More than 3,000 miles (4,800 kilometers) away, the people of Scituate, Massachusetts, received a letter that same month cautioning about the same group of contaminants in their drinking water.
At issue wasn't any of the well-known and widely feared water infiltrators such as E. coli or per- and polyfluoroalkyl substances (PFAS). The culprit chemicals tainting taps from Cocoa, Florida, to the Finger Lakes of New York to a correctional facility in Only, Tennessee, are, in fact, less recognized yet more ubiquitous: disinfection by-products.
"Take a glass of water. You may or may not have pesticides, pharmaceuticals, PFAS and lead in it. Usually not," says Susan Richardson, a professor of biochemistry at the University of South Carolina in Columbia. "But there's always something that is in your drinking water, and that's disinfection by-products."
Aptly named, the chemicals form in water when disinfectants that are widely used to kill pathogens in municipal drinking water facilities react with organic compounds. These compounds may be present in the water as a result of natural processes such as the decay of leaves and animal matter, as well as human activities that may release solvents, pharmaceuticals, pesticides and industrial chemicals. Exposure to disinfection by-products through drinking, bathing or swimming has been linked to potential increased risks of low birthweight babies, birth defects, miscarriages and cancer.
"Disinfection is hugely important. We've got to kill those pathogens," says Richardson. "We had millions of people dying from waterborne illnesses before we started disinfecting water in the 1800s."
Cholera and typhoid fever were once deadly and pervasive threats. Still today, when concentrations of disinfectants fall too low, drinking water can become a breeding ground for dangerous pathogens such as Legionella, E. coli, even cholera.
"It's a trade-off between inactivating pathogens that are going to make people sick today versus the long-term, low-level risk of chemicals in the water," says Christy Remucal, an associate professor of civil and environmental engineering at the University of Wisconsin–Madison.
Striking a balance may be even more challenging today as waters become increasingly compromised due to population growth, wastewater intrusion, energy exploration, climate change — and now the Covid-19 pandemic, according to Richardson.
During the pandemic, many places have increased use of chlorine for disinfection in indoor and outdoor settings and during wastewater treatment, resulting in the potential for higher levels of disinfection by-products. Authors of a study published in October warn that this "upsurge and overuse of chlorine-based disinfectants" may pose a threat to human health "by impacting water quality."
Concentrations of harmful chemicals have also likely increased in buildings left vacant during Covid-19 shutdowns. The longer that water sits in pipes, explains Richardson, the longer it has to react with disinfectants and form more by-products.
Still, Gregory Korshin, a professor of civil and environmental engineering at the University of Washington in Seattle, encourages perspective on the issue of disinfection by-products. The answer, he and others say, is not to stop disinfecting water, nor is it for everyone to buy bottled water.
"There is a dark side of disinfection," adds Korshin. "But this doesn't compromise the notion that drinking water in the U.S. is safe."
Unintended Consequences
Chemists first discovered disinfection by-products in treated drinking water in the 1970s. The trihalomethanes they found, they determined, had resulted from the reaction of chlorine with natural organic matter. Since then, scientists have identified more than 700 additional disinfection by-products. "And those only represent a portion. We still don't know half of them," says Richardson, whose lab has identified hundreds of disinfection by-products.
Identification of disinfection by-products is incredibly difficult, she explains, because these chemicals are not simply flowing down a river from an industrial site or running off a farm. "They didn't exist before," she adds. "It's a complete unknown — there's no preconceived idea of what these chemicals look like."
Another research team recently discovered more previously unidentified disinfection by-products. As they described in a January 2020 study, potentially carcinogenic chemicals are formed through the interaction of chlorine and not only organic matter in the environment but also manmade materials that include phenols such as bisphenol A (BPA) and other plasticizers, as well as sunscreen agents and antimicrobials.
"These phenol compounds are incredibly widespread because of their properties," says Carsten Prasse, a coauthor on the study and an assistant professor of environmental health and environmental engineering at Johns Hopkins University. He highlights their use in both plastic pipes and plastic bottles, which frequently carry drinking water.
What’s Regulated and What’s Not?
The U.S. Environmental Protection Agency (EPA) currently regulates 11 disinfection by-products — including a handful of trihalomethanes (THM) and haloacetic acids (HAA). While these represent only a small fraction of all disinfection by-products, EPA aims to use their presence to indicate the presence of other disinfection by-products. "The general idea is if you control THMs and HAAs, you implicitly or by default control everything else as well," says Korshin.
EPA also requires drinking water facilities to use techniques to reduce the concentration of organic materials before applying disinfectants, and regulates the quantity of disinfectants that systems use. These rules ultimately can help control levels of disinfection by-products in drinking water.
Click the image for an interactive version of this chart on the Environmental Working Group website.
Still, some scientists and advocates argue that current regulations do not go far enough to protect the public. Many question whether the government is regulating the right disinfection by-products, and if water systems are doing enough to reduce disinfection by-products. EPA is now seeking public input as it considers potential revisions to regulations, including the possibility of regulating additional by-products. The agency held a two-day public meeting in October 2020 and plans to hold additional public meetings throughout 2021.
When EPA set regulations on disinfection by-products between the 1970s and early 2000s, the agency, as well as the scientific community, was primarily focused on by-products of reactions between organics and chlorine — historically the most common drinking water disinfectant. But the science has become increasingly clear that these chlorinated chemicals represent a fraction of the by-product problem.
For example, bromide or iodide can get caught up in the reaction, too. This is common where seawater penetrates a drinking water source. By itself, bromide is innocuous, says Korshin. "But it is extremely [reactive] with organics," he says. "As bromide levels increase with normal treatment, then concentrations of brominated disinfection by-products will increase quite rapidly."
Emerging data indicate that brominated and iodinated by-products are potentially more harmful than the regulated by-products.
Almost half of the U.S. population lives within 50 miles of either the Atlantic or Pacific coasts, where saltwater intrusion can be a problem for drinking water supplies. "In the U.S., the rule of thumb is the closer to the sea, the more bromide you have," says Korshin, noting there are also places where bromide naturally leaches out from the soil. Still, some coastal areas tend to be spared. For example, the city of Seattle's water comes from the mountains, never making contact with seawater and tending to pick up minimal organic matter.
Hazardous disinfection by-products can also be an issue with desalination for drinking water. "As desalination practices become more economical, then the issue of controlling bromide becomes quite important," adds Korshin.
Other Hot Spots
Coastal areas represent just one type of hot spot for disinfection by-products. Agricultural regions tend to send organic matter — such as fertilizer and animal waste — into waterways. Areas with warmer climates generally have higher levels of natural organic matter. And nearly any urban area can be prone to stormwater runoff or combined sewer overflows, which can contain rainwater as well as untreated human waste, industrial wastewater, hazardous materials and organic debris. These events are especially common along the East Coast, notes Sydney Evans, a science analyst with the nonprofit Environmental Working Group (EWG, a collaborator on this reporting project).
The only drinking water sources that might be altogether free of disinfection by-products, suggests Richardson, are private wells that are not treated with disinfectants. She used to drink water from her own well. "It was always cold, coming from great depth through clay and granite," she says. "It was fabulous."
Today, Richardson gets her water from a city system that uses chloramine.
Toxic Treadmill
Most community water systems in the U.S. use chlorine for disinfection in their treatment plant. Because disinfectants are needed to prevent bacteria growth as the water travels to the homes at the ends of the distribution lines, sometimes a second round of disinfection is also added in the pipes.
Here, systems usually opt for either chlorine or chloramine. "Chloramination is more long-lasting and does not form as many disinfection by-products through the system," says Steve Via, director of federal relations at the American Water Works Association. "Some studies show that chloramination may be more protective against organisms that inhabit biofilms such as Legionella."
