The largest-ever gathering of world leaders to discuss climate was designed to lay the groundwork for a new global climate-change treaty.
More than 120 world leaders gathered on the sidelines of the U.N. General Assembly to galvanize support for a global climate treaty to be finalized next year in Paris.
"Today we must set the world on a new course," said U.N. Secretary-General Ban Ki-moon, who added that pricing carbon was critical. "Climate change is the defining issue of our age. It is defining our present. Our response will define our future."
Obama said global warming "will define the contours of this century more dramatically than" terrorism, disease or inequality.
"The United States has made ambitious investments in clean energy and ambitious reductions in our carbon emissions," Obama said. "Today I call on all countries to join us, not next year or the year after that, but right now. Because no nation can meet this global threat alone."
Some of the tools the U.S. will offer developing nations were developed by NASA and the U.S. Geological Survey and are intended to help communities use data modeling, forecasting and science to anticipate the effects of climate change and make decisions about the best way to deal with it. Secretary of State John Kerry also announced that the U.S. would contribute $15 million to a World Bank program designed to stimulate funding for projects that reduce methane pollution.
The United States decided not to join 73 countries in supporting a price on carbon, which Congress has indicated it would reject.
"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 global community to tackle this global threat before it is too late."
Chinese Vice Premier Zhang Gaoli insisted the world treat developing nations, including China, differently than developed nations, allowing them to release more heat-trapping pollution. China, the No. 1 carbon-polluting nation, signed on in support of pricing carbon and vowed to stop the rise of carbon-dioxide emissions as soon as possible.
The European Union said its member nations next month were set to approve a plan that would cut greenhouse gases back to 40 percent below 1990 levels by 2030. The EU also called for using renewable energy for 27 percent of the bloc's power needs and increasing energy efficiency by 30 percent.
The United States will not release its new emissions targets until early next year.
By 2020, China will reduce its emissions per gross domestic product by 45 percent from 2005 levels, Zhang said. But because economic growth in China has more than tripled since 2005, that means Chinese carbon pollution can continue to soar. Still, outside environmentalists hailed the country's promises because they went beyond any of China's previous statements.
World leaders pledged to spend at least $5 billion making the world more sustainable. France promised $1 billion. Korea pledged $100 million. Others, like Chile, pledged cuts in greenhouse gas emissions by 2020.
Tim Phillips, president of conservative political advocacy group Americans For Prosperity said it is telling that Obama will go before the United Nations to talk climate change before he will go to Congress.
"Because they know the American people are opposed to these new environmental rules and regulations," Phillips said. "These rules will dramatically inhibit job creation, they will drive up gasoline prices, utility bills, and they will limit long term opportunity for the middle class and for those most vulnerable in our society — the two groups the president says he wants to help the most."
Conservative/libertarian think tank, The Heartland Institute, said in a release that efforts to address climate change are a "giant wealth transfer scheme."
“President Obama may be taking the lead on new global warming initiatives, but few world leaders critical to the success of any prominent climate agreement appear willing to follow. The leaders of China, India, Russia, and Germany are all skipping the U.N. climate gathering," according to a Heartland Institute release. "Since they are among the largest CO2 emitters, without their agreement, CO2 will continue to rise whatever America and the rest of the world does."
Sierra Club Executive Director Michael Brune said street protests in major U.S. cities show the public's desire for action on climate change.
"On Sunday, a massive, diverse, and powerful movement for truly ambitious action on climate came together in the streets of New York, where we demanded our elected leaders hear our calls to action. Today at the United Nations, President Obama made it clear that he was listening," according to a Sierra Club release.
“By affirming his commitment to setting ambitious emissions reduction targets early next year and firmly calling on other major global economies to do the same, the President is choosing to lead. That leadership must include seizing all the opportunities he has at home to act on climate. His goals and policies must be ambitious, but they must also align with what the best science says is necessary to avoid the worst consequences of climate disruption."