A hundred years later, we are still learning.
In addition to cleaning air pollution, trees absorb excess nutrients from soil, preventing algae blooms in waterways.
Workers are still cleaning up after the 2011 Fukushima Daiichi nuclear power plant partial meltdown. There's a lot of contaminated material to contend with.
Rare earth elements are used in virtually all electronics, and mining them is a messy business.
If the 81 million U.S. households with yards adopt these practices, they could absorb more carbon and help combat climate change.
According to one critic, the BBC documentary inspired more appreciation for HD television than it did for engaged environmentalism.
On a sunny day, a city can be several degrees warmer than the surrounding countryside. Could better building materials make cities absorb less heat?
They may look like random puddles, but some states are building million-dollar tunnels to direct wildlife to these seasonal refuges.
The Faroe Islands owe their untouched nature to their remote location and stormy climate. And to a weekend closure.
Inge Lehmann was the seismologist and mathematician who figured out what the Earth's core was actually made of.