Rare earth elements are finding their way into Colorado water supplies, driven by changes in climate, finds a new study published in the journal Environmental Science & Technology.
Rare earth elements are necessary components of many computing and other high-tech devices, like cell phones and hard drives. But there is growing recognition that they can be hazardous in the environment even at low levels of concentration.
“This is of concern because their concentrations are not monitored and there are no water quality standards set for them,” says study author Diane McKnight, who is an INSTAAR Fellow and Engineering professor at the University of Colorado Boulder.
The study is the first to look at how rare earth elements move within a watershed that is rich in minerals. It is also the first to investigate how climate change, by altering stream flow and natural weathering processes, is releasing more rare earth elements into streams.
Sampling water quality in the Snake River. Photo credit: Instaar
Diane McKnight has led her students in investigations of water quality in the Snake River watershed of Colorado since the 1990s. Their main focus has been measuring and observing acid rock drainage. In this process, rocks that include sulfide-based minerals, such as pyrite, oxidize when exposed to air and water. The resulting chemical reaction produces sulfuric acid and dissolved metals like iron, which drain into streams. More acidic water can further dissolve heavy metals, like lead, cadmium, and zinc, and as it turns out can carry rare earth elements as well.
“What really controls the mobility of rare earth elements is pH. Acid literally leaches it out of the rocks,” says first author Garrett Rue, who earned a masters degree studying limnology with McKnight and a subsequent PhD from the University of Colorado Boulder.
Acid rock drainage happens naturally throughout the western United States, with its pyrite-rich geology. But historic mines that disturb large amounts of rocks and soil amp up the process dramatically and cause downstream water pollution.
Within the Snake River watershed, towns impacted by acid mine drainage have been forced to adapt to poor water quality. Some former mining boomtowns, like Silverton, import water from distant sources. Others rely on expensive water treatment plants. All fish in the Snake River are stocked, since the water is too high in zinc for any native fish species to survive. The problem is endemic to the western United States, says Rue: “Upwards of forty percent of the headwaters to major rivers in the West are contaminated by some form of acid mine or rock drainage.”
The Snake River has made a good natural laboratory for investigating both, since the Peru Creek part of the watershed was heavily mined, while the Upper Snake River was not. But Rue and McKnight found that both parts of the watershed are now contributing significant amounts of metals downstream, as climate change has brought longer summers and less snow in the winters. Longer, lower stream flows make it easier for metals to leach into the watershed, and concentrate the metals that would otherwise be diluted by snowmelt.
The same processes that mean more heavy metals are finding their way into streams are also acting on rare earth elements. The researchers found rare earth elements throughout the Snake River. “We documented a concentration range of one to hundreds of micrograms per liter—several orders of magnitude higher than typical for surface waters—with the highest concentrations nearest the headwaters and areas receiving drainage from abandoned mine workings,” says Rue.
They also documented that increases in rare earth elements in the Snake River corresponded to warming summer air temperatures, and that rare earth elements are accumulating in insects living in streams at concentrations comparable to other metals such as lead and cadmium shown to be toxic.
“We’re starting to understand that once rare earth elements get in the water, they tend to stay there,” says Rue. “They aren’t removed by traditional treatment processes either, which has implications for reuse and has led some European cities to designate REEs as an emerging contaminant to drinking water supplies. And considering that the Snake River flows directly into Dillion Reservoir, which is Denver’s largest source of stored water, this could be a concern for the future.”
The researchers suggest that investigating and investing in technologies to recover rare earth elements from natural waters could yield valuable commodities and help address the problems associated with acid rock and mine drainage, which are poised to worsen as the climate shifts.
“Rare earth elements are used to make a lot of products. But most of the supply comes from China. So our government has been looking for sources, but at the same time mining has left an indelible mark on the waters of the West,” says Rue. “If we can harvest some of these materials that are already coming into our environment, it might be worthwhile to treat that water and recover these materials at the same time.”
“This problem is getting worse and we need to deal with it,” adds McKnight. “If we can solve the problem holistically, we can have a valuable resource and also think about climate adaptation.”
“We know who pooped in the river, now we’re trying to figure out where it’s coming from,” Alyssa Richmond said as she took a sample of water recently from the muddy San Juan River, in the blazing high desert outside Farmington.
Richmond is coordinator for the San Juan Watershed Group, a collection of local agencies and volunteers working to improve water quality on the San Juan River as it runs through northern New Mexico. The group’s ultimate goal, Richmond said, is to have the stretch of river meet national water quality standards. But as it stands, it’s not going well.
Among a plethora of water-quality issues that include mine pollution, urban runoff and rising water temperatures amid an increasing drought, is the issue of E. coli contamination. A naturally occurring bacteria that lives in all humans and animal stools, E. coli can contaminate ground and surface water, and lead to health implications.
