b. Climate plays an important role in the global distribution of freshwater resources. Changing precipitation patterns and temperature conditions will alter the distribution and availability of freshwater resources, reducing reliable access to water for many people and their crops. Winter snowpack and mountain glaciers that provide water for human use are declining as a result of global warming.

A collection of repeat photography of glaciers from the National Snow and Ice Data Center (NSIDC). The photos are taken years apart at or near the same location, and at the same time of year. These images illustrate how dramatically glacier positions can change even over a relatively short period in geological time: 60 to 100 years. Background essay and discussion questions are included.

With this simulation from the NASA Climate website, learners explore different examples of how ice is melting due to climate change in four places where large quantities of ice are found. The photo comparisons, graphs, animations, and especially the time lapse video clips of glaciers receding are astonishing and dramatic.

This video discusses how the populous areas west of the Andes are largely desert and rely on glacial meltwater as an important source of fresh water. Because the Peruvian glaciers high in the Andes are in rapid retreat, scientists are monitoring the steadily shrinking glaciers and the impact of their reduction on local populations.

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 short video features the Alaska Lake Ice and Snow Observatory Network (ALISON project), a citizen science program in which 4th and 5th graders help scientists study the relationship between climate change and lake ice and snow conditions.

This video documents the impact of the 2011 drought on the water supply of two Texas towns. It discusses how the higher temperatures have increased the evaporation from open reservoirs, resulting in a drop in water levels. The use of water in fighting wildfires has also contributed to this drawdown. While some jurisdictions have been able to develop pipelines to other sources, others have had to resort to trucking water in.

This video describes why tropical ice cores are important and provide different information than polar ice cores, why getting them now is important (they are disappearing), and how scientists get them. The work of glaciologist Lonnie Thompson is featured, with a focus on his work collecting cores of ice from high mountain glaciers that contain significant data about past climate change.

This is an interactive map of California and the Sierra Nevada mountains, showing how the amount of water stored in the snowpack will vary under different climate scenarios. The tool shows observations and projections from 1950 to 2090, and uses low or high emission scenarios to model future snowpack. The tool can be adjusted to show different months of the year and various climate models, graphed by site.

This visualization, from the US Geological Survey, provides a simple schematic of the various pathways that water can take as it cycles through ocean, lakes, atmosphere, surface and ground.

In this activity, students learn about sea ice extent in both polar regions (Arctic and Antarctic). They start out by forming a hypothesis on the variability of sea ice, testing the hypothesis by graphing real data from a recent 3-year period to learn about seasonal variations and over a 25-year period to learn about longer-term trends, and finish with a discussion of their results and predictions.

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