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How Your Diet Contributes to Nutrient Pollution and Dead Zones in Lakes and Bays

Insights + Opinion
How Your Diet Contributes to Nutrient Pollution and Dead Zones in Lakes and Bays
iStockr / iStock / Getty Images Plus

By Donald Scavia

Every year in early summer, scientists at universities, research institutions and federal agencies release forecasts for the formation of "dead zones" and harmful algal blooms in the Gulf of Mexico, the Chesapeake Bay and Lake Erie. This year the outlook is not good.


The dead zone that forms annually in the Gulf of Mexico is likely to approach, if not surpass, record size at roughly 7,250 square miles. Another dead zone in the Chesapeake Bay is projected to be within the top 20% recorded over the past 20 years — about 2.1 cubic miles, equivalent to over 3.5 million Olympic-size swimming pools. And Lake Erie is also projected to set records, with almost 50,000 tons of potentially toxic algae.

The key factor driving these forecasts is winter and spring rainfall considerably above normal across the central U.S. The winter of 2018-2019 was the wettest on record across the nation, and May was the second-wettest month on record.

Predicting the results isn't rocket science. More rain means more flooding and more runoff from farmlands. These waters carry heavy loads of nutrients, mainly from fertilizer, that fuel algal blooms. The end results include fish kills, closed beaches, possible drinking water alerts and loss of coastal property value.

Treading Water

Algal blooms occur when water bodies become overloaded with nitrogen and phosphorus from farms, water treatment plants and other sources. Warm water and nutrients promote rapid growth of algae. Some strains can be toxic or even fatal to aquatic life and humans.

Eventually algae settle to the bottom and decay. This process depletes dissolved oxygen in the water, creating "dead zones" where oxygen levels are low enough to kill fish.

Scientists and public officials have understood this problem for decades, but progress toward addressing it has been painfully slow. Nutrient loads, dead zones and harmful algal blooms in these systems dominated by agriculture have increased or held grudgingly steady for decades.

Dead zone and harmful algal bloom trends with 2019 forecasts in red.


From http://scavia.seas.umich.edu/hypoxia-forecasts/

The main policy tool available now to combat nutrient losses from agricultural lands is the Farm Bill, enacted about every five years, which provides funds for voluntary conservation efforts. Between 1995 and 2015, the U.S. Department of Agriculture provided almost $32 billion in conservation incentive payments. U.S. water quality would be much worse without these programs, but they simply have not been sufficient to reduce nutrient loads over time.

Nutrient load trends; 2019 loads in red.

From: http://scavia.seas.umich.edu/hypoxia-forecasts/

Warmer and Wetter

Scientists predict that as the climate warms, this problem is likely to get worse.

Most climate models forecast increased precipitation, especially intense spring rains, for most of the Midwest, the Great Lakes basin and the mid-Atlantic. As air warms, it can hold increasing amounts of water vapor, which contributes to more precipitation during extreme weather events. In turn, heavier rainfall will impact nutrient runoff and dead zone formation.

Under a worst-case climate change scenario, in which global temperatures rise nearly 5 degrees Celsius above preindustrial levels by 2100, very heavy precipitation events in the Midwest, Great Plains and Southeast regions would increase sharply.

NOAA

A Dietary Strategy

Farm-based conservation programs are important, and some new practices could improve nutrient management. For example, farmers can widen drainage ditches to create two-stage ditches, which allow water to flow onto vegetated side "benches" that capture nutrients during periods of heavy rainfall.

A two-stage ditch has a low-flow channel and a vegetated side 'benches' that are flooded during higher flows. The grass slows water flow and allows nutrients to settle out.

Ohio State University Extension, CC BY

But even these measures would have to be implemented at unprecedented scales to be effective. The challenge is even more daunting when recognizing that, for example, while the annual total phosphorus load to Lake Erie is large, it is only 10% of the amount applied in fertilizer each year. In addition, as with the Chesapeake and Mississippi watersheds, soils around Lake Erie are already laden with nitrogen and phosphorus.