For at least the past 10 years, researchers have launched a full-scale investigation to better understand E. coli issues up and down the San Juan River watershed, from high up in the San Juan Mountains to its major tributary, the Animas River, to stretches that run into the Navajo Nation.
Early results are not encouraging: the EPA’s standard for acceptable E. coli levels is 126 colony-forming units (CFU) per 100 milliliters. In stretches of the San Juan River through Farmington, water samples taken this summer exceeded nearly 1,500 CFUs. “We didn’t expect it to be as high as it was,” Richmond said on a sampling day in late August. “It was shocking.”
But it’s not all doom and poop. The San Juan Watershed Group’s efforts will ultimately help inform where cleanup projects should be focused to achieve the highest improvement in water health. And, all up and down the watershed, even to the highest reaches of the Animas River around Silverton, there is a concerted push to face E. coli issues head on.
“The good news is everyone agrees there should be no human poop in the water,” said San Juan Citizens Alliance’s Animas Riverkeeper Marcel Gaztambide, who probably never thought he’d have to make so obvious a statement to the local paper. “And it’s an issue of concern, so it’s good we’re talking about it now.”
Defecation detectives
E. coli is a difficult contaminant to fully contextualize because not only is it naturally occurring, it is also one of the most common bacteria. It can come from livestock as well as wildlife like elk, deer, birds, beaver – pretty much any animal that poops. And to complicate matters further, only some strains of the bacteria are harmful to human health.
In the early 2010s, however, researchers knew high E. coli levels were an issue in the San Juan River in northern New Mexico, but the question was, who was the main culprit? After conducting two years of microbial source testing, which not only shows the level of E. coli but also pinpoints the exact source, the results were not what researches were expecting. It came back that the largest contributors were … drumroll, please … humans.
In fact, test results showed human feces in 70 to 100 percent of samples taken from the Animas River at the Colorado-New Mexico state line down to the border of the Navajo Nation.
With the guilty party exposed, funding was again secured to take the investigation a step further this summer by understanding where exactly the human waste was coming from, Richmond said. It’s a process that’s rather simple, by testing upstream and downstream of suspected source points, and then seeing where the spikes in E. coli levels occur. And already, there are some potential smoking guns: failing septic tanks from homes and development, outdated wastewater treatment plants and illegal RV dumping.
What the sampling has also shown, Richmond said, is the high E. coli levels aren’t necessarily coming from upstream communities in Durango and elsewhere. Instead, early results indicate the highest spikes happen in and around Farmington…
It’s a watershed moment
But that doesn’t necessarily mean upstream communities are swimming in sparkling clean waters.
The Animas River, for instance, has issues all its own. Remember that EPA standard of 126 cfu/100 mL? Well, one study conducted by Fort Lewis College in October 2018 found E. coli levels in the Animas at Santa Rita Park, near the Whitewater Park (close your eyes kayakers and surfers) at 226 CFUs. Bare in mind, this was before the completion of the City’s new water reclamation facility in December 2019…
Over in the Florida River, which runs into the Animas about 18 miles south of Durango, progress is also being made, said Warren Rider, coordinator for the Animas Watershed Partnership, which focuses on water quality issues on the Colorado side of the border.
The Florida River for years has exceeded safety standards for E. coli and accounts for nearly a quarter of the bacteria and nutrients dumped into the Animas River before the state line. In a bit of a shock, the Florida was delisted last year, but that was mostly due to a lack of data, researchers say.
While natural sources do account for a portion of contamination in the Florida, agriculture and livestock operations also contribute a good amount of harmful bacteria. As a result, Rider said the Animas Watershed Partnership has tried to work with landowners to fence off waterways to livestock and reestablish vegetation along stream banks…
Up in the high country
And no one has forgotten about the highest reaches of the watershed atop the San Juan Mountains, where an unprecedented increase in recreation, and therefore human waste, has been well noted and nosed in the past year or so.
This summer, the U.S. Forest Service and Mountain Studies Institute partnered to test heavily trafficked recreation areas for E. coli. Colleen Magee-Uhlik, a forest ambassador with MSI, said areas with high use of recreation showed much higher concentrations than locations with little human impact.
In the obvious case study, South Mineral Creek – that of Ice Lakes fame – water samples taken above the highest areas of recreation tested at about 22 CFUs. Farther downstream, in a location that would catch all the cumulative impacts of recreation and camping, samples were more than four times as high, at nearly 90 CFUs. (And, it should be noted, South Mineral was closed this year because of fire damage, which likely means levels would be even higher if people were in the area)…
Christie Chatterley, Fort Lewis College assistant professor of physics and engineering, said in the popular backpacking spot Chicago Basin in the Weminuche Wilderness, a student-led research program also found high levels of E. coli in streams. FLC has plans to conduct microbial source testing to see exactly where the bacteria is coming from, but Chatterley said it’s probably safe to assume hikers and campers…
So what can be done?
