Evidence that the climate is changing
It is unequivocal that human influence has warmed the atmosphere, ocean, and land. Measurements of the average temperature at the Earths surface show it has risen by about 1.34 to 1.41 C since the pre-industrial period. Each of the last three decades have been hotter than the previous one and the last 10 years 2015-2024 were the warmest 10 years on record. This change in temperature hasnt been the same everywhere. It has increased more over land than over the oceans and has been more than twice as fast in the Arctic. The United Kingdom UK is experiencing rising temperatures. The most recent decade 2015-2024 has been on average 1.24C warmer than the 1961-1990 average. All ten of the warmest years in the UK in a series from 1884 have occurred in the 21st Century. 2022 was the UKs hottest year on record, with an average year-round temperature above 10C seen for the first time. 40C was recorded in the UK for the first time in 2022. While the climate is warming, temperatures arent expected to rise every single year.
Natural variability will still cause comparatively cold years and seasons, but these events will become less common. Along with warming at the Earths surface, many other changes in the climate are occurring, such as
Warming oceans
Its not only the temperature at the Earths surface that is rising. The temperature of the oceans has been increasing too. This warming has been seen all the way down to 2 km beneath the surface. The chemistry of the oceans is also changing. They have absorbed about one third of the total carbon dioxide emissions since 1980.
This is causing the acidity of the oceans to increase ten times faster than at any point in the last 65 million years. Melting polar ice and glaciers
Over the past few decades, the ice sheets the great masses of land ice at the poles in Greenland and the Antarctic have shrunk. Glaciers have shrunk too, between 2000 and 2023, it is estimated that globally glaciers lost 5 of their remaining ice. This loss varies by region, with Central European glaciers seeing nearly 40 decline. At present melt rates, many glaciers globally will not survive the 21st century. Arctic Sea ice has decreased in area since the 1970s, by about 40 in September and about 10 in March. There is no significant trend in Antarctic Sea ice, likely due to other regional effects. Rising sea levels
The expansion of water in warming oceans and melting land ice and have caused sea levels to rise. Global sea level has risen by around 20 cm over the past century, likely faster than at any point in the last 3,000 years. From 1993 to 2018, glacier melt accounted for about 21 of global sea-level rise, and ocean warming 42. The rate of sea level rise has more than doubled since satellite measurements began, increasing from 2.1 mmyr in 1993-2002 to 4.7 mmyr in 2015-2024.
Sea-level rise will continue for centuries even after global-mean temperatures have stabilised, but the full extent to which it will rise will depend on the total amount of greenhouse gas emissions we emit. More extreme weather events
More damaging extreme weather events are being seen around the world. Heatwaves, heavy rainfall events and droughts are occurring more often, and they are more intense. We expect these trends to continue as greenhouse gases emissions and global temperature continue to rise. Causes of climate change
Rising levels of carbon dioxide and other greenhouse gases such as methane in the atmosphere enhance the greenhouse effect. More of the Suns energy is trapped, causing the Earth to warm.
Heating of the ocean accounts for over 90 of the trapped energy. Scientists have known about the greenhouse effect since the 19th Century. The more greenhouse gases there are in the atmosphere, the warmer the Earth becomes. While the plants and the oceans absorb about half of the carbon dioxide from human activities, the rest goes into the atmosphere. Recent warming is being driven by
Natural influences on the climate, such as changes in the strength of the sun, or volcanic eruptions, can affect global temperature.
But they can predict they can predict average changes in global climate and how the statistics of extreme events will be affected in the future. Climate models can also show us the effects of changing our global greenhouse gas emissions. For example, if we reach net zero, the point where carbon dioxide emissions are balanced by natural carbon sinks and carbon dioxide removal, models show that global temperatures will stabilise. However, if greenhouse gas emissions continue to increase, global temperatures will also continue to increase. Under the IPCCs high-emissions scenario SSP3-7.0, where emissions continue to increase throughout the century, global temperatures could rise by 3.6 to 4.6C above pre-industrial levels by 2100. Because these are global averages, the temperature increase in some regions will likely be even higher. For instance, warming in the Arctic, which is 2.4C above the 1991-2020 baseline, and more than three and a half times the global average. For more information, see the Met Office What is climate change?. Impacts of climate change
We can already see the effects of climate change. They are projected to become more severe and widespread as greenhouse gas emissions and global temperatures continue to rise. How big these impacts are depends on the degree to which we reduce greenhouse gas emissions, and on our ability to adapt to these changes. Some of the effects of changes to our climate include
Adapting to climate change is essential to protect people, communities and infrastructure from the impacts we are already experiencing. However, adaptation options decrease with increased warming as some options become unfeasible.
