Following today's announcement that the Liberal Democrats and Conservatives are to unite in pushing for a tough new policy on climate change, Green Party Environment, Food & Rural Affairs spokesperson Penny Kemp welcomed any step in the right direction and said she hoped the motivations were sincere.

"This initiative shows the profile of climate change has been raised to such a level that the big three parties have to take it seriously," she said.

"This is a positive step towards reversing Britain's rising CO2 emissions. The Green Party has repeatedly stressed the urgent need for a voice on climate change in Westminster. We only hope this coalition will ask the right questions."

Referring to an Oliver Letwin comment asking Conservatives to support green issues merely as a huge vote-winner, she added: "We hope this is more than green posturing. "Today the United Nations University said there will be 50 million environmental refugees worldwide in just five years. Over 2000 people in the UK died from a climate change-related heat wave in 2003. This issue is only going to get worse, only serious commitment will do."

Principal speaker Keith Taylor said: "We welcome this pact as a positive step, but its aim - a compulsory annual reduction in CO2 emissions - should be one of many such steps. These are parties with dyed-in-the-wool commitments to economic liberalisation, economic growth and unfettered consumption - how well do these principles sit with any genuine attempt to tackle climate change? A serious commitment to tackling climate change will require a radical and far-reaching overhaul of all three major parties' policies and ideals.

"The Green Party has recently adopted a policy of Domestic Tradable Quotas to reduce carbon emissions, where everyone is given a carbon emissions allowance, thereby increasing individual responsibility. We call on the government to do so too. Halting global warming will require personal behaviour change, stimulated by initiatives such as this, not just regulatory frameworks."