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Climate change

Introduction

What is climate change?

Carbon dioxide is a greenhouse gas. The presence of greenhouse gases in our atmosphere has helped to provide conditions that are suitable for life. Greenhouse gases, of which water vapour is the most important and abundant, allow the radiation from the sun to penetrate to the earth, but trap the re-radiated heat from the earth's surface. This leads to a warmed layer of atmosphere that keeps temperatures on the earth's surface within an appropriate band for human comfort. Emissions of greenhouse gases from human activity are increasing the level of greenhouse gases and thus increasing the amount of heat trapped. These changes in the earth's atmosphere have been found to contribute to changing the global climate.

The dynamics of the atmosphere are driven by the radiation received from the sun. Over time the radiation received has varied and the atmospheric systems have responded to these changes. This variation is seen in changes of climate. Records from ice core data, geological records, studies of soil and vegetation have produced evidence of past changes in the global climate. Thus climate change is a natural phenomenon. With this in mind what has then caused the need to urgently address the changing climate?

Over the last thousand years or so, human beings have begun to influence the planet in many ways. There has been a marked increase in the use of energy across the globe and a shift from biomass fuel (such as wood and so on) to fossil fuels (coal, oil and gas). Humans have harnessed the power of fossil fuels to drive machines. We have also cleared forests, releasing stored carbon back into the atmosphere and reducing the areas where carbon can be stored (in plants and trees). These actions have increased the concentration of carbon dioxide and other greenhouse gases in the atmosphere. The changes in greenhouse gas concentration have begun to feed into the atmospheric systems leading to changes in climate that cannot be accounted for by natural climate variability.

The changes we are currently observing are due to emissions over the last 100 years. The influence of the emissions we are creating today will be seen in the next twenty to fifty years. Any future emissions will impact on future generations. As human action has influenced the climate, so human action can reduce future climate impacts.

Whilst we can act to reduce future emissions, there are indications that some level of climate change is now inevitable. Current research estimates suggest that even if greenhouse gas emissions were stabilised immediately (requiring a reduction of around sixty percent overnight) the response of the climate system to past emissions would still lead to a rise of around 1ºC in global mean temperature, and a one-metre rise in sea level due to thermal expansion of the oceans. Thus policy makers are turning their thoughts to addressing the likely impacts of predicted climate change.

Evidence of climate change in the UK

Knowledge of possible future impacts on climate change is important for guiding policy. The UK Government set up the UK Climate Impacts Program (UKCIP) in 1997 to assess the impacts of climate change in the UK. The UKCIPS program has used current best scientific knowledge of atmospheric processes to draw out the possible impacts for the UK in more detail.

The forecast impacts of climate change from the studies under this programme suggest that the UK will experience:

• Annual warming of 1ºC to 5ºC by 2080
• Greater warming in summer and autumn than spring and winter
• Wetter winters, drier summers, but little change in annual average rainfall
• Decrease in snow fall
• More frequent winter storms
• More intense winter rainfall
• Increase in number of very hot days
• Decrease in number of very cold days, with reduction in heating days
• Lengthening of thermal growing season
• Sea level rise of 9 to 69cm by 2080 with continued rise for many centuries
• Increase in sea surface temperature
• Significant reduction in storm surge return periods for some locations.

Evidence of climate change in Yorkshire and Humber Region

Looking regionally, the climate predictions for the Yorkshire and Humber will change significantly by 2050 and dramatically by 2080. Below is a summary of the main impacts:

• Mean annual temperature is expected to rise by between 1ºC and 2.5ºC by the 2050s and 1.5ºC and 4ºC by the 2080s. Warming will take place throughout the year with the greatest rise in the summer months.
• The warming will be accompanied by wetter winters, but drier summers, autumns and springs leading to a reduction in rainfall of up to ten percent. Heavy rainfall events in winter will increase in frequency and intensity.
• There will be a four-fold decrease in frost nights, a five-fold increase in warm summer nights and a two- or three-fold increase in warm summers days.
• A reduction in the number of days with fog is anticipated and reductions in cloud cover of between ten and twenty percent along the coast.
• Soil moisture will be reduced during the summer months.
• Sea level rise along the Yorkshire coast is estimated to be higher than 1961-90 levels for low emissions scenario by the 2080s. Under the high emissions scenario the rise is estimated at 75cm.

To find out more about what the council is doing to tackle climate change, see Sustainability: Environmental projects and campaigns.

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