Matt Damon investigates the impact of extreme heat on human health and mortality, with a focus on research that has uncovered how rising temperatures are creating a worldwide public health emergency. Michael C. Hall visits Bangladesh to explore the prediction that by 2050, a global migration of upwards of 150 million people will produce the single most daunting burden to our future. And Thomas L. Friedman travels to Yemen to conclude his look into how climate stress can push volatile political situations over the edge.

The energy market has an estimated global value of $6 trillion — a number that could be greatly affected by an increase in renewable sources, especially solar. In his first television project since retiring as host of CBS’s “The Late Show,” David Letterman travels to India for the first time to find out what the world’s soon-to-be most populous country is going to do to expand its inadequate energy grid, power its booming economy and bring basic electricity to 300 million citizens who have never plugged in. Letterman interviews the prime minister, travels to rural villages where power is a luxury few can afford and finds out why the U.S. may play a key role in India’s energy future. “Saturday Night Live” cast member Cecily Strong travels to Florida and Nevada to investigate what’s blocking the growth of solar energy in the U.S. — and she gets the real story from industry insiders and a retired commissioner now willing to tell their stories.

Action hero, politician, climate crusader and Years of Living Dangerously executive producer Arnold Schwarzenegger sets out to explore the military’s relationship with a changing climate, including how our armed forces are dealing with an increasing number of climate-related disasters and how the military is working to reduce its own carbon footprint. Schwarzenegger travels to Kuwait to visit soldiers and travel in a fuel convoy (where more than 3,000 soldiers have been killed or injured since 9/11). He learns how serious a threat the military perceives climate change to be, talks to top-level military leaders and meets the brave men and women who are dealing with climate change threats and disasters on the front lines. The battle to save the Amazon in Brazil — the “lungs of the planet” — is the ultimate race against time. There are ever-increasing threats from cattle ranching, drought, deforestation, massive hydroelectric dams and illegal mining. Supermodel and activist Gisele Bündchen travels to her home country to see the extent of the damage and investigates what’s being done to save the rainforest for all of us. Deep in the Amazon, she joins the national environmental police on a mission to put an end to illegal deforestation; in Alta Floresta, she meets with Greenpeace for a flyover of the forest, which reveals huge patches of deforested land, logs piled high on trucks and barges, drought-stricken fields, burnt rainforests and vast cattle ranches that were once lush, thousand-year-old tropical rainforests.

Joshua Jackson investigates the one place on Earth where the impacts of climate change are most profound yet practically invisible: the oceans. Josh travels to Australia’s Great Barrier Reef to look at the devastating impacts of ocean warming on the world’s largest reef system, and he explores the predicted impact of ocean acidification. In the Philippines, he looks at the impact of climate change in a place where hundreds of millions of people rely on healthy reefs for food, income and protection from storms.

New York Times columnist Tom Friedman investigates the increasing population of climate refugees — migrants forced to leave their homes due to climate change-induced sea-level rise, natural disasters and destroyed livelihoods. He travels from the COP21 climate conference in Paris to the Sahel region of a parched and war-torn Africa, where he hears from refugees themselves. He explores this new wave and what the future may bring. Actor Don Cheadle is on the ground in California, where the worst drought in 1,200 years is devastating the nation’s most populous state and the world’s seventh-largest economy. He investigates how Gov. Jerry Brown’s administration is fighting the drought while also fighting climate change. Along the way, Cheadle meets a scientist who warns of a global water and food crisis as well as a family of farmers whose lives may never be the same as they struggle to find water in the parched Central Valley.

Jessica Alba meets three members of Climate Corps - an innovative MBA-focused program - as they try to convince America's corporations that sustainability can actually boost their bottom lines. Pulitzer Prize-winner Thomas L. Friedman finds himself in Egypt to explore how what happens in the wheat fields of Kansas plays out on the volatile streets of Cairo. And MSNBC's Chris Hayes reveals an intimate story about life after Superstorm Sandy, with the most economically vulnerable trying to survive the impacts of climate change.

If nothing is done to curb carbon emissions, Miami is in danger of being underwater by the end of the century. Jack Black is there to find out if and how the city and other low-lying coastal areas can survive rising seas. He finds a political and business community in denial and talks to a few lone legislators, residents, activists and scientists trying to do something before it’s too late. Ian Somerhalder journeys to the Bahamas to investigate the future threat of superstorms, caused by rising sea temperatures, whose devastating effects could reach biblical proportions. At the Woods Hole Oceanographic Institute, he joins scientists on a deep dive to explore blue holes, underwater caves that have collected the remnants of past storms for centuries.

Lesley Stahl of '60 Minutes' travels to Greenland to investigate the effects of global warming in the Arctic. Down south, Ian Somerhalder travels to North Carolina to listen in on both sides of the evangelical community's debate over climate change and finds himself caught in the middle of not only a religious debate, but a familial one: the father is a megachurch preacher who doesn't believe in climate change; the daughter is an activist trying to shut down the local coal-fired power plant.