If a drinking water facility fails to meet EPA regulations for disinfection by-products, one relatively easy and cheap modification is to add ammonia to the existing treatment, turning chlorine to chloramine. Many large community water systems in the U.S. now use chloramine. By doing so, according to Richardson, they have dropped levels of regulated disinfection by-products by up to as much as 90%.
However, there is one major drawback to this shift: the creation of potentially more harmful by-products. "It might push down on regulated disinfection by-products, but then other things pop up that are even more toxic," says Richardson, whose research team discovered previously unknown disinfection by-products in chloraminated drinking water. One of those finds, iodoacetic acid, is the most DNA-damaging disinfection by-product known to date.
Prasse underscored the concern: "From a regulatory perspective, we could say we're fine. But it's a false sense of security."
Rather than continuing on the toxic treadmill of replacing one potentially toxic chemical for another, a more effective solution may be to focus upstream in the treatment process — such as keeping organics out of the system in the first place. "That requires engineers, chemists, toxicologists and regulators to come together and figure something out," says Prasse.
Alternative Approaches
When he moved to the U.S. from Germany, Prasse says he immediately noticed the bad taste of the water. "You can taste the chlorine here. That's not the case in Germany," he says.
In his home country, water systems use chlorine — if at all — at lower concentrations and at the very end of treatment. In the Netherlands, chlorine isn't used at all as the risks are considered to outweigh the benefits, says Prasse. He notes the challenge in making a convincing connection between exposure to low concentrations of disinfection by-products and health effects, such as cancer, that can occur decades later. In contrast, exposure to a pathogen can make someone sick very quickly.
But many countries in Europe have not waited for proof and have taken a precautionary approach to reduce potential risk. The emphasis there is on alternative approaches for primary disinfection such as ozone or ultraviolet light. Reverse osmosis is among the "high-end" options, used to remove organic and inorganics from the water. While expensive, says Prasse, the method of forcing water through a semipermeable membrane is growing in popularity for systems that want to reuse wastewater for drinking water purposes.
Remucal notes that some treatment technologies may be good at removing a particular type of contaminant while being ineffective at removing another. "We need to think about the whole soup when we think about treatment," she says. What's more, Remucal explains, the mixture of contaminants may impact the body differently than any one chemical on its own.
Richardson's preferred treatment method is filtering the water with granulated activated carbon, followed by a low dose of chlorine.
Granulated activated carbon is essentially the same stuff that's in a household filter. (EWG recommends that consumers use a countertop carbon filter to reduce levels of disinfection by-products.) While such a filter "would remove disinfection by-products after they're formed, in the plant they remove precursors before they form by-products," explains Richardson. She coauthored a 2019 paper that concluded the treatment method is effective in reducing a wide range of regulated and unregulated disinfection by-products.
Greater Cincinnati Water Works installed a granulated activated carbon system in 1992, and is still one of relatively few full-scale plants that uses the technology. Courtesy of Greater Cincinnati Water Works.
Despite the technology and its benefits being known for decades, relatively few full-scale plants use granulated active carbon. They often cite its high cost, Richardson says. "They say that, but the city of Cincinnati [Ohio] has not gone bankrupt using it," she says. "So, I'm not buying that argument anymore."
Greater Cincinnati Water Works installed a granulated activated carbon system in 1992. On a video call in December, Jeff Swertfeger, the superintendent of Greater Cincinnati Water Works, poured grains of what looks like black sand out of a glass tube and into his hand. It was actually crushed coal that has been baked in a furnace. Under a microscope, each grain looks like a sponge, said Swertfeger. When water passes over the carbon grains, he explained, open tunnels and pores provide extensive surface area to absorb contaminants.
While the granulated activated carbon initially was installed to address chemical spills and other industrial contamination concerns in the Ohio River, Cincinnati's main drinking water source, Swertfeger notes that the substance has turned out to "remove a lot of other stuff, too," including PFAS and disinfection by-product precursors.
"We use about one-third the amount of chlorine as we did before. It smells and tastes a lot better," he says. "The use of granulated activated carbon has resulted in lower disinfection by-products across the board."
Richardson is optimistic about being able to reduce risks from disinfection by-products in the future. "If we're smart, we can still kill those pathogens and lower our chemical disinfection by-product exposure at the same time," she says.
Reposted with permission from Ensia.
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These climate migrants traversed barren and dusty landscapes, or traveled through torrential rains, in search of food and shelter. Many ended up in refugee camps in urban areas such as Badbaado, a sea of makeshift tents on the outskirts of Mogadishu that is now home to tens of thousands of internally displaced persons.
The challenges they face are profound, says Ben Mbaura, national emergency response and disaster risk reduction coordinator at the International Organization for Migration (IOM), including inter clan conflict, poor sanitation, limited education and insufficient access to food. On top of that, many "do not have the necessary skills to match labor market needs, which also results in high levels of unemployment and exclusion," Mbaura notes.
The response to internal displacement like this has long been to provide emergency or short-term assistance. In recent years, however, with so many internally displaced persons living in protracted displacement, humanitarian organizations have increasingly recognized the need to empower them to move toward greater self-reliance. As a result, in 2016 the U.N. and the government of Somalia created the Durable Solutions Initiative (DSI) as a way to introduce long-term solutions for internally displaced persons in Somalia. The DSI gives these people a voice in decision-making processes that shape their future — and offers a model for other cities that are, or soon will be, in similar circumstances.
Fragile Cities
Every year, millions of people around the world are forced to abandon their lands, livelihoods and communities due to the effects of climate change. And the rate of climate-induced migration is increasing — with most taking place in the form of rural-urban migration within countries.
According to a recent World Bank report, "internal climate migrants" could number more than 143 million by 2050, mainly in sub-Saharan Africa, Latin America and South Asia. If the past is any indication, most will be forced from their homes by extreme weather events. Others will move from rural areas to cities due to slow-onset climate-related events, such as desertification.
Humanitarian experts predict that the current trajectory of climate change will displace millions of people in the Global South. Source: Kanta et al. 2018. Groundswell: Preparing for Internal Climate Migration. Washington, D.C.: The World Bank.
Pablo Escribano, a specialist on migration and climate change in Latin America for the IOM, says this migration will create "urban hot spots" where displaced persons converge in search of shelter, food and jobs.
Climate migrants who arrive in cities are likely to move to informal settlements, and many of these hot spots will occur in rapidly expanding cities in low- and middle-income countries with weak governance and limited capacities to provide social services and infrastructure.
"In Asia, recent estimates of the increase in sea-level rise have strong implications for cities like Jakarta, Bangkok and Dhaka," Escribano says.
In Latin America, he says, Rio de Janeiro, Lima, La Paz and Mexico City will experience migration pressure from sea-level rise, melting glaciers and other climate-change effects. "Fast-growing cities in Africa, such as Lagos, Luanda and Kinshasa are also considered to be city hot spots," he adds.
Urban development expert Robert Muggah has dubbed these urban settings as "fragile cities." As the co-founder and research and innovation director of the think tank Igarapé Institute in Brazil, Muggah developed 11 indicators that determine urban fragility, including crime, inequality, lack of access to services and climate change threats.
Ani Dasgupta, global director for the Ross Center for Sustainable Cities at the World Resources Institute (WRI), says fast-growing cities face multiple threats that increase the vulnerability of new arrivals.
"As cities expand, many municipal governments are overburdened. They are not able to keep up with increasing demand for basic services, like housing, jobs, electricity and transport," he says. "The climate crisis is an additional challenge on top of this. Flooding, heat waves, water shortages and more powerful storms tend to affect new migrants and already vulnerable populations most severely."