For starters, using best practices in the high country, such as burying waste 6 to 8 inches deep and 200 feet away from water, and packing out toilet paper can go a long way. This message is even more important as record numbers of people visit the backcountry, many without a working knowledge of how to protect the very landscape they come to enjoy.
Farther downstream, upgrading septic tanks is seen as another obvious target. Brian Devine, with San Juan Basin Public Health, said new septic regulations require people selling their homes to have septic systems inspected. In 2020 alone, more than 500 systems were inspected, which led to many leeching septic tanks being fixed. “It’s resulting in systems getting repaired,” he said. Richmond, with the San Juan Watershed Group, said agencies are working with New Mexico health officials to tackle failing and outdated septic systems as well.
And, the city of Durango’s Biggs said the Clean Water Act continues to push water quality standards. “The Clean Water Act has really improved water quality, and the Animas would be a testament to that,” he said. “And everyone benefits, including our downstream users.”
So yes, there’s no quick and easy fix to E. coli issues in the Animas and San Juan rivers, but all these efforts are folded into the long history of communities along the watershed, and the responsibilities they have to one another, Biggs said. It’s an issue that dates back to the 1800s when Silverton would send down water contaminated by mining operations to Durango, and a few decades later, when Durango’s uranium pile sat along the banks of the Animas River, only to be swept downstream.
At least 54% of the state now is experiencing drought conditions, compared to 100% this time last year. But record-breaking heat and a dry winter could mean conditions worsen, a climatologist says.
As drought loosened its grip across nearly half Colorado in the past year, parts of Colorado could see conditions worsen in the coming months due to an autumn and winter that experts say will be hotter and drier than normal.
About 52% of the state’s geographic area now faces some type of drought — ranging from abnormally dry to exceptional drought. This time last year, the entire state was plagued by the lack of rain, according to the U.S. Drought Monitor. While the drought was somewhat eased by the summer monsoon season, already punishing drought conditions have begun to worsen, with the most severe impacts hitting the Western Slope.
Colorado Drought Monitor map September 7, 2021.
Record-breaking heat coupled with a dry winter forecast could mean that drought in Colorado will likely get worse in the coming months, according to Peter Goble, a climatologist with the Colorado Climate Center at Colorado State University.
“The outlook is not encouraging,” Goble said. “It looks like summer is going to hang on here for a little while and as we look forward to winter, (we’re) looking at a high probability of another La Nina year,” he said, the second La Nina winter in a row…
“In recent history, those double-dip La Nina years — or years we have it come back a second time — have been quite dry across the center of the country and only really wet in the northwest and northeast corners,” Goble said. “If that pattern were to resurface, we could see drought conditions worsen over the next three to nine months.”
[…]
Colorado also saw its fourth warmest June through August period on record, Goble said…
Now, about 15% of the state is seeing conditions of the severity recorded last September, maps show.
Despite the decrease, Goble said he’s still concerned about the state’s current drought conditions and for what’s to come.
“The biggest thing that concerns me is, as good as the precipitation was in western Colorado over the summer, we didn’t see that big of a recovery to the overall water supply system or our lakes, streams and reservoirs,” he said…
The boat ramp at Elk Creek Marina had to be temporarily closed so the docks could be moved out into deeper water. Colorado water managers are not happy that emergency releases from Blue Mesa Reservoir are impacting late summer lake recreation. CREDIT: HEATHER SACKETT/ASPEN JOURNALISM
In the east, worsening drought conditions also raise concerns regarding the winter wheat planting season. Without a layer of moisture in the top level of soil, it becomes harder for seeds to stay put and can affect how much grows, he said.
The graph shows average annual global temperatures since 1880 (source data) compared to the long-term average (1901-2000). The zero line represents the long-term average temperature for the whole planet; blue and red bars show the difference above or below average for each year. (These data were among the sources of data used in the State of the Climate in 2020’s temperature analysis, but here are compared to the 20th-century average. In the report, they are compared to the 1981-2010 average.)
U.S. Senator Michael Bennet held a telephone town hall event on Friday, Sept. 3 to answer questions and address concerns for Coloradoans. Though Bennet spends a lot of time in Washington D.C., he has been back in Colorado for the past few weeks. He has held 30 events in 13 different counties across the state and came away observing three things in need of attention: climate change, both man-made and natural infrastructure, and affordable healthcare, housing and education.
“I think the United States has not been investing in our people or our infrastructure for a very, very long time, and it shows. But things are beginning to change. Last month, the Senate passed a historic $1.2 trillion infrastructure bill on a bipartisan vote,” said Bennet…
Bennet is focusing on both paid family leave and climate change, as well. He advocates for paid parent leave so Coloradoans can stay home with a sick child or an elderly family member without losing his or her job.
