NBC News is reporting that millions of people are set to join demonstrations today, demanding action on climate change in scores of cities around the world. Some of the cities include London, New York, San Francisco and Seattle.

Many groups are involved in organizing the strikes including schoolchildren, trade unions, environmental groups and employees at large tech companies such as Amazon and Google, and their demands are all similar: reducing the use of fossil fuels to try to halt climate change.

In day of coordinated global action:

• Australia saw some of the first protests kick off Friday morning with organizers estimating that upwards of 300,000 students and workers filled the streets of Melbourne, Sydney and other cities in the biggest protests the country has seen in years.

• New Delhi, India, one of the world’s most polluted cities, saw dozens of students and environmental activists chant “we want climate action” while hundreds marched in Thailand’s capital Bangkok, before staging a “die-in” outside the Ministry of Natural Resources

• In London, thousands of people from infants to grandparents blocked traffic outside the Houses of Parliament chanting “save our planet.”

• Crowds had gathered in European capitals including Berlin and Warsaw, African capitals such as Nairobi, Kenya, while organizers say there are some 800 events planned to take places in the U.S. later. New York City’s 1.1 million public school students were told they would be allowed to skip class to attend protests.

A coalition of environmental groups, youth organizations, unions and others using the hashtag #strikewithus have demanded passage of a “Green New Deal.”

The demonstrations are timed to nearly coincide with Monday’s U.N. Climate Summit in New York, where United Nations Secretary-General Antonio Guterres has said he wants to see governments and businesses pledge to abandon fossil fuels. “We are losing the fight against climate change,” he said at a news conference on Wednesday, according to Reuters.

Fridays for Future began as a weekly demonstration by Swedish teenager Greta Thunberg in August 2018 but has since spread to more than 150 countries