millions of refugees force their way into Scandanavia and the British Isles. World food supplies run out

+6.4°: Most of life is exterminated

Warming seas lead to the possible release of methane hydrates trapped in sub-oceanic sediments: methane fireballs tear across the sky, causing further warming. The oceans lose their oxygen and turn stagnant, releasing poisonous hydrogen sulphide gas and destroying the ozone layer. Deserts extend almost to the Arctic. “Hypercanes” (hurricanes of unimaginable ferocity) circumnavigate the globe, causing flash floods which strip the land of soil. Humanity reduced to a few survivors eking out a living in polar refuges. Most of life on Earth has been snuffed out, as temperatures rise higher than for hundreds of millions of years.