As for climate change, Bennet recognizes the problems at hand: “We’ve got to act urgently on climate. If we don’t, I really worry that we’re not going to recognize our own state in a few years, and I think all of us refuse to hand our kids and grandkids a state where you can’t see the mountains or you can’t go outside half the summer and families live in fear of wildfire… droughts… There’s a lot of work to do ahead, and I’m more optimistic than I’ve been in a long time that the agenda in Washington (D.C.) reflects our priorities in Colorado. And that’s, in large part, thanks to the feedback I receive in conversations like this that I can carry back to Washington (D.C.).”
[…]
A caller from Westminster in Adams County, Ellen, expressed her disappointment in Bennet’s lack of actions taken to combat climate change: “I appreciate you saying you feel urgency over the climate crisis, but you need to act in line with that urgency. Your vote to prohibit banning fossil fuel development on public lands and your vote to support a liquefied natural gas export terminal in Texas (were) so unacceptable. To prevent more severe climate crises than we already face, we have to end extracting and burning fossil fuels.”
While Bennet made it clear he did not regret those votes, he did explain his reasoning for them: “I believe very strongly that if we are ever going to actually get off of fossil fuels, we have to have a plan to transition off of fossil fuels. I don’t believe that we could just get off them tomorrow and be done with it without driving energy prices through the roof… what we need is a thoughtful approach over the next 10, 20, 30 years to get this economy to a net zero carbon economy. If we don’t have a plan to get to net zero by 2050, then we’re not ever going to do it.”
[…]
A woman named Irma submitted an online question asking Bennet how he is protecting Colorado’s watershed and water supply.
From his research over the past year or so, Bennet discovered that it would cost $60 billion to protect the west’s watershed. While that seems like a steep price, Colorado has spent $60 billion in the past four to five years fighting fires. Bennet wrote a bill called the Outdoor Restoration Partnership Act which pushes to use funds for forest mitigation and watershed restoration. Bennet sits on the Senate’s Agriculture Committee, and he hopes his bill will be passed as part of the reconciliation package…
Marti from Lafayette in Boulder County, originally from Ohio, moved to Colorado to be closer to her family and enjoys the Colorado weather. She called with a question about poor air quality and frequent ozone alerts. More specifically, she shared her research on Suncor Energy in Denver and how it has not met federal admission standards for toxic gasses. She questioned how the company could be held accountable. Bennet was not as familiar with Suncor and made a note to look into whether or not that problem could be solved on a state or federal level or instead handled by the Environmental Protection Agency (EPA). Bennet also shared his wish to reinstate a law from when Hickenlooper was in office with a goal to capture fugitive methane from pipelines and drilling rigs, a law which President Trump removed.
FromColorado Public Radio (Michael Elizabeth Sakas):
Colorado’s Eastern Plains saw a lot of rain in the spring, which helped half of the state escape drought.
Summer was a different story. Many areas got much less rain than normal, and some spots around Washington and Yuma counties recorded their lowest amount of precipitation on record.
Courtesy of Russ Schumacher, from West Wide Drought Tracker
State climatologist Russ Schumacher said a weather station in Akron recorded its second-wettest spring, followed by the driest summer recorded there.
Joel Schneekloth, a regional water resource specialist with Colorado State University Extension, said if the extra spring moisture had been met with average summer rainfall, it would have been a “fantastic” year for many crops.
Schneekloth said the “saving grace” of this summer for the plains was the wet spring and closer-to-normal temperatures meant farmers used just a little more water than average. He said that made the biggest difference compared to historically dry summers in years like 2012 and 2002…
The wet spring meant most corn growers in Washington County will likely have a better year than they did in 2020, Schneekloth said. The county’s average corn crop yielded around 15 bushels per acre in 2020, but that average could increase to 35 this year.
What’s hurting the most this summer is proso millet, which was the third-largest crop for Washington County, according to 2017 data from the USDA.
“In our area for the most part, it’s a disaster,” Schneekloth said.
The millet is planted in early June, and the area’s last good rain was weeks before that. Schneekloth said the shallow roots failed in the dry soil. Those dry soils will have a long-term effect going into the fall because they will make planting wheat before the winter tough, Schneekloth said. He hopes some rain will fall before then…
Ron Meyer, an agronomist for Colorado State University Extension, said the extreme rain helped some crops on the Eastern Plains.
Meyer worried there wouldn’t be any wheat to harvest after a dry fall and winter in 2020 and into 2021. But the moisture got the wheat-growing again in March, which resulted in an above-average crop.
Once it stopped raining again in the summer, spring-planted crops like corn, sunflower and millet are now struggling.
