Green cities on the MIT and WEF list included Vancouver and Tel Aviv.Green cities on the MIT and WEF list included Vancouver and Tel Aviv.

Photos: The world's 7 greenest cities

According to MIT and the World Economic Forum, these are the most livable and environmentally friendly cities on the globe.

What indigenous Amazonians taught me about hiking

Learn how to walk across logs, deal with mud and go downhill without falling.

Can you guess what this green stuff is?

Here's a hint: you may want to put on a bathing suit.

The arrival of spring has us going up, up and away

There's no need for scarves and mittens with weather like this.

Aw! 9 cute photos of baby animals that will make you smile

Brighten your day by bookmarking this page for whenever you need a jolt of happiness.

Waze for wildlife: GPS app is looking out for animals

New initiative will create maps and seek safer alternative routes for traveling herds.

Plumber reaches summit of Mount Kilimanjaro

After heart surgery, Joshua Strahl fulfills a lifelong goal.

15 of the most gorgeous wildlife photos you've ever seen

These entries are best bets to win at this year's Sony World Photography Awards.

Study says birds are selfish, but are they really?

A new study examines the behavior of babblers that decide to go it alone.

The best bat-spotting destinations around the world

Here's where to get up close to these fascinating creatures of the night.

Scientists just accidentally discovered that trees share food with each other

'The Giving Tree' is way more accurate than we ever realized.

Rocks of ages: Climbing hotspots around the world

Gear up and discover some of the best crags on this planet.

U.N. showcases a country that's a force of nature

Israel's natural beauty is celebrated with riveting photography display.

Peacock's plume packs a picturesque punch

Zoo is just one popular attraction by the Dead Sea.

Archaeology proves that Earth's magnetic field won't kill us

Scientists studying 600-year-old pottery prove the geomagnetic field is not going to disappear.

Exploding supernova spotted in record time

What usually takes weeks, or even months, took these lucky scientists only three hours.