Climate change

•  Annual average daily mean temperature in the South West increased by 1.37°C between 1961 and 2006
• Between 1961 and 2006 precipitation in the South West increased by 28.6% increase in the autumn and decreased by 8.8% decrease in the summer
• Over the 20th century, absolute sea level (i.e. corrected for land movement) around the South West rose by around 1 mm/yr
• Climate change projections (UKCP09)

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.

Climate change is a cross cutting issue – the impacts of which will affect all sectors, organisations and communities. It presents both challenges and opportunities in relation to flooding, the quality of our air and soils, the availability and quality of water.  It will also affect our landscapes, heritage, habitats and species.  Climate change is an integral part of achieving sustainable development and delivering sustainable communities. Therefore preparing for its impacts will help reduce vulnerability as well as increase the resilience of our natural environment, economy and communities.  Achieving a reduction in greenhouse gas emissions will help to minimise the effects of future climate change.

Observed Climate Trends in the South West

Temperature

Annual average daily mean temperature in the South West increased by 1.37°C between 1961 and 2006.  This was  similar to annual trends seen in London, the South East and the East of England.  The region saw a larger increase in winter temperatures (1.72°C) than in summer (1.41°C) (UKCP09).

Observed change in average daily temperature in the South West between 1961 and 2006, based on a linear trend (statistically significant at the 95% level)

	Spring	Summer	Autumn	Winter	Annual
Change in daily mean temperature (°C)	+1.40	+1.41	+1.15	+1.72	+1.37
Change in daily minimum temperature (°C)	+1.55	+1.65	+1.26	+1.89	+1.54
Change in daily maximum temperature (°C)	+1.23	+1.18	+1.07	+1.58	+1.21

UKCP09

The annual number of days with air frost has reduced in all regions of the UK between 1961 and 2006. There are now typically between 20 and 30 fewer days of air frost per year, compared to the 1960s, with the largest reductions in northern England and Scotland.  The South West saw an average decline of 20.9 days (UKCP09).

Observed change in variables derived from temperature in the South West between 1961 and 2006, based on a linear trend (statistically significant at the 95% level)

Change in Heating Degree Days	Change in Cooling Degree Days	Change in days of air frost
-16.90%	+11.6 days	-20.9 days

UKCP09

Definitions of cooling degree days and heating degree days can be found in the Annex of the Climate of the UK and recent trends report

Precipitation

Annual average precipitation has not significantly changed in England and Wales since records began in 1766, although the South West has experienced an increase between 1961 and 2006.  

Seasonal rainfall is highly variable, however, we are seeing a decline in summer rain and an increase in the amount falling in winter.  This trend was experienced in the South West between 1961 and 2006, with a 28.6% increase in autumn precipitation and an 8.8% decrease in summer.  During the same time period, the region also saw a small increase in the number of days of rain in autumn and winter and a small decrease in the number of days of rain in spring and summer (UKCP09).

Observed change in precipitation totals and the number of days of rain in the South West between 1961 and 2006, based on a linear trend (Note: neither precipitation trends are statistically significant at the 95% level)

	Spring	Summer	Autumn	Winter	Annual
Change in total precipitation (%)	4	-8.8	28.6	15.9	9.7
Change in number of days with  ≥1 mm rain	-1.4	-1.3	4.1	2.2	1.9

 UKCP09

Rising sea levels and more frequent storms will result in an increase in risk of inland and coastal flooding and our low lying communities are particularly vulnerable.  There are around 81,019 households and businesses in the region within the Environment Agency’s Flood Zone 2.  These are areas with an annual probability of flooding between 1 in 1000 (0.1%), 1 in 100 (1%) in the case of river flooding, or 1 in 200 (0.5%) in relation to coastal flooding (Environment Agency Flood Map).

By the 2080s it is expected that inland flooding will have increased by four to six times compared to present levels, with a Standard of Protection of 1 in 100 event now becoming a 1 in 17 event. 

Sea level rise

Sea level around the UK, relative to land, is changing for two reasons; firstly because the volume of the oceans is changing and secondly because land is moving in response to the melting of the ice-sheet following the end of the last ice age – the latter is causing a general upward land movement in northern Britain and downward movement in southern England (UKCP09).

Over the 20th century, absolute sea level (i.e. corrected for land movement) around the South West rose by around 1 mm/yr.  However, there are indications that the increase has been at a faster rate than this in the 1990s and 2000s.

Sea level in Newlyn (Cornwall), a location with one of the five longest sea level records in the UK, has risen by approximately 20 cm since 1920 (Defra, 2009).

 Changes in sea level at Newlyn (Cornwall) since 1946

Average annual change in mean sea-level (mm/yr)	1.0
Average annual change in extreme high water level (mm/yr)	2.1
Average annual change in extreme low water level (mm/yr)	1.3

Defra, 2009

There is also evidence that annual average extremes in high water are increasing faster than annual average extremes in low water.

Climate change projections in the South West (UKCP09)

The UK's Climate Impacts Programme published projections of the likely UK climate for the rest of this century.  These new forecasts, known as the UKCP09 Projections, are based on complex modelling of the global atmosphere and oceans.

The Government indicates that we are currently on the medium emissions path in terms of greenhouse gas emissions.  Based on the data from UKCP09, the data below provides an overview of the key findings for the South West of England for the 2020s, 2050s and 2080s under the central estimate of the medium emissions scenarios.

 South West climate change projections for 2020, 2050 and 2080

	Amount of change from 1961 – 1990 (1)
Potential change		In the 2020s	In the 2050s	In the 2080s
Hotter summers	Increase in summer mean temperature	+1.6oC (0.5oC to 2.7oC)	2.7oC (1.3oC to 4.6oC)	3.1oC (1.4oC to 5.1oC)
	Increase in mean daily maximum temperature	2.1oC (0.5oC to 4oC)	3.8oC (1.4oC to 6.8oC)	4.3oC (1.7oC to 7.6oC)
	Increase in mean daily minimum temperature	1.6oC (0.5oC to 2.9oC)	2.9oC (1.2oC to 5oC)	3.3oC (1.5oC to 5.5oC)
Warmer winters	Increase in mean temperature	+1.3oC (0.6oC to 2oC	2.1oC (1.1oC to 3.2oC)	2.3oC (1.3oC to 3.5oC)
Change in precipitation	Change in annual mean precipitation	0% (-5% to 6%)	0% (-5% to 6%)	0% (-6% to 6%)
Wetter winters	Change in winter mean precipitation	7% (-2% to 20%)	17% (4% to 38%)	18% (3% to 41%)
Drier summers	Change in summer mean precipitation	-8% (-27% to 14%)	-20% (-42% to 7%)	-20% (-45% to 8%)

 UKCP09

Projections of UK coastal absolute sea level rise (not including land movement) for 2095 are in the range from approximately 12–76 cm. A high sea level range has been defined to assess vulnerability to an extreme, low probability rise in sea level rise. For the UK this absolute sea level rise estimate is 93 cm to 1.9 m by 2100.

Vertical land movement in the SW region is approximately -0.5 mm per year.

Table Projected sea level rise in the south West 2040s and 2080s *

	2040	2080
Weston-super-Mare	18 cm	37 cm
Newlyn	20 cm	40 cm
Poole	18cm	37 cm

*Under a medium emissions scenario, central estimate (including land movement).

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