Move Toward Self-Reliance
The goal of the DSI is to strengthen the ability of government at all levels — local, state and federal — to help internally displaced persons integrate into society. It has mobilized funding from donors such as the World Bank, U.N. agencies and the Peacebuilding Fund (the U.N.'s financial resource for supporting peace in areas experiencing or at risk of conflict) to support initiatives that allow internally displaced persons to present their ideas for community infrastructure projects along with strategies to become self-reliant.
Teresa Del Ministro, the DSI coordinator for Somalia, says the DSI is a response to a growing global awareness of the limitations of traditional humanitarian approaches to deal effectively with internally displaced persons. "With that trend increasing worldwide, it appeared that multi-stakeholder partnerships are needed at all levels," she says.
The DSI is considered particularly innovative because it lets internally displaced persons articulate the kinds of solutions they need to move toward self-reliance.
"A participatory, locally owned approach is one of the programming principles for the DSI," says Isabelle Peter, the DSI's coordination officer.
One example is the Midnimo I project supported by the Peacebuilding Fund with the IOM and UN-Habitat as partners.
With support from Midnimo I ("midnomo" means "unity" in Somali), climate migrants and other displaced persons in southern and central Somalia met with representatives of their host communities, along with city and national government officials, to develop creative solutions to the many challenges they face. Among other things, the initiative sought to help communities define and drive their own recovery — most prominently through community action plans (CAPs), documents that lay out local priorities for community-driven recovery.
As part of Midnimo I, the IOM trained Somali government representatives to engage displaced persons in visioning exercises to help them articulate their short-term needs and present ideas on strategies to move toward greater self-reliance.
Ali Hussein camp on the outskirts of Burao, Somaliland, is home to numerous families displaced by conflict and drought. Photo courtesy of Oxfam East Africa from Wikimedia, licensed under CC BY 2.0
Midnimo I was implemented in the cities of Kismayo and Baidoa, home to more than 450,000 internally displaced persons.
"Together they would come up with priorities for infrastructure investments or other types of investments. If a project didn't have funding for these priorities, the government would convene other actors and ask for their support," says Del Ministro.
According to an evaluation report by the IOM, the Midnimo I project created short-term employment opportunities, led to the construction of community infrastructure projects and contributed to the establishment of a land commission and to improved relations between authorities and displaced communities. Nearly 350,000 people directly benefited from the Midnimo I project as a result of constructing or upgrading community-prioritized schools, hospitals, water sources, police stations, prisons, airports and more, according to the IOM's Mbaura.
The DSI in Ethiopia
The DSI also has been implemented in Ethiopia, where a drought that began in 2015 left millions dependent upon emergency food aid. The government of Ethiopia, with support from U.N. agencies, governments, donor agencies and non-governmental organizations, launched its own DSI in December 2019. As in Somalia, the focus is on long-term self-reliance.
"The scale of the displacement surprised many in the international community, and there was recognition that collectively we needed to support Ethiopia," says Hélène Harroff Atrafi, the DSI coordinator in the U.N. Resident Coordinator's Office. "In doing so, we looked at international good practices, including in neighboring Somalia."
At this point, the governance structure for the DSI is being established with the government of Ethiopia in the lead. "We have agreed on the vision forward, we have brought together all of the partners who want to work together. Now the operational rollout must begin," says Atrafi.
In the Somali region, one of 10 regions in of Ethiopia, the DSI is now at the stage of detailing the options that internally displaced families have: urban and rural relocation, return to the location of origin, and potential integration in the settlements where the displaced individuals currently reside.
According to the World Bank report "Groundswell: Preparing for Internal Climate Migration," the number of climate migrants in Ethiopia could close to triple by 2050, with Addis Ababa set to become an urban hot spot for climate induced migration. Smaller cities, such as Jigjiga and Deri Dawa, are also expected to receive increasing waves of climate migrants.
In February 2020, Ethiopia ratified the African Union Convention for the Protection and Assistance of Internally Displaced Persons (IDPs) in Africa, a legally binding instrument for protecting internally displaced persons in Africa. There is hope this will bring greater awareness about the need to support innovative, participatory initiatives for internally displaced persons there.
Looking Forward
Around the world, fragile city governments can partner with international humanitarian organizations, NGOs, research institutions, the private sector, U.N. agencies and other city governments to strengthen their capacities to tackle challenges at the intersection of urbanization, climate and migration.
For the Internal Displacement Monitoring Center (IDMC), a think tank based in Geneva, multi-stakeholder partnerships play a crucial role in gathering information about internally displaced persons.
"We start with the people affected — internally displaced persons and host communities — and from there, we build up the agenda, collaborating with national governments, U.N. agencies, NGOs, academia and research centers," says Pablo Ferrández, a research associate with the IDMC.
Andrew Fuys, senior director for global migration at the nonprofit Church World Service, says that one of the priorities for research is to identify how the risks climate migrants face are similar to, or differ from, those of other internally displaced persons in cities so that organizations can provide the appropriate services for climate migrants.
Del Ministro and Peter say the long-term success of the DSI in Somalia will depend on overcoming a number of challenges. Organizers will need to ensure there are sufficient resources for community-led initiatives, overcome obstacles to coordination, and strengthen the capacities of city governments.
"Stronger capacities are needed in human resources in city planning," Peter says. "There is a need to have financial resources available. Developing the skills and knowledge of people who are equipped to deal with challenges in cities is needed."
Oana Baloi, a program management consultant for UN-Habitat in Ethiopia, emphasizes the need for city governments to gain greater access to climate-related finance opportunities.
"Despite the well-designed programmatic approach to implement durable solutions, unless a climate change adaptation strategy is delivered at the regional and local levels, we may expect further climate change–induced displacement," says Baloi. "Accessing climate financing for large scale interventions to ensure adaptation and displacement prevention remains a challenge."
Ferrández says there is also a need for decentralization so towns and smaller cities receive adequate resources to support internally displaced persons.
"Bringing efforts to achieve durable solutions from the national to municipal level also means intervening beyond areas such as Baidoa, Kismayo and Mogadishu, where the international presence is strong, to secondary cities and rural areas," he says.
With the coming years, climate-induced migration to "urban hot spots" is likely to intensify. As it does, collaborations across sectors can help fragile city governments deliver a more effective humanitarian response in times of crisis while empowering internally displaced persons to play a central role in efforts to fully integrate into society. The hope is that, when climate migrants are given a voice in decision-making processes in fragile cities they can devise solutions that will lead to a more secure future not only for themselves and the cities in which they live, but for future generations.
Reposted with permission from Ensia.
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By Lynne Peeples
Editor's note: This story is part of a nine-month investigation of drinking water contamination across the U.S. The series is supported by funding from the Park Foundation and Water Foundation. Read the launch story, “Thirsting for Solutions," here.
The Safe Drinking Water Act (SDWA) forms the foundation of federal oversight of public water systems — those that provide water to multiple homes or customers. Congress passed the landmark law in 1974 during a decade marked by accumulating evidence of cancer and other health damage caused by industrial chemicals that found their way into drinking water. The act authorized the U.S. Environmental Protection Agency for the first time to set national standards for contaminants in drinking water. The EPA has since developed standards for 91 contaminants, a medley of undesirable intruders that range from arsenic and nitrate to lead, copper and volatile organic chemicals like benzene.
In 1996, amendments to the SDWA revised the process for developing drinking water standards, which limit the levels of specific contaminants. Nearly a quarter century after those amendments, an increasing number of policymakers and public health advocates today argue that the act is failing its mission to protect public health and is once again in need of major revision.
Setting Limits
The process for setting federal drinking water contaminant limits, which is overseen by the EPA, was not designed to be speedy.
First, the EPA identifies a list of several dozen unregulated chemical and microbial contaminants that might be harmful. Then water utilities, which are in charge of water quality monitoring, test their treated water to see what shows up. The identification and testing is done on a five-year cycle. The EPA examines those results and, for at least five contaminants, as required by the SDWA, it determines whether a regulation is needed.
