Washington, DC—Strategies for limiting climate change must take into account their potential impact on water quality through nutrient overload, according to a new study from Carnegie’s Eva Sinha and Anna Michalak published by Nature Communications. Some efforts at reducing carbon emissions could actually increase the risk of water quality impairments, they found.
and other precipitation wash nutrients from human activities like agriculture
into waterways. When waterways get overloaded with nutrients, a dangerous
phenomenon called eutrophication can occur, which can sometime lead to
toxin-producing algal blooms or low-oxygen dead zones called hypoxia.
For several years, Sinha and Michalak have
been studying the effects of nitrogen runoff and the ways that expected changes
in rainfall patterns due to climate change could lead to severe water quality
In this latest work, they analyzed how an
array of different societal decisions about land use, development, agriculture,
and climate mitigation could affect the already complex equation of projecting
future risks to water quality throughout the continental U.S. They then
factored in how climate change-related differences in precipitation patterns
would additionally contribute to this overall water quality risk.
They found that climate change mitigation
efforts that rely heavily on biofuels could have the unintended consequence of
increasing the amount of nitrogen entering U.S. waterways, causing water
quality problems. Scenarios that required a large expansion of domestic food
production would fare even worse, by increasing both fossil fuel emissions and
water quality problems.
But win-win solutions are also possible.
“It is entirely possible to fight climate
change in ways that don’t have unintended consequences for water quality,”
Michalak emphasized. “We need an approach that takes multiple benefits into
account in the planning process.”
Perhaps unsurprisingly, the most
successful scenarios considered in the study relied on sustainable growth and
Looking at regional differences within the
U.S., Sinha and Michalak found that the impact of excess nitrogen due to both
land management decisions and climate-change-related precipitation changes
would be the strongest in the Northeast.
Globally, Asia would be at the greatest
risk of eutrophication due to projected increases in fertilizer use and
anticipated precipitation increases.
“Our findings show that
it is crucial to consider the potential for water quality impairments when
making societal choices about how land is used and developed, as well as about
how we work to fight climate change,” Sinha said. “Access
to clean water is essential for human survival, food and energy
production, and a healthy ecosystem. Preserving our ability to access clean water
must be a top priority.”__________________
This work was supported by the U.S. NSF and the U.S. DOE Office of Science. The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.