The world faces decades of turbulent weather even if it takes drastic action to tackle climate change, the Government’s chief scientific adviser said today in a final stark warning as he prepares to step down.

Professor Sir John Beddington said that time lags in the climate system meant that accumulations of greenhouse gases in the atmosphere now will determine the weather we experience for the next 25 years.

Climate change is already manifesting itself in huge variations in the weather, clearly illustrated by the way Britain experienced both drought and extreme rainfall last year, he said.

The scientist said that the international community’s failure to agree binding targets for cutting carbon emissions meant problems were being stored up for the future.

“They may reach agreement, and they may start to reduce greenhouse gases in the next five years, or it may be a little longer,” he told BBC Radio 4’s Today programme.

“But they are still climbing, and when that increase is reversed, we will be left with the weather and the climate for the next 25 years from whenever that happens.”

He added: “The delays in the climate system mean that the greenhouse gases in the atmosphere now will determine climate and therefore weather for the next 25 years.”

Sir John said the world had huge problems of food, water and energy security as the global population increases, all of which will be exacerbated by climate change.

“In 12 years’ time there will be another billion people on the planet and we have big issues of food security, water security and energy security and many, many people will start to be living in cities,” he said.

“These are massive problems. Climate change is just going to make it worse.”

He admitted there were some “uncertainties” in the analysis of climate change but stressed that there was clear evidence that it is happening in the way that climate models suggest.

“For example the Arctic is heating up vastly faster than other parts of the world - this is exactly what the climate scientists are predicting,” he said.

Sir John’s remarks were made as Britain experienced freezing cold weather and snow, with thousands of homes across the UK without power and many roads still impassable.

Almost 8,000 homes and businesses were flooded in 2012, as the UK was battered by repeated heavy rain, storms and floods.

England and Wales experienced 10 separate flooding events between April and December last year after widespread drought gave way to the wettest summer in a century, with unusually high rainfall totals and river levels around the country.

Sir Mark Walport, currently director of the Wellcome Trust, takes over as the Government’s chief scientific adviser on April 1.

Responding to Sir John’s comments, Craig Bennett, policy and campaigns director for the environmental campaign group Friends of the Earth, said: “Climate change is one of the biggest threats the planet faces – and unless we urgently act to cut emissions we face an economic and environmental catastrophe.

“From droughts and floods to snow storms, Britain is increasingly battered by extreme weather.

“Ministers must listen to Professor Beddington and other leading scientists and slash UK emissions – starting with an amendment in the Energy Bill to decarbonise the power sector by 2030.”