(ABC 6 News) — Two University of Minnesota professors are being honored with the National Medal of Science, the nation’s highest scientific award.

R. Lawrence Edwards is an isotopes geochemist who helped develop the modern method of uranium thorium dating, which helps figure out how climate has changed over time.

David Tillman is the most highly-cited ecologist in the world. He is a pioneer in biodiversity, helping combine math and biology to understand how plant species interact and react to human impacts like habitat destruction.