How might climate change affect London’s trees?

A new report, commissioned by the Greater London Authority and the Forestry Commission, assesses how well London’s public realm trees are likely to cope with projected climate conditions in 2090.

Future Climate Suitability of London’s Public Realm Trees is by Dr Andrew Hirons, a Director at Urban Plant Lab and a Senior Lecturer in Arboriculture and Urban Forestry at University Centre Myerscough, and Kevin Martin, a Research Fellow at Urban Plant Lab and the Head of Tree Collections at the Royal Botanic Gardens Kew.

London is the first city in the world to commission such a comprehensive climate suitability assessment of its public trees. What follows are extracts from the executive summary.

Key findings

If no changes are made, in total, 73% of London’s public trees may struggle to thrive or survive as the climate changes. Only 0.38% of London’s current trees are considered highly suitable for future climate conditions. 22% have moderate suitability to future climate. 62% are rated as having low suitability to future climate. 10.6% are considered vulnerable to future climate.

The authors say that the impact of this analysis will only be borne if nothing is done to adapt and address the composition of London’s urban forest. Therefore, huge opportunities exist to improve the suitability of London’s trees to future climate through positive shifts in policy and practice.

How the assessment was done

The study analysed data from over 1.1 million public trees across London. Each species was assessed for its suitability to London’s projected climate in 2090 using a composite scoring system that combined global species distribution data and plant trait analysis.

Species were grouped into four climate suitability categories:

• High suitability: Likely to thrive under future conditions.
• Moderate suitability: May perform well, especially if sourced from regions with compatible climates.
• Low suitability: Expected to struggle, though some improvement may be possible through careful sourcing.
• Vulnerable: Unlikely to survive or thrive, with no presence in analogues of London’s future climate.

Why this matters

Trees that are poorly suited to future conditions may grow slowly, be more vulnerable to pests and pathogens, and die prematurely – reducing the many benefits they provide. Publicly owned trees deliver around 60% of the ecosystem services London’s urban forest provides; this includes cooling, air purification, and stormwater management.

Recommendations

To protect London’s urban forest, the authors make the following recommendations:

1. Enhance the health of existing trees.
2. Strategically diversify London’s urban forest.
3. Fund tree establishment, not tree planting.
4. Adopt a London tree data standard.
5. Collaborate with tree nurseries.
6. Develop a strategic mechanism to get novel plant material into horticultural production.
7. Address gaps in plant trait data.
8. Evaluate potential canopy cover impacts of species climate suitability.
9. Develop London-wide strategies and structures to manage the whole of London’s urban forest.
10. Apply this analytical framework to other cities and regions.

The report says: ‘Ensuring the resilience of London’s urban forest requires collective action from strategic authorities, tree managers, nurseries, researchers, funders and government. Each has role to play in enacting the recommendations of this report; by working together, we can ensure London’s treescapes remain healthy, diverse, and resilient whilst providing benefits for generations to come.’

Hirons, A. D. and Martin, K. W. E. (2025) Future climate suitability of London’s public realm trees. Urban Plant Lab. Download from: www.doi.org/10.13140/RG.2.2.30088.69129

This article was taken from Issue 212 Spring 2026 of the ARB Magazine, which is available to view free to members by simply logging in to the website and viewing your profile area.