Heat kills more Americans than hurricanes and wildfires combined, yet it remains the most invisible threat of climate change. Miles O’Brien travels from a Phoenix playground redesigned to fight scorching pavement, to an Australian shade lab, to a climate chamber where he’s put under the broiler, to meet scientists engineering how humans might adapt to a hotter world.

New Bedford, Massachusetts, made its fortune hunting whales for oil. Nearly two centuries later, Mayor Jon Mitchell is wagering the city’s comeback on offshore wind. Miles O’Brien flies out to the turbines, rides with fishermen wary of losing their scallop grounds, and examines the political storm, from whale die-off claims to Donald Trump’s stop-work orders, testing the future of wind power.

Kris Tompkins went from Patagonia CEO to conservation visionary, spending her fortune with late husband Doug to protect over 16 million acres in Chile and Argentina. Miles O’Brien joins her in Argentina’s Ibera wetlands as jaguars, extinct there for a century, are captured, collared, and released into the wild. It’s a bold experiment in reversing extinction that comes with risk, loss, and hope.

Thwaites Glacier is melting faster than any glacier on Earth, and its collapse could raise global sea levels by feet, not inches. Miles O’Brien sails to Antarctica aboard a Korean icebreaker with scientists drilling through 3,000 feet of ice to reach the water below and explore a radical idea: an underwater curtain that might buy the world some time before the “Doomsday Glacier” gives way.

Beneath our feet lies a nearly endless supply of clean energy. Miles O’Brien traces the unlikely rise of enhanced geothermal power, from a Cold War-era experiment at Los Alamos to Texas oil fields, where veteran frackers repurpose drilling technology to tap hot rock instead of crude. With billion-dollar startups and oil majors now betting on it, geothermal may finally be ready to reshape the grid.