UN Secretary-General Ban Ki-moon on Monday called for international efforts to fight climate change as growing world population and urbanization continue to worsen the problem.

Ban, in his message marking the World Habitat Day which fell on Monday this year, addressed the "50-50-50 challenge," referring to scientists'prediction that by 2050, global population will increase by 50 percent from what it was in 1999, and in order to survive, the human race has to cut greenhouse gas emissions by 50 percent compared to levels at the turn of the millennium.

"Rising sea levels are a major impact of climate change -- and an urgent concern," Ban said, highlighting that 60 million people now live within one meter of sea level and major coastal cities such as New York, Shanghai, Tokyo and Amsterdam could face serious threats from storm surges.

Cities are centers of industrialization and sources of emissions, but they are also home to solutions by developing new energy such as wind, solar and geothermal energy, Ban said.

"Local efforts are critical to success, but they must be supported by international initiates," the secretary-general said in the message.

The world efforts have already created the Climate Change Adaptation Fund and all countries have agreed on the goal of limiting global temperature rise to below 2 degree Celsius, Ban said, adding that "now we need to build on these advances."

"The United Nations Climate Change Conference in Durban this December must achieve decisive progress," the secretary-general said. "Urbanization will be on the agenda at next year's Rio+20 UN Conference on Sustainable Development."

Also on Monday, the United Nations kicked off the preparatory negotiations in Panama -- the last formal negotiations before world leaders meet in Durban, South Africa, next month to discuss ways to implement existing climate change agreements such as the Kyoto Protocol and the Cancun Agreements.

The Kyoto Protocol has been ratified by 192 of the 195 Parties to the United Nations Framework Convention on Climate Change ( UNFCCC). Under the Protocol, 37 States, consisting of highly industrialized countries and countries transitioning to a market economy, have legally binding emission limitation and reduction commitments.

Ban said our planet's 7 billionth inhabitant will be born at the end of this month, and "the future that this child and its generation will inherit depends to a great degree on how we handle the competing pressures of growing population growth, urbanization and climate change."

The United Nations has celebrated World Habitat Day every year on the first Monday of October since 1986, aiming to remind the world of its collective responsibility for the habitat of future generations.