In my view, part of the solution could be using markets to drive a shift away from industrial-scale corn production, which is a major source of nutrient pollution. One major step would be eliminating the federal mandate requiring oil companies to blend corn-based ethanol into gasoline, which consumes 40% of U.S. corn production.

This will be politically difficult as long as presidential primaries start in Iowa. But other strategies may be more feasible, such as encouraging private-sector companies to demand corn raised through more sustainable practices.

Reducing meat consumption, which consumes another 36% of U.S. corn production for animal feed, could also have a significant impact. Studies have shown that reducing this demand for row crops reduces nutrient pollution.

This idea has gained momentum with the growth of the alternative meat industry. The success of startups like Beyond Meat and Impossible Foods is luring giants like Tyson and Perdue into the game. Some are even struggling to keep up with demand for plant-based meat alternatives, particularly in China. One recent market analysis suggests that plant-based "meat" will surpass animal sources globally by 2040.

AT Kearney, CC BY-ND

Shrinking Agriculture's Footprint

Scientists have understood for decades that excess nitrogen and phosphorus degrade Lake Erie, the Chesapeake Bay and the Gulf of Mexico. Nutrient inputs from sewage treatment plants and other discreet, easily identifiable sources have declined because they are regulated under the Clean Water Act.

But the nutrients fouling these water bodies now come mostly from diffuse sources, particularly industrial-scale row crop agriculture. Those operations are not subject to the Clean Water Act, and voluntary conservation programs seem to have at best kept pace with the expansion of large-scale farming.

After analyzing these issues and providing policy advice on them for much of my 45-year career, it's frustrating to see so little change. But I am hopeful that current work that addresses agricultural pollution in broader contexts may have an impact.

For example, recent reports connecting reduced meat consumption to both positive environmental effects and improved health should provide additional incentives for change. Research institutes and scholars are laying out comprehensive global pathways to more sustainable agriculture that are designed to feed the world and protect and restore natural ecosystems.

My hope lies in the combination of health- and market-driven movement toward plant-based meat substitutes and enlightened policies that support more sustainable practices in agriculture's critical role of providing food and fiber to the world.

Donald Scavia is professor emeritus at the School for Environment and Sustainability, University of Michigan.
Disclosure statement: Donald Scavia has received funding from the National Science Foundation, the Environmental Protection Agency, the National Oceanic and Atmospheric Administration, Environment and Climate Change Canada, the Erb Family Foundation, the Joyce Foundation, and the C.S. Mott Foundation.

Reposted with permission from our media associate The Conversation.

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In early October, Britain's Prince William teamed up with conservationist David Attenborough to launch the Earthshot Prize, a new award for environmentalist innovation. The Earthshot brands itself the "most prestigious global environment prize in history."

The world-famous wildlife broadcaster and his royal sidekick appear to have played an active role in the prize's inception, and media coverage has focused largely on them as the faces of the campaign.

But the pair are only the frontmen of a much larger movement which has been in development for several years. In addition to a panel of experts who will decide on the winners, the prize's formation took advice from the World Wildlife Fund, Greenpeace and the Jack Ma Foundation.

With more and more global attention on the climate crisis, celebrity endorsement of environmental causes has become more common. But why do environmental causes recruit famous faces for their campaigns? And what difference can it make?

'Count Me In'

"We need celebrities to reach those people who we cannot reach ourselves," says Sarah Marchildon from the United Nations Climate Change secretariat (UNFCCC) in Bonn, Germany.

Marchildon is a proponent of the use of celebrities to raise awareness of environmental causes. In addition to promoting a selection of climate ambassadors who represent the UN on sustainability issues, Marchildon's team has produced videos with well-known narrators from the entertainment world: among them, Morgan Freeman and Mark Ruffalo.

"We choose celebrities who have a lifestyle where they are already talking about these issues," Marchildon explains.

"Sometimes they reach out to us themselves, as David Attenborough did recently. And then they can promote the videos on their own social channels which reach more people than we do — for example, if they have 20 million followers and we have 750,000."

Environmental groups focused on their own domestic markets are also taking this approach. One Germany-based organization that uses celebrities in campaigns is the German Zero NGO. Set up in 2019, it advocates for a climate-neutral Germany by 2035.

