The Technical Report concluded that global warming is already bringing substantial risks to the UK's natural environment, infrastructure, human health, communities and businesses.
Global warming of 4°C by 2100 still cannot be ruled out, according to experts whose work informed a new UK government report.
As required by the Climate Change Act 2008, the government has today [Monday 17 January] submitted the Third UK Climate Change Risk Assessment (CCRA3) to Parliament.
The CCRA3 is partly based on an independent Technical Report by a large team of experts led by the University of Exeter, in partnership with the Met Office.
Professor Richard Betts MBE, who led this team, said: "One of the key conclusions from the University of Exeter's work was that current worldwide policies could result in up to 4°C warming by 2100.
"The agreements made at the COP26 climate summit in November have reduced the likelihood of this, but it remains possible."
The Technical Report concluded that global warming is already bringing substantial risks to the UK's natural environment, infrastructure, human health, communities and businesses.
It also concluded that the UK is subject to international risks relating to issues such as security, migration and supply chains.
All these risks are expected to be higher at global warming of 2°C, and would be even greater if warming were to reach 4°C.
Professor Betts continued: "COP26 fell short of its aims, and it is becoming less likely that we will be able limit global warming to low levels. The Paris Agreement's 1.5°C goal is slipping out of reach.
"We need to be better prepared for the climate changes we have already caused."
Professor Betts, of the University of Exeter and the Met Office, welcomed the publication of the CCRA3.
"We are glad to see our science included in this key report, which does not shy away from the high levels of warming that could occur," he added.
The Technical Report, the findings of which were presented by Professor Betts at COP26 in Glasgow, involved more than two years of work, drawing on numerous scientific papers and other reports as well as new research.
It also involved extensive engagement with a large number of stakeholders in government, the private sector and civil society organisations with responsibility for adapting to climate change or expertise in how this can take place.
The CCRA3 report published today also relied on independent advice from the Climate Change Committee (CCC) on the risks posed to the UK from climate change, and the extent to which the UK is unprepared.
Baroness Brown of Cambridge, chair of the CCC's Adaptation Committee, said: "Expert input to CCRA3 process was vital to ensure that the assessment is based on sound evidence.
"The team led by the University of Exeter produced a robust, authoritative Technical Report which provided a solid foundation for the CCC's advice to government, and provides crucial information for the UK to act on under the National Adaption Programme."
Professor Lisa Roberts, Vice-Chancellor of the University of Exeter, said: "We are proud to have played a leading role in this vital piece of climate change work.
"This was achieved by working together with the Met Office, the CCC and other universities and organisations, to bring together the required expertise and viewpoints from a wide range of disciplines.
"Adapting and responding to life-changing climate change is the biggest challenge of our generation and that is why the University of Exeter has brought together the strength and power of more than 600 of our researchers working on the climate and ecological crisis at the heart of our 2030 strategy.
"We are committed to working in partnership with governments, businesses and communities in the critical decade ahead."
Experts from many institutions, including Exeter, are already working on research that will underpin the next CCRA.
