Emergency management officials in Madison County said four were injured in addition to those killed when the tornado touched down southwest of Des Moines.

The facilities are located in every state, and are threatened by floods, hurricanes and wildfires that can cause dangerous leaks and explosions, according to a federal watchdog.

Local authorities have placed up to 300,000 people under evacuation warnings in one of the country's worst flooding incidents.

Some ecosystems have already been irreversibly altered, scientists say. And climate change is wreaking havoc on human health.

Environmental writer Oliver Milman says habitat loss, pesticides and climate change are killing off insects worldwide, which, in turn, threatens humans. His new book is The Insect Crisis.

A watchdog group says Facebook only labeled about half of posts promoting articles from the world's main publishers of climate denial. Facebook says it was still rolling out its system at the time.

Anywhere from tens of millions to a billion people could become climate migrants by 2050, according to a report from the RAND Corporation. The number varies widely depending on the definition used.

Arctic communities have long been plagued by soot that drives snow melt and respiratory disease. Now, humans are making their mark in Antarctica.

For decades, they've been told to rip out the Guiera senegalensis shrub. But now there's a new philosophy: The scrappy green plant could be the key to a better harvest.

Authorities in China said they planted nearly 200,000 acres of forest and green areas prior to the Winter Games. But they also transplanted nearly 20,000 trees, which could endanger animal habitats.

Chevron, ExxonMobil, BP and Shell used terms like "climate" and "low-carbon" more frequently in recent annual reports, but their actions on clean energy didn't match their words, researchers conclude.

Sea levels are rising even faster on the East Coast and Gulf Coast. And advances in climate science mean we can see the future clearly for the first time.

In tree ring records dating back to AD 800, the only multidecade drought that came close to today's was in the 1500s. Researchers say climate change is a factor and the U.S. must plan for less water.

Big dairy farms are profiting from California's tougher limits on greenhouse emissions. They're getting paid to capture methane from cow manure. But critics say the system subsidizes polluters.

For the first time, the federal government is making a sizeable investment in wildlife road crossings. The goal is to help slow extinctions, and also protect people from animal collisions.