The changes may mean a longer growing season and a tourism boom as heat in the Mediterranean becomes unbearable.

But droughts, floods, erosion and water shortages could blight Dorset and Natural England says action must be taken.

Natural England’s new Climate Change Project focuses on four of England’s 159 ‘character areas’, including the Dorset Downs and Cranborne Chase.

It says the county will be hit hard over the next 70 years, transforming it into a region much like Portugal.

Natural England says around 80 per cent of water drunk in Dorchester and Blandford comes from the surrounding chalk landscape.

But there is already less water per person than some Mediterranean countries, the study warns.

It says River Stour flow will be down by at least 50 per cent by 2080 and the chalk network will shrink.

Autumn rainfall has already risen by nearly a third over the last 40 years, according to the report.

Dorset County Council renewable energy development officer Pete West said the project was a wake-up call.

He said: “The effects of climate change are going to be more dramatic than people expect.

“At the moment people seem to think it’s going to be business as usual, but this report makes it clear that it’s not.”

Mr West said Dorset could lose 40 per cent of its biodiversity if the predictions were correct and nothing was done. He added: “We’re facing very real changes in Dorset and we need to start thinking about things more seriously,” he added.

Natural England says possible solutions include creating ponds and woods along streams and re-establishing chalk grasslands or hedges on slopes.

Planting native but drought tolerant trees and introducing better floodplain management and water storage are also recommended.

Dorset County Council sustainable development manager Kate Hall said the project helped identify which natural assets were at risk.

She said: “They’ve brought a range of partners together to think about how changes in the use and management of land can help people and their environment.

“For example, the creation of more woodland, pasture and ponds in the valleys of the upper Frome could reduce the incidence of flooding in Dorchester.”

Natural England said local land managers and planners would now be involved in deciding how to secure a natural environment ‘resilient to future climate’.