The annual United Nations climate summit has urged world leaders to change their course towards climate change with emphasis on global warming and reducing greenhouse gas emissions.

Tuesday's one-day summit in New York was the first high level gathering since the 2009 Copenhagen conference on climate change which ended in disarray.

"Today, we must set the world on a new course," UN Secretary General Ban Ki-moon told leaders from 120 countries. "I am asking you to lead."

"Climate change threatens hard-won peace, prosperity, and opportunity for billions of people," Ban said. "We are not here to talk. We are here to make history."

We are not here to talk. We are here to make history.

UN Secretary General Ban Ki-moon.

In his address, Ban called for a reduction in greenhouse gas emissions and declared that by the end of the century the world must be carbon neutral.

More than 100 world leaders attended the summit, with no-shows from the leaders of China, the world's biggest polluter, and India, the world's third largest carbon-emitter.

Leaders pledge to coordinate

World leaders took over with the first of many of the non-binding pledges, promising by mid-morning a total of at least $5 billion to help the world become more sustainable.

Pledges include turning away from the burning of coal, oil and gas and away from the destruction of the world's carbon-absorbing forests.

The European Union offered a rare proposal with specific targets beyond 2020 saying its member nations would cut greenhouse gases so that by 2030 they would be 40 percent below the 1990 level.

In a brief speech on Tuesday, Jose Manuel Barroso, the president of the European Commission, stressed it could be done without harming the economy.

"The European Union is on track to meet our targets and at same time we have seen our economy grow,'' Barroso said. "We prove climate protection and a strong economy must go hand in hand.''

French President Francois Hollande pledged $1b distributed over the next four years to help developing nations adapt to the effects of climate change, while South Korea's President Park Geun-hye pledged $100m to the Green Climate Fund.

Developing countries have called for a target total of $15b in 2014. Others countries, like Chile, pledged cuts in greenhouse gas emissions by 2020.

Ban, Hollywood actor Leonardo DiCaprio who is also the UN representative on climate change, former US Vice-President Al Gore and Rajendra K Pachauri, who headed the Nobel Prize-winning panel of scientists who studied the issue, warned that time was running out .

The summit followed worldwide marches that brought together thousands of demonstrators in cities worldwide on Sunday calling for urgent global action.

Source: Agencies