The United Kingdom's climate is changing, with hotter drier summers and warmer wetter winters. Storms, floods, droughts and heatwaves are becoming more frequent and intense, and sea level rise is affecting coastal areas. The UK is also a contributor to climate change, having emitted more greenhouse gas per person than the world average. Climate change is having economic effects on the UK and presents risks to human health and ecosystems.

The UK has more than halved its greenhouse gas emissions since 1990, and under the Paris Agreement has committed to net zero emissions by 2050, via a series of carbon budgets. Parliament passed Acts related to climate change in 2006 and 2008, the latter being the first time a government legally mandated a reduction in greenhouse gas emissions. The UK Climate Change Programme was established in 2000 and the Climate Change Committee provides policy advice towards mitigation targets. In 2019, Parliament declared a 'climate change emergency'. The country phased out coal power in 2024. The UK has been prominent in international cooperation on climate change, including through UN conferences and during its European Union membership.

Climate change has been discussed by British politicians since the late 20th century, but it has attracted greater political, public and media attention in the UK from the 2000s, with the commitment to net zero now opposed by some political parties. Public opinion polls show concern amongst the majority of Britons. Various climate change activism initiatives have taken place in the UK.

Greenhouse gas emissions

Effects on the natural environment Temperature and weather changes

The Central England temperature series, recorded since 1659 in the Midlands, shows an observed increase in temperature, consistent with anthropogenic climate change rather than natural climate variability and change. According to the Met Office, climate change will affect the climate of the United Kingdom with warmer and wetter winters and hotter and drier summers. Spanish plumes will continue but bring more intense weather conditions such as hotter summer weather and summer thunderstorms.

By 2014, the United Kingdom's seven warmest and 4 out of its 5 wettest years had occurred between the years of 2000–2014. Higher temperatures increase evaporation and consequently rainfall. In 2014, England recorded its wettest winter in over 250 years with widespread flooding.

In parts of the south east of the UK, the temperature in the hottest days of the year increased by 1 °C per decade in the years 1960–2019. The highest ever recorded temperature in the United Kingdom was recorded in 2022 in Coningsby at . In 2020, the chances of reaching a temperature above were low, but they are 10 times higher than in a climate without human presence. In modest emissions scenario, by the end of the century, it will happen every 15 years and in high emissions scenario every 3–4 years. Summers with temperatures above occur in the UK every 5 years, but will occur almost every other year in the high emission scenario by 2100.

Extreme weather events The Met Office outlines that more frequent and intense extreme weather events will affect the UK due to climate change.

Floods

Due to increased rainfall from warmer and wetter winters, increased flooding is expected. An interactive map from the UK government shows areas at risk of flooding.

Heat waves

Heat waves are becoming more intense and more likely in the UK due to climate change. Of the UK's top ten hottest days on record, nine have been recorded between 1990 and 2022. The 2022 heatwave resulted in the first code red extreme heat warning in the country, instigating a declaration of national emergency, and causing wildfires and widespread infrastructure damage.

Sea level rise Between 1900 and 2022, the UK's sea level rose by . The rate of rise more than doubled between the early 20th and early 21st century to a rate of 3–5.2 millimetres per year. By 2050, it is predicted that around a third of England's coast will be affected, leading to almost 200,000 homes needing to be abandoned. The most affected regions will be the South West, North West and East Anglia.

Water and drought Droughts in the United Kingdom are expected to become more severe. Water quality in rivers and lakes may decline due to higher temperatures, reduced river flows and increased algal blooms in summer, and increased river flows in winter.

Effects on ecosystems

Warming temperatures are affecting wildlife and plant life. Some species' ranges are shifting north, and Scottish alpine plants have declined. With spring coming earlier each year, many plant and animal species are unable to adapt quickly enough. Birds are affected by climate change, with warm weather species like cattle egrets and purple herons observed breeding in the UK for the first time in the 2010s, while cold-adapted birds like lapwings have declined. More regular droughts also have cumulative implications for many British species and ecosystems. For example, in 2022, Ouse Washes wetlands was at risk of drying out.

Climate change will also affect marine life around the British Isles, including some commercially valuable fish species. The distributions of many fish species are expected to shift, with cold adapted species declining and warm adapted species becoming established.

Effects on people

Health effects

The National Health Service describes climate change as a "health emergency", citing the effects of heat waves, floods, and storms on health, as well as the increased spread of infectious diseases such as tick-borne encephalitis and vibriosis.

Due to climate change, the UK has experienced a significant increase in severe heat waves which have dire health consequences. The 2022 heatwaves contributed to nearly 3000 excess deaths – meaning people who are not expected to die during this period. This represents the highest number of deaths during heatwaves since 2004. Most of the extra deaths occurred in those aged over 65. Without climate change mitigation or adaptation measures, heat-related deaths could increase sixfold by the 2050s, particularly affecting children, the elderly and people with pre-existing conditions.

