This video is part two of a seven-part National Academies series, Climate Change: Lines of Evidence. The video outlines, with the use of recent research and historical data, how we know that the Earth is warming.

This animation shows the Arctic sea ice September (minimum) extents from 1979-2014.

This short video clip summarizes NOAA's annual State of the Climate Report for 2009. It presents a comprehensive summary of Earth's climate in 2009 and establishes the last decade as the warmest on record. Reduced extent of Arctic sea ice, glacier volume, and snow cover reflect the effects of rising global temperature.

This video provides an overview of changes happening in the Arctic.

This short video, is the fifth in the National Academies Climate Change, Lines of Evidence series. It focuses on greenhouse gases, climate forcing (natural and human-caused), and global energy balance.

This series of visualizations show the annual Arctic sea ice minimum from 1979 to 2015. The decrease in Arctic sea ice over time is shown in an animation and a graph plotted simultaneously, but can be parsed so that the change in sea ice area can be shown without the graph.

This video on phenology of plants and bees discusses the MODIS satellite finding that springtime greening is happening one half-day earlier each year and correlates this to bee pollination field studies.

This video features scientists in New Zealand's Southern Alps, examining samples from the rocky landscape once dominated by glaciers. Their research, combined with other climate records, has revealed a link between glacial retreat and rising levels of carbon dioxide in the air.

In this audio slideshow, an ecologist from the University of Florida describes the radiocarbon dating technique that scientists use to determine the amount of carbon within the permafrost of the Arctic tundra. Understanding the rate of carbon released as permafrost thaws is necessary to understand how this positive feedback mechanism is contributing to climate change that may further increase global surface temperatures.

This short video shows an example of melting alpine glaciers in the Austrian Alps (Goldberg Glacier). Disappearing alpine glaciers have social and environmental impacts, including the decline of fresh water supplies and contributions to sea level rise.

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