We arrive at Coyote Run Farm late on a Sunday morning, the sky the kind of gray that makes every plant and flower look more alive. Matt Russell comes outside to meet us in rubber boots and his Sunday best, a blue plaid shirt tucked neatly into belted jeans. He’s used to visitors: Beto O’Rourke and Tim Ryan have been here, reporters too. Kamala Harris’s campaign staffers are staging the barn for her visit this afternoon. All of them want to talk to Mr. Russell about climate change. A fifth-generation farmer with a master’s degree in rural sociology, Mr. Russell, who is 49, has been working on issues of economic and environmental sustainability in agriculture for nearly two decades. Led by his religious faith, he has spent his life teaching, organizing and preaching. Over the past couple of years, he has taken an increasingly public role in organizing farmers to drive climate change policy in industrial agriculture. Both Republicans and Democrats treat farmers as victims...