This week, the U.S. submitted its pledge to the United Nations to cut greenhouse gas emissions by 26-28 percent of 2005 levels over the next 10 years. Eric Holthaus, a meteorologist who writes about weather and climate for Slate, joins us to break down the promise.

Plus, modern-day microbiologists have brewed up an antibiotic potion from a medieval book. The tincture contains garlic, onion, wine, copper, and cow bile—and in preliminary tests, it appears to work as well as the antibiotic vancomycin at destroying antibiotic-resistant bacteria.

And Arielle Duhaime-Ross, a science reporter at The Verge, tells us about an exoskeletal boot and other stories that crossed her desk this week.