Local authorities have issued warnings after a notable rise in incidents of sudden branch drop syndrome — a phenomenon where branches unexpectedly fall, posing safety risks to residents. Harrow Council has urged people to avoid sitting or gathering under large trees during this period.

Experts from the charity Trees for Cities warn that such events are likely to become more frequent as the climate warms, putting London's tree population under growing pressure.

With climate projections indicating hotter summers ahead, trees play a crucial role in the city's efforts to reduce carbon emissions, filter pollution, and cool urban heat islands. The Mayor of London has pledged to increase the city's tree canopy by 10% by 2050 as part of the climate resilience strategy.

However, maintaining and adapting London's green canopy is becoming increasingly complex. Native species, which support local wildlife, are struggling to cope with new temperature extremes.

Seb Herst, senior urban forest coordinator at Trees for Cities, highlights the importance of proactive tree care: "We must protect native trees because of their ecological value, but also consider introducing similar species from warmer climates — such as oak trees from southern France — that are better suited to the conditions we expect."

He also stresses the need for improved urban infrastructure: "Our trees often grow in small, compacted pits with limited soil aeration. Increasing soil space and moisture retention will be vital to help trees survive severe heat and intense rainfall."

Deputy Mayor for Environment Mete Coban acknowledges the immediate impacts of climate change on London's trees. "Heatwaves are stressing our urban forests. We need to plant more trees that can withstand extreme heat and ensure we have the right infrastructure to protect them as temperatures continue to rise."

On the ground in West London's Greenford area, Georgie Power, another senior urban forest coordinator, has been helping to water young trees and apply bark mulch to retain moisture. She explains sudden branch drop syndrome as a form of "self-amputation" where drought-stressed trees shed branches to conserve water and energy.

"This summer's relentless heat has put immense pressure on our trees," Power says. "With climate change, these stresses will only intensify, leading to more instances of tree decline and branch loss."

To prepare for this future, Trees for Cities is already planting more drought-resistant species. For example, the Italian Alder is increasingly favored over the common Alder due to its resilience to both drought and flooding.

"The choice of species is evolving with the climate," Power adds. "We need to plant trees that can thrive in the warmer, more variable conditions coming our way."

As London's urban forest faces unprecedented challenges, experts agree that careful management, species selection, and community involvement will be key to sustaining the city's green lungs in a hotter future.