Former President Clinton has launched an initiative with several of the world's largest cities to reduce global warming.

Mr. Clinton announced Tuesday in the western U.S. city of Los Angeles, California that his foundation has formed a partnership with the Large Cities Climate Leadership Group to reduce emissions of greenhouse gases. The initiative will help cities pool their resources in order to purchase cheaper energy-saving products.

It will also offer technical assistance to the participating cities, and create tools to measure the effectiveness of programs aimed at reducing greenhouse gases.

A total of 22 major cities will participate in the initiative, including Los Angeles, New York City, Chicago in the midwestern U.S. state of Illinois, and London.

California Governor Arnold Schwarzenegger and British Prime Minister Tony Blair announced a joint effort on Monday to fight global warming.

Scientists say an increase in the use of fossil fuels has led to a rise in the levels of carbon dioxide that are trapped in the Earth's atmosphere, causing a so-called "greenhouse gas" effect that increases the planet's temperatures.

Global warming has been blamed for such environmental changes as the melting of polar ice and stronger tropical storms.

Some information for this report was provided by AP.