Yet, the "good news is that if we act now, we have the means to build a more sustainable world," he said, explaining that quick and decisive action that draws on many readily available tools and technologies can put the world on the right track. Renewable energy sources are increasingly economically competitive. Energy efficiency has long proven its value. It was a myth that climate action would be costly, he said, stressing that in fact, inaction "will cost much, much more," he added.

R. K. Pachauri, Chair of the IPCC, underscored that the means to limit climate change are at had. "The solutions are many and allow for continued economic and human development. All we need is the will to change, which we trust will be motivated by knowledge and an understanding of the science of climate change."

Speaking later at the Copenhagen Energy Security Dialogues, the Secretary-General commended the global vision of European Union leaders who had taken decisive action to cut greenhouse gas emissions by 40 per cent from by 2030.

"This is one of the major achievements immediately after the Climate Change Summit which I convened," in late September, said the UN chief, adding that while he has made the issue one of the Organization's top priorities, he wanted to broaden the scope of measures aimed at tackling it.

Indeed as climate change "is not just a matter for environmentalists and/or scientists. It is a major development challenge that can also lead to serious security threats", Mr. Ban said, noting that mobilizing for climate change is also mobilizing for sustainable development.

As such, the United Nations would focus on three linked priorities for next year: accelerating continued efforts to meet the targets of the Millennium Development Goals (MDGs); shaping a "bold and ambitious" post-2015 development agenda by the end of next year; and agreeing a meaningful climate change agreement by next December next year in Paris.

"A transformative approach to energy can drive all these priorities to a successful realization," of those aims, said the Secretary-General, noting that the Sustainable Energy for All initiative he had launched in 2011is mobilizing governments, businesses, finance and civil society to transform the world's energy systems.

"The United Nations is bringing the world together on energy because energy is central to our future well-being as a human family," he said.

(UN contributed to the story)