Five top United Nations officials have added their names to a petition urging world leaders to ‘seal the deal’ in Copenhagen, Denmark, this December on an ambitious new climate change pact aimed at curbing greenhouse gas emissions.

Joining the ever-growing list of names are Margaret Chan, Director-General of the World Health Organization (WHO); Michel Jarraud, Secretary-General of the World Meteorological Organization (WMO); Kanayo F. Nwanze, President of the International Fund for Agricultural Development (IFAD); Pascal Lamy, Director General of the World Trade Organization (WTO); and Francis Gurry, Director General of the World Intellectual Property Organization (WIPO).

They signed the online petition, which will be presented to leaders at the UN Framework Convention on Climate Change (UNFCCC) gathering in Copenhagen, where negotiations are expected to wrap up on a successor pact to the Kyoto Protocol, whose first commitment period ends in 2012.

The campaign calls for binding targets to be set on cutting emissions by 2020 and help for vulnerable countries so they can adapt to the effects of climate change.

It also highlights the urgent need for a new deal that will spur ‘green’ growth, protect the planet and build a more sustainable and prosperous global economy that will benefit all countries and people.

Last week, Secretary-General Ban Ki-moon said that the cuts in emissions proposed by the world’s largest economies are not deep enough, warning that greater efforts must be exerted by governments if a meaningful agreement on climate change is to be reached in the Danish capital.

The climate change commitments made by the leaders of those countries and other participants during the Major Economies Forum (MEF) meeting, “while welcome, are not sufficient,” he said in L’Aquila, Italy, where the annual summit of the Group of Eight (G8) industrialized nations was taking place.

“The time for delays and half-measures is over,” Mr. Ban said. “The personal leadership of every head of State or government is needed to seize this moment to protect people and the planet from one of the most serious challenges ever to confront humanity.”

G8 leaders have agreed to a long-term goal of reducing emissions by 2050, but Mr. Ban said that this target was not credible without “ambitious mid-term targets, and baselines.”

With G8 countries responsible for more than 80 per cent of global emissions, “that is why they bear special responsibility for finding a solution to the political impasse. If they fail to act this year, they will have squandered a unique historical opportunity that may not come again… We stand at a historical crossroads. Business as usual is no longer viable,” he added.