The Titanic sank in 1912, the Lusitania sank in 1915. In each case, about 32 percent of passengers survived. But women and children did much better on Titanic, which took 160 minutes to slide underwater, than on Lusitania, which went down in 18 minutes. Ditto for rich people. Why?

Climate scientists worry about feedbacks, glacial melting, sea level rise, using tax policy to slow warming, and the complexity of climate science. Is it realistic to base our economy on endless growth? What does human behavior tell us about dealing with warming?

Aftershocks and triggered earthquakes both follow a large earthquake, and they don’t happen at random. Can lessons about the sequence and timing of quakes improve safety?

Buried charcoal stimulates microbes and plant growth, helping farmers on poor soil. Studies show that charcoal is stable for hundreds of years.

Scientists propose 9 limits on human actions: Wrecking ozone, over-using fertilizer, killing species could block key “ecosystem services.” Are there natural limits to fresh water use and pollution?

How many dead? Research and real-life experience prove that people die when drivers pick up the cellphone. Even worse: texting on the road!

The ozone layer protects Earth from UV rays: Twenty-two years after a treaty to protect ozone, how is the layer doing? What has happened to the ozone hole above Antarctica?

Underground nuclear tests have been the biggest roadblock to a comprehensive test ban. How are these explosions detected, and how reliably?

A new study finds a surprising number of fish, birds and mammals in the oceans 100 and 1,000 years ago. Can this information help regulators slow the decline of important marine animals?

The Why Files asks why mass killers pull the trigger. What are the warning signs of “rampage” shootings? Can they be prevented?