NEW YORK (AP) -- Mayoral delegations representing big cities around the world are tackling global warming this week in New York.

For the next few days, mayors of 32 of the world's largest cities will compare notes on global climate change. Cities produce the vast majority of carbon dioxide emissions and London mayor Ken Livingstone says the chief executives can learn a lot from one another.

Livingstone says rising sea levels pose a huge threat to his city, and notes New York could also suffer devastation.

Former president Bill Clinton and New York Mayor Michael Bloomberg -- who recently outlined an ambitious plan to reduce the city's carbon output -- are among the main speakers.