This policy note provides a snapshot of the sources of nutrient pollution and the corresponding socioeconomic drivers that are increasing nutrient levels in our waterways.
Nutrient over-enrichment of freshwater and coastal ecosystems, or
eutrophication, is a rapidly growing environmental crisis. Worldwide,
the number of coastal areas impacted by eutrophication stands
at over 500. In coastal areas, occurrences of dead zones, which are
caused by eutrophic conditions, have increased from 10 documented
cases in 1960 to 405 documented cases in 2008. In addition, many
of the world’s freshwater lakes, streams, and reservoirs suffer from
eutrophication; in the United States, eutrophication is thought to
be the primary cause of freshwater impairment. Many of our largest
freshwater lakes are entrophic, including Lake Erie (United States),
Lake Victoria (Tanzania/Uganda/Kenya), and Tai Lake (China).
The increase in eutrophication is the result of human activities. Major
sources of nutrients to freshwater and coastal ecosystems include
wastewater, agriculture, and atmospheric deposition of nitrogen from
burning fossil fuels.
The drivers of eutrophication are expected to increase for the foreseeable
World population will continue to grow, reaching an estimated 9.2
billion by 2050, which will increase pressures on the productive
capacity of agriculture and industry.
Intensive agriculture and land use conversion—for crops, livestock,
and aquaculture—will increase, especially in the developing world.
In addition to population growth, intensifi cation is driven by changing
dietary patterns. For example, over the period from 2002 to 2030,
global meat consumption is expected to increase by 54 percent.
Energy consumption is expected to grow 50 percent from 2005
to 2030. Fossil fuels, which release nitrogen oxides (NOx) into the
environment when burned, will continue to be the dominant fuel
source in this century.
As a result of these increasing global trends in population growth,
energy use, and agricultural production, we expect that coastal and
freshwater systems impacted by eutrophication and hypoxia will continue
to increase, especially in the developing world.