Three factors go into the decision: Is the contaminant harmful? Is it widespread at high levels? Will a regulation meaningfully reduce health risks? If the answer is "Yes" to all three, then a national standard will be forthcoming. Altogether, the process can take a decade or more from start to finish.
Usually, however, one of the three answers is "No." Since the 1996 amendments were passed, the EPA has not regulated any new contaminants through this process, though it has strengthened existing rules for arsenic, microbes and the chemical byproducts of drinking water disinfection. The agency did decide in 2011 that it should regulate perchlorate — which is used in explosives and rocket fuel and damages the thyroid — but reversed that decision in June 2020, claiming that the chemical is not widespread enough to warrant a national regulation.
Two other chemicals have recently advanced to the standard-writing stage. In February, EPA administrator Andrew Wheeler announced that the agency would regulate PFOA and PFOS, both members of the class of non-stick, flame-retarding chemicals known as PFAS. For those two chemicals, the EPA currently has issued a health advisory, which is a non-enforceable guideline.
The act of writing a national standard introduces more calculations: health risks, cost of treatment to remove the contaminant from water and availability of treatment technology. Considering these, the EPA establishes what is known as a maximum contaminant level goal (MCLG), which is the level at which no one is expected to become ill from the contaminant over a lifetime. The agency then sets a standard as close to the goal as possible, taking treatment cost into account.
Standards, in the end, are not purely based on health protection and sometimes are higher than the MCLG. These standards, except for lead, apply to water as it leaves the treatment plant or moves throughout the distribution system. They do not apply to water from a home faucet, which could be compromised by old plumbing.
The EPA also has 15 "secondary" standards that relate to how water tastes and smells. Unless mandated by a state, utilities are not required to meet these standards.
Once the EPA sets a drinking water standard, the nation's roughly 50,000 community water systems — plus tens of thousands of schools, office buildings, gas stations and campgrounds that operate their own water systems — are obligated to test for the contaminant. If a regulated substance is found, system operators must treat the water so that contaminant concentrations fall below the standard.
Omissions and Nuances
That is the regulatory process at the federal level. But there are omissions and nuances.
One big omission is private wells. Water in wells that supply individual homes is not regulated by federal statute. Rather, private well owners are responsible for testing and treating their own well water. The U.S. Geological Survey estimates that about 15% of U.S. residents use a private well. Some states, such as New Jersey, require that private wells be tested for contaminants before a home is sold. County health departments might also have similar point-of-sale requirements.
The nuance comes at the state level. States generally carry out the day-to-day grunt work of gathering water quality data from utilities and enforcing action against violations. To gain this authority, they must set drinking water standards that are at least as protective as the federal ones. If they want, they can set stricter limits or regulate contaminants that the EPA has not touched.
State authority had long been uncontroversial because only a few states — California and some northeastern states — were setting their own standards. That has changed in the last few years as states, responding to public pressure in the absence of an EPA standard, began regulating PFAS compounds.
"There was always a little bit of state standards-setting," says Alan Roberson, executive director of the Association of State Drinking Water Administrators, an umbrella group for state regulators. "But it's gone from a little bit to a lot."
Six states — Massachusetts, Michigan, New Hampshire, New Jersey, New York and Vermont — adopted drinking water standards for certain PFAS compounds, while four others, including North Carolina and Minnesota, have issued health advisories or guidelines for groundwater cleanup.
States are also putting limits on other chemicals that the EPA has ignored. In July, New York adopted the nation's first drinking water standard for 1,4-dioxane, a synthetic chemical that was used before the 1990s as an additive to industrial solvents. The EPA deems it likely to cause cancer, but the agency has not regulated it in drinking water. In 2017, California approved a limit for 1,2,3-TCP, another manufactured industrial solvent that the EPA considers likely to be carcinogenic.
The burst of state standards, especially for PFAS chemicals, has raised eyebrows. Some lawmakers worry that mismatched standards are confusing to residents. New York and New Jersey, for instance, set different limits on PFOA and PFOS in drinking water.
"This can create poor risk communication and a crisis of confidence by the public who have diminished trust in their state's standard when it fails to align with a neighboring state," Rep. Paul Tonko of New York said during a House Energy and Commerce subcommittee hearing in July.
Other representatives countered with the view that the EPA should concentrate on a select number of the most concerning contaminants so as not to overwhelm utilities and states with too many rules that are too hastily put together. Rep. John Shimkus from Illinois, echoing statements made by other committee members, said he does not want a system in which "quantity makes quality."
Tonko, however, argued that the federal process "has not worked," pointing to the two-plus decades since a new contaminant was regulated.
This debate, and other considerations like regional drinking water standards, is likely to carry over into the next Congress.
Editor's note: This story is part of a nine-month investigation of drinking water contamination across the U.S. The series is supported by funding from the Park Foundation and Water Foundation. Read the launch story, "Thirsting for Solutions," here.
Reposted with permission from Ensia.
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By Jen Monnier
In the summer of 2015, Laurie Weitkamp was walking on the beach near her coastal Oregon home when she saw something strange: The water was purple. A colony of tunicates, squishy cylindrical critters that rarely come to shore, had congregated in a swarm so thick that you could scoop them out of the water with your hand. "I'd never seen anything like it," she says.
Weitkamp, a research fisheries biologist with the Northwest Fisheries Science Center in Newport, Oregon, knew that something had been afoot in the northeast part of the Pacific Ocean since the fall of 2013, which was unusually sunny, warm and calm. A mass of warm water stretched from Mexico to Alaska and lingered through 2016, disrupting marine life. Tunicates weren't the only creature affected; sea nettle jellyfish all but disappeared, while water jellyfish populations moved north to take their place, and young salmon starved to death out at sea, according to a report by Weitkamp and colleagues. Scientists dubbed this event "The Blob."
Marine heat waves like The Blob have cropped up around the globe more and more often over the past few decades. Scientists expect climate change to make them even more common and long lasting, harming vulnerable aquatic species as well as human enterprises such as fishing that revolve around ocean ecosystems. But there's no reliable way to know when one is about to hit, which means that fishers and wildlife managers are left scrambling to reduce harm in real time.
Fisheries biologist Laurie Weitkamp is helping develop policies to reduce the threat of marine heat waves, which can devastate ocean life. Photo courtesy of Laurie Weitkamp
Now, oceanographers are trying to uncover what drives these events so that people can forecast them and so minimize the ecological and economic damage they cause.
Unprecedented Heat
The Blob, which lasted three years, is the longest marine heat wave on record. Before that, a heat wave that began in 2015 in the Tasman Sea lasted more than eight months, killing abalone and oysters. A 2012 heat wave off the East Coast of Canada and the U.S., the largest on record at the time, pushed lobsters northward. It beat the previous record — a 2011 marine heat wave that uprooted seaweed, fish and sharks off western Australia. Before that, a 2003 heat wave in the Mediterranean Sea clinched the record while ravaging marine life.
As Earth's climate warms, record-setting marine heat waves are becoming more frequent and severe. Map adapted from Marine Heatwaves International Working Group.
Heat waves are a natural part of ocean systems, says Eric Oliver, an assistant professor of oceanography at Dalhousie University in Nova Scotia, Canada. As with temperature on land, there's an average ocean temperature on any particular day of the year: Sometimes the water will be warmer, sometimes it will be colder, and every once in a while it will be extremely warm or cold.
But greenhouse gas emissions have bumped up the average temperature. Now, temperatures that used to be considered extremely warm happen more often — and every so often, large sections of the ocean are pushed into unprecedented heat, Oliver says.
