North Atlantic ocean current: Melt-water from Arctic ice sheets could slow the North Atlantic ocean current, leading to cooling in northern Europe.
Asian monsoon: Changes to weather systems in the Atlantic could have a serious effect on the reliability of Asia’s annual rainfall.
Sahara desert: Dust from the Sahara fertilises the Amazon, but if the region gets wetter, there will be less soil erosion and more chance of plants returning to the Sahara.
Scientists are working to understand how such hotspots could affect the climate – and what impact climate change will have on the hotspots themselves.
The IPCC’s fourth report, issued in 2007, highlighted the growing evidence of observed climate change from around the world and looked at future predictions.
Its evidence is based on a consensus among the scientists involved. It is mainstream thinking – endorsed by international governments – and as such it can err on the side of caution. Some have suggested that the IPCC is in fact presenting a ‘bestcase scenario’, underplaying the evidence for more violent climate change. One author based at the Met Office Hadley Centre Richard Betts says that means that the result is ‘bullet proof’ in terms of the certainty of the science it contains. ‘When I read this [the IPCC report] for the first time I did feel fear – I had worked on it for three years and I knew it was right,’ he says.
what will the world be like with a changed climate?
Scientists can predict with increasing accuracy how the climate will respond to rising levels of pollution in the atmosphere. In 2007 the IPCC highlighted the scientific predictions about the impacts of climate change over the next 50 to 100 years, revealing a world in which billions of people will be at risk. Sub-Saharan Africa, large river delta areas in parts of Asia, small island states and the Arctic regions are likely to be particularly vulnerable.
“ It’s the poorest of the poor in the world, and this includes poor people even in prosperous societies, who are going to be the worst hit and who are the most vulnerable as far as the impacts of climate change are concerned.
Rajendra Pachauri, Chair of the IPCC
the Hadley Centre’s global climate models
The UK’s Met Office Hadley Centre is spearheading international research. Early climate models were simplistic replicas of the climate, covering temperature, rain and carbon dioxide, and were more useful for monitoring changes in the weather than for predicting future climate. Today’s models include a vast number of variables and have been shown to be capable of describing historical changes in the climate with reasonable accuracy. Interactive cloud systems, oceans, land-surface cover and aerosol pollution are all factored into the predictions made by models such as the Hadley Centre’s latest (global climate model) HadGEM1. This looks at 38 different layers of the atmosphere – allowing for greater accuracy in the predictions, and more regional detail than in older models.
Africa: Many countries are already becoming drier and this is predicted to get worse. Some 75-250 million people likely to face water shortages by 2020. Farm yields in some parts will be reduced by half by 2020. Greater risk of flooding near the Equator. Sea-level rise will affect some coastal areas by the end of the century. A quarter of Africa’s population lives in coastal areas.
Continental temperature trends
Asia: More than 1 billion people facing reduced supplies of fresh water in large river basins by mid-century. Deltas in China, India and Bangladesh at risk from rising seas. Salt water likely to contaminate the ground water. Floods may bring diseases like diarrhoea and cholera. Warming oceans will affect fish and fishing communities.
Europe: More flash floods and greater coastal erosion. In Southern Europe heat and less rainfall will be bad news for farming. Human health at risk from heat waves and smoke from wildfires. Drier summers in Central and Eastern Europe will put water supplies under stress. Forests and peat areas at risk from wildfires. In Northern Europe growing seasons likely to increase, and forest likely to flourish. Less need to heat homes but risk of more winter floods.
South America: Tropical rainforest in Eastern Amazonia likely to be dry grassland by mid-century. Species such as black spider monkeys, bearded sakis, red-handed tamarins, jaguar and pumas, will come under severe threat and some truly magnificent and significant species are likely to be lost for ever. Drier, and in some areas, saltier conditions could reduce food yields. Warmer conditions could boost soybean production in temperate areas. Vanishing glaciers will threaten water supplies in cities such as Lima, Peru, as well as hydroelectric power and farming.
North America: Farmers in northern regions could have longer growing seasons for a few decades. California may dry out and become more vulnerable to winter floods. Hotter weather and wildfires will pose health hazards. Parts of the eastern coast will see more intense hurricanes and tropical storms, storm surges and flooding.
Australia and New Zealand: Australia sees increasing water shortages by 2030 and significant loss of animal and plant varieties by 2020, particularly from the Great Barrier Reef and the Queensland Wet Tropics. Water shortages predicted for New Zealand’s North Island and rising temperatures will benefit farm yields for a time on the South Island. Risk of coastal flooding from mid-century in Australia and New Zealand.
UK climate change in the 21st century
Projected temperature increases, based on one of two IPCC scenarios – Low Emissions (+2.0°C, 525 ppm CO2 in 2080s) or High Emissions (+3.9°C, 810 ppm CO2 in 2080s)
climate change in the UK
With UK temperatures expected to increase by 2-3.5 °C by the 2080s, hot summers will be more frequent and very cold winters rare. Winter flooding is predicted to become more common, while farmers face shifts in growing seasons.
Sea levels will go on rising by 26-86 cm in the South East by 2080. Extreme high-water levels are likely to become more frequent, particularly on the east coast of England, and houses on floodplains are especially vulnerable. The Thames Barrier is likely to need replacing by 2030 if today’s levels of protection are to be maintained. Flooding is likely to hit the least well-off most: the most deprived 10 per cent of the population are eight times more likely to be living in the coastal floodplain than the wealthiest 10 per cent.
A study of UK wildlife found that eight species are under threat from climate change because of changes to habitat. Increased drought could mean fewer slugs and snails available as food for song thrushes in the south of England, with the population at risk across England, Wales and Ireland if warming continues. Skylarks, black grouse, common scoter and capercaillie are also likely to see their preferred habitat disappear. Stag beetles, currently only found in southern England, could find more suitable habitat further north. A warmer South East will attract new species: mosquitoes are already on the up and there are fears that malaria carriers could soon be in the UK. Some species will find they cannot adapt: the Snowdon lily could die out while the snow bunting is unlikely to be found in the UK.
the human cost
The human costs of inaction on climate change are incalculable. Millions of the world’s poorest people will experience dramatic changes in their way of life.
Regions close to the Equator – many of which rely on small-scale farming for food – will see bad harvests from a temperature rise of just 1-2°C. Farmers may be able to adapt by using different crop varieties and relying more on irrigation. But studies suggest that temperature increases above 3°C will be hard to accommodate. Heat will be bad news for dairy farmers: cows are less fertile, produce less milk and do not live as long