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Our world, 4 degrees warmer Add to ...

In an effort to understand the consequences of "high-end climate change," the U.K.'s Met Office Hadley Centre climate research team built a map illustrating the effects of a worldwide average temperature increase of four degrees Celsius. It isn't date-specific, but is based on a pair of socioeconomic climate change scenarios developed by the UN's Nobel Peace Prize-winning Intergovernmental Panel on Climate Change (IPCC). The researchers picked four degrees as their benchmark after 34 simulations that projected long-term effects of climate change. In 23, the overall temperature increase reached an average of four degrees Celsius, suggesting that this is a realistic projected outcome of global warming. The increases are projected to vary by region. The models indicate that temperature increases would be higher further north (16 Celsius in the Arctic). Temperatures in Alaska would jump as much as 10 degrees, while New Zealand would come in under the average, going up just two degrees.The map was released as a warning of what the future could hold should world leaders fail to reach a binding deal to slow climate change at December's Copenhagen summit.

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The Evidence

The British office says that climate researchers have discovered that:

  • Levels of carbon dioxide in the atmosphere have risen by 40 per cent since the industrial revolution.
  • Global sea levels have risen 10 centimetres in the past 50 years.
  • Temperatures in the arctic have increased at twice the global average.
  • Snow cover in the northern hemisphere has dropped five per cent in the past two decades
  • An overall temperature increase of two degrees Celsius worldwide would be manageable, but is unlikely. Even if emissions peak in 2015 and fall rapidly thereafter (an optimistic scenario), the chance of staying under 2 degrees is still only 50-50.
  • More than 40 per cent of worldwide carbon dioxide emissions are caused by everyday choices by individuals.

In Canada

If emissions continue their global rise, Canada is in line for drastic changes, according to the UK office's predictions. Temperature increases range from five degrees Celsius on Vancouver Island and in Nova Scotia to six degrees in the Prairies, seven degrees throughout Central Canada and as high as 10 degrees in the far north.

Eastern cities will be hard-hit - the hottest days in Toronto and Ottawa will be 10 to 12 degrees Celsius warmer.

Melting permafrost will undermine infrastructure in the far north.

Life in coastal Canada is perhaps most threatened. Ocean acidification will cause a "significant impact" on both Pacific and Atlantic fisheries, while sea levels could rise as much as seven metres in the centuries to come.

Corn and wheat crop yields could drop by up to 40 per cent in central Canada.

The Nine Effects

The fallout from a world that's four degrees warmer is spread across nine categories.

Forest fire danger will "affect every popular continent," but will be more severe in the United States than in Canada.

Crops will suffer at low altitudes, with corn and wheat yields dropping by as much as 40 per cent. Soy bean crops in the United States, South America, Africa and Asia could also drop an average of 50 per cent.

Water supplies will be pinched as South American and Asian glaciers melt and run-off drops up to 70 per cent in South America, Africa and the Mediterranean. Glaciers in Canada, however, are expected to fare better.

Sea levels could rise up to seven metres in the long term, and 80 centimetres by the end of the century - and possibly more, if a precarious Antarctic ice sheet doesn't hold out. That could flood out 175 million people in low-lying areas, largely in Asia.

Fisheries will feel a "significant" impact due to ocean acidification, which will cause "substantial loss in revenue and jobs." Coral reef habitats will be seriously affected.

Drought could occur twice as frequently across Africa, Southeast Asia and the Mediterranean, with about two-thirds of the world's land experiencing drought more //frequently than a century ago.

Permafrost will be reduced in Canada and will almost disappear from Siberia, threatening infrastructure such as roads and homes built on it.

Tropical cyclones will increase in severity across the world, and cause increasing numbers of deaths because of rising sea levels.

Extreme temperature will plague urban eastern North America, with Toronto, Ottawa, New York, Chicago and Washington seeing their hottest days of the year jump another 10 to 12 Celsius. Similar effects will be felt in Europe (eight Celsius) and China (six Celsius).

Health problems associated with the warmer world include a spread in malaria, diarrhea and malnutrition, and an increase in heat-related deaths, which are significant - a 2003 European heat wave killed 35,000 people.

Source: Met Office Hadley Centre, UK

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