Ep 17. Snowball Earth

The show Naked Science season 4 episode 17, titled "Snowball Earth," explores one of the most extreme climate events in the history of our planet. The episode seeks to answer the question: what causes a Snowball Earth?

The show starts by introducing the concept of a Snowball Earth - a period of geological time where the Earth's surface was almost entirely covered in ice, making it look like a snowball from space. The host explains that these events have occurred several times in the past, and the last one happened around 700 million years ago.

In order to understand why Snowball Earth occurred, the show explores the complex interaction between the Earth's climate, geology, and biology. The episode explains that there are three main factors that contribute to the onset of Snowball Earth: changes in the Earth's orbit, changes in the carbon cycle, and the presence of ice-albedo feedback.

First, the show describes how changes in the Earth's orbit can trigger Snowball Earth events. In particular, it explains how variations in the tilt and precession of the Earth's axis can cause the amount of solar radiation reaching the poles to increase or decrease. This, in turn, can lead to the formation or melting of ice sheets that cover the polar regions.

Next, the episode explores the role of the carbon cycle in Snowball Earth events. It explains that carbon dioxide is a greenhouse gas that helps trap heat in the Earth's atmosphere. However, when carbon dioxide is removed from the atmosphere and stored in rock formations, the Earth's temperature can drop dramatically. The show discusses how this removal of carbon dioxide can occur through a variety of geological processes, such as weathering of rocks or the formation of organic matter.

Finally, the episode discusses the role of ice-albedo feedback in Snowball Earth events. Albedo is a measure of how much radiation a surface reflects, and ice has a high albedo, meaning it reflects a lot of solar radiation back into space. As a consequence, when ice covers the Earth's surface, it causes less heat to be absorbed by the Earth's system and can lead to further cooling of the planet. This feedback loop can cause the ice to spread, and once it covers enough of the Earth's surface, it can trigger a Snowball Earth event.

Throughout the episode, the show uses the latest scientific research and cutting-edge technology to illustrate each of these factors. For example, it uses computer simulations to show how changes in the Earth's orbit can affect the amount of solar radiation reaching the poles. It also uses satellite imagery to visualize the extent of ice cover during Snowball Earth events.

In addition to explaining the causes of Snowball Earth, the show also discusses the impact that these events had on the evolution of life on our planet. It describes how the severe climate conditions of Snowball Earth led to the evolution of unique adaptations in the organisms that survived, and how these adaptations ultimately allowed for the diversification of life during the Cambrian explosion.

Overall, Naked Science season 4 episode 17 provides a fascinating and informative exploration of one of the most extreme climate events in Earth's history. Through the use of stunning visuals and the latest scientific research, it provides a comprehensive explanation of the causes of Snowball Earth and the impact that these events had on the evolution of life on our planet.