German Zero produced a video in March 2020 introducing the campaign with "66 celebrities" that supported the campaign, among them Deutschland 83 actor Jonas Nay and former professional footballer Andre Schürrle. They solicit support as well as financial contributions from viewers.

"Count me in," they say, pointing toward the camera. "You too?"

"We are incredibly grateful for the VIPs in our videos," says German Zero spokeswoman Eva-Maria McCormack.

Assessing Success Is Complex

But quantifying the effectiveness of celebrity endorsement of campaigns is not a straightforward process.

"In order to measure effectiveness, first of all you need to define what is meant by success," says Alegria Olmedo, a researcher at the Zoology Department at the University of Oxford.

Olmedo is the author of a study looking at a range of campaigns concerning pangolin consumption, fronted by local and Western celebrities, in Vietnam and China. But she says her biggest stumbling block was knowing how to measure a campaign's success.

"You need a clear theory of change," explains Olmedo. "Have the celebrities actually helped in achieving the campaign's goals? And how do you quantify these goals? Maybe it is increased donations or higher engagement with a cause."

A popular campaign in China in recent years saw famous chefs Zhao Danian and Shu Yi pledge to abstain from cooking endangered wildlife. While the pledge achieved widespread recognition, both Olmedo and Marchildon say it's difficult to know whether it made any difference to people's actions.

"In life we see a thousand messages every day, and it is very hard to pinpoint whether one campaign has actually made a difference in people's behavior," she explains.

Awareness Is Not Enough

Many campaigns that feature celebrities focus on raising awareness rather than on concrete action — which, for researcher Olmedo, raises a further problem in identifying effectiveness.

"Reach should never be a success outcome," she says. "Many campaigns say they reached a certain number of people on social media. But there has been a lot of research that shows that simply giving people information does not mean they are actually going to remember it or act upon it."

But anecdotal evidence from campaigns may suggest reach can make an active difference.

"Our VIP video is by far the most watched on our social media channels," McCormack from German Zero says. "People respond to it very directly. A lot of volunteers of all ages heard about us through that video."

However, some marketing studies have shown that celebrity endorsement of a cause or product can distract from the issue itself, as people only remember the person, not the content of what they were saying.

Choosing the Right Celebrity

Celebrity choice is also very important. Campaigns that use famous faces are often aiming to appeal to members of the public who do not necessarily follow green issues.

For certain campaigns with clear target audiences, choosing a climate scientist or well-known environmentalist rather than a celebrity could be more appealing — Attenborough is a classic example. For others, images and videos involving cute animals may be more likely to get a message heard than attaching a famous face.

"We choose celebrities who have a lifestyle where they are already talking about these issues," says Marchildon from the UN. "You need figures with credibility."

McCormack cites the example of Katharine Hayhoe, an environmental scientist who is also an evangelical Christian. In the southern United States, Hayhoe has become a celebrity in her own right, appealing to an audience that might not normally be interested in the messages of climate scientists.

But as soon as you get a celebrity involved, campaigns also put themselves at risk of the whims of that celebrity. Prince William and younger members of the royal family have come under fire in recent years for alleged hypocrisy for their backing of environmental campaigns while simultaneously using private jets to fly around the world.

But Does It Really Work?

While environmental campaigns hope that endorsement from well-known figures can boost a campaign, there is little research to back this up.

"The biggest finding [from my study] was that we were unable to produce any evidence that shows that celebrity endorsement of environmental causes makes any difference," says Olmedo.

This will come as a blow to many campaigns that have invested time and effort into relationships with celebrity ambassadors. But for many, the personal message that many celebrities offer in videos like that produced by German Zero and campaigns like the Earthshot Prize are what counts.

The research may not prove this conclusively — but if the public believes a person they respect deeply personally cares about an important issue, they are perhaps more likely to care too.

"I personally believe in the power this can have," says Marchildon. "And if having a celebrity involved can get a single 16-year-old future leader thinking about environmentalist issues — that is enough."

Reposted with permission from DW.

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