Crop residue. Photo credit: Joel Schneekloth
Meyer said the dry summer shows why it’s important for farmers and ranchers to adapt to a warming climate. One way is through “banking” soil moisture by adopting practices that promote soil health and reduce tilling, as well as using drought-adapted varieties of crops to improve their chances of having a good harvest in extreme conditions.
With purified, reuse water flowing into Castle Rock homes this summer, the town was already celebrating the ability to supply high-quality drinking water to customers.
Accolades for the success at Castle Rock Water continued last week when the department received recognition for Outstanding Water Treatment Plant by the Rocky Mountain Section of the American Water Works Association.
The Rocky Mountain Section is the regional division of the American Water Works Association, the principal association for scientific and educational opportunities dedicated to managing and treating water. The Rocky Mountain Section represents water industry organizations in Colorado, New Mexico and Wyoming.
Castle Rock won in the large department category, which includes programs serving more than 50,000 people. The award was given specifically for the operations at the Plum Creek Water Purification Facility, which has developed the advanced treatment processes to accommodate purified reuse water…
The association also presented Castle Rock Water plant mechanic Casey Devol with the Water Treatment Maintenance Award for his design of new processes to clean pipelines. The annual award is given to a maintenance professional who demonstrates exceptional performance, dedication and teamwork. Devol was also recognized for his contribution to the Water to Wire efficiency study to reduce energy usage and pumping costs.
The local and national recognition for Castle Rock Water comes as efforts to invest in the town’s sustainable water future continues. Dating back to 2006, the town invested $208 million to build the reusable water facility.
Part of that investment included the construction of the $60 million Plum Creek Purification Facility. Reuse water will account for one-third of the community’s water supply and will be a big step in providing a sustainable water supply as the town grows and drought conditions are expected to continue.
In addition to the American Water Works Association awards, Castle Rock Water also received recognition for its efforts in environmental stewardship. This is the third consecutive year the water provider has received a Gold Level in the Environmental Leadership Program by the Colorado Department of Public Health and Environment. Reducing energy consumption, increasing water conservation efforts and instituting purified reuse water were among the primary considerations for the award.
While monsoon season does not conclude officially until the end of September, it is clear the summer weather pattern that typically brings a good deal of moisture to the Southwest has helped ease the drought’s grip on much of New Mexico.
Chuck Jones, a meteorologist with the National Weather Service in Albuquerque, said the agency will not have figures on monsoon rain totals until early October, after the season has drawn to a close.
New Mexico Drought Monitor Map September 7, 2021.
But a look at the U.S. Drought Monitor map for New Mexico — and the rest of the Southwest — shows substantial improvement over the past two and a half months. Many parts of the state that were bone dry at the beginning of summer have emerged mostly, or even entirely, from the drought.
Nowhere has that change been more dramatic than in the southeast corner of the state. According to the Southwest and California Drought Status Update issued June 24 by the federal government’s National Integrated Drought Information System, parts of seven counties in that corner of New Mexico were characterized as being in exceptional drought — the worst category — and every county in that region was suffering from severe, extreme or exceptional drought, the three worst categories.
Now, two and a half months later, the picture there is much different, as portions of six of those counties are now characterized as normal. Much of the remaining territory in the southeast corner of the state is classified as being only abnormally dry or experiencing moderate drought.
While other parts of the state also saw marked improvement — portions of 13 counties in New Mexico now are drought free, compared to parts of just two counties on June 24 — others have not been so fortunate. Many parts of central, southwest and northwest New Mexico that were locked in drought at the beginning of the summer remain that way, even though their status has improved, as well.
The drought continues to take a heavy toll on San Juan, McKinley, Rio Arriba, Bernalillo, Santa Fe, Las Alamos, Catron, Grant, Hidalgo and Luna counties, with each of those counties still showing substantial territory characterized as being in extreme drought, the second-worst category.
That’s not to say those locations are as bad off as they were even a month ago, when large portions of all those counties were experiencing exceptional drought. In fact, the percentage of the state that is classified as being in exceptional drought has declined from more than 50% at the start of 2021 to approximately 33% three months ago, 4.5% on Aug. 10 and 0% on Sept. 9. And while 21.2% of New Mexico was in extreme drought on Aug. 10, that percentage declined to 19.1% by Sept. 7.
According to drought.gov, this was the 32nd wettest August in New Mexico over the last 127 years. Las Cruces has enjoyed an especially good monsoon so far, having racked up 5.06 inches of precipitation over that period, the third-wettest monsoon on record, according to drought.gov.
San Juan County has not seen that kind of bounty, but it has experienced a relatively good monsoon season, at least by the paltry standards of recent years. Jones said Farmington has received 1.6 inches of moisture at Four Corners Regional Airport over the three-month period, a figure that nearly matches the 30-year average of 1.62 inches.
