As thousands of peaceful demonstrators descended on Manhattan on Sunday to draw attention to a warming world, U.S. Secretary of State John F. Kerry called on the world's biggest economies to shake off two decades of gridlock and take significant steps to halt climate change.
Speaking at the Major Economies Forum in New York, Kerry likened the climate to the immediate threats of Ebola in West Africa and Islamic State in the Middle East, saying its implications stretch far into the future.
"We can already see climate refugees, and in some places fighting over water," Kerry said. "This has an immediacy people need to understand."
The Major Economies Forum, a gathering of foreign ministers of the world's 20 largest economies, is setting the stage for the United Nations Climate Summit, where 120 world leaders will discuss strategies for achieving a new global climate treaty.
The People's Climate March also was keyed to the climate summit. The New York march was one of more than 2,000 such demonstrations around the world Sunday, including in London, New Delhi and Melbourne, Australia, according to organizers. A Los Angeles demonstration took place Saturday.
Notable figures at the New York event included billionaire environmental activist and philanthropist Tom Steyer from California, U.S. Sens. Bernie Sanders of Vermont and Sheldon Whitehouse of Rhode Island, New York Mayor Bill de Blasio, actors Leonardo DiCaprio and Mark Ruffalo, Al Gore, Robert F. Kennedy Jr. and Mary Robinson, the former president of Ireland.
Organizers estimated that more than 310,000 people participated in the Manhattan demonstration, which Bill McKibben, chairman of the environmental group 350.org, described as "mildly chaotic but incredibly beautiful."
Speaking by phone from the march, McKibben said he hoped the demonstrators' numbers would help tilt the public debate toward action on curbing climate change.
"They have all the money, but I think we're demonstrating today [that] we have quite a few people," McKibben said. "This is what happens when people organize -- things begin to shift."
After decades of little more than symbolic action by the biggest emitters of heat-trapping greenhouse gases, expectations remain low for meaningful steps to emerge this time. In fact, the U.N. meeting is meant to elevate the issue of climate change at the start of a 16-month process to produce an agreement. The summit is more about countries showing how serious they are about global warming.
Also Sunday, scientists announced that the world's emissions had grown 2.3% last year to 39.8 billion tons -- the highest level ever -- largely because of China, the U.S. and India.
At the Major Economies Forum, Kerry spoke bluntly about the responsibility major economies bear for climate change, including the U.S.
"We all know exactly what it takes to get the job done," he said. "The solution is energy policy ... every one of our countries has the technology to do this. It's about getting the political will to make the decisions."
On the other side of the climate discussion are nations facing the earliest and most severe consequences of global warming. They are largely small island nations, mostly in the Pacific, such as the Marshall Islands. They know that the biggest carbon polluters -- such as the United States and China -- will offer only broad outlines this week of steps they will take to curb emissions, and will not issue concrete targets until March. But the most vulnerable states hope the initiatives are "not only fair, but effective and ambitious," said Tony deBrum, foreign minister of the Marshall Islands.
They also hope that rich countries will deliver more money to help small vulnerable states adapt to damage from climate change. It remains unclear whether the major polluting countries, which are among the world's biggest economies, will pledge adequate amounts of money. But the U.N. fund created to help small nations remains severely underfunded.
Out on the Manhattan streets, the sky was overcast, and fog enveloped the tops of skyscrapers. Many participants hadn't approached the march's starting line more than two hours after the parade began.
Several groups opposing the planned Keystone XL pipeline were among those joining the march. Pipeline foes argue that the pipeline could threaten important underground water resources and help promote development of carbon-intense oil production in the tar sands of Alberta, Canada.
Stanley Sturgill, a retired coal miner from Kentucky who suffers from black lung, a condition brought on by prolonged exposure to coal dust, was in the crowd.
"We have dug the coal that has generated the electricity to power this country but our people are paying a price for it," he said. "We are here to tell our world leaders that we are at the front lines of this crisis."
Marchers held a moment of silence at 1 p.m. to honor people affected by climate change. Afterward, the crowd cheered.
"We are in the race of our lives against climate change. It already affects all of us -- every person, in every country," Fred Krupp, president of the nonprofit advocacy group Environmental Defense Fund, said in a statement.
"It is having an impact on our health, our safety, our economy, our food supply, and those impacts will surely grow exponentially if we do not reduce climate pollution dramatically, starting now. And yet today's march made me more optimistic than ever that we can meet this challenge."
The march comes as polls show increasing support in the United States for policies to combat climate change.
Two of every three registered voters in the U.S. think global warming is happening, and more than half of them are worried about it, according to a poll conducted by the Yale Project on Climate Change and the George Mason University Center for Climate Change Communication.
Two-thirds of Americans say they support laws that would promote the use of renewable energy to wean the country from fossil fuels, and two-thirds also support setting limits on carbon-dioxide emissions from coal-fired power plants.