“I used to start every talk explaining in detail why reducing emissions and mitigating CO₂ was a good thing to do, because not everyone in the audience bought into the idea—even as recently as 10 years ago,” he says. Times have changed. “Now it’s a one-sentence throwaway. I get up and say, ‘CO₂ is having a negative impact on the environment, and we really need to do something about it.’ ”

Scientists and nonscientists alike have come to recognize that atmospheric CO₂ levels are rising quickly and that the greenhouse gas is adversely affecting the environment. That change in thinking leaves Bocarsly and other researchers at CO₂ conferences more time to discuss what to do with CO₂ to best address the problem. That’s another area where thinking has changed in a big way, he notes.