May 18, 1859: John Tyndall (at right), a British philosopher, mountain climber and scientist publishes a theory that many common gases have a strong ability to retain heat, or trap it near the earth's surface. It is one of the first steps in understanding greenhouse gases.
May 18, 1927: The Caernarvon levee, just south of New Orleans on the Mississippi River, is intentionally dynamited in an effort to relieve pressure on the levees protecting the city. Instead, large areas of St. Bernard and Plaquemines parishes are inundated after the levee break.
May 18, 1933: Two months after his inauguration, U.S. President Franklin D. Roosevelt signs the Tennessee Valley Authority Act. The depression-era TVA is created to make the Tennessee River navigable and bring electricity and jobs to the impoverished Valley. TVA becomes one of the nation’s largest operators of coal and nuclear power plants.
May 18, 1968: Metropolitan Edison receives a construction permit for a nuclear power plant at Three Mile Island, south of Harrisburg, Pa. The plant's Unit 2 suffers a partial meltdown in 1979, triggering a crisis in central Pennsylvania and turning public opinion sharply against nuclear power.
May 18, 1974: Under the wonderfully benign code name "Smiling Buddha," India detonates its first nuclear weapon. It does not test a nuke weapon again until 1998, after its rival, Pakistan, christens its nuclear program.
May 18, 1980: A magnitude-5.1 earthquake occurs beneath Mount St. Helens in southwestern Washington. A massive volcanic eruption follows. Ash clouds fall like snow in the city of Portland, Ore., about 60 miles away. The blast flattens 230 square miles of forest and kills 59 people.
May 18, 2010: Greenpeace, the Pew Environment Group and other organizations sign an agreement with the Forest Products Association of Canada to set aside more than a quarter million square miles of Canada's boreal forest as undisturbed habitat for songbirds and other wildlife.
May 18, 2011: Japan's nuclear safety agency acknowledges that the three reactors at Tokyo Electric’s Fukushima Dai-ichii nuclear complex likely melted down within days of a catastrophic earthquake and tsunami two months earlier.
Image: Wikimedia Commons