Obama urges global action to combat climate change: ‘Nobody gets a pass’

President Barack Obama warned on Tuesday that the world’s climate is changing at a faster pace than efforts to address it, issuing a forceful appeal for greater international cooperation on carbon caps.

"Nobody gets a pass," he declared. "We have to raise our collective ambition."

He made his plea during the United Nations Climate Summit in New York, attended by political and business leaders and aimed at galvanizing support for a global treaty to be finalized next year. Obama said that the United States is doing its part and that it will meet a goal to cut carbon pollution by 17 percent from 2005 levels by 2020. He also announced modest new U.S. commitments to help other countries address climate change challenges.

But his strongest remarks came as he sought to unify the international conclave behind actions to reduce global warming.

"The alarm bells keep ringing. Our citizens keep marching," he said. "We can't pretend we can't hear them. We need to answer the call. We need to cut carbon emission in our countries to prevent worse effects, adapt and work together as a global community to tackle this global threat before it is too late."

Obama said the U.S. and China, as the largest polluters, have a responsibility to lead, adding, “We recognize our role in creating this problem.” But, he said, "no nation can meet this global threat alone."

China, for its part, pledged carbon cuts of 40 to 45 percent by 2020 from 2005 levels — more than double the percentage that Obama announced for the U.S.

About 120 world leaders gathered for the summit, organized on the sidelines of the U.N. General Assembly. U.N. Secretary General Ban Ki-moon asked representatives to arrive in New York with specific pledges in hand to mitigate climate change, as a way to show they are serious about ambitious emissions reductions in the treaty.

Some of the tools the U.S. intend to offer developing nations as part of efforts to combat climate change have been developed by NASA and the U.S. Geological Survey. They are aimed at helping communities use data modeling, forecasting and science to anticipate the effects of global warming and make decisions about the best way to lessen its impact. Secretary of State John Kerry announced that the U.S. would contribute $15 million to a World Bank program designed to stimulate funding for projects that reduce methane pollution.

But the pledges were modest compared with what some hoped the U.S. would commit to. By midmorning, other nations attending the summit had pledged at least $5 billion.

Representatives of vulnerable nations at the summit underscored the need for immediate action. For residents of island states and other low-lying areas around the world, the effects can already be seen in rising sea levels and extreme weather.

President Baron Waqa of the Pacific island nation of Nauru attended the conference as a representative of the Alliance of Small Island States — a body comprising 44 countries that are seen as among the most vulnerable to climate change.

He said the very viability of those states as sovereign nations is under threat. At the summit Nauru announced actions that it has been working on, including a rapid transition to clean energy under a framework called the Lighthouse Initiative. Waqa added that the island nations have presented an intelligence report on tackling the challenges of climate change.

The “window to achieve a (sustainable temperature rise) … is rapidly closing,” he said.

Al Jazeera and wire services. Renee Lewis contributed to this report.