Climate Characters: Martial artist dodges punches and climate change warnings.

Editor's note: Climate Characters follows five people with varied views on climate change with the goal of bringing a greater degree of compassion and understanding to the highly polarized conversation.

Tucked into the far corner of BRICK CrossFit in West Hollywood is a padded 15-by-20-foot room where the main activity is punching. One hundred-pound heavy bags line the walls, swaying several inches above the ground, ready to take a hit. Gloves, mitts, hand wraps, dumbbells and a first aid kit sit on shelves.

Michael Casey, or Coach Casey to his clients, circles his opponent, a muscular woman in her mid-30s. He shuffles left and right, feet bare, gloved fists protecting his face. After thousands of hours training in martial arts, Casey knows a blow could come at any minute. He can never let himself be complacent.

When he was a child growing up in Paderborn, Germany, he was faced with a different kind of threat: one that he couldn't see, but was terrifying nonetheless. Parents, school teachers, radio programs and the TV news constantly echoed the fearful forecast: an ice age was coming.

“As kids, we would fantasize about this stuff," he says. “What would we do if there was an ice age? I would always have to wear warm clothes but I could ride my sled all of the time." And of course they'd have to worry about running out of food. He was again preparing for the unexpected to knock him down.

But the ice age never came. “By the time I finished high school, the lakes where I ice-skated as a kid didn't freeze over anymore," he said.

One might assume that when the lakes started melting, Casey would have shifted from believing the earth was freezing to realizing it was warming. But to this day, he believes government warnings about warming “are mostly fearmongering."

This inability to change his view seems strange coming from someone like Casey, who's had plenty of experience with diversity and novel situations. He grew up in Europe with an African-American father, and his parents always encouraged acceptance of diverse people and points of view. He moved to America in his 20s, after his active childhood inspired him to study sports science at a German University. Casey's career as a trainer led him all over the country, from New York, Illinois, Kentucky, and Florida to Arizona, and finally to California.

“I always tried to stay open-minded, to look at things from more than one point of view, because I've seen how people live differently," Casey says.

Throughout his life, Casey has always been prepared to change when he encountered a new situation, be it a fight or a new town. “Understand: I'm a martial artist. You can literally have information today and the next day you get punched in the face. And if you don't change, you're going to keep getting punched in the face."

But climate change is less tangible. It's not a fist coming at you. And when threats aren't concrete, people's minds can be very difficult to change. Especially with a multifaceted scientific issue, weighing the facts may be difficult or impossible for the average person.

"Instead of investigating a complex issue, we often simply learn what our referent group believes and seek to integrate those beliefs with our own views," writes Andrew Hoffman, a sociologist who specializes in sustainable enterprise at the University of Michigan. In his 2012 article “Climate Science as Culture War," he says relying on cultural groups for information further strengthens a person's ties to the group in a positive feedback loop.

Referent groups can be church congregations, sports teams, business colleagues. Consider a water-cooler chat where the boss leans in, sneering: “Did you hear about those sleazy climate scientists fudging their data? I always knew it was a hoax." Two nearby colleagues laugh and agree. Everyone walks away feeling stronger in their beliefs and more connected to their referent group, whether or not they started out with strong opinions on the subject.

Casey's referent group is his fellow athletes. Whether he's blocking punches or deadlifting a barbell, he forges his deepest personal connections on the training floor, where practicality rules. Focusing on the task at hand, Casey and his partners are relatively unconcerned about abstract and invisible threats.

Once people form beliefs, they quickly get set in their ways. And they feel the need to self-justify, or internally rationalize their decisions, according to Carol Tavris, psychologist and author of “Mistakes Were Made but Not by Me."

Imagine you're at a car dealership, deciding between a fuel-efficient Prius and a gas-guzzling SUV. Each has its pros and cons and the decision is a tossup, so you flip a coin and end up buying the SUV.

After you buy the SUV, you'll start to embrace any evidence that validates the decision. When you unload the groceries, you realize you couldn't live without the extra storage space. If gas prices go up, you tell yourself it's just normal fluctuation. It's mentally easier to convince yourself you've made the right decision than to admit you made a big mistake buying an unsustainable, fuel-thirsty vehicle. You're caught in the grip of self-justification.

“People become more certain they are right about something they just did if they can't undo it," writes Tavris. For this reason, she cautions against asking for advice about an important decision (buying a car, for instance) from someone who just did it. They'll be eager to voice their self-justifications aloud for you to hear.

Once the cycle of self-justification has begun, presenting new scientific information is unlikely to change any minds.

“When you have someone who says climate change is not real, do not whip out your PowerPoint deck," says Hoffman, the sociologist. “And don't tell them that the car they drive or the house they live in is unsustainable…because it's not going to change their mind."

This is not a knowledge deficit issue. In fact, providing more information can often backfire with a political topic, resulting in increased polarization. In a 2010 study, researchers showed 240 participants simulated news stories about the risks associated with climate change. Political partisanship predicted whether readers accepted the new information.

Democratic participants embraced the news, while Republican participants left the study with increased opposition to climate change mitigation policies, in what the researchers call a “boomerang effect." When presented with information that ran contrary to their beliefs, they felt threatened and dug in against it.

“Once we are invested in a belief and have justified its wisdom, changing our minds is literally hard work," writes Tavris. “It's much easier to slot that new evidence into an existing framework and do the mental justification to keep it there than it is to change the framework."

Conservative participants rejected what they read because they didn't trust the source. Casey's ice age scare left him similarly doubtful of experts, especially those speaking about climate-related threats. For now, it's easier to listen to his referent group, and they're unconcerned.