Madeline Ostrander on “At Home on an Unruly Planet: Finding Refuge on a Changed Earth."

Penn State climatologist Michael Mann on the Biden-Harris administration and climate.

Dr. Alan Stern and Dr. David Grinspoon on their book on Pluto: “Chasing New Horizons.”

Oren Harman on his new book “Evolutions: 15 Myths That Explain Our World."

“Good Germs, Bad Germs” author Jessica Snyder Sachs on the rise of drug resistance.

Congressional Candidate, Millennial and geologist Jess Phoenix on representative democracy

James Hansen of Columbia University on preserving the planet for the next generation.

Dr. Nora Volkow, talks about the science of opioid addiction and treatment.

Mexican conservationist Gerardo Ceballos talks about the dramatic decay of biodiversity.

Public health historian David Rosner on origins of the lead epidemic in Flint and beyond

CDC Director Tom Frieden talks about combating addiction and disease.

Weill Cornell Medical Dean Laurie Glimcher on scientific discoveries combating cancer.

Karenna Gore of the Center for Earth Ethics on a moral view of the planet.

Bestselling artist Moby talks about his worldview

Harvard University earth scientist Naomi Oreskes on a climate change concensus.

Kate Gordon explains the Risky Business initiative.