sponges
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Ocean-dwelling species are disappearing twice as quickly as land animals
Researchers point toward marine creatures' inability to adapt to changing water temperatures, lack of adequate shelter.
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phys.org
Could symbiotic microbes help ecosystems survive global warming?
Studies of the relationships between microbes and the organisms they live on are revealing how plants and animals could adapt to climate change.
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thetyee.ca
Glass sponges, climate change and BC's ocean environment
New research on 'shapeshifters of the sea' highlights critical role in ecosystem.
Beyond biodiversity: A new way of looking at how species interconnect.
In a development that has important implications for conservation, scientists are increasingly focusing not just on what species are present in an ecosystem, but on the roles that certain key species play in shaping their environment.
In 1966, an ecologist at the University of Washington named Robert Paine removed all the ochre starfish from a short stretch of Pacific shoreline on Washington’s Olympic Peninsula. The absence of the predator had a dramatic effect on its ecosystem. In less than a year, a diverse tidal environment collapsed into a monoculture of mussels because the starfish was no longer around to eat them.
By keeping mussel numbers down, the starfish had allowed many other species to thrive, from seaweed to sponges. Paine’s research led to the well-known concept of keystone species: The idea that some species in an ecosystem have prevailing traits — in this case preying on mussels — whose importance is far greater than the dominant traits of other species in that ecosystem.
Now, a half-century later, researchers are taking the study of traits much farther, with some scientists concluding that understanding the function of species can tell us more about ecosystems than knowing which species are present — a concept known as functional diversity. This idea is not merely academic, as scientists say that understanding functional diversity can play an important role in shaping conservation programs to enhance biodiversity and preserve or restore ecosystems.
“The trait perspective is very powerful,” says Jonathan Lefcheck, a researcher at the Bigelow Marine Lab in East Boothbay, Maine who studies functional diversity in marine environments. “Some species in an ecosystem are redundant, and some species are very powerful.”
Much about the concept is also unknown. One case study is taking place along the Mekong River, a 2,700-mile waterway that serves as a vital fishery for millions of people in Southeast Asia. While the fishery is healthy now, widespread changes in the ecosystem — including the proposed construction of numerous dams and the development of riparian forests and wetlands — could mean that key fish species might not be around to carry out important functions, such as keeping prey numbers in check or recycling nutrients.
“There is simply no understanding of how the construction of a dam today, and another five years from now, and another in 10 years — all in the same river basin — will impact the biodiversity and push it past a point of no return, where large scale species extinctions are imminent,” said Leo Saenz, director of eco-hydrology for Conservation International.
So a team of ecologists from Conservation International is trying to determine which roles various species in the Mekong fill that are critical to perpetuating a healthy ecosystem. Those species might be predators like the giant snakehead, which helps control other fish populations so they don’t become too numerous, or thick groves of mangrove forests in shallow areas that provide a nursery for a wide variety of fish species. Models can then predict the best way to protect these key species and ensure a healthy river over the long term.
“Ecosystem resilience is an important part of what we aim to maintain, both for the interest of biodiversity conservation and for the maintenance of the ecosystem services that nature provides,” says Trond Larsen, a biologist who heads Conservation International’s Rapid Assessment Program for biodiversity.
Some scientists now compare knowing which species are present in an ecosystem to knowing only which parts of a car are present. Functional trait ecology is a deeper dive into ecosystem dynamics to help understand how the parts come together to create a natural environment that runs smoothly, like a well-tuned automobile, thus enabling a more focused protection of the vital parts that keep it going.
“Say you have two habitats with 10 different species in each,” explains Marc Cadotte, a professor of Urban Forest Conservation and Biology at the University of Toronto. “Yet, they might not be comparable at all if in one of those habitats eight of those 10 species are similar and redundant, while in the other habitat, all 10 species are unique from one other. We need alternative measures for biodiversity that tell us something about the niche differences, trait differences, how species are interacting, and how they are using resources. Functional diversity and phylogenetic diversity are meant to capture that.”
