The money spent on preparing the UK for the impacts of global warming has almost halved since the environment secretary, Owen Paterson –widely regarded as a climate change sceptic – took office. Critics called the cuts "shocking" and "complacent".

Figures released under freedom of information rules show annual spending falling from £29.1m in 2012-13 to £17.2m in 2013-14. The drop in funding follows a previous slashing of staff working on the issue from 38 to six in May 2013.

The adaptation funding at the Department of Environment, Food and Rural Affairs (Defra) is spent on finding ways to cope with the increased floods, droughts and heatwaves expected in the UK due to global warming. It had risen by almost 20% under Paterson's predecessor, Caroline Spelman, but fell 41% after Paterson replaced her in September 2012. Some was also spent on cutting greenhouse gas emissions but the Department of Energy and Climate Change takes the lead on that issue.

In September 2013, Paterson said global warming could be positive, reducing winter deaths and extending crop growing seasons. "People get very emotional about this subject and I think we should just accept that the climate has been changing for centuries. I think the relief of this latest [Intergovermental Report on Climate Change] report is that it shows a really quite modest increase, half of which has already happened," he said. "We need to take [the report] seriously, but I am rather relieved that it is not as catastrophic in its forecast as we had been led to believe early on and what it is saying is something we can adapt to over time and we are very good as a race at adapting," he said.

Flooding in Somerset

Friends of the Earth climate campaigner Guy Shrubsole said: "David Cameron gets climate change, but it's clear that the appointment of a climate sceptic as Environment Secretary has drastically affected Defra's priorities. Owen Paterson has shown that he's unfit for office. He continues to put more people and their livelihoods at risk as flooding, drought and other impacts of climate change get worse."

Bob Ward, policy director at the London School of Economics' Grantham Research Institute, told the Independent on Sunday: "These shocking figures should worry everyone in the UK. Defra is the lead government department for climate change adaptation and is primarily responsible for making the UK resilient to the impacts of global warming, such as increased flood risk."

Maria Eagle, shadow environment secretary, said the deep cut in adaptation funding "reveals an incredible level of complacency about the threat to the UK from climate change." She added: "This is further evidence that Paterson's unwillingness to accept the science on climate change is leading him to make the wrong choices on spending cuts within his department."

The government's own scientists have identified increased flooding as the greatest risk posed by global warming to the UK, but Paterson failed to back the view of prime minister David Cameron that climate change was very likely to have played a part in the widespread recent flooding.

Research has already demonstrated that the heavy floods in England in 2000 were made twice as likely by climate change. However, annual real-terms spending on flood defences will fall by 15% under the coalition government.

A Defra spokesman told the Independent on Sunday: "Defra funds programmes that help protect international forests, cut greenhouse gas emissions and help the UK adapt to a changing climate." The department's international spending on adaptation increased from £10m to £30m between 2011-12 and 2013-14. However, much of this stems from a UN climate change agreement sealed before Paterson became environment secretary.