Mexico City plants lawns on roofs to fight warming

By Mica Rosenberg

MEXICO CITY (Reuters) - Mexico City, one of the world's most polluted capitals, is planting rooftop gardens on public buildings as part of a program launched on Thursday to combat global warming.

The smog-choked metropolis plans to replace gas tanks, clothes lines and heat-reflecting asphalt on 100,000 square feet of publicly owned roof space each year with grass and bushes that will absorb carbon dioxide.

The city also plans to offer tax breaks for businesses or individuals who put gardens on top of their offices and apartment buildings.

Left-wing Mayor Marcelo Ebrard has pledged $5.5 billion over five years to reduce greenhouse gases in Mexico City, home to some 20 million people and 4 million cars.

"These are not generic objectives or wishes -- we have a clear goal," Ebrard said at an event to inaugurate the environmental plan.

The aim is to cut carbon emissions by 4.4 million tonnes a year, still a fraction of the 643 million tonnes of gas Mexico produces nationwide each year, ranking it among the world's top polluters.

The mayor has encouraged cycling by providing bicycle paths and some car-free roads on weekends.

His program also aims to capture gas that bubbles up from overflowing landfills and calls for a new subway line and more express bus routes.