By Sid Farrar
Writer, editor, and volunteer with MN350's Communications Team

In his 2009 book, Storms of My Grandchildren, climate scientist and activist James Hansen talks about how, two years earlier, environmentalist leader and writer Bill McKibben approached him to confirm that the 450 parts per million (ppm) he had estimated as an upper limit for CO2 in the atmosphere was correct. McKibben was looking for confirmation for the number he should use in naming his new website that was to be devoted to activism and education about the climate crisis. Hansen had been working on determining this number since the 1990s and had published the 450 ppm limit in a paper in 2000. But with further study of the melting rate of the Arctic and other ice sheets, increases in species destruction, projected sea-level rise from methane, and especially new projected increases of future CO2 as the dominant climate forcing agent, he concluded that it would be “exceedingly foolish and dangerous” to allow CO2 to approach 450 ppm and was therefore unwilling to commit to that number for McKibben.

Hansen finally promised him a number by December 2007, when he was presenting on the rationale for such a limit at the American Geophysical Union meeting. In that talk, Hansen laid out the data and key phenomena that implied an appropriate initial target limit should, in fact, be no higher than 350 ppm. (We’ve already passed the 350 ppm mark: The current concentration of atmospheric CO2 being released is well over 400 ppm and increasing at a rate of approximately 2 ppm per year.) He gave Bill McKibben that number, who then built his website, and—and later, MN350 and MN350Action—was born. Many years prior to this, both men had established themselves as climate change pioneers, Hansen with the presentation of his seminal report in 1988 to a congressional committee on the future devastation from the ongoing release of greenhouse gases into the atmosphere, and McKibben with his publication the following year of The End of Nature, the first consumer book warning the public of the catastrophic consequences of their CO2-producing behaviors. The tenth-anniversary edition of McKibben’s book is still in print.

In the late 1960s and ’70s, Hansen, then a scientist at the Goddard Institute for Space Studies (GISS), had been conducting studies of the sulfuric composition of clouds on  planet Venus and concluded with an important article in the journal Science. He then applied the techniques he’d developed to a GISS global temperature analysis published in 1981 and, for the next 5 years, he and his colleagues were able to measure the temperature changes in the Earth’s atmosphere more accurately than ever using new computer analysis techniques. They discovered that warming in the past century was 0.5-0.7°C in both hemispheres. When they updated the analysis in 1988, they found the four warmest years on record were all in the 1980s. Hansen was able to use this startling data to make projections for increases in warming over the next several decades, which were the basis for his groundbreaking report to the Senate Committee on Energy and Natural Resources on June 23, 1988, arranged by then-climate advocate Senator Tim Wirth of Colorado.

As early as the late 19th century, scientists had argued that human emissions of greenhouse gases could change the climate. But serious research in which scientists expressed concern about future possible climate change didn’t happen until more than a decade before Hansen’s testimony. This was also seven years after the first Earth Day in 1970, when more people had begun to recognize the importance of protecting the quality of life on our planet. The report from the National Academy of Sciences released to the public in 1977 warned that average temperatures may rise 6 degrees Celsius by 2050 due to the burning of coal. But it was Hansen’s predictions of progressive global warming over the next several decades in the paper he presented to the Senate committee in 1988 that truly initiated serious public consideration of the havoc that climate change would wreak over the years to come. His presentation initially generated significant publicity, with the headline in the June 24, 1988, New York Times reading, “Global Warming Has Begun, Expert Tells Senate.” But the coverage died down, and he was eventually ignored by the politicians at that meeting and by most government leaders thereafter until Obama was elected in 2008, even though his predictions in that paper about greenhouse gas warming were remarkably accurate. Many scientists have pointed to an “eerie match” between Hansen’s forecasts and actual observed warming in the succeeding decades. In the years since, James Hansen has continued his research, publishing dozens of papers and appearing at countless climate conferences and in radio and TV interviews to make the scientific case for taking the threat of global warming seriously.

“We live at the end of nature, the instant when the essential character of the world is changing. If our way of life is ending nature, it is not radical to talk about transforming our way of life.” This is a quote from the lengthy excerpt from Bill McKibben’s book, The End of Nature, published in the New Yorker September 11, 1989, which continues to regularly publish McKibben’s essays on climate change since he turned over leadership of and assumed an emeritus role the summer of 2020. The book had a mostly positive critical reception, with acknowledgment of its importance as the first book to thoroughly address the science of climate change for general readers. He mined the breadth of existing scientific research, including that of James Hansen, to show how we have lost the concept of nature as wild. Instead, we have  assumed the role of natural system “managers” to produce raw materials and gain technological mastery over the planet. While we poison our air, waters, and soil, overpopulate the Earth, deplete our forests, and destroy countless species, we continue to pour large amounts of CO2 and methane into the atmosphere,  increasing global temperatures that are melting our ice caps and creating widespread megastorms, drought, forest fires, and flooding.

Like Hansen’s predictions, McKibben’s are coming true; in fact, the climate crisis looks to be much worse than he predicted in his revolutionary book. What was startling and hard to take in then, with its radical view of the wholesale destruction of our natural systems, has become commonplace knowledge for anyone paying attention to current climate news. That 60% of Americans now believe climate change is a major threat to our country, up from 44% just 11 years ago, is due to a large extent to the pioneering effort and continued climate advocacy of these two men. Just as important, if not more, was their example in saying what needed to be said in the face of disinterest, opposition, and outright hostility from most government leaders and much of the public over so many years. We may not be able to match the extraordinary achievements of these two men, but we can take inspiration from their willingness to stand up to resistance and persist in doing what is right by following their example and continuing the difficult everyday work of making the climate crisis a priority for people in power. As we challenge the advocates of the Line 3 pipeline, support small farmers in the face of the dominance of greenhouse gas-polluting industrial farms, make clean transportation a primary concern as car companies continue to flood the market with gas-guzzling SUVs and trucks, and get behind the Green New Deal faced with continued pressure to protect oil companies’ profits, we stand with James Hansen and Bill McKibben on the front lines of the climate change revolution.

This is how we can live up to the “350” in our name, given to us by these two true climate heroes.

To learn more about James Hansen, you can watch his speeches on YouTube and view his excellent presentation on the TED radio hour. To learn more about Bill McKibben, visit his website and read his new book, Falter, as well as his regular articles in the New Yorker.

Sid Farrar is a writer, editor, and volunteer with MN350’s Communications Team.