Pelagic ocean ecosystems, however, have not caught up to these hotter temperatures. Organisms may be able to survive a steady temperature rise, but a heat wave can push them over the edge.
When blue swimmer crabs started dying in western Australia's Shark Bay after the 2011 heat wave, the government shut down blue crab fishing for a year and a half. This was hard on industry at the time, says Peter Jecks, managing director of Abacus Fisheries, but it managed to save crab populations. Not all creatures were so lucky — abalone near the heat wave's epicenter still haven't recovered.
"If you don't have strong predictions [of marine heat waves], you can't be proactive. You're left to be reactive," says Thomas Wernberg, an associate professor of marine ecology at the University of Western Australia.
See Them Coming
After Wernberg saw his region's sea life devastated by the heat wave, he recruited scientists from many disciplines in 2014 to begin studying these extreme events in what became the Marine Heatwaves International Working Group. The group held their first meeting in early 2015 and has since created protocols for defining and naming marine heat waves, tracking where they happen and measuring their ecological and socioeconomic impacts.
If we could see heat waves coming, aquaculturists, fishers and wildlife managers would have a better chance at saving money and species, Wernberg says. Seafood farmers could hold off stocking their aquaculture facilities with vulnerable species. Lawmakers could enact seasonal fishing closures or temporarily expand protected areas. Scientists could store animals or seeds of vulnerable plants.
That's why scientists around the world are trying to understand what triggers extreme warming in the ocean. Oliver is one such scientist. He feeds ocean data gathered by scientists, satellites, buoys, and deep-diving robots into computer modeling software to identify the forces that drive marine heat waves.
It's a relatively new field of research for which there are still few definitive answers. But past heat waves can be broadly classified into two categories, Oliver says: those driven by the ocean and those driven by the atmosphere.
For an example of an ocean-driven heat wave, Oliver points to the 2015 Tasman Sea heat wave. An ocean current that flows south down the East Coast of Australia normally veers toward New Zealand, but in 2015 it pulsed westward toward Tasmania, bringing a wave of warm water from the tropics that lingered more than six months. "Tropical fish were seen in water that is normally almost subpolar in temperature," Oliver says.
On the other hand, a 2019 heat wave in the Pacific, the so-called "Blob 2.0," was brought down from the atmosphere, according to Dillon Amaya, a climate scientist at the University of Colorado, Boulder. Using computer models, Amaya found that this heat wave emerged when a weather system over the Pacific lost steam, leading to weaker-than-usual winds. Wind helps cool the ocean by evaporating surface water in the same way a breeze cools a person's sweaty skin. But stagnant air above the Pacific locked more of the sun's heat into the water that year.
The recent "Blob 2.0" heat wave bears some resemblance to "The Blob," which disrupted marine life from Mexico to Alaska over the course of three years. NOAA Coral Reef Watch
Amaya is able to simulate heat waves thanks to recent technological advances. Scientists have known for decades that marine heat waves exist, he says, but "we have just begun to recognize these events as unique and deterministic — something we can predict — in the last five to 10 years."
That understanding inspired researchers to build computer simulations capable of playing out complicated ocean processes by weaving together information about ocean and atmospheric currents, sea surface temperature and salinity. Creating these simulations helps them learn more about heat wave mechanics, which lays the groundwork for predicting future events.
Back in Oregon, Weitkamp is part of the group that manages the Pacific Salmon Treaty between the U.S. and Canada. As heat waves like The Blob and Blob 2.0 deplete fish populations, the group is trying to figure out how to create policies better suited to this new normal. Knowing when the next one might hit could help.
"These heat waves have been a good wake-up call," she says. "People are trying to figure out how they're going to adapt."
Reposted with permission from Ensia.
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In the past 100 years, the planet has warmed in the range of 10 times faster than it did on average over the past 5,000. In response, thousands of species are traveling poleward, climbing to higher elevations, and diving deeper into the seas, seeking their preferred environmental conditions. This great migration is challenging traditional ideas about native species, the role of conservation biology and what kind of environment is desirable for the future.
In a 2017 review for Science, University of Tasmania marine ecology professor Gretta Pecl and colleagues wrote, "[C]limate change is impelling a universal redistribution of life on Earth. For marine, freshwater, and terrestrial species alike, the first response to changing climate is often a shift in location." In fact, Pecl says, data suggest that at least 25% and perhaps as much as 85% of Earth's estimated 8.7 million species are already shifting ranges in response to climate change.
But when they arrive, will they be welcome? Traditional definitions classify species according to place. "Native" species arrived without human help and usually before widespread human colonization, so are likely to have natural predators and are unlikely to go rogue. Non-natives are newcomers and suspect. Though 90% cause no lasting damage, 10% become invasive — meaning that they harm the environment, the economy or human health. Last year a multinational report flagged invasive species as a key driver of Earth's biodiversity crisis.
Known and anticipated changes in species distribution due to climate change around the world have implications for culture, society ecosystems, governance and climate change. Figure used with permission from Gretta T. Pecl, originally published on 31 Mar 2017 in Science 355(6332).
How we define species is critical, because these definitions influence perceptions, policy and management. The U.S. National Invasive Species Council (NISC) defines a biological invasion as "the process by which non-native species breach biogeographical barriers and extend their range" and states that "preventing the introduction of potentially harmful organisms is … the first line of defense." But some say excluding newcomers is myopic.
"If you were trying to maintain the status quo, so every time a new species comes in, you chuck it out," says Camille Parmesan, director of the French National Centre for Scientific Research, you could gradually "lose so many that that ecosystem will lose its coherence." If climate change is driving native species extinct, she says, "you need to allow new ones coming in to take over those same functions."
As University of Florida conservation ecologist Brett Scheffers and Pecl warned in a 2019 paper in Nature Climate Change, "past management of redistributed species … has yielded mixed actions and results." They concluded that "we cannot leave the fate of biodiversity critical to human survival to be randomly persecuted, protected or ignored."
Existing Tools
One approach to managing these climate-driven habitat shifts, suggested by University of California, Irvine marine ecologist Piper Wallingford and colleagues in a recent issue of Nature Climate Change, is for scientists to adapt existing tools like the Environmental Impact Classification of Alien Taxa (EICAT) to assess potential risks associated with moving species. Because range-shifting species pose impacts to communities similar to those of species introduced by humans, the authors argue, new management strategies are unnecessary, and each new arrival can be evaluated on a case-by-case basis.
Karen Lips, a professor of biology at University of Maryland who was not associated with the study, echoes the idea that each case is so varied and nuanced that trying to fit climate shifting species into a single category with broad management goals may be impractical. "Things may be fine today, but add a new mosquito vector or add a new tick or a new disease, and all of a sudden things spiral out of control," she says. "The nuance means that the answer to any particular problem might be pretty different."
In recent years, northern flying squirrels in Canada have found themselves in the company of new neighbors — southern flying squirrels expanding their range as the climate warms. Public Domain / USFW
Laura Meyerson, a professor in the Department of Natural Resources Science at the University of Rhode Island says scientists should use existing tools to identify and address invasive species to deal with climate-shifting species. "I would like to operate under the precautionary principle and then reevaluate as things shift. You're sort of shifting one piece in this machinery; as you insert a new species into a system, everything is going to respond," she says. "Will some of the species that are expanding their ranges because of climate change become problematic? Perhaps they might."
The reality is that some climate-shifting species may be harmful to some conservation or economic goals while being helpful to others. While sport fisherman are excited about red snapper moving down the East Coast of Australia, for example, if they eat juvenile lobsters in Tasmania they could harm this environmentally and economically important crustacean. "At the end of the day … you're going to have to look at whether that range expansion has some sort of impact and presumably be more concerned about the negative impacts," says NISC executive director Stas Burgiel. "Many of the [risk assessment] tools we have are set up to look at negative impact." As a result, positive effects may be deemphasized or overlooked. "So that notion of cost versus benefit … I don't think it has played out in this particular context."
