London’s pollution-busting trees valued at £6.1 billion in new survey

24 November 2015

London’s eight million trees are worth a staggering £6.1 billion to the capital and contribute £130 million in wider benefits, a new survey has calculated.  

The iTree urban forest survey used over 300 volunteers to analyse and count trees on the ‘services’ they provide from the carbon they store, the pollution they remove, and rainwater they hold. Trees play a huge role in improving air quality and remove 299 tonnes of PM10 and 698 tonnes of NO2 pollution across London annually.

Today as part of his wider work to make the city greener the Mayor has announced a new partnership with Unilever which will deliver 40,000 new trees. 20,000 will be offered to London’s schools and 20,000 will create a new urban woodland in West London. Hundreds of volunteers rolled up their sleeves in Ealing today to start planting some of the new woodland forest in Southall.

The Mayor has already supported the planting of nearly half a million trees in London including 20,000 street trees along some of the busiest roads.

The Mayor of London, Boris Johnson said: “London is one of the greenest, leafiest cities on the planet and as this survey proves, our canopy does a ‘tree mendous’ job of lowering pollution, alleviating flood water and boosting our environment. I encourage as many schools as possible to sign up for a great array of free foliage and I look forward to seeing the new Ealing woodland take shape.”

Charlotte Carroll, Unilever UK Sustainability and Communications Director, commented:  “Trees are one of the most important defences in the fight against climate change and at Unilever we're working on this important issue through our brightFuture movement. We hope this partnership will help Londoners reconnect with their love of trees and we're delighted to be planting 40,000 trees to help create a more sustainable future.  We are a founding signatory of the New York Declaration on Forests and with the UN Climate Conference, COP21 later this month, now is the time to engage in the importance of trees in our everyday lives.”

Today’s Ealing tree planting took place at the 29.5 acre King George’s Field, which is set to be transformed into native woodland habitat with thousands of whips and fruit trees. Hundreds of volunteers joined the planting, which was organised by Trees for Cities, including Deputy Mayor Roger Evans.

Kate Sheldon, Acting Chief Executive at Trees for Cities said: “This project demonstrates the powerful effect of bringing people together to plant trees. People of all ages love to plant a tree; it is great exercise, great fun, and makes such a difference to community spaces. The trees here in Ealing will help improve local air quality and create new wildlife habitat.”

The i-Tree survey, produced by the Mayor of London and The Forestry Commission and sponsored by Unilever, is a recognised method of valuing the benefits that trees provide that people often take for granted. Key services London’s trees provide include:

-        storm water alleviation = 3,414,000m3 per annum worth £2.8 Million

-        carbon storage = 2,367,000t per annum worth £146.9 Million

-        pollution removal = 2241t per annum worth £126.1 Million

-        It would cost £6.1bn to replace all of London’s tree canopy

Craig Harrison, Forestry Commission London Manager said ‘The i-Tree report tells us how many and what type of trees there are in London – and crucially, proves they deliver huge benefits such as cleaning the air and storing carbon. To ensure future generations receive these benefits and London grows sustainably, we all need to protect existing trees and plant new trees”

Notes to editors

1. For the Love of Trees –London is a Greater London Authority partnership with Unilever UK to deliver 40,000 new trees and support activities relating woodlands. 20,000 to create a new woodland in Ealing kick-started by a mass tree planting today and schools across the city can apply for 20,000 new trees that come in packs with an array of different breeds, and instructions and volunteer help on successful planting. Hundreds of Team London volunteers will also be available to help schools with trees planting. For more information visit


2. London iTree survey - The project is a partnership project including Forestry Commission, Greater London Authority, London Tree Officers Association, Trees for Cities, Tree Council, Natural England and Treeconomics. More information about the project:

Summary results from the iTree report are available on The full iTree report will be available on the Forestry Commission website on 2 December 2015:


3. More information on trees: Trees can help mitigate climate change by sequestering atmospheric carbon as part of the carbon cycle. Since about 50% of wood by dry weight is comprised of carbon, tree stems and roots can store up carbon for decades or even centuries. Over the lifetime of a single tree, several tons of atmospheric carbon dioxide can be absorbed. Carbon storage relates to the carbon currently held in trees tissue (roots, stem, and branches), whereas carbon sequestration is the estimated amount of carbon removed annually by trees. An estimated 2,367,000 tonnes (approximately 15t/ha) of carbon is stored in London’s trees with an estimated value of £147 million. Trees are also good at lowering N02 and PM10  some of the UK’s most common pollutants.


 4. For images of the tree planting or the mayor with a school tree pack email [email protected]


MEDIA ENQUIRIES: Press information is available from Rachelle Laurence on 020 7 983 4599 / 07771 814 478 or by emailing [email protected]

GENERAL PUBLIC/NON-MEDIA ENQUIRIES: Call the Public Liaison Unit at the Greater London Authority on 020 7983 4100

DUTY PRESS OFFICER: For out-of-hours media enquiries, please call 020 7983 4000