How marsh grass could help protect us from climate change

Photo by Steve Adams on Unsplash
Marshland in Holden Beach, USA, likely to have prevented storms and surges from having a worse impact in North Carolina. Photo by Steve Adams on Unsplash

By David L. Chandler, World Economic Forum (Public License).

  • Coastal marsh plants provide significant protection from surges and devastating storms.

  • Research in MIT’s Parson’s lab can help coastal planners to take important details into account when planning projects.

  • Countries must take advantage of this modeling in order to restore marshland with specific plants in certain areas.

Marsh plants, which are ubiquitous along the world’s shorelines, can play a major role in mitigating the damage to coastlines as sea levels rise and storm surges increase. Now, a new MIT study provides greater detail about how these protective benefits work under real-world conditions shaped by waves and currents.

The study combined laboratory experiments using simulated plants in a large wave tank along with mathematical modeling. It appears in the journal Physical Review — Fluids, in a paper by former MIT visiting doctoral student Xiaoxia Zhang, now a postdoc at Dalian University of Technology, and professor of civil and environmental engineering Heidi Nepf.

“After a few years, the marsh grasses start to trap and hold the sediment, and the elevation gets higher and higher, which might keep up with sea level rise.”

—Xiaoxia Zhang, now a postdoc at Dalian University of Technology, and professor of civil and environmental engineering Heidi Nepf
A new MIT study provides greater detail about how thes protective benefits of marsh plants work under real-world conditions shaped by waves and currents. The simulated plants used in lab experiments were designed based on Spartina alterniflora, which is a common coastal marsh plant. Credit: Xiaoxia Zhang.
A new MIT study provides greater detail about how thes protective benefits of marsh plants work under real-world conditions shaped by waves and currents. The simulated plants used in lab experiments were designed based on Spartina alterniflora, which is a common coastal marsh plant. Credit: Xiaoxia Zhang.

It’s already clear that coastal marsh plants provide significant protection from surges and devastating storms. For example, it has been estimated that the damage caused by Hurricane Sandy was reduced by $625 million thanks to the damping of wave energy provided by extensive areas of marsh along the affected coasts. But the new MIT analysis incorporates details of plant morphology, such as the number and spacing of flexible leaves versus stiffer stems, and the complex interactions of currents and waves that may be coming from different directions.

This level of detail could enable coastal restoration planners to determine the area of marsh needed to mitigate expected amounts of storm surge or sea-level rise, and to decide which types of plants to introduce to maximize protection.

“When you go to a marsh, you often will see that the plants are arranged in zones,” says Nepf, who is the Donald and Martha Harleman Professor of Civil and Environmental Engineering. “Along the edge, you tend to have plants that are more flexible, because they are using their flexibility to reduce the wave forces they feel. In the next zone, the plants are a little more rigid and have a bit more leaves.”

As the zones progress, the plants become stiffer, leafier, and more effective at absorbing wave energy thanks to their greater leaf area. The new modeling done in this research, which incorporated work with simulated plants in the 24-meter-long wave tank at MIT’s Parsons Lab, can enable coastal planners to take these kinds of details into account when planning protection, mitigation, or restoration projects.

“If you put the stiffest plants at the edge, they might not survive, because they’re feeling very high wave forces. By describing why Mother Nature organizes plants in this way, we can hopefully design a more sustainable restoration,” Nepf says.

Once established, the marsh plants provide a positive feedback cycle that helps to not only stabilize but also build up these delicate coastal lands, Zhang says. “After a few years, the marsh grasses start to trap and hold the sediment, and the elevation gets higher and higher, which might keep up with sea level rise,” she says.

Awareness of the protective effects of marshland has been growing, Nepf says. For example, the Netherlands has been restoring lost marshland outside the dikes that surround much of the nation’s agricultural land, finding that the marsh can protect the dikes from erosion; the marsh and dikes work together much more effectively than the dikes alone at preventing flooding.

But most such efforts so far have been largely empirical, trial-and-error plans, Nepf says. Now, they could take advantage of this modeling to know just how much marshland with what types of plants would be needed to provide the desired level of protection.

