The impacts of global warming<br />AS Geography<br />
Prediction problems <br />Projected temperature changes relative to 1980–99 based on three economic scenarios<br />
Prediction problems <br /><ul><li>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 6.0C by 2100.
The large range reflects the fact that there are many uncertain factors impacting on predictions of future climate change. </li></li></ul><li>Prediction problems <br /><ul><li>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. </li></li></ul><li>Sea-level rise<br /><ul><li>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. </li></li></ul><li>A tipping point? <br /><ul><li>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.</li></li></ul><li>A tipping point? <br />Possible feedback mechanisms:<br /><ul><li>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).</li></li></ul><li>The Arctic <br /><ul><li>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. </li></li></ul><li>The Arctic <br />Arctic region: summary of key changes<br />
The Arctic <br /><ul><li>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. </li></li></ul><li>The Arctic <br /><ul><li>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. </li></li></ul><li>Africa <br /><ul><li>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.</li></li></ul><li>Africa <br />Global warming vulnerability in Africa<br />
Africa <br /><ul><li>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: