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There is an overwhelming scientific consensus worldwide, and a broad political consensus, that greenhouse gas emissions are affecting global climate, and that measures are needed to reduce these emissions significantly so as to limit the extent of climate change. The term 'climate change' is used predominantly to refer to global warming and its consequences, and this policy briefing will address these issues.

What is global warming?

Although long-term fluctuations in global temperature occur due to various factors such as solar activity, there is scientific agreement that the rapid global warming that has occurred in recent years is mostly anthropogenic, i.e. due to human activity. The absorption and emission of solar radiation by greenhouse gases causes the atmosphere to warm.

What global warming has occurred?

Human activities such as fossil fuel consumption and deforestation have elevated atmospheric levels of greenhouse gases such as carbon dioxide, methane and nitrous oxide significantly since pre-industrial times. This has contributed to an increase of land temperatures by 0.25 °C per decade since 1979. Ocean temperatures have also risen, and numerous other indicators of increasing temperature include the retreat of glaciers, the melting of polar ice, and changes in wildlife behaviour. An increase in temperature of 1.1-6.4 °C between 1990 and 2100 is expected, depending on the model used and on the extent to which greenhouse gas emissions are reduced.

What will the consequences of global warming be?

A rise in sea levels due to melting of ice caps is expected to occur. Rises in temperature will have complex and frequently localised effects on weather, but an overall increase in extreme weather conditions and changes in precipitation patterns are probable, resulting in flooding and drought. The spread of tropical diseases is also expected. The repercussions for agriculture and ecology are likely to be severe. A slowing of the thermohaline circulation in the oceans is possible, and would result in considerable changes in Northern European climate.

What can be done to reduce climate change?

  • Reduce energy demands The most effective reduction in greenhouse gas emissions will come from a reduction in demand for energy. This can take the form of changes in lifestyle, such as the use of public transport instead of private cars, and a reduction in flights. Numerous measures and technologies can be used to increase efficiency; for example, low-energy lightbulbs, and domestic appliances that are designed to waste less electricity. Combined heat and power (CHP) harnesses the heat that is produced as a by-product of electricity generation and utilises it, greatly increasing the efficiency of power stations.
  • Renewable energy The harvesting of renewable energy sources has the potential to replace a proportion of our fossil fuel demands. The UK already derives 2% of its electricity from hydro-electric schemes, but the difficulty of finding suitable sites means this is unlikely to increase significantly. Most recent renewable energy projects have been in the form of wind farms, although there is debate over how much energy these can supply, and concern over the visual impact of wind turbines. The UK has as yet done little to exploit its resources in terms of geothermal, solar, tidal or wave power.
  • Biofuels Biodiesel and bioethanol can replace fossil fuels in road transport and energy generation and are potentially an attractive strategy to combat climate change. However, cultivation of crops for biofuels uses land which could otherwise be used for food crops, and in parts of the developing world is a significant cause of deforestation, thereby contributing to carbon emissions. Importing and processing biofuel crops also results in the emission of carbon, so careful regulation and choice of technology, and of the source of plant material, is necessary. Marine algae, including phytoplankton and kelp, may offer alternatives to land-based biofuel crops. Biotechnology to generate liquid fuels from whole plants, including wood and stems, will make second generation biofuels more efficient than first generation fuels that are also used as food.
  • Nuclear power Nuclear power already supplies a quarter of UK electricity, but this proportion will fall as power stations are decommissioned in the next few years. A new generation of nuclear power stations could generate sufficient energy to provide a realistic alternative to fossil fuels. However, concerns about safety and nuclear waste mean that a long review process would be necessary before any new nuclear power stations could be built, and this technology is very expensive.
  • Carbon sequestration Natural carbon sequestration occurs in forests and soils, and measures such as reforestation and changes in farming practices can be taken to increase this. The capture and storage of carbon dioxide from large emitters, such as power stations, at source would also reduce atmospheric carbon emissions. Various technologies to do this are promising and could reduce power station emissions by 90%, although the energy demands of the power plant would be increased. Carbon dioxide could be stored in deep geological formations, deep oceans or by mineral storage.
  • Adaptation to climate change Global warming is already affecting the climate, and even if all greenhouse gas emissions were halted immediately further increases in temperature would be expected to occur. Consequently, any policy on climate change needs to address the issue of adaptation to changed weather patterns, for example by creating areas of marshland to alleviate flooding.

Government measures

UK government attempts to reduce greenhouse gas emissions have focused largely on the emissions trading scheme by which companies with lower emissions are financially rewarded. Impetus for action came from the Stern Review, which concluded that the economic consequences of failure to tackle climate change would be much more severe than the costs of immediate action.

The UK has been signed up to the Kyoto Protocol since 1995. The Kyoto Protocol is an international agreement linked to the United Nations Framework Convention on Climate Change, which commits its Parties by setting internationally binding emission reduction targets.

The UK government did not meet its own target of a 20% reduction in greenhouse gas emissions from 1990-2010, but it did pass the Climate Change Act in 2008 and established a framework to develop an economically credible emissions reduction path.  The Act provides the UK with a legal framework, including a long-term target for emissions in 2050, 5-year carbon budgets on track to that target, and the development of a climate change adaptation plan.

The Committee on Climate Change (CCC) advises the government on emissions targets and reports to Parliament on progress made in reducing greenhouse gas emissions.


Further information

Reporting Greenhouse Gas Emissions - POST Note 428

Climate Variability and Weather - POST Note 400

Climate change science - POST Note 295

The United Nations Framework Commission on Climate Change

The Intergovernmental Panel on Climate Change

Stern Review on the Economics of Climate Change

Royal Society on Climate Change


We made the following policy responses on climate change and statements on related issues:

22 September 2008
Towards Carbon Capture and Storage (with RSC and IoP)
Department for Business, Enterprise and Regulatory Reform

19 September 2008
Renewable energy strategy
Department for Business, Enterprise and Regulatory Reform

2 June 2008
Carbon capture and storage (with IoP and RSC)
Environmental Audit Committee

25 April 2008
Greener homes for the future?
Environmental Audit Committee
1 Oct 2007
Are biofuels sustainable?
Response to the Environmental Audit Committee

3 Mar 2006
Climate Change: Bioenergy
A response to the Environment, Food and Rural Affairs Committee

27 Jan 2005
Climate Change: Looking forward
A response to the Environment, Food and Rural Affairs Committee