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they tend to breed less.

      Adapting to climate change will be difficult for small and family farms, for pastoralists and people who make a subsistence living on poor land, especially in parts of Africa and Asia. Without adaptation, crop yields are likely to fall and be badly affected by extreme weather events. Wealthy areas rich in resources are likely to adapt more easily.

      Fishing communities will struggle as fish species migrate or die out. River fish will be affected as rainfall and snow melt patterns change. Millions of people, particularly in some of the poorest communities, rely on fishing to supplement their families’ diet.

      Food will not be the only area of the economy that is damaged. The timber industry will see extreme weather and more wildfires, insects and pests.

      Thousands – if not millions – of people have already left their homes because of the changing climate. The International Red Cross says 25 million people could already be classified as ‘environmental refugees’ in 2001 and it has been estimated that climate change could push the total number of displaced people worldwide to 1 billion by 2050. One study estimated that around 15 million were likely to be displaced from Bangladesh alone. In China 4,000 villages are likely to be abandoned as a result of the spread of the Gobi desert. Huge numbers of people on the move are thought likely to increase the risk of conflict in some areas where resources are most scarce.

      health risks

      The health of millions is at risk. The very young and very old will be most vulnerable. The IPCC warns of:

       more malnutrition with long-term impacts for child growth and development

       more deaths, disease and injury due to extreme weather events; people in urban areas will be most at risk – cities intensify temperatures because buildings hold heat

       an increase in diseases, including diarrhoea and cholera as a result of water contamination caused by flooding

       more problems such as chest infections and asthma because of increased low-level ozone

       changes to the way infectious diseases spread.

      The warming of colder regions will lead to fewer people dying of the cold. And changes to the climate could limit the spread of malaria in some parts of Africa. But over all, the health benefits of climate change are vastly outweighed by the negative effects, particularly in poorer areas.

      Mortality and climate change Estimated deaths in 2000 attributed to climate change (compared to a 1961–1990 baseline) show that Sub-Saharan Africa and the rest of the developing world bear the health burden of climate change.

      the cost to wildlife

      Plants, birds and animals cannot easily adjust to rapid changes – either in temperatures or in their food supply. The potential toll on the wildlife-rich rainforest of the Amazon is an extreme example. Experts believe the golden toad and harlequin frog – both native to Costa Rica – have disappeared as a direct result of climate change. Animals as diverse as polar bears, tigers, penguins and pikas are at risk. Some 70 per cent of coral in the Indian Ocean has already died as a result of the heat.

      The IPCC predicts that 20-30 per cent of plant and animal species are at an increased risk of being wiped off the face of the Earth if global average temperatures rise by more than 1.5-2.5°C. Indeed some scientists put climate change at the top of the list of threats to biodiversity in many regions.

      JUMPING OFF POINT:

      Scientist JA Pounds says Central American frog species have disappeared due to deadly infectious diseases spurred by global warming. ‘Disease is the bullet killing frogs, but climate change is pulling the trigger,’ he said.

      In the UK long dry periods damage food supplies for migrating birds. Breeding redshanks, lapwings and snipe dropped by up to 80 per cent at five reserves in the south of England following the dry summer in 2005. And warmer seas are leading to fewer plankton off the British coast, with an impact on the sand eel population – resulting in less food for nesting birds like puffins.

      As plants, insects, birds and animals migrate so the nature of our landscape will change. Traditional English woodland, populated with oak, beech and bluebells could become a thing of the past, as sycamore becomes the more dominant species and cow parsley could force snowdrops and bluebells out.

      the economic cost

      It’s easy to see the immediate costs of clearing up damage caused by floods, storms or warping railway tracks; less obviously, farmers across the world are paying the price in lost harvests, lower yields and higher prices. People who rely on rainforests for food, farming and forestry are losing their way of life.

      In the developed world, the insurance industry generally picks up the tab for extreme weather. But in Europe the cost of flood damage alone would be expected to rise by up to £82 billion a year, and the costs of Hurricane Katrina have been put at US $125 billion. Many people in the poorest countries do not have insurance policies; but even in the rich developed world, many can’t afford insurance as the risk of extreme weather rises – particularly for those living in flood plains.

      An economic assessment of the cost of climate change, commissioned by the UK Government and published in 2006, suggested that unchecked climate change could damage economic well-being worldwide by at least 5 per cent and by as much as 20 per cent. In other words a fifth of the world economy is at risk.

      ‘The impacts of climate change are not evenly distributed – the poorest countries and people will suffer earliest and most.’ The Stern Review, October 2006

      how different temperature rises could affect us

      The IPCC predicts temperature increases of 1.8-6.4 °C this century, depending on the amount of fossil fuel used. Its best estimate is 4 °C. While rises at the lower end of this spectrum would have terrible impacts for millions of people around the world, a rise of more than 6 °C could spell shocking global consequences.

      HOT TIP:

      A future with extreme climate change? Don’t go there. Experiments in South Africa’s Succulent Karoo desert show that a 4-6 °C rise in daytime temperature kills three quarters of plant species.

      the six-degree scenario

      Evidence suggests that the end-Permian extinction, 251 million years ago, may have been triggered by a rise of temperatures of 6 °C: it almost wiped out life on Earth. Forests, swamps and savannahs were washed away, land turned to desert; the warming oceans, which lose oxygen as temperatures rise, would have become stagnant and toxic. Some scientists believe the warming of the ocean would have been enough to trigger the release of huge clouds of methane from the sea bed, poisoning the atmosphere. Life on Earth did survive 6 °C of warming, but those changes took place over 10,000 years. Human releases of carbon dioxide are almost certainly happening faster than any natural releases since the beginning of life on Earth.

      Writer Mark Lynas has studied historical records to examine the potential effects of temperature rises of up to 6 °C. Here is a summary of his six-degree scenario:

      +1 °C: Deserts spread across parts of the United States, turning farmland to dust from Canada in the north to Texas in the south. The Gulf Stream could switch off – plunging Europe into an icy winter. Coral reefs around the world are wiped out.

      + 2 °C: Oceans turn increasingly acidic, killing off plankton and affecting sea life. European summers are plagued by heat waves as strong as the killer of 2003. Wildfires spread around the Mediterranean. Greenland tips into irreversible melt, accelerating sea-level rise and threatening coastal cities. The polar bear and walrus become extinct.

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