The 1970s brought the United States a string of fierce winters and a spate of speculation on a cooling climate. Many atmospheric scientists had a different worry: they knew that carbon dioxide in the air had been increasing for decades and that global temperatures should rise before long.

When scientists around the world began planning the most ambitious weather observing study in history, NCAR was a natural partner.

Rarely before the 1980s did a scientific issue jump from the corridors of research to the halls of international diplomacy in less than a decade. Such was the case when a profound threat to the Antarctic’s protective layer of stratospheric ozone became apparent.

The biggest swarm of tornadoes ever recorded—148 in all—rumbled across the U.S. Midwest and South on 3–4 April 1974.

The periodic cooling of the eastern tropical Pacific Ocean helps bring rain to Alaska and blizzards to Colorado.