Phylogenetic diversity refers to species that have few or no close relatives and that are very different from other species, which may mean that they can contribute in very different ways to an ecosystem. Protecting phylogenetic diversity, then, is part of protecting important functions. The distinctive pearl bubble coral is one example, as it provides shelter to shrimp, an important food for the highly endangered hawksbill turtle.
Better understanding these aspects of ecosystems is a game-changer for the conservation of biodiversity. The Indo-West Pacific region, between the east coast of Africa and South Asia, has the highest diversity of life in the world’s oceans. But many species there, such as damselfishes and butterfly fishes, have a lot of overlap with other species in terms of traits — somewhat similar body sizes, similar habitats and habits, how and where they school, etc. That means they may have a narrower range of traits that may be important for ecosystem function.
“In the Galapagos, on the other hand, there are fewer species, but each of those species is doing something much different than the others,” says Lefcheck, who worked on research looking at functional diversity there. “If you were prioritizing your conservation efforts, you might focus on the Galapagos. Even though it doesn’t have as much biodiversity in the traditional sense, it has a much greater diversity of form and function.”
“Functional diversity is incredibly difficult to determine,” says Larsen of Conservation International, “but generating an improved understanding of the relationship between species and their functional diversity is key to understanding and mitigating impacts or threats from development.” His organization works to protect tuna and sharks, for example, because these predators help maintain a healthy and balanced ecosystem by keeping numbers of prey from growing too large and by culling the sick and the weak.
In a recent study in the journal Nature, researchers say that focusing on species function and evolutionary heritage can narrow the focus on what needs to be protected most urgently. “Biodiversity conservation has mostly focused on species, but some species may offer much more critical or unique functions or evolutionary heritage than others — something current conservation planning does not readily address,” says Walter Jetz, a professor of ecology and evolutionary biology at Yale University.
The researchers noted that 26 percent of the world’s bird and mammal species are not included in protected reserves. Focusing on the most important traits and evolutionary heritage of those species would allow conservationists to narrow their protection of critical biodiversity with just a 5 percent increase in protected areas, and would be far less costly than trying to protect them all, the Nature study shows.
As traits are better understood in ecosystems, Lefcheck says, it allows tweaking and management of ecosystems for certain outcomes. “You could choose to conserve the species that are very different than others that might lead to changes in the ecosystem that could be considered beneficial,” he says. That has potential for fisheries management, for example. “When I tell someone, ‘This species has been around for 2.6 million years,’ that’s very esoteric in a way,” says Lefcheck. “But if I can say, ‘This large-bodied species produces a lot of biomass, and it can crop down invasive algae, and it plays a high-functioning and critical role in the ecosystem,’ you might want to protect species that have that trait.”
Such is the case with parrotfish and surgeonfish — “reef-grazers” that eat algae and keep coral reefs healthy. Because of these key traits, the government of Belize has enacted a law to protect these two species.
Understanding traits also can enhance ecosystem restoration projects. While building a new oyster aquaculture fishery can provide a commercial harvest, “we also know that oysters provide a lot of other services,” says Lefcheck. “They filter the water. They provide nooks and crannies for small fish and invertebrates to live in, and they are fish food for the tasty things we like to catch and to put on the dinner table. Where is the optimum placement of this restoration to enhance the variety of services we get from the oysters beyond just having the reefs there?”
The benefits of understanding functional diversity can go well beyond ecosystem restoration. In Toronto, for example, green (plant-covered) roofs are required on most new commercial buildings to help cool the city and reduce storm water runoff. A monoculture of grass called sedum is used. In studies, though, Cadotte and colleagues have found that if grass species that are distantly related and dissimilar are used in the mix, they have different traits that provide more shade for the soil and help the roof keep the building cooler. This mix also reduces stormwater runoff by about 20 percent.
The formal study of functional traits can be traced back to the 1990s, when ecologist David Tilman at the University of Minnesota did research on grasslands. He found that those regions with more species diversity did better during a drought, and only a few of the grasses resistant to drought were needed. Later, he and his colleagues discovered that the presence of some grasses with certain traits, such as an ability to fix nitrogen, was more important than overall species diversity.
