The biggest population growth in the world was taking place in cities and planners had to design policies that will mitigate against the effects of such rapid growth, the agencies warned. The agencies stressing the urban dimension of climate change included the United Nations Environment Programme (UNEP), the United Nations Population Fund (UNFPA), and the UN Economic Commission for Europe.
"One thing we must always be aware of is that the least able are the most exposed to the ravages of climate change. With some one billion people already in slums and inadequate housing conditions we must carefully take into consideration their interests," said UN-HABITAT Executive Director Mrs. Anna Tibaijuka said.
World mayors gathering in Copehagen also made a similar warning and pledged further action on climate change.
Mrs. Tibaijuka, a winner this year of the world's top environment award, added that climate change also had a gender dimension which was yet to be fully explored. "Women and children are the most vulnerable to the effects of climate change we must prioritise how to help them," she said.
One of the best ways of preparing to deal with the effect of climate change was sustainable urbanization, she stressed. According to the Executive Director, chaotic urbanization was the bane of many countries especially in the developing world. She gave the example of Africa where she said about 60 percent of urban residents were living in coastal cities hence highly vulnerable to climate change like rise in sea levels.
Her remarks came as world leaders gathered for the final phase of climate talks that have taken years of preparation.
Arriving in Copenhagen, to inject fresh energy into climate change talks, UN Secretary-General Ban Ki-moon exhorted nations to "seal the deal" on an ambitious new agreement, warning that the well-being of all of the world's people is at stake.
The two-week summit under way in the Danish capital is "as momentous as the negotiations that created our great United Nations... from the ashes of war more than 60 years ago," Mr. Ban said at the opening of the conference's high-level segment on Tuesday.
"Once again, we are on the cusp of history," Mr. Ban said. With the two-week summit set to wrap up on Friday, he said countries must not allow the talks to fail in the home stretch. He joined a chorus of leaders in urging all to put aside their "maximalist" negotiating positions and "unreasonable" demands.
"We do not have another year to negotiate," he said. "Nature does not negotiate."
Over 130 heads of State and government have confirmed their participation at conference, "clear proof that climate change has risen to the top of the global agenda," the Secretary-General noted.
An agreement that all nations can embrace must be forged in Copenhagen that brings all countries together with the common goal of reigning in a global temperature rise to within two degrees centigrade and promotes 'green' growth, he said.
In his welcoming address, Danish Prime Minister Mr. Lars Rasmussen set the tone when he appealed for a compromise at the talks. "Time is running out. The world is watching. The world is literally holding its breath and we have only up to the end of this week to reach an agreement," he said.
He said climate change was now higher on the agenda than ever before. "And that is the way it should be."
Addressing reporters earlier Tuesday, Yvo de Boer, Executive Secretary of the UN Framework Convention on Climate Change (UNFCCC), said that the process is "not about ramming the interests of a few down the throats of many. This process is about many trying to address all interests."
Complicating the negotiations in Copenhagen are the various interests, he said, including small island nations'fears that they will be inundated by sea level rise, oil producers fearing the future of the economy and major developing nations which are concerned about economic growth and poverty eradication.
Others who addressed the meeting included the President of 15TH Conference of the Parties (COP 15) Ms. Connie Hedegaard of Denmark, United Natons Convention on Climate Change Executive Secretary Mr. Yvo de Boer and Prince Charles of the United Kingdom.
The Prince challenged the world to change from pessimistic view on the challenges of climate change and start looking at things positively: "Imagine a healthier, safer, and more sustainable, economically robust world. Because if we share in that vision, we can share the will to action that is now required."