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, which includes background information, graph interpretation and discussion questions, and the Student Handout, which includes the image and background information, have been remediated to comply with Section 508 of the National Rehabilitation Act for accessibility and can be used with screen readers.
Figure 1 from:
Diaz, R.J. and Rosenberg, R. Spreading Dead Zones and Consequences for Marine Ecosystems. 2008. Science. 321: 926–929.