The People's Climate March may end up being the biggest protest to urge action to restrain global warming yet. The march in New York City on September 21 is predicted to draw more than 100,000 people, which would top the tens of thousands who showed up in Copenhagen back in 2009. But how many scientists, whether they study climate change or not, will be there?
The idea of the march—first proposed by writer and activist Bill McKibben of—is intended to remind world leaders gathering in New York City for a United Nations climate summit that people around the world demand action to halt global warming. And action to combat climate change is what many scientists have been calling for since at least the 1970s, in a series of scientific publications and reports, such as the Intergovernmental Panel on Climate Change series. "Writing more such articles is not going to change minds," says geologist James Powell of the University of Southern California, who is attending the march and helping to organize scientific involvement. "We need to do something more dramatic." Like many older scientists, Powell says he is doing it for his grandchildren. "I imagine my grandchildren and their children decades in the future asking: 'What did grandpa do?' I want to have an answer."
Powell, who was president of both Franklin and Marshall College and Reed College during the apartheid divestment movement, believes that it will take political muscle to force politicians to act. So he partnered with former professional biologist Lucky Tran to help organize Science Stands, which helped attract scientists from across the country and organizations such as the New York Academy of Sciences, which urged member via email to gather at the American Museum of Natural History to participate in the march. "If the most well-informed citizens are not willing to act, what hope do we have of averting climate catastrophe?" asks Pattanun "Ploy" Achakulwisut, a PhD student in atmospheric science. She enlisted other graduate students from Harvard University to join the march, partially with the help of a scientist / superhero poster exhorting scientists to "mobilize march [and] make history."
As the world's most famous physicist Albert Einstein is once reputed to have said: "those who have the privilege to know have the duty to act," a sentiment echoed by conservation biologist Jessica Hellman of the University of Notre Dame, who notes that it is also now time to adapt to the climate change already detected and underway.

Such communication to leaders and individuals is vital, according to scientific organizations like the American Geophysical Union. "While AGU is not a sponsor or participant in this particular event, we strongly encourage our member scientists to talk to their communities and their elected leaders about the impacts climate change is already having on their communities and families," says Chris McEntee, executive director of the premier planetary science organization. "Unfortunately, our window for meaningful action won't be open forever."
Many branches of science are likely to be represented at the march: climate scientists of course, but also geologists, meteorologists, materials scientists and even engineers. "I'm marching because last Christmas, my hometown of Winchester—the ancient capital of England—saw its worst flooding in at least a quarter of a millennium," says Geoffrey Supran, a PhD candidate at the Massachusetts Institute of Technology and one of 70 MIT students and faculty attending the march. "We have the technologies to begin to tackle the climate crisis. What we lack is the political will to make it happen."
In the lab, Supran has worked on trying to make more efficient photovoltaic cells to convert sunshine to electricity and better light-emitting diodes, or LEDs, to cut down on the amount of electricity needed to produce lighting. Such technologies can help reduce emissions of carbon dioxide and other greenhouse gases into the atmosphere. That effort may include using more solar, wind, geothermal, hydropower and/or nuclear power, as well as placing a price on the CO2 pollution from burning fossil fuels. Many economists believe such a switch to renewable sources of energy can contribute to a stronger economy and better human lives rather than slow such growth. And the infrastructure decisions made in the next 15 years or so will determine levels of greenhouse gas pollution for the remainder of the century. At the same time, technologies to pull CO2 back out of the atmosphere may prove vital since atmospheric concentrations are nearing 400 parts-per-million—and rising.
Scientists have not traditionally expressed policy preferences, preferring to maintain a stance of impartiality. Such dispassion, neutrality and objectivity will remain fundamental to the scientific method. At the same time, says Powell, "we have detected a threat, the greatest threat ever detected in human history." Sea level rise alone could force mass migration inland here in the U.S. in coming centuries, he says. "At this point we need to abandon our reticence and speak out forcefully, and just speaking may not be enough."
That's because the threat is large. As a geologist, Powell notes that by burning fossil fuels humans have sped up geologic processes like climate change more than 1000-fold. Whereas the Earth cooled or warmed over centuries or millennia in the past, it is now warming over the course of decades and even years. A new record for total CO2 pollution was set in 2013—including the fastest rate of CO2 pollution growth—and is likely to be broken again this year.
Or, as paleoclimatologist Peter deMenocal of Columbia University puts it: the "modern climate is exceptionally warm relative to the last millennium, and future decades will be another world, unlike anything modern civilization has ever seen. This is a really sobering fact."
So he will be joining the march along with Columbia colleagues and his twin 8-year-old girls. "It's important they witness that a lot of people care about this issue and are willing to do something about it," he says. "This is about their future."