Researchers in Jena, Germany established the Jena Experiment to follow up on this work. They found that there are plants, such as wild tobacco, that emit “messenger molecules” when they are under assault by herbivores to attract predators from miles away that eat their enemies. This trait not only benefits the tobacco, but other species in the neighboring plant community.
Experts say these findings could also help agriculture rely less on pesticides by understanding the right mix of plants to maximize predator defenses. “Varying the expression of just a few genes in a few individuals can have large protective effects for the whole field,” says Meredith Schuman, a researcher on the Jena Experiment at the Max Planck Institute for Chemical Ecology. “It’s an economically tenable way to recover the lost benefits of biodiversity for the vast expanses of land that have already been converted from natural, biodiverse habitats into agricultural monocultures.”
These new approaches to ecology show how limited the science has been. Many researchers welcome the change. “Ecology has moved from counting species to accounting for species,” says Cadotte.
Jim Robbins is a veteran journalist based in Helena, Montana. He has written for the New York Times, Conde Nast Traveler, and numerous other publications. His latest book, The Wonder of Birds: What they Tell Us about the World, Ourselves and a Better Future, is due out in May.
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What needs to be done to stop wildfires in drought-killed forests.
A century of fire suppression followed by the worst drought in recorded history has put California’s forest landscapes and water supply at risk.
WITH 17 LARGE wildfires in California igniting in 24 hours this week, October is shaping up to be a brutal month for wildfires, as it often is. It’s too soon to know what caused multiple conflagrations spreading across Northern California’s wine country, but elsewhere in the state dead and dying trees have been the subject of much concern. The five-year drought in California killed more than 102 million trees on national forest lands. That is a gigantic problem in itself that will lead to huge wildfire risks in the future and big changes in wildlife habitat.
With that huge number in mind, it is easy to forget that the forests were already in a sorry state. It’s now widely understood that a century of misguided – but well-intentioned – policies over the past 100 years produced forests that are too densely packed with small trees and too vulnerable to possibly catastrophic fires.
Water supplies are also a concern, because the forests are nature’s water-storage sponges. They capture snowfall and release it slowly, helping Californians survive long, dry summers. But there’s also a concern that overgrown forests consume too much water, and that thinning some forests could generate more runoff.
A new report by the Public Policy Institute of California proposes some different approaches to begin chipping away at the problem. It recommends some changes in state law and new contracting practices, among other things. It also suggests some changes in public attitudes.
To learn more, Water Deeply recently spoke with Van Butsic, the study’s lead author. Butsic is a land system scientist with a Ph.D. in forestry; he works as an assistant cooperative extension specialist in the University of California, Berkeley, Department of Environmental Science, Policy and Management.
Water Deeply: How are California’s forests doing in the wake of the drought?
Van Butsic: The drought, coupled with the last century of management actions, caused a huge pulse in tree mortality. There are always dead trees in the woods, but the additional dead trees in the environment due to the drought is about 15 million a year.
One hundred years ago many, many large trees were harvested. Then we have a century of fire suppression, so we take fire out of the equation. So new trees are coming back and they’re not burning. Then, about 30 years ago, we stopped harvesting on most national forests. So we have a condition where the forests are of a much higher density than they’ve ever been before. Then we have the drought, and lots of trees on the landscape are susceptible to bark beetle outbreaks due to lack of water.
Water Deeply: How much additional prescribed fire is needed to bring the forests back to a healthy state?
Butsic: We didn’t quantify that ourselves. But what I would say is, the statistics we’ve seen from a number of good scientists have put the number of additional acres that need to be treated at somewhere between 200,000 and 500,000 per year. So a very large amount. The numbers in those studies come from a historical look at what was normal 100 or 150 years ago. That’s more than a doubling of what’s going on now. So it’s a substantial increase. I want to say that right now the Forest Service is doing somewhere between 100,000 and 200,000 per year.
Water Deeply: There’s also a need for more mechanical thinning, or logging. How do we get past the controversy over that?
Butsic: One thing that has happened in California is sort of a distrust of mechanical thinning. Often, when the Forest Service or private landowners say they’re doing mechanical thinning, certain environmental groups think that’s code for clearcutting. One thing we try to say in the paper is this is a valuable tool and it needs to be on the table if we want to get this work done. So making sure mechanical thinning is not written off as code for clearcutting is going to be important if we’re going to manage forests.
