Hong Kong - Mayors from some of the world’s major cities on Friday vowed to do their part in curbing the carbon emissions blamed for global warming, ahead of a major UN climate meeting later this month.

Mayors from New York, Johannesburg and Toronto – part of the “C40” group – were among those in Hong Kong discussing ways to tackle the problem, including making buildings energy efficient and putting more electric-powered vehicles on roads.

The “C40”, launched in 2005, is an initiative of more than 40 cities which work together to reduce carbon emissions and increase energy efficiency in large cities around the world.

“Each of our cities share common goals – to reduce our carbon footprint, to make our environment more livable and to join hands to combat global warming and climate change,” Hong Kong’s chief executive Donald Tsang told delegates at the C40 forum, which started Friday.

“Cities are home to more than half of the world’s population, they consume over two-thirds of the world’s energy and emit more than 70 percent of total carbon dioxides.”

Tsang warned climate change has posed an “unprecedented challenge” and that there is “clear consensus” that action is urgently required. He called on cities to “unlock the full potential of low carbon technologies”.

Hong Kong has been wrestling with worsening air pollution that frequently shrouds its world-famous Victoria Harbour in smog.

“We need a variety of policies, programmes and projects with, and between, cities to succeed,” Toronto mayor David Miller, the outgoing C40 chair, told the conference.

“The C40 has provided its network with an exceptional opportunity to share and learn on how to successfully remove greenhouse gas emissions,” he added.

Miller handed over the chairmanship to New York mayor Michael Bloomberg, who told the conference that the US city was focusing on several green strategies, such as planting more trees and reducing building pollution.

The Hong Kong meeting comes ahead of the United Nations’ annual climate summit, in Cancun, Mexico, where countries are hoping to secure a binding global treaty on how to limit and cope with climate change.