b. Environmental observations are the foundation for understanding the climate system. From the bottom of the ocean to the surface of the Sun, instruments on weather stations, buoys, satellites, and other platforms collect climate data. To learn about past climates, scientists use natural records, such as tree rings, ice cores, and sedimentary layers. Historical observations, such as native knowledge and personal journals, also document past climate change.

This video describes how field research -- in this case, making water measurements in rugged mountain locations -- helps us to understand the complex relationships among changing climate, populations, and water usage.

This static visualization shows that the global carbon cycle is determined by the interactions of climate, the environment, and Earth's living systems at many levels, from molecular to global.

This video is part of the Climate Science in a Nutshell series. This short, animated video looks at evidence of a rapidly warming planet. It discusses how air bubbles in ice cores can be used to estimate Earth's average air temperature for thousands of years and how direct measurements document air temperatures from 1880.

This is a multi-faceted activity that offers students a variety of opportunities to learn about permafrost through an important sink and source of greenhouse gas (methane), about which most students living in lower latitudes know little.

This video highlights a team of scientists who work on reconstructing the mass extinction that occurred 250 million years ago, the end of the Permian Period. This event wiped out the majority of life on our planet, resetting the evolution of life. Clues suggest that deadly bacteria might have set off a chemical chain reaction that poisoned the Permian seas and atmosphere.

In this video from the Polaris Project Website, American and Siberian university students describe their research on permafrost.

In this video, students see how data from the ice core record is used to help scientists predict the future of our climate. Video features ice cores extracted from the WAIS Divide, a research station on the West Antarctic Ice Sheet.

In this video segment, two students discuss the greenhouse effect and visit with research scientists at Biosphere 2 in Arizona, who research the effects of global climate change on organisms in a controlled facility. Their current research (as of 2002) focuses on the response to increased quantities of CO2 in a number of different model ecosystems.