For the year, Farmington has drawn 4.31 inches of precipitation, which comes close to matching the figure of 4.68 inches the city has received on average through the end of August for the last 30 years. Over the last three decades, Farmington has averaged a total of 7.76 inches annually.
As of Sept. 7, the vast majority of San Juan County was still characterized as being in extreme drought, with only slivers of the southwest and southeast corners in severe drought. But on Aug. 10, approximately half the county was in exceptional drought, and now none of it is.
Climate change made the devastating flooding in Belgium, Germany and other European countries in July 2021 more likely. Anthony Dehez/Belga/AFP via Getty Images
Extreme rainfall and flooding have left paths of destruction through communities around the world this summer. In New York City, remnants of Hurricane Ida flooded streets and subway lines as more than 3.15 inches of rain fell in an hour and more than 7 inches fell in all on Sept. 1-2, 2021. A week earlier in Tennessee, a record-shattering 17 inches of rain fell in 24 hours, turning creeks into rivers that flooded hundreds of homes and killed 20 people.
A lot of people are asking: Was it climate change? Answering that question isn’t so simple.
A decade ago, scientists weren’t able to confidently connect any individual weather event to climate change, even though the broader climate change trends were clear. Today, attribution studies can show whether extreme events were affected by climate change and whether they can be explained by natural variability alone. With rapid advances from research and increasing computing power, extreme event attribution has become a burgeoning new branch of climate science.
The latest attribution study, released Aug. 23, 2021, looked at the rainfall from the European storm that killed more than 220 people when floods swept through Germany, Belgium, Luxembourg and the Netherlands in July 2021.
A team of climate scientists with the group World Weather Attribution analyzed the record-breaking storm, dubbed Bernd, focusing on two of the most severely affected areas. Their analysis found that human-induced climate change made a storm of that severity between 1.2 and nine times more likely than it would have been in a world 1.2 degrees Celsius (2.1 F) cooler. The planet has warmed just over 1 C since the industrial era began.
Parts of Tennessee saw about 17 inches of rainfall in 24 hours in late August, shattering the state’s previous record. AP Photo/John Amis
Similar studies haven’t yet been conducted on Hurricane Ida’s rainfall or the Tennessee storm, but they likely will be.
So, how do scientists figure this out? As an atmospheric scientist, I have been involved in attribution studies. Here’s how the process works:
How do attribution studies work?
Attribution studies usually involve four steps.
The first step is to define the event’s magnitude and frequency based on observational data. For example, the July rainfall in Germany and Belgium broke records by large margins. The scientists determined that in today’s climate, a storm like that would occur on average every 400 years in the wider region.
The second step is to use computers to run climate models and compare those models’ results with observational data. To have confidence in a climate model’s results, the model needs to be able to realistically simulate such extreme events in the past and accurately represent the physical factors that help these events occur.
The third step is to define the baseline environment without climate change – essentially create a virtual world of Earth as it would be if no human activities had warmed the planet. Then run the same climate models again.
The differences between the second and third steps represent the impact of human-caused climate change. The last step is to quantify these differences in the magnitude and frequency of the extreme event, using statistical methods.
For instance, we analyzed how Hurricane Harvey in August 2017 and a unique weather pattern interacted with each other to produce the record-breaking rainstorm in Texas. Two attribution studies found that human-caused climate change increased the probability of such an event by roughly a factor of three, and increased Harvey’s rainfall by 15%.
Another study determined that the western North American extreme heat in late June 2021 would have been virtually impossible without human-caused climate change.
The extreme heat wave in the Pacific Northwest in June 2021 sent temperatures more than 27 F (15 C) above normal in some areas. NASA Earth Observatory
How good are attribution studies?
The accuracy of attribution studies is affected by uncertainties associated with each of the above four steps.
Some types of events lend themselves to attribution studies better than others. For instance, among long-term measurements, temperature data is most reliable. We understand how human-caused climate change affects heat waves better than other extreme events. Climate models are also usually skillful in simulating heat waves.
Even for heat waves, the impact of human-caused climate change on the magnitude and frequency could be quite different, such as the case of the extraordinary heat wave across western Russia in 2010. Climate change was found to have had minimal impact on the magnitude but substantial impact on the frequency.
There can also be legitimate differences in the methods underpinning different attribution studies.
However, people can make decisions for the future without knowing everything with certainty. Even when planning a backyard barbecue, one does not have to have all the weather information.
