Jaipur joined this league along with four other cities - Durban, Quito, Amman and Salvador - as members to this global network, known as 'C40 Cities Climate Leadership Group' (C40), on Thursday.

The addition of these five cities has increased the C40's overall membership to 75 cities. It is a network of the world's mega cities taking action to reduce greenhouse gas emissions.

"By taking bold action and collaborating, mayors around the world are driving the climate change agenda on a global scale toward lower emissions and greater resilience," said C40 Chair and Rio de Janeiro Mayor Eduardo Paes.

"These five cities truly represent the diversity and ethos of the C40 - they span three continents but are united in their desire to increase the health, well-being and economic opportunities of urban citizens," an official statement of the group quoted Paes as saying.

The C40 was created in 2005 by former Mayor of London Ken Livingstone, and forged a partnership in 2006 with the Cities Program of President Clinton's Climate Initiative (CCI) to reduce carbon emissions and increase energy efficiency in large cities across the world.

Under the leadership of then Mayor of Toronto David Miller, who served after Mayor Livingstone as C40 Chair, the organization advanced programs and partnerships that drew international recognition for the role of cities as leaders in climate action.

"The C40 network keeps growing because more and more cities are finding opportunities to confront climate change in ways that improve people's lives today," said UN Special Envoy for Cities and Climate Change and President of the C40 Board Michael R Bloomberg.

He said, "For the UN climate treaty negotiations this December to be successful, nations will have to commit to doing more and acting faster to shrink their carbon footprints - and cities, including the five new members of C40, are helping point the way forward."

Former Mayor of New York City Michael Bloomberg had served as C40 Chair from November 2010 to December 2013.

The five new member cities represent an estimated 21 million people and have each demonstrated strong leadership in climate action in their regions, noted the network in its statement, issued from London.

All big cities like London, Paris, Washington DC, New York, Beijing, Hong Kong, Seoul, Shanghai, Oslo, Madrid, Warsaw, Houston, Boston, Chicago, Tokyo are members of this network. Besides three Indian cities, Dhaka (Bangladesh) and Karachi (Pakistan) are the other South Asian cities in the group.

Under the city-to-city collaboration, city officials can be bombarded with advice from constituents, advocates, experts, and consultants, representing various agendas and perspectives.

"But when faced with a challenge, one valuable type of advice is often forgotten: insight from another megacity official who has been in the same position. Such experience can help city officials perform their jobs faster, better, and smarter", said the group's website.

The C40 Networks facilitate knowledge transfer and peer-to-peer exchange between individual city staff members responsible for implementation with the aim of sharing challenges, opportunities and best practices. Networks can also provide a platform for joint problem solving.