This ThinkTV segment demonstrates the effect of climate change on the coastal population of Peru. As climate change forces the mountain glaciers which provide fresh water into retreat, the quality of the fresh water supply is negatively effected.
In Peru, as in many countries around the world, glaciers are losing mass—they are getting shorter and thinner. Glacial melt is often measured in loss of extent or area, as changes in thickness are not as easily measured. Due to global climate change, glaciers in the Andes Mountains have lost at least 22% of their area since 1970. The rate of loss has increased in recent years.
The loss of glacial mass can have a direct impact on local populations because nearly 69% of the world’s fresh water is stored in glaciers, which cover about 10% of the world’s landmass. In countries such as Peru, which are in tropical latitudes but have high mountain glaciers, much of the local water supply can come from glacier meltwater.
Peruvians on the dry western side of the Andes depend on glacial meltwater for mining, industry, growing their food, and personal uses such as drinking water and washing clothes. Further downstream, along the coast, is Lima, the world's second largest desert city. The eight million residents of Lima depend upon glacier meltwater for drinking water and hydroelectric power.
As Peru's glaciers retreat, or lose mass, they will have an impact on both the quantity and quality of fresh water available. Water quality can be affected first, as shrinking glaciers can expose rocks containing metals and sulfur, which are potentially toxic if released into the water supply. The diminishing quantity of water is also a concern, in an area that already has an inadequate supply of water. Estimates are that between one and two million people in Lima are already without sufficient clean drinking water.
At their present rate of shrinkage, the ice fields of Peru could disappear within 20 years, due to climate change. Scientists will continue to monitor them closely, as water shortages and water quality issues become an increasingly important issue in many areas of the world.
Here are suggested ways to engage students with this video and with activities related to this topic.
Beginning a lesson: Before viewing the video, ask students to locate Peru and the Andes Mountains on a world map with topographical features. Ask students what kind of climate they would expect to find on either side of the mountain range—would the climates be the same or different? Why? Notice where Lima, the capital of the country, is located.
Doing research projects—individual: How much of Earth’s fresh water is in ice caps, glaciers, and permanent snow? Where is the rest of the fresh water located? What are the sources of fresh water that people use every day? Have students report back to class after conducting research using the following resource: Global Water Distribution.
Doing research projects—groups: If the water quality of the rivers in Peru is deteriorating due to climate change, what can be done to clean them up? Research how one polluted river was restored by viewing the following resource: Pollution Along the Rhine River.
What steps could be taken to prevent additional pollution and clean up the rivers in Peru? Report back to class.
Assign directly to your students using the code or link above, without having them log in. Simply tell your students to go to
www.pbsstudents.org and enter the Assignment Code, or click on the Assignment URL to share the assignment as a link.