Met Office: catastrophic climate change could happen with 50 years

An average global temperature rise of 7.2F (4C), considered a dangerous tipping point, could happen by 2060, causing droughts around the world, sea level rises and the collapse of important ecosystems, it warns.

The Arctic could see an increase in temperatures of 28.8F (16C), while parts of sub Saharan Africa and North America would be devastated by an increase in temperature of up to 18F (10C).

Britain's temperature would rise by the average 7.2F (4C) which would mean Mediterranean summers and an extended growing season for new crops like olives, vines and apricots.

However deaths from heat waves will increase, droughts and floods would become more common, diseases like malaria may spread to Britain and climate change refugees from across the world are likely to head to the country.

The Government-funded study, which has been sent to the Department for Energy and Climate Change, included new figures on increased emissions from fossil fuels and considered the effect global warming will have on the ability of the oceans and rainforests to absorb carbon dioxide.

More than 190 countries are meeting in Bangkok this week for the latest round of UN negotiations to try to prevent catastrophic climate change. It is hoped a global deal to limit emissions will be made in Copenhagen this December.

Dr Richard Betts, Head of Climate Impacts at the Met Office Hadley Centre, said the new study showed how important it was to try and reduce emissions.

The global picture shows rainfall could decrease by 20 per cent in Central America, the Mediterranean and parts of coastal Australia, causing mass drought. Temperature rises in the Amazon would cause the rainforests to die, while Alaska and Siberia would see the melting of the permafrost causing more carbon dioxide to be released.

"Four degrees C of warming averaged over the globe translates into even greater warming in many regions, along with major changes in rainfall," said Dr Betts. "If greenhouse gas emissions are not cut soon then we could see major climate changes within our lifetimes."

The study is being presented today (Monday) at a conference at Oxford University, which consider problems for Britain, such as water shortages in the South East, die back of tree species like beech in the south of the country and the need to build coastal defence around counties like Norfolk.

Dr Mark New, of the Oxford University School of Geography and the Environment, said scientists now have a better understanding of the recent increase in carbon emissions because of developing countries like China and India building coal fired power stations.

There is also more information on the affect global warming will have on certain "carbon cycles". It is thought more carbon dioxide will be released into the atmosphere by organic materials in the soil decomposing at a faster rate, while warmer oceans are less able to absorb the greenhouse gas.

He said: "The eventual temperature we reach is a result of the carbon we put in the atmosphere so if we do not reduce emissions faster, the timing is much sooner. The faster the rate of change in getting to four degrees, the less time we have to adapt. Four degrees by the 2050s compared to four degrees by 2100 gives us half as much time to adapt to a new climate and that must have massive implications."

World leaders have agreed to try to keep global warming less than 2C above pre-industrial levels by the end of the century. However temperature rises have already gone above 1.3C and are likely to meet 2C because of carbon dioxide that is locked into the atmosphere.

Dr New said the world must now concentrate on keeping the rise below 4C to try to prevent the worst effects of climate change.

"Two degrees is important politically but in terms of what is going to happen, I think a lot of people think it is a lost cause already," he said. "Four degrees is highly plausible given the evidence and it is different enough from two degrees that we can start exploring the difficulties and what the world will look like."

DECC said ministers will use the new study to push for a tough deal at Copenhagen calling for rich countries to reduce emissions by 80 per cent by 2050 and poor countries to limit carbon dioxide in return for financial help.

A spokesman said: “A four degree rise in global temperatures would have serious consequences for mankind with food security, water availability and health all being adversely affected. This report illustrates why it imperative for the world to reach an ambitious climate deal at Copenhagen which keeps the global temperature increase to below two degrees.”