Water Deeply: How do we ensure that it’s not clearcutting?
Butsic: There are very strong forest practice laws in California. My understanding of the current regulations governing forest management on federal lands is that in Forest Service Region 5, which California belongs to, it’s really nearly impossible to harvest trees [with a diameter] over 30in (76cm). So these trees are not really at risk, I would say, as long as the Forest Service follows its own recommendations. And yet this is still a stumbling block in conversations about mechanical thinning. People are still very worried about these trees because they’ve seen in the past some large trees disappear. That’s a difficult situation to work with. The laws are in place to protect those trees, and yet people don’t really trust them.
Water Deeply: You recommend state and federal land management agencies justify their continued fire suppression. Why do you suggest that?
Butsic: Most ecologists would agree the long-term suppression of fire has led to a change in forest structure, and probably a decline in forest health. Typically, when agencies do any activity that might cause environmental harm, they need to justify it. We don’t see that for fire suppression. And there’s good reason why you wouldn’t do this on a case-by-case basis. If a fire breaks out around a house, you want to go and put it out. But making sure agencies explain their management choices around wildfire would lead them to use some of their tools, like managed wildfire, more often.
Water Deeply: You report that state law treats wildfire and prescribed fire differently in regard to air quality. Is that still appropriate?
Butsic: There’s a growing body of evidence that prescribed fires are less harmful to humans than non-managed wildfires, because they burn at lower severity, typically. And we know an area burned with a prescribed fire is less likely to burn at high severity in the near future. So clearly, there are long-term air quality benefits to prescribed fire.
But with prescribed fires, there are short-term costs caused by regulation. There’s a lot of planning that needs to go into conducting a prescribed fire for air-quality reasons. And the air-quality reasons are real. We’re not saying people with asthma are not affected by smoke. But we can manage it with prescribed fire and know when the fire is going to happen and know that in the future, we’ll have less risk of severe wildfire. Or we can just leave it to chance and, eventually, we’ll probably get a severe wildfire anyway.
So treating those differently under state law is just problematic.
Water Deeply: What kind of additional mechanical thinning are you calling for?
Butsic: We think mechanical thinning can be really useful in a few ways. If you’re near homes or near roads, mechanical thinning has a very key role to play in those instances. The other is where there are logs that could be harvested that could offset the cost of other treatments. Prescribed fire and managed wildfire are both costly.
There is a number of studies that show mechanical thinning with removal of some sawlogs can be a net profit in certain areas, and the largest trees we looked at removing in the report are 16in (in diameter).
Water Deeply: So why isn’t it happening?
Butsic: There is a number of barriers that we’ve identified to getting the work done. Part of it is the history of distrust. One roadblock is that it is somewhat risky for leadership to try to do these big treatments. If you’re going to do big prescribed fires or let wildfires be managed, there’s risk to the leadership that things could go wrong. And if they do, they look bad. So I do think these groups do not have a risk-taking culture. That’s just not the Forest Service culture. I do think that’s probably hindered them a little bit.
Another barrier is there still are issues with the infrastructure. In some parts of the state, there just are not great places to take the material: sawmills and biomass plants. Some people have said that’s the main roadblock. I’m not sure we agree with that.
Water Deeply: Will these things improve water supply?
Butsic: We think there’s real potential. There’s probably more uncertainty in that science than in other areas. But we do think there’s real potential for the maintenance of the quality and quantity of waters we have today under a healthy forest regime versus an unhealthy one.
Water Deeply: What’s the public’s role? Do we need to be more open-minded about prescribed fire and some kind of logging?
Butsic: I think understanding the role of fire and the necessity of it in the landscape, having the public appreciate the role that fires plays in keeping forests healthy, is something we could improve upon. We need to build the social license to do treatments.
The media often portray fire in the forest as a total destruction. After a fire goes through, it’s not pretty. You see a lot of charred and dead trees. It’s not an appealing landscape. But understanding the long-term importance of having that disturbance on the landscape is certainly something the media could help educate the public on.
