Thursday night, about 40 people gathered in the basement of the Gilford Community Church for a potluck dinner. After about an hour of chatting, four scientists in the crowd fired up a PowerPoint presentation.
They were with the group Climate Up Close, which tours different states each year to try to explain what is and isn’t known about climate change in a way that's accessible to non-scientists.
Andrew Williams, a postdoctoral research fellow at Princeton, used charts to explain how the concentration of carbon dioxide in the atmosphere has grown since the late 1800s, ramping up even faster since the 1960s.
Carbon dioxide concentrations are measured in parts per million, he explained: Right now, the atmosphere has about 420 molecules of carbon dioxide per million molecules of air.
“Sometimes you’ll hear people saying, that’s like, a tiny, tiny number,” he said.
After a pause, he asked coffee drinkers in the room to raise their hands. Then, he explained that the amount of caffeine in coffee is about 350 parts per million.
“If you've ever been able to tell the difference between caffeinated coffee and decaffeinated coffee, your body has detected something that is 350 parts per million,” he said. “It's a small number, but it can really make a big difference.”
Williams showed the connection between rising global temperatures and rising concentrations of carbon dioxide in the atmosphere, and explained the models scientists have run to determine with confidence that increasing carbon dioxide levels have driven temperature changes.
He explained why scientists have confidence that more intense heat waves and sea level rise are connected to climate change.
Then, he passed the microphone to New York University researcher Aaron Match, who covered topics that scientists are somewhat settled on but somewhat uncertain about: heavy rainfall, hurricanes, droughts, and wildfires.
He also explained that there are topics scientists are more uncertain about: what will happen to the West Antarctic ice sheet, or massive stores of carbon in frozen Arctic soil? Those “tipping points,” he said, far from being inevitable, are very uncertain.
“Some of the nightmare scenarios that people have told us that keep them up at night, you can see that those are in the very uncertain, speculative part of the landscape,” he said. “We've tried to carefully show what parts of the science are settled, what parts are on the boundary, what parts are uncertain. And in the public conversation, what happens is this landscape gets scrambled.”
Nadir Jeevanjee, a research scientist at the NOAA Geophysical Fluid Dynamics Laboratory, presented on how emissions could affect warming in the future, explaining that if all emissions stopped today, temperatures wouldn’t drop or keep rising — they would plateau.
That scientific understanding is the underpinning for conversations about “net zero” emissions, for the idea that there’s a “budget” of carbon humans can emit before we hit certain temperature targets, he said.
“So future warming comes from future emissions. And I find that empowering, right? It's not that the planet is going to spin out of control in ways that we won't have any agency over,” he said.
At the same time, he explained, temperatures stay flat over a long period of time — centuries to millennia.
“What that's saying is that the global warming that we already have with us, we've committed to for a very long time. The future may be up to us, but that future is long,” he said.
Jeevanjee laid out a variety of policy choices — mitigation or adaptation? carrots or sticks? — and asked participants to remember that those are not just about science, but also about social values.
“What we hope is that now that we're closing out this talk, that you'll have some clarity about climate science, but also an openness to further conversation, to dialog in your homes, in your workplaces, in your communities about what we want to do and how it reflects who we are and what our priorities are,” he said.
Most attendees stayed long after the presentation ended to participate in a Q&A session. Match, the NYU researcher, said that kind of conversational engagement is what drew him to Climate Up Close. He helped co-found the group in 2019, sensing that the public conversation around climate change was increasingly divisive.
“I felt that as a climate scientist, I wanted to correct the record, to stave off some of that fracturing and align the conversation more with the consensus science and try to restore some civility, some grace to the types of climate conversations that we might have,” he said. “We try to model that by emphasizing our own uncertainty.”
The group aims to welcome people who are skeptical about climate science and who are alarmed in ways that go beyond what scientists know about the impacts of global warming.
Ultimately, Match said, changing peoples’ minds isn’t the ultimate goal. Instead, the group is hoping to bring more courtesy into climate conversations.
Plus, he said, reading climate reports and giving presentations has made him feel more optimistic about the future.
Climate Up Close is giving presentations in Franklin, Concord and Plymouth this weekend. More information can be found on their website.