It also provides a more quantitative way to estimate the value provided by marshes, she says. “It could allow you to more accurately say, ‘40 meters of marsh will reduce waves this much and therefore will reduce overtopping of your levee by this much.’ Someone could use that to say, ‘I’m going to save this much money over the next 10 years if I reduce flooding by maintaining this marsh.’ It might help generate some political motivation for restoration efforts.”

Nepf herself is already trying to get some of these findings included in coastal planning processes. She serves on a practitioner panel led by Chris Esposito of the Water Institute of the Gulf, which serves the storm-battered Louisiana coastline. “We’d like to get this work into the coatal simulations that are used for large-scale restoration and coastal planning,” she says.

This photo shows examples of Spartina alterniflora in China. Credit: Xiaoxia Zhang.
This photo shows examples of Spartina alterniflora in China. Credit: Xiaoxia Zhang.

“Understanding the wave damping process in real vegetation wetlands is of critical value, as it is needed in the assessment of the coastal defense value of these wetlands,” says Zhan Hu, an associate professor of marine sciences at Sun Yat-Sen University, who was not associated with this work. “The challenge, however, lies in the quantitative representation of the wave damping process, in which many factors are at play, such as plant flexibility, morphology, and coexisting currents.”

The new study, Hu says, “neatly combines experimental findings and analytical modeling to reveal the impact of each factor in the wave damping process. … Overall, this work is a solid step forward toward a more accurate assessment of wave damping capacity of real coastal wetlands, which is needed for science-based design and management of nature-based coastal protection.”

The work was partly supported by the National Science Foundation and the China Scholarship Council.

Moving Beyond America’s War on Wildfire: 4 Ways to Avoid Future Megafires

Tools for a prescribed burn conducted in the Sierra Nevada in November 2019. Susan Kocher, CC BY-ND
Tools for a prescribed burn conducted in the Sierra Nevada in November 2019. Susan Kocher, CC BY-ND

By Susan Kocher, University of California, Division of Agriculture and Natural Resources and Ryan E. Tompkins, University of California, Division of Agriculture and Natural Resources, The Conversation (CC BY-ND 3.0).

Californians have been concerned about wildfires for a long time, but the past two years have left many of them fearful and questioning whether any solutions to the fire crisis truly exist.

The Dixie Fire in the Sierra Nevada burned nearly 1 million acres in 2021, including almost the entire community of Greenville. Then strong winds near Lake Tahoe sent the Caldor Fire racing through the community of Grizzly Flats and to the edges of urban neighborhoods, forcing the evacuation of tens of thousands of people – including one of us. Those were only the biggest of the 2021 fires, and the risk isn’t over. A wind-blown fire that started Oct. 11 was spreading quickly near Santa Barbara on the Southern California coast.

As foresters who have been working on wildfire and forest restoration issues in the Sierra Nevada for over a quarter of a century, we have found it painful to watch communities destroyed and forests continuing to burn to a crisp.

The main lesson we gather from how these fires have burned is that forest fuels reduction projects are our best tools for mitigating wildfire impacts under a changing climate, and not nearly enough of them are being done.

Thinned areas like this one in California’s Genessee Valley were more resistant to 2021’s Dixie Fire. Ryan Tompkins, CC BY-ND
Thinned areas like this one in California’s Genessee Valley were more resistant to 2021’s Dixie Fire. Ryan Tompkins, CC BY-ND

Two historic policies, in our view, led the western U.S. to the point where its forests have become so overgrown they’re fueling megafires that burn down whole communities.

Fire suppression

The first policy problem is fire suppression and exclusion.

Fire is an essential ecological process, and many of the ecosystems in the West are adapted to frequent fire, meaning plant and wildlife species have evolved to survive or even thrive after wildfires. But most people arriving in California during colonization, both before and after the Gold Rush of 1849, fundamentally misunderstood the nature of frequent fire forests.

As state and federal agencies evolved policies on forest management, they considered all fire to be an existential problem and declared war. The U.S. Forest Service kicked off a century of fire suppression in the West after the devastating fires of 1910, known as the “Big Blowup” or “Big Burn,” by implementing the 10 a.m. policy. It aimed for full suppression of all fires by 10 a.m. the day after they broke out.