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The water under Colorado’s Eastern Plains is running dry as farmers keep irrigating “great American desert.”
Farmers say they’re trying to wean from groundwater, but admit there are no easy answers amid pressures of corn prices, urban growth and interstate water agreements.
By BRUCE FINLEY | bfinley@denverpost.com
WRAY — Colorado farmers who defied nature’s limits and nourished a pastoral paradise by irrigating drought-prone prairie are pushing ahead in the face of worsening environmental fallout: Overpumping of groundwater has drained the High Plains Aquifer to the point that streams are drying up at the rate of 6 miles a year.
The drawdown has become so severe that highly resilient fish are disappearing, evidence of ecological collapse. A Denver Post analysis of federal data shows the aquifer shrank twice as fast over the past six years compared with the previous 60.
While the drying out of America’s agricultural bread basket ($35 billion in crops a year) ultimately may pinch people in cities, it is hitting rural areas hardest.
“Now I never know, from one minute to the next, when I turn on a faucet or hydrant, whether there will be water or not. The aquifer is being depleted,” said Lois Scott, 75, who lives west of Cope, north of the frequently bone-dry bed of the Arikaree River.
A 40-foot well her grandfather dug by hand in 1914 gave water until recently, she said, lamenting the loss of lawns where children once frolicked and green pastures for cows. Scott has been considering a move to Brush and leaving her family’s historic homestead farm.
“This will truly become the Great American Desert,” she said.
The agricultural overpumping from thousands of wells continues despite decades of warnings from researchers that the aquifer — also known as the Ogallala, the world’s largest underground body of fresh water — is shrinking.
Even if farmers radically reduced pumping, the latest research finds, the aquifer wouldn’t refill for centuries. Farmers say they cannot handle this on their own.
But there is no agreement among the eight affected states (Colorado, Kansas, Nebraska, New Mexico, Texas, Oklahoma, Wyoming, South Dakota) to try to save the aquifer. And state rules allow total depletion.
In fact, Colorado officials faced with legal challenges from Kansas over dwindling surface water in the Republican River have found that their best option to comply with a 1942 compact is to take more water out of the aquifer. The state bought wells from farmers during the past decade and has been pumping out 11,500 acre-feet of water a year, enough to satisfy a small city, delivering it through a $60 million, 12-mile pipeline northeast of Wray to artificially resuscitate the river.
The overpumping reflects a pattern, seen worldwide, where people with knowledge that they’re exceeding nature’s limits nevertheless cling to destructive practices that hasten an environmental backlash.
The drawdown
The depletion of the High Plains Aquifer has been happening for decades, according to bulletins U.S. Geological Survey has put out since 1988. Colorado farmers this year pumped groundwater out of 4,000 wells, state records show, siphoning as much as 500 gallons a minute from each well to irrigate roughly 580,000 acres — mostly to grow corn, a water-intensive crop.
The depth where groundwater can be tapped has fallen by as much as 100 feet in eastern Colorado, USGS data show. That means pump motors must work harder to pull up the same amount of water, using more energy — raising costs for farmers. The amount of water siphoned from the aquifer since 1950 to irrigate farm fields across the eight states tops 273 million acre-feet (89 trillion gallons) — about 70 percent of the water in Lake Erie.
On one hand, the industrial center-pivot irrigation techniques perfected after World War II have brought consistency to farming by tapping the “sponge” of saturated sediment that links the aquifer to surface water in streams and rivers. America’s breadbasket produces $35 billion of crops a year. On the other hand, intense irrigation is breaking ecosystems apart.
Overpumping has dried up 358 miles of surface rivers and streams across a 200-square-mile area covering eastern Colorado, western Kansas and Nebraska, according to U.S. Fish and Wildlife-backed researchers from Colorado State University and Kansas State University who published a peer-reviewed report in the Proceedings of the National Academy of Sciences. The researchers also determined that, if farmers keep pumping water at the current pace, another 177 miles of rivers and streams will be lost before 2060.
“Intermittent streams are more likely to be dry. Permanent streams are more likely to become intermittent. Large streams are more likely to be small. Everything has changed,” said KSU conservation biologist Keith Gido, one of the authors. “We have almost completely changed the species of fish that can survive in those streams, compared with what was there historically. This is really a catastrophic change.”