This is why urgent action is needed on both adaptation and reducing emissions. For more details, see the Met Office Effects of climate change. The effects of climate change on the UK
The UKs climate is changing already. The UKs 300 year continuous temperature record shows recent warming is moving outside the envelope of historical observations. This means the past cant be used as a reliable guide to what we expect in the future. As greenhouse gas emissions continue to rise, climate models project that we will see
The UKs weather will continue to be variable, and we will still experience much of the weather we do today. But it is likely that we will see more of the weather listed above. In a high greenhouse gas scenario by 2070, UK winters are projected to be between 0.6 and 3.8C warmer and between 3 to 39 wetter depending on the region, compared to our climate in 1990. This is because warmer air can hold more water. We will likely experience heavier rains and more rain could fall during winter storms. Similarly, by 2070, UK summers are projected to be between 1.3 and 5.1C warmer, depending on the region. Higher summer temperatures will likely cause more severe heatwaves. This will be a risk to public health, particularly vulnerable people. In July 2022, UK temperatures exceeded 40C for the first time on record. Temperatures remained above 20C overnight and the highest daily minimum record was also broken. Research has shown that the chance of the UK seeing 40C days is about 10 times more likely in the current climate than in the past. By 2070, regions in the south could have average hottest days reaching 40C . Warmer, drier summers are likely to increase the risk of wildfires in the UK, as seen in the summer of 2022. Climate change will also affect summer rainfall events in the UK. Flash flooding events are already more likely, especially in urban areas. By 2070, the UK is forecast to experience flash floods twice as often as it did in 1990.
IPCC Assessment Reports are released on a roughly seven-year cycle. During the sixth assessment cycle, the IPCC published three flagship Working Group WG reports
as well as three Special Reports and a Methodology Report
The Sixth assessment cycle concluded with a synthesis of all the reports of the cycle, published on 20 March 2023
The IPCC report preparation and approval process
The UK Government fully supports the work of the IPCC. It regards the IPCCs assessments as the most authoritative view on the science of climate change. IPCC reports undergo an unparalleled, rigorous and transparent international preparation and peer-review process by scientific experts and governments before they are published. The governments of the IPCCs 195 member countries, which includes the UK, are involved in all major steps. This includes agreeing the scope of a report, nomination of experts as authors, reviewing the reports, and their final approval. IPCC assessments are highly influential. They informed the creation of the United Nations Framework Convention on Climate Change UNFCCC, and the subsequent Kyoto Protocol. They drove the Paris Agreements goal to limit temperature rises to well below 2C and pursue efforts to limit the increase to 1.5C, as well as underpinning the Glasgow Climate Pact agreed at COP26. The 2018 IPCC Special Report on Global Warming of 1.5C was a major influence on the UKs net zero 2050 target and led to net zero targets being set around the world. Tackling climate change
In 2015, the 196 parties of the UNFCCC adopted the Paris Agreement. Its overarching goal is to hold the increase in the global average temperature to well below 2C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5C above pre-industrial levels, recognising that this would significantly reduce the risks and impacts of climate change. Limiting global warming to 1.5C or 2C requires reduced global carbon dioxide emissions to at least net zero by the 2050s and 2070s, respectively. Deep and sustained reductions in the emissions of all other greenhouse gases are also required. There are many benefits to limiting global warming, with each fraction of a degree making a substantial difference. The severity of the impacts of climate change increases with temperature and many changes are irreversible for centuries to millennia. Reducing greenhouse gas emissions will always reduce risk, regardless of specific temperature goals. To minimise the negative effects of climate change, actions to mitigate and adapt need to be taken in this decade. Mitigation and adaptation action can provide other benefits. For example, reduced methane emissions will limit near-term warming and improve air quality. The benefits of such actions will be felt globally, such as improving agricultural productivity, increasing innovation, better health, and wellbeing, increasing food security, and reducing biodiversity loss.