Climate threat spurs London’s Kew Gardens to look for resilient trees

By Sachin Ravikumar and Toby Melville

Behind the lush greenery, roses in bloom and birdsong at London’s famous Kew Gardens lies the darker reality of climate change, which threatens to kill thousands of its trees in the coming decades.

Some trees at the botanical gardens, which were first opened in 1759 and today are a Unesco World Heritage Site, are already in a state of irreversible decline.

Experts at Kew have used climate modelling to show that over half of the gardens’ 11,000 trees may be at risk of dying by 2090, as a warming climate makes the soil drier and reduces the amount of water trees can access.

Kew’s problem is worsened by the warmth radiating from London’s dense metropolis towards the gardens, known as the urban heat island effect, which makes night-time temperatures much warmer than in rural regions.

Kew’s 8.5 million plant and fungal specimens have long been drawn not just from Britain but from around the world – from the cherry blossoms of Japan to the water lilies of the Amazon – and solutions to withstanding climate change may also lie thousands of miles away.

Plant material from the Hyrcanian forest of Iran and Azerbaijan, the great steppes of Eurasia, the southwestern United States or parts of continental Europe would all be resilient enough to withstand climate change in Britain, experts said in a report published last week.

This sort of replacement could also become a model for urban planners to mitigate the effects of climate change, the report said.

Kew is warmer by about 3 degrees Celsius than it was in the 1980s, putting much-loved British natives such as the English oak (Quercus robur) at risk, said Kevin Martin, head of tree collections at the gardens and a former tree surgeon.

A drought in 2022, when temperatures around the British capital reached a record 40 C, killed 400 of Kew’s trees, spurring the need to think about introducing more resilient species, said Martin, who will travel to Georgia in September to collect seeds to plant at Kew.

“It’s going to be vitally important, not only for our generation, but for the next generation,” he said, standing beside a 124-year-old weeping beech (Fagus sylvatica ‘Pendula’) in decline.