On May 21st, McKibben published an article on the website of Rolling Stone magazine (later appearing in the magazine's print issue of June 5th), entitled "A Call to Arms,"[4] which invited readers to a major climate march in New York City for the weekend of September 20–21.[note 1] In the article, McKibben calls climate change "the biggest crisis our civilization has ever faced," and predicts that the march will be "the largest demonstration yet of human resolve in the face of climate change."[4]

After criticizing world leaders, including President Obama, for not moving fast enough or going far enough to combat climate change, McKibben cites increasing evidence of environmental deterioration, including the melting of Arctic and Antarctic ice, the acidification of the oceans, and violent weather and quotes one climate scientist as exclaiming "We're all sitting ducks." He blames this state of affairs primarily on the fossil-fuel industry, which “by virtue of being perhaps the richest enterprise in human history, has been able to delay effective action, almost to the point where it's too late.” Although he claims that local, small-scale activism is crucial, the global climate justice movement sometimes "needs to come together and show the world how big it's gotten," and to allow for "opening up space for change."

Writes McKibben: "A loud movement – one that gives our 'leaders' permission to actually lead, and then scares them into doing so – is the only hope of upending" the "prophecy" that it’s already too late to reverse the problem.[4]