While COVID-19 has had humans worrying for their health, the environment has gotten to take a bit of a breather. In 2020, carbon emissions fell for the first time in decades—but that drop was short-lived. Now with vacation travel, work travel, and other parts of life revving up, coal consumption is on the uptick, and CO2 emissions are on the rise once more.

That’s the opposite, of course, of what needs to happen to reach the global warming goals set by the Paris Agreement in 2015.

One surprising place to look for innovation on this front is the concrete industry. The second-most-used material on earth—water tops the list—concrete is “cheap, it’s durable, it doesn’t rust, and it doesn’t rot,” says CarbonCure CEO and founder Robert Niven. “It doesn’t require highly skilled labor [and] it’s made from limestone, and limestone is everywhere.”

Niven’s company helps make concrete that produces less carbon. He joins Michal Lev-Ram and Brian O’Keefe, the hosts of Fortune Brainstorm, to talk about pandemic-era travel. Each week the podcast explores how technology is changing our lives.

Also on the show is Andrew Beebe, managing director of Obvious Ventures, a group of investors “on a mission to support purpose-driven entrepreneurs across three investment pillars: sustainable systems, healthy living, and people power,” according to the firm’s website. Beebe has been a player in environmentally minded businesses since 2003, when he started a solar company.

Rounding out the show is JB Straubel, cofounder and CEO of Redwood Materials, which works to reduce environmental damage by recycling EV and other batteries, as well as other electronic waste. Before starting Redwood, Straubel was cofounder and CTO of Tesla Motors.