Four capital cities sign up to 10:10 Eso esperamos...

Mexico City's taxis and Paris's city halls are about to become greener after four worldwide capitals signed up to the 10:10 climate campaign.

The mayors of Amsterdam, Zagreb, Paris and Mexico City announced this week that they intend to cut their cities' carbon emissions by 10% in the next year.

The 10:10 campaign, supported by the Guardian, is championed in 40 countries with 3,000 businesses and 100,000 individuals signing up, including celebrities Sienna Miller and Hugh Fearnley-Whittingstall

This is the first time that capital cities have signed up, said campaigners.

Speaking from the Hôtel de Ville, Paris mayor, Bertrand Delanoë, said: "10:10 is an invitation to act concretely and determinedly. I am very happy about this partnership."

Social housing complexes will be renovated, head offices of the 20 arrondissements given energy-saving refurbishments and the city's fleet of public vehicles will be "rationalised" in an attempt to cut carbon emissions.

Plans have also been unveiled for geothermal wells in the north-east of the city which will power 12,000 homes.

The formal agreement from Paris came just before a separate day of international mass participation climate action on 10/10/10, when 7,000 events took place around the world.

Twenty four hours later, Paris was joined by the largest city in the Americas, as Mexico City signed the pledge.

Its carbon-cutting programme includes the opening of a new line of its Metrobus system (saving 35,000 tonnes of carbon dioxide), replacing all the city's taxis (saving 100,000 tonnes of CO₂), building more sustainable homes and large-scale water-saving methane-capture programmes.

"It's about the survival of our civilisation," said mayor, Marcelo Ebrard, as he appealed to the city's 21.2 million residents to use less electricity and water and make more journeys by bicycle and public transport.

The city's average temperature had risen by 3C in the previous century, he said.

Fuente: Guardian Science.