Native people who practiced prescribed fire to manage forests were removed from their homelands, and burning was criminalized. California made prescribed fire illegal in 1924, and it remained illegal for decades until a better appreciation of its importance emerged in the 1970s.

Past harvesting practices lead to regulations

The second policy issue is the regulatory approach that grew out of past logging practices.

Foresters and early California communities were interested in forests for lumber and fuel wood. They sent the largest – and most fire-tolerant – trees to mills to be turned into lumber, which was used to build California’s cities and towns.

Poorly executed logging in some areas led to concerns from residents that forest cover and habitat was shrinking. As a result, state and federal regulations were developed in the 1970s that require managers proposing forest projects to consider a “no action alternative.” In other words, maintaining dense forest habitat in the long term was considered a viable management choice.

A few walls of buildings are standing but most of the town is burned and melted rubble.
Little remained of downtown Greenville after the Dixie Fire. Justin Sullivan/Getty Images

On private land, few owners today thin the forest to levels that would mimic the more fire-resilient forests found in the Sierra at colonization. The California Forest Practices Act until recently required replanting after timber harvest to levels much more dense than were found at colonization. In other words, our current regulatory framework promotes maintaining high levels of forest density, when much more drastic removal of vegetation is needed.

Taken together, these policies have promoted 21st-century forests that are younger, denser and more homogenous – making them vulnerable to increasingly severe disturbances such as drought, insect outbreaks and fire. This new reality is exacerbated by a changing climate, which turns the regulatory assumption that active and widespread forest management is riskier than no management on its head.

Agency priorities change as the crisis grows

Just as forests have changed, so too have the agencies that manage and regulate them. The U.S. Forest Service has seen its budgets for fighting fires balloon while its capacity to proactively manage forests has been shrinking. The California Department of Forestry and Fire Protection, known as CAL FIRE, has also seen large increases in firefighting budgets, though the state legislature has recently moved to increase fire prevention funds, too.

Living in communities threatened by wildfires this summer, we are very grateful to firefighters who have saved our homes. Yet we also are concerned that more large, high-severity wildfires burning across the landscape mean less funding and staff will be available for proactive fuels reduction projects like forest thinning and prescribed fires.

The Caldor Fire burned on both sides of Christmas Valley, but was stopped from burning into the community by firefighters using areas where fuels were reduced before the blaze. Susie Kocher, CC BY-ND
The Caldor Fire burned on both sides of Christmas Valley, but was stopped from burning into the community by firefighters using areas where fuels were reduced before the blaze. Susie Kocher, CC BY-ND

How do we get out of this mess?

The Dixie and Caldor fires that destroyed Greenville and Grizzly Flats provided evidence that forest fuels reduction projects can work.

Both fires burned less severely in areas with proactive forest restoration and fuels management projects, including near South Lake Tahoe and near Quincy.

Fuels reduction projects include thinning out trees, burning off woody debris and reducing “ladder fuels” like small trees and brush that can allow fire to reach the tree canopy. They create more open forests that are less likely to fuel severe megafires. They also create strategic areas where firefighters can more easily fight future blazes. And, because fires burn less intensely in thinned forests, they leave more intact forest after a fire for regenerating new trees and sequestering carbon. Prescribed fires and managed ignitions paid huge dividends for containing the Dixie and Caldor fires.

During the Dixie Fire, firefighters used an area that had been strategically thinned in the past to set backfires to prevent the wildfire from spreading into the community of Quincy. Ryan Tompkins, CC BY-ND
During the Dixie Fire, firefighters used an area that had been strategically thinned in the past to set backfires to prevent the wildfire from spreading into the community of Quincy. Ryan Tompkins, CC BY-ND

To manage fires in an era of climate change, where drier, hotter weather creates ideal conditions for burning, experts estimate that the area treated for fuels reduction needs to increase by at least an order of magnitude. We believe government needs to accomplish these four things to succeed:

  1. Drastically increase funding and staff for agencies’ fuels reduction projects, as well as outreach, cost-sharing and technical assistance for private forestland owners. Although the Biden administration’s proposal for a Civilian Climate Corps proposes funding to bring in more young and unskilled workers, funding more federal and state agency positions would recruit more natural resource professionals, provide career-track opportunities and better add forest restoration capacity for the long term.

