Scientists call to expand the way drought is determined
January 4, 2018
The National Drought Mitigation Center in Lincoln, Neb., keeps tabs on drought impacts nationwide. Reports from the month of November alone paint an illustrative picture of the ongoing drought there:
Custer State Park kept on fewer bison than usual due to poor winter forage.
A ranching operation in Meade County deeply culled their cow herd to survive the winter.
“Now that there’s more competition for water from a variety of sectors and it’s a more finite resource, people are understanding that droughts have a much broader impact. The ecological impacts are becoming more important.”Dr. Michael Hayes, climatologist at the University of Nebraska
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And drought slowed the delivery of corn to eager decorators at the Corn Palace in Mitchell. (Decorators also complained the corn was more brittle than in previous years.)
A new report in the bulletin of the American Meteorological Society calls for a change to the way we define drought to include some of its more wide-ranging impacts.
"There's historically been this understanding that droughts in the U.S., or anywhere around the world, have impacts on agriculture," explains Dr. Michael Hayes, one of the paper's authors and a climatologist at the University of Nebraska.
"It's only more recently that we've come to the understanding that the impacts of drought are more complex than that."
Hayes is talking about drought's effect on ecosystems, in particular.
"Now that there's more competition for water from a variety of sectors and it's a more finite resource, people are understanding that droughts have a much broader impact. The ecological impacts are becoming more important."
Healthy ecosystems provide benefits to human activities beyond agriculture.
Hayes points to fish as an example.
"Fish are so important to the western U.S. in terms of fishing, recreation and tourism," Hayes explains.
Those benefits are called "ecosystem services," and they traditionally haven't been on equal footing alongside agriculture when drought's at hand.
The team's report took a close look at the Millennium Drought in southern Australia. It started in the late '90s and persisted for more than a decade. It was notable for its duration and severity.
Initial response to the drought was human-centric, striving to buoy agriculture at the expense of ecosystem health.
"Lakes and rivers acidified, lagoons salinized, and the diversity of invertebrates, fish and birds declined," wrote the paper's 19 authors, who came together from academia, government institutions and NGOs.
"Government purchase of water rights from irrigators facilitated reallocation of water from irrigated agriculture to the environment," the report continues.
The Australian government's decision to buy water from farmers and ranchers and redistribute it to river ecosystems was seen a novel tactic in drought mitigation at the time.
The report continues: "Well-functioning water markets require strong legal and institutional underpinnings, and are more likely to be successful at benefitting both nature and people when an ecosystem services approach is used to evaluate the trade-offs between consumptive and ecological water needs."
Dr. Hayes of the National Drought Mitigation Center points out that the U.S., too, has a poignant example from its past — a situation where agriculture inadvertently exacerbated the negative effects of a drought by compromising ecosystem health.
In the run-up to the Dust Bowl years of the 1930s, deep plowing exposed the topsoil of the Great Plains. When drought set in, crops couldn't thrive, and the native grasses that had once held moisture in the soil were gone. Farmers watched their soil blow away in wind storms. Tens of thousands of families abandoned their farms as a result.
"Land use problems [of the time] reduced the resilience of that landscape," explains Hayes.
In other words, had the Plains not been so intensively plowed in the years before the drought, the ecosystem may have weathered it better.
Redefining drought to include the ecological impacts alongside the human impacts is the discussion Hayes' team hoped to bring to light. The more scientists and stakeholders understand about drought's impact on healthy ecosystems, the better poised they are to structure potential responses or policies.
"Droughts are a normal part of climate in the U.S. We've always had droughts in the past. We have them today, and we'll have them in the future," Hayes says.
Between higher temperatures due to climate change and the destabilization of large-scale climate patterns (like El Nino), droughts are generally forecasted to become more severe and more prevalent.