How different is America's weather today from the world the founding fathers knew 250 years ago?

On July 4, 1776, as 56 men gathered to declare independence. That same day, Thomas Jefferson bought a brand-new thermometer, and started taking meticulous notes. Those very readings marked the birth of an American climate record that stretches all the way to the present day.

In this episode of Atmosphere, host Emily Gracey sits down with Kaitlyn Trudeau, an applied climate scientist at Climate Central, to unpack two and a half centuries of American weather data. Together, they explore how our climate has shifted from the brutal winters of the Little Ice Age to the rapid warming of the modern era... and what the data tells us to expect by the time the nation turns 300.

• The Weather of 1776: What it was really like in that Philadelphia room (think wool coats, horseflies, and no AC), and how Jefferson became America's original "weather nerd."
• Nature’s Time Capsules: How scientists use paleoclimate proxies—like tree rings, ice cores, and coral—to unlock millions of years of climate history.
• The Rate of Change: Why the dramatic shift in global carbon emissions over the last 50 to 75 years is the real cause for concern.
• Climate Controls: Why the climate is warming differently in places like the Southwest compared to the Great Lakes.
• A Story We Are Still Writing: Why the next 50 years aren't predetermined, and how collective action today dictates our future.

Articles referenced in this episode:

https://www.monticello.org/encyclopedia/thermometer

https://founders.archives.gov/documents/Jefferson/02-01-02-0010

https://jefferson-weather-records.org/node/41019

https://journals.ametsoc.org/view/journals/bams/84/1/bams-84-1-57.pdf

https://www.amrevmuseum.org/john-adams-and-revolutionary-philadelphia-s-summer-heat

https://emergingrevolutionarywar.org/2016/01/23/the-hard-winter-of-1779-1780/

• Follow Emily on Facebook: Meteorologist Emily Gracey
• Follow the Show on Instagram: @AtmospherePodcast
• Deep Dive on Substack: Subscribe to the Atmosphere Substack for weekly science breakdowns.
• Listen to the Weekly Weather Brief: Catch Emily and meteorologist Kerrin Jeromin every Friday for a quick rundown of the week’s biggest science stories.