The map illustrates the severity of our global “human footprint” rated on a scale from 0 to 100. Green areas are the least influenced by humans and black areas are the most heavily influenced. The human footprint index includes measures of population density; land use; light pollution; and the region’s accessibility by roads, railroads, rivers, and coasts. The white dots on the map are hypoxic systems, or dead zones, caused by eutrophication.
The accompanying downloadable Educator Materials PDF includes background information, graph interpretation and discussion questions. The Student Handout includes the image and background information.
Figure 1 from:
Diaz, R.J. and Rosenberg, R. Spreading Dead Zones and Consequences for Marine Ecosystems. 2008. Science. 321: 926–929.