Richard Harris

If you're driving down the road someday and you come across a camper with a 50-foot periscope sticking up into the sky, you just might have crossed paths with Ira Leifer. His quirky vehicle is on a serious mission. It's sniffing the air for methane, a gas that contributes to global warming.

Leifer is an atmospheric scientist at the University of California, Santa Barbara. But you'll more often find him off campus, in a garage, next to a string of auto body shops near the airport.

Earth's atmosphere is entering a new era. A mountaintop research station that has been tracking carbon dioxide for more than 50 years says the level of that gas in our air has reached a milestone: 400 parts per million.

That number is one of the clearest measures of how human beings are changing the planet. It shows how much carbon we have put into the air from burning fossil fuels — and that carbon dioxide drives global warming.

This measurement comes from Mauna Loa, Hawaii, a remote volcano where the air is largely free of local influences.

It's easy to feel dispirited about climate change because the challenge of dealing with it seems so overwhelming. But Miguel Modestino is actually excited about the challenge. He's part of a large team hoping to make an artificial leaf — a device that would make motor fuel from sunlight and carbon dioxide rather than from fossil fuels.

Most scientists find a topic that interests them and keep digging deeper and deeper into the details. But Ken Caldeira takes the opposite approach in search for solutions to climate change. He goes after the big questions, and leaves the details to others.

NPR Science Correspondent Richard Harris traveled to Australia's Great Barrier Reef to find out how the coral reefs are coping with increased water temperature and increasing ocean acidity, brought about by our burning of fossil fuels. Day 4: Richard catches up with one of the gurus of climate science out on the reef.

Ken Caldeira loves a challenge, and he has a big one right under his feet. He's standing on an expanse of coral reef out in Australia's Great Barrier Reef. It's being washed with water as the tide streams over the reef, from a lagoon to the open sea.

NPR Science Correspondent Richard Harris traveled to Australia's Great Barrier Reef to find out how the coral reefs are coping with increased water temperature and increasing ocean acidity, brought about by our burning of fossil fuels. Day 3: Waiting for a boat to the next island, Richard meets some rowdy birds.

Weeds are not a true category of plant. A weed is simply a plant that's growing where a person wishes it weren't.

NPR Science Correspondent Richard Harris traveled to Australia's Great Barrier Reef to find out how the coral reefs are coping with increased water temperature and increasing ocean acidity, brought about by our burning of fossil fuels. Day 1: Richard gets a hefty dose of bad news.

I've seen the future, and it isn't pretty.