This July 7, 2021 image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite shows the nearly snow-free mountain peaks of the Sierra Nevada mountain range. According to state and federal scientists, snowmelt in this region happened three to four weeks earlier than normal, and instead of flowing downstream, most of this water soaked into mountain soils still parched from previous droughts. Credit: NASA’s Earth Observatory / Lauren Dauphin Photo credit: NASA
Seasonal summer rains have done little to offset drought conditions gripping the western United States, with California and Nevada seeing record July heat and moderate-to-exceptional drought according to the National Oceanic and Atmospheric Administration (NOAA). Now, new NASA research is showing how drought in the region is expected to change in the future, providing stakeholders with crucial information for decision making.
The study, published in the peer-reviewed journal, Earth’s Future, was led by scientists at NASA’s Goddard Institute for Space Studies (GISS) and funded by NOAA’s Climate Program Office and NASA’s Modeling, Analysis and Prediction (MAP) Program. It found that the western United States is headed for prolonged drought conditions whether greenhouse gas emissions continue to climb or are aggressively reined in.
While the risk of intense single-year droughts increases as greenhouse gas emissions increase in the model results, the risk of multi-year droughts is high regardless of the emissions scenario, the study found. Credits: NOAA Climate Program Office / Anna Eshelman
However, the study also showed that the severity of acute, extreme drought events and the overall severity of prolonged drought conditions can be reduced with emissions-curbing efforts compared to a high-emissions future. This is important information for decision-makers considering two tools they can use to reduce climate impacts: Adaptation and mitigation.
Adaptation is a term used by the scientific community and policymakers to describe policies that address impacts that will occur or are already occurring. For example, adaptation to rising sea levels might include relocating low-lying infrastructure. By contrast, mitigation – efforts to reduce the amount of greenhouse gases in the atmosphere – can limit the severity of future impacts or even prevent them from happening by limiting how much the climate changes. Switching to cleaner energy sources and reducing greenhouse warming-driven ice melt are examples of mitigation to sea level rise.
Rather than representing competing options, adaptation and mitigation can both be used to address climate impacts. This new research shows how the two can complement each other when it comes to drought.
“Mitigation has clear benefits for reducing the frequency and severity of single-year droughts,” said lead author Ben Cook, a research scientist at GISS and an adjunct associate research scientist at Columbia University. “We may have more of these 20-year drought periods, but if we can avoid the really sharp, short-term, extreme spikes, then that may be something that’s easier to adapt to.”
Turning to the Past to Understand the Future
Both acute single-year and prolonged multi-year droughts occur naturally due to variations in ocean currents, precipitation and other factors. But climate change is turning up the heat in addition to these natural variations, causing even more water to evaporate from plants and soil, resulting in increased dryness even in the absence of major precipitation deficits.
As greenhouse gas emissions increase and Earth’s temperature rises, the southwestern United States is forecasted to become drier, with the risk of future soil moisture deficits increasing as emissions increase. Credits: NOAA Climate Program Office / Hunter Allen and Anna Eshelman
To understand the southwest’s vulnerability and tendency towards drought and the factors that contribute to it, the team selected the severe single-year drought of 2002 and the extended drought of 2000 to 2020 as examples of acute and prolonged droughts respectively. They then looked at how common these acute and prolonged droughts were, not only during the period of instrumental records, but also using reconstructed drought conditions stretching back more than a thousand years and state-of-the-art supercomputer simulations of the future.
The team reconstructed soil moisture from the years 800 to 1900 using tree ring data from the region. The thickness of tree rings varies due to the wetness or dryness of each year, providing scientists with a reliable way of estimating how much rain fell in a given year. For years after 1900, they used directly measured soil moisture values. To look at a range of possible futures, the team used data from the latest version of the Coupled Model Intercomparison Project, or CMIP6. CMIP6 is an ensemble of climate model simulations that provide climate change projections depending on a range of possible greenhouse gas emission scenarios, allowing scientists and policymakers to directly compare the impacts of different emissions policies. And under different emissions scenarios, drought behaves differently.
The southwestern United States has been prone to drought for millennia. But warming temperatures dry the soil further, and the region’s natural aridity becomes the backdrop for a higher risk of severe and prolonged droughts if greenhouse gas emissions continue to climb, said Kate Marvel, a research scientist at GISS and Columbia University.
“The paleoclimate record shows that this region is prone to drought,” she said. “There have been really, really severe droughts in the past: For instance, we know there were megadroughts in the 13th century. But against the backdrop of natural climate variability — the things the climate would do even without human influence — we are confident increases in greenhouse gases make the temperature rise, and we’re fairly confident that increases drought risk in this region.”
In addition to single- and multi-year droughts alone, there’s also a risk of intense single-year droughts occurring within longer periods of drought. This risk increases as greenhouse gas emissions increase, according to the study. Credits: NOAA Climate Program Office / Anna Eshelman
A Future Not Yet Set in Stone
Understanding that some amount of increased drought can be expected under high and low emission scenarios alike has implications for adaptation strategies like rationing water usage and changing agricultural practices. At the same time, the study’s finding that greenhouse emissions reductions still matter for extreme drought underscores the value of mitigation.