Flooding in the UK presents another major threat, currently affecting over six million people. This number expected to rise significantly as temperatures increase. Beyond physical risks, floods have severe long-lasting mental health consequences for survivors, including post-traumatic stress disorder (PTSD).

Economic effects According to the Government, the number of households in flood risk will be up to 970,000 homes in the 2020s, up from around 370,000 in January 2012.Government gambles by excluding climate change from flood insurance deal FOE 6 December 2013 The effects of flooding and managing flood risk cost the country about £2.2bn a year, compared with the less than £1bn spent on flood protection and management. WWF-UK May 2017 UK agriculture is also being affected by drought and weather changes.

In 2020 PricewaterhouseCoopers estimated that Storm Dennis damage to homes, businesses and cars could be between £175m and £225m and Storm Ciara cost up to £200m.Storm Dennis damage could cost insurance companies £225m The Guardian. 20 February 2020Storm Ciara expected to cost up to £200m in insurance claims Guardian 14 February 2020 Friends of the Earth criticised British government of the intended cuts to flood defence spending. The protection against increasing flood risk as a result of climate change requires rising investment. In 2009, the Environment Agency calculated that the UK needs to be spending £20m more compared to 2010 to 2011 as the baseline, each and every year out to 2035, just to keep pace with climate change.Cameron's claims on flood defences don't stack up FOE 6 January 2014

The British government and the economist Nicholas Stern published the Stern Review on the Economics of Climate Change in 2006. The report states that climate change is the greatest and widest-ranging market failure ever seen, presenting a unique challenge for economics. The Review provides prescriptions including environmental taxes to minimise economic and social disruptions. The Stern Review's main conclusion is that the benefits of strong, early action on climate change far outweigh the costs of not acting. The Review points to the potential effects of climate change on water resources, food production, health, and the environment. According to the Review, without action, the overall costs of climate change will be equivalent to losing at least 5% of global gross domestic product (GDP) each year, now and forever. Including a wider range of risks and costs could increase this to 20% of GDP or more. The review leads to a simple conclusion: the benefits of strong, early action considerably outweigh the costs.

Climate change made the unusual rainfall in autumn and winter 2023–2024, 10 times more probable and 20% stronger. The rainfall led to "severe damage to homes and infrastructure, power blackouts, travel cancellations, and heavy losses of crops and livestock". The damage to arable crops alone is £1.2 billion, without counting vegetables. Claims for house insurance from weather related disasters increased by more than a third. Policies to address climate change can also reduce poverty according to some experts.

Mitigation

In 2019, Prime Minister Theresa May announced the UK would strive to reach carbon neutrality by 2050, making the country the first major economy to do so. Prime Minister Boris Johnson announced in 2020 that UK would set a target of 68% reduction in greenhouse gas emissions by 2030 and include this target in its commitments in the Paris Agreement.

Calculations in 2021 indicated that, to give the world a 50% chance of avoiding a temperature rise of 2 degrees or more, the United Kingdom should increase its climate commitments by 17%. For a 95% chance, it should increase the commitments by 58%. To give a 50% chance of staying below 1.5 degrees, the UK should increase its commitments by 97%.

Energy

Under Margaret Thatcher, the UK's coal industry was reduced, with subsidies cut and coal miners' union weakened following a significant miners' strike in 1984. In 2015, the government announced all coal-fired power stations would be closed by 2025. In 2021, it brought forward this coal phase-out target to 2024.

Electric vehicles

Policies and legislation

The Climate Change Programme was launched in 2000 by the Government in response to the United Kingdom's commitments under the 1992 United Nations Conference on Environment and Development.and subsequent international climate agreements.

There are in place national legislation, international agreements and the EU directives. The Climate Change and Sustainable Energy Act 2006 aimed to boost heat and electricity micro-generation installations in the UK, helping to cut emissions and reduce fuel poverty. The Climate Change Act 2008 makes it the duty of the Secretary of State to ensure the net UK carbon account for all six Kyoto greenhouse gases for 2050 is at least 80% lower than 1990. It also created the independent Climate Change Committee to advise the government on policies to reach its goals. The Act made the UK the first country to legally mandate reductions in greenhouse gas emissions.

These targets have since been expanded on in the UK's Sixth Carbon Budget of 2021, which set the targets of reducing carbon emissions by 78% in relation to 1990 levels by 2035, and reaching net zero emissions by 2050. The Health and Care Act 2022 includes a target of carbon neutrality for the National Health Service by 2040, and an 80% reduction in emissions by 2028–32.