Background: People all over the world live near glacier-fed streams and rivers because the rivers provide a reliable year-round source of water for drinking, cooking, cleaning, and irrigation. A changing climate is causing these glaciers to shrink, threatening the well-being of billions of people. For this reason, the ability to accurately predict changes in glaciers is essential for planning ahead and adapting to climate change.

The graph shows a scatter plot of Peruvian glaciers where observed ice-covered areas are plotted on the X axis and simulated or predicted ice-covered areas are plotted on the Y axis. The diagonal line down the middle of the data shows where perfect predictions would fall on the graph. The data on the graph represent observations (what scientists measured) and predictions from 1987 and 1999. Notice that each larger unit on the axes is 10 times as large as the one before it. This is called a logarithmic scale, and it is used by scientists to fit data with a very large range onto a small graph.

Data Source: Condom, T., Escobar, M., Purkey, D., Pouget, J. C., Suarez, W., Ramos, C., … Gomez, J. (2012). Simulating the implications of glaciers’ retreat for water management: a case study in the Rio Santa basin, Peru. Water International, 37(4), 442–459.