Increased Consumption


Photosynthetic "primary productivity" refers to the amount of new plant growth (both micro- and macroscopic) each year - made possible by plants' ability to convert sunlight into chemical energy. Apart from other relatively small sources of chemical energy in various ecosystems, this plant productivity is the basis for all other life on Earth.

Humans, a single species out of approximately 13 million, were estimated to use about 40% of the productivity capacity of the terrestrial biosphere in 1986. This percentage has undoubtedly increased since then with increases in human population and resource consumption.

In 1986, about one-fourth of the lake and river productivity capacity was also being used to support freshwater fisheries. From the oceans, we use about a third of the primary productivity available near coastal regions to support our marine fisheries (1995 estimate). Sea urchin harvest, Friday Harbor Photo By: Alan J. Kohn

Since about two-thirds of these fisheries are already fully exploited or overexploited, and some catch methods (e.g., trawling) further erode fisheries productivity by destroying bottom habitats and wastefully killing non-target species ("by-catch" or "by-kill"), we are probably already at or beyond the limits of sustainable consumption of wild coastal marine resources. By Catch Photo by: U.S. Coast Guard

In recent centuries, in addition to resources based directly on primary productivity (e.g., grain, meat, or paper), humans have increasingly consumed other sources of energy, especially non-renewable and polluting fossil fuels, for transportation, heating, and manufacturing. Due primarily to this energy use, the atmospheric concentration of carbon dioxide has increased by nearly 30% since pre-industrial times.

Another indicator of human consumption levels, combining aspects of both primary production and fossil sources, is the amount of waste created and incinerated, deposited in landfills, or dumped at sea. Various indicators can be used to assess how different regions, countries, or economic strata consume resources on a per capita basis.

Losses of Species and Habitats menu