Location, Location, Location
In a companion paper to Wallingford's, University of Connecticut ecology and evolutionary biology associate professor Mark Urban stressed key differences between invasive species, which are both non-native and harmful, and what he calls "climate tracking species." Whereas invasive species originate from places very unlike the communities they overtake, he says, climate tracking species expand from largely similar environments, seeking to follow preferred conditions as these environments move. For example, an American pika may relocate to a higher mountain elevation, or a marbled salamander might expand its New England range northward to seek cooler temperatures, but these new locations are not drastically different than the places they had called home before.
Climate tracking species may move faster than their competitors at first, Urban says, but competing species will likely catch up. "Applying perspectives from invasion biology to climate-tracking species … arbitrarily chooses local winners over colonizing losers," he writes.
The marbled salamander, a native of the eastern U.S., is among species whose range could expand northward to accommodate rising temperatures. Seánín Óg / Flickr / CC BY-NC-ND 2.0
Urban stresses that if people prevent range shifts, some climate-tracking species may have nowhere to go. He suggests that humans should even facilitate movement as the planet warms. "The goal in this crazy warming world is to keep everything alive. But it may not be in the same place," Urban says.
Parmesan echoes Urban, emphasizing it's the distance that makes the difference. "[Invasives] come from a different continent or a different ocean. You're having these enormous trans-global movements and that's what ends up causing the species that's exotic to be invasive," she says. "Things moving around with climate change is a few hundred miles. Invasive species are moving a few thousand miles."
In 2019 University of Vienna conservation biology associate professor Franz Essl published a similar argument for species classification beyond the native/non-native dichotomy. Essl uses "neonatives" to refer to species that have expanded outside their native areas and established populations because of climate change but not direct human agency. He argues that these species should be considered as native in their new range.
They Never Come Alone
Meyerson calls for caution. "I don't think we should be introducing species" into ecosystems, she says. "I mean, they never come alone. They bring all their friends, their microflora, and maybe parasites and things clinging to their roots or their leaves. … It's like bringing some mattress off the street into your house."
Burgiel warns that labeling can have unintended consequences. We in the invasive species field … focus on non-native species that cause harm," he says. "Some people think that anything that's not native is invasive, which isn't necessarily the case." Because resources are limited and land management and conservation are publicly funded, Burgiel says, it is critical that the public understands how the decisions are being made.
Piero Genovesi, chair of the International Union for the Conservation of Nature's Invasive Species Specialist Group, sees the debate about classification — and therefore about management — as a potential distraction from more pressing conservation issues.
"The real bulk of conservation is that we want to focus on the narrow proportion of alien species that are really harmful," he says. In Hawaii "we don't discuss species that are there [but aren't] causing any problem because we don't even have the energy for dealing with them all. And I can tell you, no one wants to remove [non-native] cypresses from Tuscany. So, I think that some of the discussions are probably not so real in the work that we do in conservation."
Indigenous frameworks offer another way to look at species searching for a new home in the face of climate change. According to a study published in Sustainability Science in 2018 by Dartmouth Native American studies and environmental studies associate professor Nicholas Reo, a citizen of the Sault Ste. Marie Tribe of Chippewa Indians, and Dartmouth anthropology associate professor Laura Ogden, some Anishnaabe people view plants as persons and the arrival of new plants as a natural form of migration, which is not inherently good or bad. They may seek to discover the purpose of new species, at times with animals as their teachers. In their paper Reo and Ogden quote Anishnaabe tribal chairman Aaron Payment as saying, "We are an extension of our natural environment; we're not separate from it."
The Need for Collaboration
The successful conservation of Earth's species in a way that keeps biodiversity functional and healthy will likely depend on collaboration. Without global agreements, one can envision scenarios in which countries try to impede high-value species from moving beyond their borders, or newly arriving species are quickly overharvested.
In Nature Climate Change, Sheffers and Pecl call for a Climate Change Redistribution Treaty that would recognize species redistribution beyond political boundaries and establish governance to deal with it. Treaties already in place, such as the Convention on International Trade in Endangered Species of Wild Fauna and Flora, which regulates trade in wild plants and animals; the Migratory Bird Treaty Act; and the Agreed Measures for the Conservation of Antarctic Fauna and Flora, can help guide these new agreements.
"We are living through the greatest redistribution of life on Earth for … potentially hundreds of thousands of years, so we definitely need to think about how we want to manage that," Pecl says.
Genovesi agrees that conservationists need a vision for the future. "What we do is more to be reactive [to known threats]. … It's so simple to say that destroying the Amazon is probably not a good idea that you don't need to think of a step ahead of that." But, he adds, "I don't think we have a real answer in terms of okay, this is a threshold of species, or this is the temporal line where we should aim to." Defining a vision for what success would look like, Genovesi says, "is a question that hasn't been addressed enough by science and by decision makers."
At the heart of these questions are values. "All of these perceptions around what's good and what's bad, all [are based on] some kind of value system," Pecl says. "As a whole society, we haven't talked about what we value and who gets to say what's of value and what isn't."
This is especially important when it comes to marginalized voices, and Pecl says she is concerned because she doesn't "think we have enough consideration or representation of Indigenous worldviews." Reo and colleagues wrote in American Indian Quarterly in 2017 that climate change literature and media coverage tend to portray native people as vulnerable and without agency. Yet, says Pecl, "The regions of the world where [biodiversity and ecosystems] are either not declining or are declining at a much slower rate are Indigenous controlled" — suggesting that Indigenous people have potentially managed species more effectively in the past, and may be able to manage changing species distributions in a way that could be informative to others working on these issues.
Meanwhile, researchers such as Lips see species classification as native or other as stemming from a perspective that there is a better environmental time and place to return to. "There is no pristine, there's no way to go back," says Lips. "The entire world is always very dynamic and changing. And I think it's a better idea to consider just simply what is it that we do want, and let's work on that."
Reposted with permission from Ensia.
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Lackner is one of hundreds, if not thousands, of scientists around the world who are working on ways to remove CO2 from the atmosphere, capturing carbon from the atmosphere using plants, rocks or engineered chemical reactions and storing it in soil, products such as concrete and plastic, rocks, underground reservoirs or the deep blue sea.
Some of the strategies—known collectively as carbon dioxide removal or negative emissions technologies—are just twinkles in their envisioners' eyes. Others—low-tech schemes like planting more forests or leaving crop residues in the field, or more high-tech "negative emissions" setups like the CO2-capturing biomass fuel plant that went online last spring in Decatur, Illinois—are already underway. Their common aim: To help us out of the climate change fix we've gotten ourselves into.
"We can't just decarbonize our economy, or we won't meet our carbon goal," said Noah Deich, co-founder and executive director with the Center for Carbon Removal in Oakland, California. "We have to go beyond to clean up carbon from the atmosphere ... [And] we need to start urgently if we are to have real markets and real solutions available to us that are safe and cost effective by 2030."
Many Approaches
Virtually all climate change experts agree that to avoid catastrophe we must first and foremost put everything we can into reducing CO2 emissions. But an increasing number are saying that's not enough. If we are to limit atmospheric warming to a level below which irreversible changes become inevitable, they argue, we'll need to actively remove CO2 from the air in fairly hefty quantities as well.
"It's almost impossible that we would hit 2°C, and even less so 1.5°C, without some sort of negative emissions technology," said Pete Smith, chair in plant and soil science at the University of Aberdeen and one of the world's leaders in climate change mitigation.
