Episode Guide

1. Many Planets, One Earth — The early Earth was a much different planet than the one we know today. Ancient rocks provide evidence of the emergence of oxygen in the atmosphere and of a frozen Snowball Earth.

2. Atmosphere — The atmosphere is what makes the Earth habitable. While the NOAA Global Monitoring Project documents the fluctuations in greenhouse gases worldwide, MIT’s Kerry Emanuel looks at the role of hurricanes in regulating global climate.

3. Oceans — Ocean systems operate on a range of scales, from massive systems such as El Niño that affects weather across the globe to tiny photosynthetic organisms near the ocean surface that take in large amounts of carbon dioxide.

4. Ecosystems — Scientists from the Smithsonian Center for Tropical Research document the astounding abundance of diversity in tropical rainforests to discover why so many species coexist that are competing for the same resources.

5. Human Population Dynamics — The human population of our planet now exceeds 6.5 billion and is rising. Will studying the history of the world’s population growth help predict the Earth’s “carrying capacity”?

6. Risk, Exposure, and Health — We all require food, air, and water to survive — which are contaminated to some extent by man-made pollutants. Two studies, one in a rural western mining town and another in a dense urban population, reveal how these exposures impact health, and what can be done to reduce the risks.

7. Agriculture — The “Green Revolution” of the 20th century multiplied crop yields, in part through increasing inputs of pesticides and fertilizers. How can farmers reduce their use of agricultural chemicals and still produce enough food?

8. Water Resources — Scientists in Florida’s Everglades and the water challenged Southwest consider the optimum use of existing sources of fresh water for both humans and ecosystems.

9. Biodiversity Decline Species are being lost at a rapid rate in rainforests and coral reefs. Yet many species still have not been discovered. Tropical scientists struggle to keep ahead of the bulldozers as they work to understand this complex ecosystem.

10. Energy Challenges — Global energy use increases by the day. Can new technologies such as carbon sequestration and ethanol production help provide the energy we need without pushing the concentrations of CO2 to dangerous levels?

11. Atmospheric Pollution — A company in the Northeast U.S. tracks the emission of pollutants at street level, while an international long-term study follows plumes of pollution from Mexico City across the continent and beyond.

12. Earth’s Changing Climate — A California project tries to predict whether natural ecosystems will be able to absorb enough additional carbon dioxide from the atmosphere in the next 50 years to mitigate the full impact of human-induced greenhouse gas emissions.

13. Looking Forward: Our Global Experiment — Earth’s essential systems are being stressed in many ways. There are many tipping points in the environment, beyond which there could be serious consequences. Will human ingenuity, resiliency, and cooperation save us from the worst outcomes of our global experiment?