The earth is warming, scientists tell us. Yet many of us in North America experienced one of the harshest winters in decades, with multiple blizzards and record-breaking low temperatures. How can our planet be warming when we still experience such extreme cold? The reason, as Neil deGrasse Tyson points out in a recent episode of Cosmos: A Spacetime Odyssey, comes down to the difference between weather and climate.

Tyson provides an eloquent illustration while walking a dog along a beach. Weather, he notes, is what the atmosphere does in the short term: rain, sun, snow, hail, etc. Climate, on the other hand, is the measurement of weather patterns over time and is shaped by the energy balance of the atmosphere. Thus you can have a record-breaking winter and still have an annual temperature that is warmer than usual. Weather, Tyson says, is like the dog on the leash: unpredictably running from side to side, but ultimately following the path the man (i.e., climate) lays out. “Keep your eye on the man, not the dog,” says Tyson, noting that changes in the atmosphere create a climate pattern that we can observe—and even predict. And as we pump more CO2 into the atmosphere than at any other time in history, scientists can calculate how this is changing the climate of our earth.

Unfortunately, this crucial difference between weather and climate eludes many people, especially climate skeptics, who point to extreme winters as proof that climate change is fiction. Clearly we need to improve science literacy in this country. The return of the Cosmos series is a great step, bringing science into prime time and encouraging curiosity and awareness on key science issues. Even more crucial is integrating climate science into the classroom. Our Climate Change unit in the Earth Matters high school curriculum explores how our growing population exacerbates climate change, and prepares students to approach these concepts as knowledgeable and informed adults.

You can watch the Cosmos clip by clicking here.