The impacts of global warming
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The impacts of global warming






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    The impacts of global warming The impacts of global warming Presentation Transcript

    • The impacts of global warming
      AS Geography
    • Prediction problems
      Projected temperature changes relative to 1980–99 based on three economic scenarios
    • Prediction problems
      • The Intergovernmental Panel on Climate Change (IPCC) has produced a range of ‘scenarios’ showing possible future temperature rises (see previous slide).
      • The forecasts of warming range from 1.5 to 6.0C by 2100.
      • The large range reflects the fact that there are many uncertain factors impacting on predictions of future climate change.
    • Prediction problems
      • There is uncertainty about the size of the global population in 2100.
      • The rates of economic growth and related growth in emissions are not known.
      • The future energy mix, i.e. fossil fuels versus renewable sources, is difficult to predict.
      • The exact physical response of the climate system to enhanced greenhouse emissions is unclear, especially the scales of positive and negative feedback.
      • If people adopt a ‘sustainable’ approach to economic growth, global warming might be minimal, but a ‘business as usual’ track may lead to major warming.
    • Sea-level rise
      • Sea-level rise is also uncertain. The IPCC estimates a rise in the range of 0.2 to 0.8 m by the 2090s.
      • Uncertainty about the exact rise is cause for concern for low-lying coastal countries such as the Netherlands, Bangladesh, and many small island states in the Pacific and Indian Oceans.
    • A tipping point?
      • There are concerns that global warming may not be gradual.
      • The idea of a tipping point is that the Earth’s climate may ‘jump’ quickly from its current state to a new one rather than changing by gradual transition.
      • A possible cause of this ‘jump’ might be positive feedback mechanisms that amplify minor changes.
    • A tipping point?
      Possible feedback mechanisms:
      • Mass forest death, caused by small temperature rises, triggering huge releases of carbon dioxide.
      • Arctic sea-ice melt leading to a huge rise in albedo. This would lead to the retention of more solar radiation and the reflection of less back into space. The outcome would be ‘runaway’ warming.
      • Changes to the pattern of ocean current circulations could drastically alter temperatures in some latitudes (a Day After Tomorrow scenario).
    • The Arctic
      • The high northern latitudes above the Arctic Circle are a unique environment.
      • Indigenous people, such as the Inuit and Saami, eke out an existence in an incredibly harsh climate.
      • In 2005 the Arctic Climate Impact Assessment (ACIA) identified a series of major climate change impacts in the Arctic.
      • The Arctic is probably the first location in the world to record a full range of clear global warming signals.
    • The Arctic
      Arctic region: summary of key changes
    • The Arctic
      • Ecosystems are under particular threat as sea ice and tundra recede.
      • Tundra areas are likely to become forested and this will have a huge impact on both flora and fauna.
      • Migratory mammals, such as caribou and polar bears, are particularly threatened.
      • The impacts on people are likely to be equally severe.
    • The Arctic
      • There may be positive outcomes, such as a longer tourist season, shorter winters and more opportunities for farming.
      • In Greenland, retreating ice is already exposing mineral and fossil fuel deposits.
      • On balance, however, the 2005 ACIA paints a gloomy future for one of the last pristine environments left on Earth.
    • Africa
      • Much of Africa is vulnerable to climate change.
      • High poverty rates, heavy dependence on subsistence farming or a few cash crops, high rates of HIV/AIDS and low levels of investment are commonplace.
      • Reliance on farming and scarce natural water resources, plus a lack of capital, make adapting to climate change a major challenge.
      • Some areas may benefit from a longer growing season, but most areas will suffer.
    • Africa
      Global warming vulnerability in Africa
    • Africa
      • An Oxfam report, ‘Africa up in Smoke’ (2005), suggested that climate-change stress could lead to a range of disastrous scenarios for much of Africa, including:
      • more frequent drought and associated famine
      • heightened tensions over scarce resources, leading to more conflict
      • reduced food security due to more unreliable rainfall
      • reduced cash crop yields and/or failure of some cash crops in some areas
      • rising water stress
      • changes to ecosystems as climate belts shift
      • possibly more frequent cyclones and floods