Climate change

• Annual average daily mean temperature in the South West has increased by 1.37°C between 1961 and 2006.
• There has been increased seasonal and annual total precipitation in the South West between 1961 and 2006, with the largest increase seen in autumn (28.6%).
• Absolute sea level around the South West has risen by around 1 mm/yr over the 20^th century.

The Earth would be about 33°C colder if it were not surrounded by gases such as water vapour, carbon dioxide and methane, which trap heat from the sun. However, if the amount of heat-trapping gases increases, less heat can escape back into space, the natural greenhouse effect is enhanced and the Earth gets warmer.  An animated guide to climate change is available from the BBC.

For about a thousand years before the Industrial Revolution, the amount of greenhouse gases in the atmosphere remained relatively constant. Since then, the concentration of various greenhouse gases, including carbon dioxide, methane, nitrous oxide and fluorinated gases, has increased. The amount of carbon dioxide, for example, has increased by more than 30% since pre-industrial times and is still increasing at an unprecedented average rate of 0.4% per year. This is mainly due to the combustion of fossil fuels and deforestation.

The Intergovernmental Panel on Climate Change (IPCC) reported in 2001 that this increase comes from human activities, because the changing isotopic composition of the atmospheric carbon dioxide is different from that of fossil origin.The climatic response to these increased greenhouse gas concentrations is complex, but can, to an extent, be predicted using atmosphere and ocean mathematical models. Predictions may also be carried out for possible future scenarios of economic development and anthropogenic (man-made) greenhouse gas emissions.

The UK is acting now to adapt to climate change and to reduce the risk by reducing our contribution to the causes.  Under the Kyoto Protocol, the UK must reduce its greenhouse gas emissions by 12.5% below base year levels over the 2008 to 2012 commitment period.

In 1997, the UK committed itself beyond to go beyond our Kyoto Protocol target by setting a national goal to reduce carbon dioxide emissions by 20% below 1990 levels by 2010. In 2003, the Energy White Paper adopted a longer term goal to put the UK on a path to reduce carbon dioxide emissions by some 60% by 2050, with real progress by 2020.

Although the UK is on line for meeting greenhouse gas targets set by the Kyoto agreement by 2008–2012 (12.5% below 1990 levels), it is currently unlikely that it will meet its own domestically set target of 20% below 1990 levels by 2010. Despite making carbon dioxide cuts we still need to adapt to the changes in the climate system that are unavoidable, due to past emissions.

Research published by the Royal Society concludes that climate policy has essentially ignored the crucial importance of current emission trends and their impact on cumulative emissions. As a consequence, although we should aim to reduce global emissions in line with a 2ºC target, adaptation policy must focus on climate change impacts associated with 4ºC or more.

The first South West Climate Change Action Plan, led by the SW Regional Assembly, was launched in September 2008. The Plan focuses on the immediate practical, regional action up to 2011 that will be most effective in reducing our vulnerability to climate change and reducing our emissions.

Annual average daily mean temperature in the South West has increased by 1.37°C between 1961 and 2006. The increase in average daily mean temperature between 1961 and 2006 has been larger in winter (1.72°C) than in summer.  The average annual number of days of air frost has also decreased by 20.9 days between 1961 and 2006.

There has been increased seasonal and annual total precipitation in the South West between 1961 and 2006, with the largest increase seen in autumn (28.6%). The only exception to this pattern is a small decrease in total precipitation during summer (8.8%). In addition to changes in the seasonality of precipitation, there have also been changes to its characteristics. In the South West there has been an increase of approximately 5% from 1961-2006 in the contribution from heavy precipitation to winter precipitation. In summer, there has been a decrease of around 5%.

Absolute sea level (i.e. corrected for land movement) around the South West has risen by around 1 mm/yr over the 20^th century, and there are indications that the increase has been at a faster rate than this in the 1990s and 2000s. The nature of land movement in the South West (where land levels are generally getting lower through time) is likely to enhance the effect of rising sea levels. There is some evidence that annual average extremes in high water are increasing faster than annual average extremes in low water (Proudman Oceanographic Laboratory)

There is a growing evidence base of local data that can be used to help analyse the impacts of climate change in the South West's counties.

We have made a start in bringing this data together in one place for each of our counties, which can be downloaded to the right of this screen.

These profiles contain climate related data sets for the counties of Cornwall, Devon, Dorset, Gloucestershire, Somerset and Wiltshire. They include both directly related climate variables such as temperature and sea level along with more indirectly related information such as energy use, carbon/ecological footprints and the occurrence of skin cancer.

Most of this data is freely available on the internet and where possible sources and web links have been provided for those requiring further information. In some situations data is not freely available and in these cases contact details or web addresses have been provided for those who may wish to request or purchase the data.

If there is any additional data you know of, or would like to see included in these profiles please contact Annette Carr.

• South West Climate Change Action Plan
• South West Regional Climate Change Impacts Scoping Study - Warming to the Idea