  2. Reduce regulations on forest and fuels management efforts for both public and private land. While California and the federal government have made recent strides to streamline regulations, land management agencies need to acknowledge the biggest risk in frequent fire forests is doing nothing, and time is running out. Agencies need to drastically cut the time needed to plan and implement fuels reduction projects.

  3. Invest in communities’ capacity to carry out local forest restoration work by providing long-term support to local organizations that provide outreach, technical assistance and project coordination services. Funding restoration through competitive grants makes development of long-term community capacity challenging at best.

  4. Provide funds and financial incentives for at risk communities to retrofit homes to withstand wildfires and reduce fuels around homes, communities and infrastructure.
The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Warning of Looming ‘List of Horrors,’ Pacific Island Leaders Demand Urgent COP 26 Climate Action

Fijian Prime Minister Frank Bainimarama stressed that world leaders should not be allowed to “sneak in and out of Glasgow without making a single serious commitment.”

Photo by Adli Wahid on Unsplash
Photo by Adli Wahid on Unsplash

By Brett Wilkins, Common Dreams (CC BY-ND 3.0).

As world leaders prepare to jet off to this month’s United Nations Climate Change Conference in Scotland, the heads of several Pacific island nations in recent days urged world leaders to leave their good intentions at home and commit to urgent, meaningful climate action.

“We refuse to be the proverbial canaries in the coal mine, as we are so often called.”

—Fiji’s Prime Minister Frank Bainimarama 

On Thursday, Fijian Prime Minister Frank Bainimarama, Marshallese President David Kabua, and Samoan Prime Minister Fiamē Naomi Mata’afa addressed the European Union-Indo-Pacific Virtual Conference on Climate Change.

“For our sake and all of humanity’s, small island developing states will use the full measure of our moral authority against major emitters who refuse to arrive in Glasgow with strong commitments,” Bainimarama told the conference, according to Agence France-Presse.

Bainimarama lamented that low-lying Pacific island nations—which are among the least responsible for the climate emergency and but most adversely affected by it—stressed that the Glasgow summit, also known as COP 26, must not end in “a litany of good intentions.”

“The consequences of inaction are unthinkable,” he said. “The loss of entire islands, as well as vast stretches of coastline from Lagos to Venice to Miami, the coastal belt of Bangladesh. Mass climate-driven migration, wildfire seasons in arid regions that incinerate homes, farms, ecosystems, and an unimaginable loss of biodiversity—the list of horrors goes on.”

Earlier this week, Bainimarama angrily told a forum organized by former U.S. Vice President Al Gore’s Climate Reality Project that “we refuse to be the proverbial canaries in the coal mine, as we are so often called.”

“We want more of ourselves than to be helpless songbirds whose demand serves as a warning to others,” he said, urging Pacific island nations to not allow world leaders to “sneak in and out of Glasgow without making a single serious commitment.”

According to The Syndey Morning Herald:

Bainimarama said Pacific Island nations will demand that… wealthier countries make good on the commitment they made during the Paris talks to extend to developing nations $100 billion in finance annually for climate adaptation and mitigation; and to commit to emission cuts that keep the 1.5°C warming target within reach.

“That is our expectation for every nation,” said Bainimarama. “Our actions will decide whether islands exist or are lost to the rising seas.”

Kabua said Thursday that “my country and this region needs the world to recognize that this cannot wait.”

“We face the most difficult questions—which islands to preserve, what happens when our people are forced to move against their will, how will we preserve our culture?” he said. “We need a signal from the rest of the world, particularly the large emitters, that our voices and our needs are being heard.”

Mata’afa told the E.U.-backed conference that “we are already experiencing intense and frequent tropical cyclones and droughts, increased heavy precipitation and floods, ocean warming, and acidification. The impacts are detrimental to our health, wellbeing, livelihoods, and way of life.”

Speaking late last month at the United Nations General Assembly, she stressed: “It is about action for survival, and we all need to shoulder our responsibilities and play our part. The big polluters and emitters need to demonstrate more commitment and leadership.”

“The upcoming COP in Glasgow is our point of no return,” she added. “Our commitments from there onwards will determine the future trajectory of our planet. Can we avoid a climate catastrophe in our children’s lifetime?”