Densely populated megacities in the developing world, which are most in need of tree cover, often have the least.

With the constant turnover of land, many American cities are facing legacy hazardous waste that they didn't even know was there.

Just take a look at Minnesota.

Also in this episode, digging into sustainable agriculture and what's in store at the upcoming Sustainable Innovation Forum, being held alongside COP24 in Poland.

As local leaders increasingly take action on environmental issues, Americans reaffirmed what mattered to them and their everyday lives.

Urban areas are growing rapidly — but green policies can build them to last.