The UK could suffer more water shortages and coastal flooding if climate change is not tackled, the Met Office has warned.
As much as 24 per cent of the population in 2100 - around 18 million people - could face increased pressure on their water supplies, while up to 160,000 more people could be at risk of coastal flooding in the face of sea level rises.
The Met Office compiled a series of projections charting the predicted impacts of global warming on 24 countries around the world which also revealed that, in a worst-case scenario, there could be a three-and-a-half times greater risk of river flooding in the UK.
The latest warning on the impacts of climate change, launched during international talks on tackling global warming in Durban, South Africa, comes in the wake of one of the driest 12 months on record for some parts of Britain.
"This report highlights some of the very real dangers we face if we don't limit emissions to combat the rise in global temperature," said Climate Change Secretary Chris Huhne, who is in South Africa to take part in the UN talks on tackling global warming.
"The UK wants a legally binding global agreement to keep the global temperature rise below 2C.
"If this is achieved this study shows that some of the most significant impacts of climate change could be reduced significantly."
The south and south east of England are already facing pressure on water resources, and those regions are likely to see an increase in the frequency of droughts and water scarcity, the Met Office Hadley Centre report said.
But almost all of the agricultural land currently farmed in the UK will become more suitable for growing crops, largely as a result of decreasing frosts and cold nights as the country warms.
The study confirmed that the UK was already getting warmer as a result of climate change, experiencing 35 more unseasonably warm days a year in this decade than in the 1960s.
The Met Office projects temperatures could rise by 3C above the 1960-1990 average of 8.3C in the south and 2.5C in the north of the UK without global efforts to cut greenhouse gas emissions.
Elsewhere in the world the analysis, which used 21 climate models to come up with a range of projected impacts for each country, found that up to 49 million more people worldwide would be at risk of coastal flooding by 2100.
Up to five million extra people could be threatened by coastal flooding in Bangladesh and as many as 19 million more at risk in China.
The data showed that all 24 countries studied would see more people at risk of coastal flooding due to rising sea levels, with temperatures predicted to rise by between 3C and 5C globally without action to tackle greenhouse gases.
The Met Office studies also showed that more than half the farmed land in the US could become less suitable for agriculture, while almost all of the land used for farming in Spain would become less good for growing crops.
The report, commissioned by the UK government, also looked at what had already been happening to the climate in the two dozen countries and found that all had warmed since the 1960s.
The projections show a range of potential positive and negative effects for various developing and developed countries, many of whom are major players in the UN climate talks, including the US, China, Indonesia and Russia.
Each of the countries have been analysed using consistent methodology to allow the potential impacts to be compared between nations, and is the first such study of different countries to be produced, the Met Office said.
It examines the risks of flooding, both on coasts and from rivers, water stress and droughts, crop yields and food security for each country.
The analysis found that limiting global warming to 2C above pre-industrial levels would substantially reduce a number of the expected impacts on countries.
"This report paints a worrying picture about future life in the UK as a result of climate change," said Keith Allott, head of climate change at WWF UK.
"It is clear that the UK can expect significant disruption to its water, transport and other critical infrastructure.
"However, we also need to remember that developing countries will be much harder hit by climate change with devastating threats to their food and water security.
"This report underlines the urgent need for countries to commit to faster cuts in emissions and to secure agreement to get the Green Climate Fund up and running in order to begin channelling funding and support to the poorest nations already feeling the impacts of climate change.
"The emission pledges on the table for 2020 would take us to a world of at least 3.5C warming - governments at Durban must take urgent action to address this yawning gulf in ambition."
See the individual country reports on the Met Office website