In recent years, we've seen an increase in the intensity of tropical storms and hurricanes due to global warming. But how and why do hurricanes form? Sigrid provides a basic explanation of this phenomenon.

We continue to explore the phenomenon of hurricanes. Why are they so dangerous? And do they serve any purpose?

We all know that whales are endangered due to hunting and pollution, but do you know how important they are for the ocean and the environment? This video shows how essential a healthy population of whales is to the ocean ecosystem. Creative Commons Attribution license (reuse allowed). Video was not modified. Please visit sustainablehuman.org for credits and more information.

A look at the communications of Humpback Whales and other baleen whales, which includes how they sing, why they sing, and why we might consider their vocalizations actual songs.

Dolphins are one of the smartest animal species on Earth. In fact, their encephalization quotient (their brain size compared to the average for their body size) is second only to humans. But exactly how smart are they? This video shares some incredible facts about dolphins.

Natalie Fee talks with candor and sensitivity about some usually taboo aspects of daily life and how they affect plastic pollution. She then shows a film clip by artist Chris Jordan that is very difficult to watch, as it shows how litter is killing seabirds.

Natalie Fee talks about impact the clip (at the end of the previous segment) had on her life and how she started out on her journey. One stop on that journey was a music video.

Natalie provides some facts and figures about how much garbage is getting flushed down the toilet in the UK, and goes on to tell us about a successful campaign she spearheaded, aimed at manufacturers of cotton swabs.

Natalie provides some tips for wasting less plastic and leaves us with a slogan to help us rethink our flushing habits. She involves the audience to bring the message home.

Natalie Fee concludes her Ted Talk with a few suggestions for what we can do to reduce how much single-use plastic we are sending into the earth's waterways.

A film about the global sustainability work of The Prince's Charities, founded by HRH The Prince of Wales.

The Prince of Wales' Accounting for Sustainablity project is offering two concrete intervention options for companies and their policies, which lead not only to tangible profits, but also help to reduce the supply chains.

The Prince of Wales and The Duke of Cambridge talk about the unprecedented levels of killing of endangered species like elephants, which are killed at a rate of 100 per day. They also highlight the grave threat the illegal wildlife trade poses to the economic and political stability in many areas around the world and make a plea for the public to support those organisations that are working to put an end to the trade.

In this second half, The Prince of Wales and The Duke of Cambridge follow up by sharing some of the things that are being done to combat the wildlife trade and encouraging the listener to take action. They end by speaking the phrase "Let's unite for wildlife" in Vietnamese, Mandarin, Swahili, Spanish, Arabic and English.

Why do some of the national parks in the United States resemble the European Alps? Geologist Dr. Robert Darga answers this question.