The charity has called for action to curb emissions and adapt to climate change as latest heatwave grips.
Heatwaves and prolonged dry weather are damaging landscapes, gardens and wildlife, the National Trust has warned.
Reports from sites the charity cares for show lichen and mosses that normally thrive in the damp atmosphere of rare temperate rainforest in Lydford Gorge on Dartmoor are shrivelling, and heather is struggling to flower on Dunwich’s lowland heath in Suffolk.
Wildfires have broken out in beauty spots in Cornwall, Devon and Norfolk.
Water features in some historic gardens dried up in July’s heatwave, bats were found disorientated and dehydrated in the daylight at Wallington in Northumberland during the hottest days, and a water wheel that powers a flour mill in Cambridgeshire has had to stop turning due to low river flows.
The National Trust said the summer’s exceptional conditions were a wake-up call to cut the greenhouse gas emissions that are driving climate change, and to adapt to the impacts already being caused by rising temperatures.
This year so far in England has been the driest in decades, with drought looming.
Temperatures soared to record highs in July, surpassing 40C for the first time for the UK, and are expected to climb to the mid 30s in some places this week – prompting a four-day amber warning for extreme heat from the Met Office.
Climate change caused by human activity such as burning fossil fuels is already making heatwaves more intense and frequent, and scientists also warn rising temperatures make extremes such as drought more likely.
The National Trust said it was responding to the ongoing hot, dry conditions with short-term measures including giving the dehydrated bats water using tiny pipettes and moving them into a cooler, darker spot, stopping mowing, and discouraging barbecues.
It is also implementing longer-term strategies such as selecting drought-resistant plants in its gardens, increasing tree cover and shade, and creating wetlands to hold more water in the landscape to curb flooding and reduce the impact of drought.
Some of those projects are already bearing fruit, the National Trust says.
At its Holnicote Estate in Somerset, where beavers which engineer the landscape to create wetlands were reintroduced in 2020, the wet habitats are still thriving despite low river levels, the charity said.
Keith Jones, national climate change adviser for the National Trust, said: “We shouldn’t be surprised by these temperatures, it’s what the science has been saying for decades.
“But even with years of planning, some of the effects are stark, and we are still learning of the precise impacts extreme weather events like this can have.
“What we can do, is adapt. At the Trust we’re taking action to make sure our sites are ready for future changes, from making our landscapes rich in nature, our rivers cooler and our gardens more resilient to helping our buildings cope with excessive heat.”
He also urged the next prime minister to put action to cut the emissions driving climate change at the top of their to-do list as the next round of global climate talks, Cop27, approaches in November.
Other impacts from the extreme weather the National Trust has seen include:
– Rangers at deer parks spent more time making sure deer were hydrated and sheltered;
– Apple saplings at the Trust’s biggest tree planting project at Wimpole in Cambridgeshire baked in the heat, though they survived. Exceptionally low moisture levels in the soil have raised concerns more young trees may need to be replaced;
– A Victorian steam yacht gondola that ferries tourists across Coniston Water in the Lake District was forced to stop sailing in the record-breaking heat, as the engine room hit unbearable temperatures;
– Moat levels at 500-year-old Oxburgh Hall in Norfolk, where the clay needs to remain wet to prevent structural problems, were down.
– Fires broke out at Zennor Head in Cornwall, closing part of the South West Coast Path, at Morden Hall Park in London, destroying part of a meadow, and at Bolberry Down in Devon where a gorse fire continued to reignite for two months.
Richard Millar, head of adaptation at the UK’s advisory Climate Change Committee, said: “We have long known that climate change is making UK heatwaves more frequent and more intense.
“These amplified heatwaves are just one of the impacts on the UK’s significant cultural heritage sites and landscapes.
“Addressing these impacts requires conservation and heritage planning to be undertaken on the basis that the UK’s climate is changing.”
National Trust teams are planting for a drier future, such as at Felbrigg Hall, in Norfolk, which has a new the new drought-tolerant garden and Cliveden in Berkshire, with more than 2,000 lavenders going in the famous parterre over the coming weeks.
The charity is introducing 20 million new trees by 2030, creating 3,000 hectares of new trees along water courses to help cool water temperatures and returning rivers to their natural shape and function.