London needs an extra two million trees if it is to cope with rising global temperatures in the future, according to the Mayor of London’s environment plan.

Current projections suggest average summer temperatures in the capital could be almost 4C higher by 2080, because of the city’s susceptibility to the urban heat island effect.

To counter the effect, which is caused by buildings absorbing and releasing heat, the report called for roofs and walls to be covered in vegetation and extra trees planted by 2025.

Isabel Dedring, the Mayor’s environment adviser, said: “People really struggle to see how an old, Victorian built-up city like London can really be a low carbon city, which if you look at the targets, it needs to be.

“There are lots of things we can do collectively offsetting those rises, and we have to start doing that now.

A total of 1,500 of the 10,000 trees the Mayor promised for London in his election campaign have so far been planted.

• Find out about more local green groups at greenguardian.co.uk