In fact, scientists from around the world who recently drew up a "road map" to a future that gives us good odds of keeping warming below the 2 ºC threshold lean heavily on reducing carbon emissions by completely phasing out fossil fuels—but also require that we actively remove CO2 from the atmosphere. Their scheme calls for sequestering 0.61 metric gigatons (a gigaton, abbreviated Gt, is a billion metric tons or 0.67 billion tons) of CO2 per year by 2030, 5.51 by 2050, and 17.72 by 2100. Human-generated CO2 emissions were around 40 Gt in 2015, according to the National Oceanic and Atmospheric Administration.
Reports periodically appear pointing out that one approach or another is not going to cut it: Trees can store carbon, but they compete with agriculture for land, soil can't store enough, machines like the ones Lackner envisions take too much energy, we don't have the engineering figured out for underground storage.
It's likely true that no one solution is the fix, all have pros and cons, and many have bugs to work out before they're ready for prime time. But in the right combination, and with some serious research and development, they could make a big difference. And, as an international team of climate scientists recently pointed out, the sooner the better, because the task of reducing greenhouse gases will only become larger and more daunting the longer we delay.
Smith suggests dividing the many approaches into two categories—relatively low-tech "no regrets" strategies that are ready to go, such as reforestation and improving agricultural practice, and advanced options that need substantial research and development to become viable. Then, he suggests, deploy the former and get working on the latter. He also advocates for minimizing the downsides and maximizing the benefits by carefully matching the right approach with the right location.
"There are probably good ways and bad ways of doing everything," Smith said. "I think we need to find the good ways of doing these things."
Deich, too, supports the simultaneous pursuit of multiple options. "We don't want a technology, we want lots of complementary solutions in a broader portfolio that updates often as new information about the solutions emerges."
With that in mind, here is a quick look at some of the main approaches being considered, including a ballpark projection based on current knowledge of CO2 storage potential distilled from a variety of sources—including preliminary results from a University of Michigan study expected to be released later this year—as well as summaries of advantages, disadvantages, maturity, uncertainties and thoughts about the circumstances under which each might best be applied.
Afforestation and Reforestation
Pay your entrance fee, drive up a winding road through Sequoia National Park in California, hike half a mile through the woods, and you'll find yourself at the feet of General Sherman, the world's largest tree. With some 52,500 cubic feet (1,487 cubic meters) of wood in its trunk, the behemoth has more than 1,400 metric tons (1,500 tons) of CO2 trapped in its trunk alone.
Though its size is clearly exceptional, the General gives an idea of trees' potential to suck CO2 from the air and store it in wood, bark, leaf and root. In fact, the Intergovernmental Panel on Climate Change estimated that a single hectare (2.5 acres) of forest can take up somewhere between 1.5 and 30 metric tons (1.6 and 33 tons) of CO2 per year, depending on the kinds of trees, how old they are, the climate and so on.
Worldwide forests currently sequester on the order of 2 Gt CO2 per year. Concerted efforts to plant trees in new places (afforest) and replant deforested acreage (reforest) could increase this by a gigaton or more, depending on species, growth patterns, economics, politics and other variables. Forest management practices emphasizing carbon storage and genetic modification of trees and other forest plants to improve their ability to take up and store carbon could push these numbers higher.
Another way to help enhance trees' ability to store carbon is to make long-lasting products from them—wood-frame buildings, books and so on. Using carbon-rich wood for construction, for example, could extend trees' storage capacity beyond forests' borders, with wood storage and afforestation combining for a potential 1.3–14 Gt CO2 per year possible, according to The Climate Institute, an Australia-based research organization.
iStockphoto.com/holgs
Carbon Farming
Most farming is intended to produce something that's harvested from the land. Carbon farming is the opposite. It uses plants to trap CO2, then strategically uses practices such as reducing tilling, planting longer-rooted crops and incorporating organic materials into the soil to encourage the trapped carbon to move into—and stay in—the soil."Currently, many agricultural, horticultural, forestry and garden soils are a net carbon source. That is, these soils are losing more carbon than they are sequestering," noted Christine Jones, founder of the Australia-based nonprofit Amazing Carbon. "The potential for reversing the net movement of CO2 to the atmosphere through improved plant and soil management is immense. Indeed, managing vegetative cover in ways that enhance the capacity of soil to sequester and store large volumes of atmospheric carbon in a stable form offers a practical and almost immediate solution to some of the most challenging issues currently facing humankind."
Soil's carbon-storing capacity could go even higher if research initiatives by the Advanced Research Projects Agency–Energy, a U.S. government agency that provides research support for innovative energy technologies, and others aimed at improving crops' capacity to transfer carbon to the soil are successful. And, points out Eric Toensmeier, author of The Carbon Farming Solution, the capacity of farmland to store carbon can be dramatically increased by including trees in the equation as well.
"Generally it is practices that incorporate trees that have the most carbon [storage]—often two to 10 times more carbon per hectare, which is a pretty big deal," Toensmeier said.
Creative Commons
Other Vegetation
Although forests and farmland have drawn the most attention, other kinds of vegetation—grasslands, coastal vegetation, peatlands—also take up and store CO2, and efforts to enhance their ability to do so could contribute to the carbon storage cause around the world.
Coastal plants, such as mangroves, seagrasses and vegetation inhabiting tidal salt marshes, excel at sequestering CO2 in vegetation—significantly more per area than terrestrial forests, according to Meredith Muth, international program manager with the National Oceanic and Atmospheric Administration.
"These are incredibly carbon-rich ecosystems," said Emily Pidgeon, Conservation International senior director of strategic marine initiatives. That's because the oxygen-poor soil in which they grow inhibits release of CO2 back to the atmosphere, so rather than cycling back into the atmosphere, carbon simply builds up layer by layer over the centuries. With mangroves sequestering roughly 1,400 metric tons (1,500 tons) per hectare (2. 5 acres); salt marshes, 900 metric tons (1,000 tons); and seagrass, 400 metric tons (400 tons), restoring lost coastal vegetation and extending coastal habitats holds potential to sequester substantial carbon. And researchers are eyeing strategies such as reducing pollution and managing sediment disturbance to make these ecosystems absorb even more CO2.
And, Pidgeon added, such vegetation provides a double climate benefit because it also helps protect coastlines from erosion as warming causes sea levels to rise.
"It's the perfect climate change ecosystem, especially in some of the more vulnerable places," she said. "It provides storm protection, erosion control, maintains the local fishery. In terms of climate change, it's immensely valuable, whether talking mitigation or adaptation."
iStockphoto.com/MorganLeeAlain
Bioenergy & Bury
In addition to tapping vegetation's capacity to store CO2 in plant parts and soil, humans can enhance sequestration by socking away the carbon plants absorb in other ways. A $208 million power plant that started operation earlier this year in the heart of Illinois farm country is a tangible example of this approach and what is currently widely seen as the most promising technology-based strategy for removing large amounts of carbon from the air: bioenergy carbon capture and storage, or BECCS.
BECCS generally starts with converting biomass into a usable energy source such as liquid fuel or electricity. But then it takes the concept one key step further. Rather than sending the CO2 released during the process into the air, as conventional facilities do, it captures and concentrates it, then traps it in material such as concrete or plastic or—as is the case for the Decatur plant—injects it into rock formations that trap the carbon far below Earth's surface.
A related strategy proposes using ocean plants such as kelp instead of land plants. This would reduce the need to compete with food production and land habitat preservation for land. This option has not been explored as much as land-based BECCS, however, so the number of unknowns is even higher.
On the storage end of things, many of the technologies proposed are still in concept or early development stage. But if developed correctly, the approach has "potentially got quite a significant impact," said professor Pete Smith of the University of Aberdeen.
