Ken Livingstone was in Camley Street Natural Park in Kings Cross today where he and Green Mayoral candidate, Sian Berry, pledged five joint environmental commitments. Ms Berry also called on Green voters to give their second preference votes to Ken - and Ken pledged to give his second preference to her.

Ken and Sian's five commitments are as follows:

• We will introduce a £25 a day CO2 charge for gas-guzzling cars like some 4x4s, high-powered sports cars, and luxury executive vehicles
• We will not reduce the size of the Congestion Charge Zone
• We will keep the Low Emission Zone to improve air quality and extend it to include lorries over 3.5 tonnes and, from 2010, heavier vans
• We will oppose all further airport expansion serving London, including at Heathrow and Boris Johnson's plan for a new airport in the Thames Gateway
• We will continue to set a target that at least 50% of all new houses should be affordable to Londoners on lower incomes

Siân Berry and Ken Livingstone have issued the following joint statement:

"Tackling climate change and creating a fairer London must be at the top of any serious Mayor's agenda. Boris Johnson, who supported George W. Bush in opposing the Kyoto Treaty and would scrap the CO2 charge on gas guzzlers, cannot be trusted with London's environment. Nor can a man who opposed the minimum wage be expected to promote fairness or tackle poverty. London - with a committed Mayor and Green Party representation on its Assembly - has taken a global lead on environmental and social justice over the last eight years. Let's keep it that way."

Ken Livingstone said:

‘London's communities and neighbourhoods will all benefit from maintaining the approach of looking after our environment, and our city must continue to be in the forefront of tackling climate change for the sake of everyone's future.

‘Over the past eight years Green Party Members on the London Assembly have been crucial to working with me to help turn London into one of the leading world cities on tackling climate change.

‘London now has a strong green agenda, with groundbreaking and innovative decisions such as introducing and then expanding the congestion charge, cutting air pollution by making London the largest Low Emission Zone in the world, delivering the most comprehensive plan to cut carbon emissions of any major city, setting tough planning regulations to require the use of renewable energy in new developments, and massively increasing investment to achieve an increase of over eighty per cent in cycling.

‘Green and Labour members on the Assembly have stopped Tory cuts to my budgets. Were it not for the support of Green Party Members on the London Assembly, funding for many of my key environmental policies would have been blocked by Boris Johnson's Tory colleagues.

‘In this mayoral election, Sian Berry and I stand alone among the Mayoral candidates in our commitment to implement further groundbreaking environmental initiatives such as the £25 a day CO2 charge on gas guzzlers. Boris Johnson and Brian Paddick oppose the £25 a day CO2 charge for gas-guzzling cars like some 4x4s, high-powered sports cars, and luxury executive cars travelling in the congestion zone.

‘Sian Berry and I support the Kyoto agreement on climate change while Boris Johnson is one of the few polticians in the world to support George W Bush in opposing it.

‘It is important that voters understand that their second vote could decide who is Mayor of London. All of the polls indicate that this will be a straight choice between Boris Johnson and myself. So I urge Londoners who vote for another candidate with their first vote to use their second vote to help decide that contest by voting for me to stop a Tory victory.

‘With the Green Party calling on its supporters to cast their second preference votes for me they are saying do not permit a candidate who would take London backwards on green policies to get elected on May 1^st.

‘I look forward to continuing to work with Green Party Assembly Members to make London an international beacon of sustainable green policy.'

'I will be casting my own second preference for the Green Party because Brian Paddick calls for the London Underground to be privatised, has abandoned green Liberal Democrat policies to side with Boris Johnson in opposing the CO2 charge on gas guzzlers and the Low Emission Zone to cut pollution from lorries.'