CLIMATE change poses the single biggest threat to the places the National Trust looks after, the charity warned, as it unveiled a strategy for protecting nature and heritage over the next decade.

The Trust, which has 4.2 million members and a number of properties in North Yorkshire, including Beningbrough Hall and Nunnington Hall, pledged to spend £1 billion in the next ten years on the conservation of its houses, gardens and countryside, with £300 million going to clear the backlog of repairs to buildings.

The countryside has been damaged by unsustainable land management over the last 70 years, with farming too often putting short-term food production ahead of the long-term health of the natural environment, the Trust claims.

Wildlife has disappeared from fields and hedgerows, over-worked soils have been washed out to sea and habitats destroyed - and the degraded landscapes are now threatened by climate change, it says.

The trust’s own places are at risk from a changing climate, its properties facing harm from extreme weather with everything from brickwork to guttering liable to be affected, while collections could be harder to preserve in the face of more humid, warm winters.

Gardens and woodlands are under threat from drought, storms and new pests and diseases and the coast faces erosion, it said.

The ten-year strategy aims to find new ways of managing land on a large scale to boost wildlife, and to adapt to a changing climate, as well as tackling the Trust’s own emissions by cutting energy use by 20 per cent by 2020 and sourcing half of its energy from renewables on its land.

The charity has pledged to work with its tenant farmers to improve all its land to a good condition, and with other organisations to protect the country’s most important landscapes, link up habitats and encourage wildlife.

It will also see changes in the way the most visited houses are presented, with new exhibitions and events - such as transforming the Edwardian interiors of Dunham Massey, in Cheshire, to tell the story of its time as a First World War hospital.

Most properties will be moving towards being open for 364 days a year so people can make the most of their membership and the charity will look at ways it can help safeguard public green spaces.