“The ongoing southwestern drought highlights the profound effects dry conditions have on people and the economy,” said Ko Barrett, senior advisor for climate in NOAA’s Office of Research and vice-chair of the Intergovernmental Panel on Climate Change’s Sixth Assessment Report. “The study clearly highlights the impact that greenhouse gas mitigation could have on the occurrence and severity of Southwestern drought. It is not too late to act and blunt impacts like severe Southwestern drought periods and short-term drought events.”
Marvel agreed. “There’s going to be a new normal regardless,” she said. “There’s going to have to be some adaptation to a drier regional climate. But the degree of that adaptation – how often these droughts happen, what happens to the drought risk – that’s basically under our control.”
Click here to read the summary. Here’s an intro from email:
A continued active monsoon pattern has resulted in further improvements to drought conditions over western Colorado while short-term abnormally dry spots have popped up over eastern Colorado.
Overall, August 2021 was what we typically expect to see, especially in recent years – hot temperatures, dry conditions, the occasional spotty shower. And similar to many of our recent years, the month ended warmer and drier than average.
For western Colorado, summer 2021 was HOT! In fact, this makes 7 summers out of the last 10 years that have been warmer than average. This was the second hottest summer in the record, going back 127 years. The hottest summer was 2018.
Click here to access the manual (Joseph M. Wheaton, Stephen N. Bennett, Nicolaas Bouwes, Jeremy D. Maestas & Scott M. Shahverdian. Contributions from: Stephen N. Bennett, Nicolaas Bouwes, Reid Camp, Christopher E. Jordan, William W. Macfarlane, Jeremy D. Maestas, Elijah Portugal, Scott Shahverdian, Nicholas Weber & Joseph M. Wheaton). Here’s the executive summary:
Stream and riverine landscapes or riverscapes are made up of a series of interconnected floodplain, groundwater, channel habitats, and their associated biotic communities that are maintained by physical and biological processes that vary across spatial and temporal scales (Ward, 1998). An over-arching goal of riverscape restoration and conservation is to improve the health of as many miles as possible, while ensuring those systems achieve and maintain their potential in self-sustaining ways. This design manual is intended to help the restoration community more efficiently maximize efforts to initiate self-sustaining recovery of degraded riverscapes at meaningful scales.
Structural-starvation of wood and beaver dams in riverscapes is one of the most common impairments affecting riverscape health. At a basic level, a riverscape starved of structure drains too quickly and efficiently, lacks connectivity with its floodplain and has simpler more homogenous habitat. By contrast, a riverscape system with an appropriate amount of structure provides obstructions to flow. What follows in the wake of structurally-forced hydraulic diversity are more complicated geomorphic processes that result in far more diverse habitat, resilience, and a rich suite of associated ecosystem services.
The purpose of this design manual is to provide restoration practitioners with guidelines for implementing a subset of low-tech tools—namely post-assisted log structures (PALS) and beaver dam analogues (BDAs)—for initiating process- based restoration in structurally-starved riverscapes. While the concept of process-based restoration in riverscapes has been advocated for at least two decades, details and specific examples on how to implement it remain sparse. Here, we describe ‘low-tech process-based restoration’ as a practice of using simple, low unit-cost, structural additions (e.g., wood and beaver dams) to riverscapes to mimic functions and initiate specific processes. Hallmarks of this approach include:
• An explicit focus on the processes that a low-tech restoration intervention is meant to promote
• A conscious effort to use cost-effective, low-tech treatments (e.g., hand-built, natural materials, non-
engineered, short-term design life-spans)
• ‘Letting the system do the work’, which defers critical decision making to riverscapes and nature’s ecosystem engineers
Importantly, the manual conveys underlying principles guiding use of low-tech tools in process-based restoration in systems impaired by insufficient structural complexity. Although intended to be simple, low-tech restoration still requires some basic understanding of watershed context, riverscape behavior and channel evolution, and careful planning. The manual provides interested practitioners with sufficient conceptual and applied information on planning, design, permitting, construction and adaptive management to get started, as well as references to additional information and resources. Detailed design and construction guidance is provided on two effective low-tech tools: 1) beaver dam analogues (BDAs) for mimicking beaver dam activity, and 2) post-assisted log structures (PALS) for mimicking wood accumulation in riverscapes. Throughout the manual, readers are reminded that the structures themselves are not the solution, but rather a means to initiate specific, desirable processes. Ultimately, embracing the design principles will help practitioners better understand the ‘why’ behind structural interventions and allow for more efficient and effective riverscape restoration.
Restoration beaver dam San Antonio Creek. Photo credit: WildEarth Guardians
