Scientists say that 350 parts per million of carbon dioxide in the atmosphere is the safe limit for humanity. However, with global warming and pollution, we have already reached 392 parts per million.

This may sound like scientific gibberish, but its implications are massive. If the carbon levels in earth’s atmosphere continue to rise coastal cities and islands, like New York City, and drinking supplies around the world could be in danger.

In an effort to try and bring the planet’s carbon back to safe levels, people around the world participated in the 350 Campaign on October 10 to “to unite the world around solutions to the climate crisis,” according to the group’s website,

Each group was determined to help the environment in a different way. In Harlem and Jamaica, Queens, that meant painting black rooftops white–one of the easiest ways to reflect rather than absorb sunlight, which can heat up the earth’s atmosphere. The roofs of Building 1 of Democracy Prep High School and SCO in Jamaica Queens were both painted white. In Brooklyn, projects ranged from a fix-your-own-bike class to park cleanups.

All in all, there were 35 official events throughout New York City and over 7,000 work parities around the world with projects in 188 countries, all with the same goal of decreasing the world’s carbon footprint.

The 350 Campaign is now gearing up for the International day of climate action on October 24.