New York, NY (BBN) – The United Nations chief on Tuesday pressed world leaders gathered at the United Nations to gear up their action on global warming and preserve the planet for future generations.

Tuesday’s summit at UN Headquarters in New York is the largest ever on climate change, with more than 100 heads of State and government in attendance, the UN said.

The summit takes place just under 80 days before the start of the Copenhagen conference, where nations are aiming to wrap up negotiations on an ambitious new agreement to curb greenhouse gas emissions that would go into effect in 2012 when the Kyoto Protocol’s first commitment period expires.

“Climate change is the pre-eminent geopolitical and economic issue of the 21st century,” Secretary-General Ban Ki-moon said, adding: “It rewrites the global equation for development, peace and security.”

He also urged developed nations to take the first steps forward, with developing nations also needing to make strides. “All countries must do more – now.”

The day-long event opened with the recitation of a portion of late astronomer Carl Sagan’s Pale Blue Dot by actor Djimon Hounsou, followed by a film both written and narrated by children from around the world.

The United Stats President Barack Obama President Mohamed Nasheed of Maldives, President Hu Jintao of China, Prime Minister Yukio Hatoyama of Japan, President Paul Kagame of Rwanda, Prime Minister Fredrik Reinfeldt of Sweden, President Óscar Arias Sánchez of Costa Rica, and President Nicolas Sarkozy of France spoke at the opening session of the gathering.

At the end of the day-long summit, this understanding will be captured in a summary presented by the UN chief, according to the UN.

BBN/SS/SI/AD-22September09-11:44 pm (BST)