Scientists believe that a certain amount of climate change is inevitable over the next few decades, irrespective of future carbon emissions. The UK Government and businesses are beginning to assess what the impacts might be for the UK and to develop strategies and tools for dealing with them. Without effective action to tackle the causes of climate change, climate-related risks and damages will increase. Although climate change may bring some opportunities and benefits as well as threats (see opposite), the larger the changes, and the rate of change, the more the adverse effects will predominate.
In the past most of the effort directed at climate change in the UK concentrated on ‘mitigation’, or minimising change by reducing greenhouse gas emissions. However, as it has become more widely accepted that certain changes are likely to happen in the next 30–40 years, planning for and adapting to them has become more important.
The changing climate
Global temperature has risen by about 0.6ºC over the past 100 years, and 1998 was the single warmest year in the 142-year global instrumental record. A large part of the warming over the latter part of this period is likely to be due to human activities and cannot be explained solely by our understanding of the natural variability of the climate system. The UK climate has also changed over the same period, and many of these changes are consistent with the warming of global climate. Central England temperature rose by almost 1ºC through the 20th century. The decade of the 1990s was the warmest in central England since records began in the 1660s. The warming over land has been accompanied by a warming of UK coastal waters. Hot summer days with daytime temperature in central England exceeding 25ºC have become more common – almost twice as many on average during the 1990s compared to the first half of the 20th century – while days with air frosts have been declining in frequency. The UK’s thermal growing season for plants is now longer than at any time since the start of the record in 1772.
Winters across the UK have been getting wetter, with a larger proportion of the precipitation falling in the heaviest downpours, while summers have been getting slightly drier. The average rate of sea-level rise during the last century around the UK coastline, after adjustment for natural land movements, has been approximately 1 mm per year. Although the last decade has seen an increase in gale frequency in the UK, this increase is not unprecedented in the historic record.
The main source of advice on preparing for climate change is the UK Climate Impacts Programme (UKCIP). It offers information about the future climate and various tools to help organisations assess the likely impacts on them and how to prepare. In 2002 UKCIP produced four climate change scenarios (often referred to as UKCIP02) which present four different descriptions of how climate may change, based on four different emission scenarios. It is not possible to say which scenario is more likely, as this is mainly dependent upon future greenhouse gas emissions. The scenarios provide alternative views of the future, and together show a broad range of changes that we may face.
The effect of greenhouse gas emissions on future climate
Much of the change in climate over the next 30–40 years has already been determined by historic emissions and because of the inertia in the climate system. We are likely, therefore, to have to adapt to some degree of climate change however much future emissions are reduced. The climate of the second half of the 21st century, and beyond, will be increasingly influenced, however, by the volume of greenhouse gases emitted by human society over the coming decades.