WATERVILLE — The effects of global warming are materializing more quickly than expected, according to author and environmentalist Bill McKibben, who told a Colby College audience Thursday night that humans need to act now to address climate change.

McKibben, the founder of the grass-roots climate change organization 350.org, was the keynote speaker at the Community, Culture and Conservation Conference at Colby, which runs through Saturday.

“Climate change is the biggest thing humans have done, and we have to stop it at all costs,” McKibben told about 300 people gathered in Lorimer Chapel. “We have to figure out how to stop it before it breaks everything around us.”

Founded on the belief that mass mobilization can lead to change, 350.org started as a response to lobbying efforts of the fossil fuel industry against action on climate policy. Renewable energy such as solar power and efforts to reduce carbon emissions, such as electric powered cars, are potential solutions to slowing climate change, but they have been hindered by corporate fossil fuel interests, McKibben said.

350.org has held about 20,000 rallies “almost everywhere” around the world in support of addressing and preventing climate change, McKibben said, but he stressed that action must go further, citing the group’s protests of the Keystone XL Pipeline. More than 1,200 people were arrested in the protests against the pipeline, according to McKibben, which he said ultimately led to President Barrack Obama’s decision to reject the pipeline’s construction last year.

“We’re winning an increasing number of these fights. In New York state we managed to stop fracking before it started,” he said. “It’s amazing to see these kinds of fights go on.”

He also commended Colby on its divestment from fossil fuels in 2013 with the addition of a biomass plant to heat campus buildings and encouraged students to participate in the climate change movement.

“This battle will be played out, much of it in the lifetimes of everyone in this room,” McKibben said. “We’re talking about decisions being made in the next few months or years, because things are starting to slip out of control in a very serious way.”

Rachel Ohm — 612-2368

[email protected]

Twitter: @rachel_ohm