London in danger of losing its urban canopy through climate change

One of the oak trees which died in the excessive heat and drought of the summer of 2022, which Kew Gardens have painted red as a reminder of climate change

London could lose most of its trees by the end of the century to heat and drought

It is London Climate Action Week this week, underlined by last night’s spectacular thunderstorm.

At Kew Gardens the Tree Collections and Arboriculture team have been working with the Greater London Authority to assess 1.2 million trees across London, and their research has shown up some alarming results:

‘The team found that 62% have low suitability and 10% are vulnerable. Meaning that by the end of the century 72% of London’s urban canopy could be at risk’. they say.

The report found that the species most at risk of failure included British natives, including the common beech (Fagus sylvatica), silver birch (Betula pendula) and holly (Ilex aquifolium), as well as the much-loved English oak (Quercus robur).

Kew Gardens lost 400 trees in the summer of 2022 because of the drought and extreme heat experienced that summer, when the UK temperature hit 40°C for the first time in recorded history.

While most of the trees which failed during this time have been felled, they have kept one oak ‘skeleton’ and painted it red (pictured above) to raise awareness of climate change.

Last month, Kew Gardens recorded the hottest May temperature on record in the UK, reaching 35.1°C on 26 May. This week, temperatures are expected to rise further, with highs in excess of 37°C expected.

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Aerial photograph of Kew Gardens; Photograph Royal Botanic Gardens

Kew Gardens works with the Greater London Authority to plant more heat-friendly trees

Kew experts estimate up to 50% of their existing 11,000 trees could be vulnerable to climate change by 2090. The prospect of losing these trees not only has a significant impact on Kew’s historic landscape but also presents a considerable threat to ecosystems and biodiversity.

In 2019, two scientific papers published by Dr h Ruth Mitchell of The James Hutton Institute established that as many as 2,300 individual species of mammals, invertebrates, fungi, birds, bryophytes and lichens are supported by the English oak tree.

‘Urban trees act as vital neighbourhood buffers in an unstable climate, cooling our streets during scorching summer droughts while their massive root systems anchor soil and absorb excess stormwater during intensely wet winters’, they say.

Kew will continue to work with the Greater London Authority to advise on planting more suitable urban trees with higher survival rates in 2100, that will also provide the cooling that is needed.

They have a number of events going on at Kew Gardens this week about climate change. It is time we all understood much more about it.

Richard Deverell, Director of Royal Botanic Gardens, Kew, said:

“Trees are vital for all life on earth, including humanity. They provide a home for a huge diversity of animals, plants and fungi. They are a source of food, rainfall, materials, cooling and great beauty. Yet they are threatened by climate change.

“The heatwave at Kew in July 2022 killed 400 of our trees. Highlighting this Climate Changed Oak brings tangible evidence to help our visitors understand that climate change is here and now and is damaging our living landscapes.

“I hope it will give visitors an opportunity to reflect on how climate change is affecting our lives and what each of us can do to address this urgent challenge”.