Meet Claire Anterea and Bob Inglis. Anterea is from the remote Pacific island of Kiribati, one of the least developed nations on Earth. Inglis is a former Republican member of the U.S. House of Representatives from South Carolina.

Anterea once thought of herself as a "nothing," while Inglis, though he no longer holds office, is well connected in the U.S. capital. Although a world apart, they both have demonstrated exceptional courage by acknowledging the science of climate change. 

That's because in many communities, climate science remains an issue of debate and sometimes derision. Andrea Cooper's profile of Inglis ("Bob Inglis Takes a Stand on Climate Change") explains how, in 2010, Inglis lost his office after telling constituents in his deep-red district that climate change is a clear and present danger. In the feature "In Kiribati, a Former Catholic Nun Has Become a Sort of Paul Revere for Climate Change," Mike Ives tells the story of Anterea's struggle to convince her devout neighbors that global warming poses a real threat to their homeland. 

Being social animals, humans are prone to groupthink. We go along to get along. Tribalism is irresistible: As recent studies in social psychology demonstrate, most of us will cherry-pick evidence and disregard inconvenient facts to stick with the beliefs of those in our squad.

Climate change is the textbook example. In general, political conservatives (even those with a knowledge of science) claim that the human causes of rising temperatures are overstated, or that global warming is a vast conspiracy. Progressives typically accept the science and are concerned. According to the director of the Yale Program on Climate Change Communication, global warming is a more polarizing issue among Americans than abortion or gay marriage. 

The guts and grit of Anterea and Inglis represent a challenge to environmentalists, some of whom (myself included) have a checklist to decide who's truly green. At the historic 2014 People's Climate March, the banners read, "To Change Everything It Takes Everyone." Exactly right. We can't afford to turn away people of good faith who might not agree with us on all points. 

Such an open-door policy will lead to difficult conversations and uncomfortable moments. And that's the point: remembering that it takes a lot of heart to be a heretic.