Millions of people worldwide may take part in a global climate strike on Friday aimed at pushing the world's leaders to take substantive steps toward halting the advance of climate change. 

Climate strike organizers say more than 3,500 individual demonstrations around the world will be held including 800 in the United States. It follows a similar coordinated protest in March that drew many tens of thousands around the world. Their message: get the world off of fossil fuels rapidly and switch to renewable sources such as solar and wind.

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A report released last year by a U.N. science panel concluded that there's still a chance to meet the 2015 Paris climate accord's goal of keeping global temperatures from rising more than 1.5 degrees Celsius (2.7 degrees Fahrenheit) by 2100 compared with pre-industrial times. But achieving this would require drastic measures, including ending the use of fossil fuels such as oil, gas and coal by mid-century.

The protests this Friday are partly inspired by the activism of Swedish teenager Greta Thunberg, who has staged weekly demonstrations under the heading "Fridays for Future" over the past year, calling on world leaders to step up their efforts against global warming. Many who have followed her lead are students, but the movement has since spread to civil society groups.

Friday's demonstrations will take place days before a U.N. climate summit in New York at which heads of government will present their long-term plans for curbing greenhouse gas emissions. Thunberg will address the summit next Monday.

The New York City school district is just one that says it will allow students an excused absence to take part in Friday's event.

A second day of strikes is planned for Sept. 27. Organizers say the reason for the back-to-back Fridays is to start a continuous, mass-mobilization effort.

An Associated Press-NORC poll released last week showed roughly three out of four Americans say they believe climate change is happening and a large majority of those think humans are at least partly to blame. In total, 47% of all Americans say they think climate change is happening and is caused mostly or entirely by human activities; 20% think it's caused about equally by human activities and natural changes in the environment; and 8% think it's happening but is caused mostly or entirely by natural changes in the environment.

About two out of three Americans say corporations have a responsibility to combat climate change, and a similar share also say it's the job of the U.S. government. About two-thirds of Americans also favor regulating carbon emissions from power and industrial plants.