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Biochar
Another way to enhance plants' ability to store carbon is to partly burn materials such as logging slash or crop waste to make a carbon-rich, slow-to-decompose substance known as biochar, which can then be buried or spread on farmland. Biochar has been used for centuries to enrich soil for farming, but of late has been drawing increased attention for its ability to sequester carbon—as evidenced by the fact that three of 10 finalists in a $25 million Earth Challenge launched by Virgin in 2007 tap this approach.
Oregon Department of Forestry
Fertilizing the Ocean
Plants and plantlike organisms that live in the ocean absorb immeasurable amounts of CO2 each year, their ability to do so limited only by the availability of iron, nitrogen and other nutrients they need to grow and multiply. So researchers are looking at strategies for fertilizing the ocean or bringing nutrients up from the depths to hyperdrive plants' ability to trap and store carbon.
A decade or so ago, companies began forming to do just that, with the plan of reaping rewards from the soon-to-be-established global carbon market. Such plans have largely remained on the drawing board, stymied by substantial uncertainties over how to put a price tag on carbon, concerns over disrupting fisheries and ocean ecosystems more generally, and the high energy requirements and costs that would likely be involved. In addition, we don't have a clear picture of how much of the carbon trapped would actually stay in the ocean rather than reentering the atmosphere.
Creative Commons
Rock Solutions
CO2 is naturally removed from the atmosphere every day through reactions between rainwater and rocks. Some climate scientists propose enhancing this process—and so increasing CO2 removal from the atmosphere—through artificial measures such as crushing rocks and exposing them to CO2 in a reaction chamber or spreading them over large areas of land or ocean, increasing the surface area over which the reactions can occur.
As currently imagined, strategies to enhance carbon storage by reacting CO2 with rocks are expensive and energy-intensive due to the need to transport and process large quantities of heavy material. Some also require extensive land use and so have potential to compete with other needs such as food production and biodiversity protection. Researchers are looking at ways to use mine waste and otherwise refine the strategy to reduce costs and increase efficiency.
iStockphoto.com/Dushlik
Direct Air Capture and Storage
The carbon-sequestering containers from Arizona State University's Lackner, along with other projects such as Climeworks' just-opened carbon-trapping facility in Switzerland, represent one of the more widely discussed greenhouse gas capture and storage technologies being proposed today. Known as direct air capture and storage, this approach uses chemicals or solids to capture the gas from thin air, then, as in the case of BECCS, stores it for the long haul underground or in long-lasting materials.
Already used in submarines beneath the surface of the ocean and in space vehicles far above it, direct air capture theoretically can remove CO2 from the air a thousand times more efficiently than plants, according to Lackner.
The technology, however, is embryonic. And because it requires plucking CO2 molecules from everything else in the air, it is a huge energy hog. On the flip side, this approach has the big advantage of being deployable anywhere on the planet.
Ari Daniel for PRI's The World
Where to From Here?
If anything is clear from this summary, it's these two things: First, there is a lot of potential to augment efforts to reduce CO2 emissions with strategies to increase the removal of CO2 from the atmosphere. Second, there's a lot of work to be done before we're able to do so at a meaningful scale and in a way that not only closes the carbon gap but also protects the environment and meets more immediate human needs.
"Based on current technology, there really is no combination of negative emissions technologies currently available that would be employable at sufficient scale to help meet the below-2 °C target without truly significant impacts," said Peter Frumhoff, director of science and policy and a chief scientist with the Union of Concerned Scientists. "We can in principle deploy negative emissions technologies, but we do not have the understanding or the policies to do so on a sufficient scale."
With the need to do something becoming ever more urgent, researchers are starting to take a closer look at the pros, cons and potential of the various opportunities and put together research agendas to advance the most promising in the right places at the right time. In May 2017, a National Academy of Sciences study panel began holding a series of strategy sessions to identify research priorities for moving forward.
"Our job on this committee is to recommend a research agenda to solve a lot of these problems, to bring the cost down, to bring the efficiency of the program up, to overcome the barriers for scale up and implementation and governance and especially verification and monitoring," panel chair Stephen Pacala, professor of ecology and evolutionary biology with Princeton University, said in a video describing the initiative.
That said, it's important to remember that technology may not be the limiting factor in the long run.
"I don't think it's a technical challenge," said Deich. "I think it's a willingness to pay and a willingness to get clear, consistent and fair regulations around these solutions." In other words, getting carbon storage up and running ultimately is about creating markets and/or policies that reward it while also taking into consideration social and environmental dimensions. "It's not necessarily, 'Can these things get to scale?' It's, 'Is there somebody who's willing to pay for them to get to scale?"
The most obvious way to do this would be to affix a price to carbon, which would translate into financial benefit for socking it away.
In the end carbon storage is not cheap, Smith admits—but, he points out, neither is climate change.
The way Lackner puts it is this: We're traveling at high speed down a mountain in a car coming up to a hairpin turn, and it's not so much a question of whether we hit the guard rail as to whether we can slow down enough, so that when we do we bounce off rather than catapult over it into oblivion.
"I cannot guarantee it will work," he said of his CO2-trapping devices. "I'm an optimist, but I likely cannot guarantee it. The fact that it might not work, the possibility that it might not work, is not by itself an excuse not to try. If we don't make it work, I am very certain we will be in for very tough times."
Reposted with permission from our media associate Ensia.
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By Mary Hoff
What should we be thinking about when we think about the future of biodiversity, conservation and the environment? An international team of experts in horizon scanning, science communication and conservation recently asked that question as participants in the eighth annual Horizon Scan of Emerging Issues for Global Conservation and Biological Diversity. The answers they came up, just published in the scientific journal Trends in Ecology & Evolution and summarized below, portend both risks and opportunities for species and ecosystems around the world.
"Our aim has been to focus attention and stimulate debate about these subjects, potentially leading to new research foci, policy developments or business innovations," the authors wrote in introducing their list of top trends to watch in 2017. "These responses should help facilitate better-informed forward-planning."
1. Altering Coral Bacteria
Around the world, coral reefs are bleaching and dying as ocean temperatures warm beyond those tolerated by bacteria that live in partnership with the corals. Scientists are eyeing the option of replacing bacteria forced out by heat with other strains more tolerant of the new temperatures—either naturally occurring or genetically engineered. Although the practice holds promise for rescuing or resurrecting damaged reefs, there are concerns about unintended consequences such as introduction of disease or disruption of ecosystems.
2. Underwater Robots Meet Invasive Species
If you think getting rid of invasive species on land is a challenge, you haven't tried doing it in the depths of the ocean. Robots that can crawl across the seafloor dispatching invaders with poisons or electric shock are being investigated as a potential tool for combating such species. The technology is now being tested to control crown-of-thorns starfish, which have devastated Great Barrier Reef corals in recent years and invasive lionfish, which are competing with native species in the Caribbean Sea.
3. Electronic Noses
The technology behind electronic sensors that detect odors has advanced markedly in recent years, leading biologists to ponder applications to conservation. Possibilities include using the devices to sniff out illegally traded wildlife at checkpoints along transportation routes and to detect the presence of DNA from rare species in the environment.
4. Blight of the Bumblebees
We tend to think of pollinating insects as our ecological friends, but in the wrong place nonnative bees can spell trouble instead by competing with native insects, promoting reproduction in nonnative plants and potentially spreading disease. And they're doing just that, thanks to people who transport them internationally for plant-pollination purposes. Out-of-place bumblebees are already spreading through New Zealand, Japan and southern South America, and there is concern they could do the same in Australia, Brazil, Uruguay, China, South Africa and Namibia.
5. Microbes Meet Agriculture
Select bacteria and fungi are emerging as potential agricultural allies for their ability to help kick back pests or stimulate growth in crops. As research advances in this area, questions are being raised about potential implications for nontarget species, ecosystems, soils and more.
Bumblebees imported to pollinate crops are a growing threat to native pollinators around the world. iStock