Disappearing fish species — minnows, suckers, catfish that had evolved to endure periodic droughts — signal to biologists that ecological effects may be reaching a tipping point.
The amount of water held in the aquifer under eastern Colorado decreased by 19.6 million acre-feet — 6.4 trillion gallons — from 1950 until 2015, USGS records show. That’s an average loss of 300,000 acre-feet a year. Between 2011 and 2015, records show, the water available under Colorado in the aquifer decreased by 3.2 million acre-feet — an annual average shrinkage of 800,000 acre-feet. Climate change factors, including rainfall, play into the rate of the drawdown.
If all pumping stopped immediately, it would still take hundreds of years for rain-fed streams and rivers to recharge the aquifer, Gido said.
“We’re not living in as sustainable a fashion as we need to be. Much of the damage has been done,” he said, “and restoring what we’ve lost could be difficult.
“It is happening all over the world in places such as Pakistan. It causes conflicts. As human populations grow, the demand for water is going to be greater. Conflicts are going to increase — unless we become more efficient in using the water we have.”
Farmers locked
For farmers, weaning themselves off groundwater is proving difficult.
They say they’re trying. They’ve reduced the land irrigated in eastern Colorado by 30,000 acres since 2006. They plan to retire another 25,000 acres over the next decade, said Rod Lenz, president of the Republican River Water Conservation District, who for years has advocated use of technology to grow more crops with less water.
“We have come to realize that, yeah, we are overmining it. We are acutely aware of that now. There’s a definite attitude to make more than just the natural progression as far as efficiency,” Lenz said, noting state officials monitor pumping and determine how many acres owners can irrigate.
“We’re constantly trying to find ways to stay in compliance,” he said. “We’re looking at serious conservation.”
For years, agriculture experts have pointed to drip-irrigation technology to do more with less. Federal agencies in the past dangled help for farmers who invest. But few in eastern Colorado have installed these systems, largely because they are expensive.
Farmer and cattleman Robert Boyd, a leader of the Arikaree Groundwater Management District, said the federal government should intervene to ensure survival of High Plains agriculture.
“Do you want us to be sustainable? Or not? It may come to a point where no one can actually irrigate,” Boyd said.
He pointed to proposals to divert water from the Missouri River Basin and move it westward through pipelines across the Great Plains.
“If the federal government wants agriculture to be sustainable, they need to pump water back toward the mountains. They need to figure out how to get water back toward the higher parts of the rivers,” he said. “The federal government needs to step in and make the states work together to make agriculture — and urban areas — sustainable.”
For now, farmers struggle, increasingly weighing water uncertainties in calculations that include corn prices falling to around $3.50 a bushel in recent years from $7. But drawing down the aquifer does not violate any law in Colorado. The state engineer’s office monitors well levels and requires permits for wells, limiting the number of acres a farmer can irrigate. But there’s no hard limit on how much water can be pumped.
In contrast, state rules limit groundwater withdrawals from the Denver Basin Aquifer — a source for many of Denver’s southern suburbs, including Castle Rock and Parker — to less than 1 percent a year. This is meant to help natural recharge keep pace with human demands.
But on the High Plains, the situation is like mining intended to fully exploit diamonds or gold.
“If you want to have it all back the way it was 150 years ago, you would have to remove everyone from the area. I’m not sure how we could do that today,” deputy state engineer Mike Sullivan said in an interview.
Sullivan and state engineer Kevin Rein emphasized that thousands of acres no longer are irrigated. “And there need to be some more retirements of land to get us into a more balanced situation,” Sullivan said.
They defended Colorado’s practice of pumping more groundwater out of the aquifer, saying this is necessary to comply with the Republican River Compact. Disputes over river flows have risen as far as the U.S. Supreme Court and Colorado’s legal obligations to deliver water to Nebraska and Kansas are clear.
“What we do with the pumping does help the streams,” Sullivan said. “It does provide a wet stream. … We could not meet our (legal) obligation without that today, even if we turned off all the wells.”
But there’s no end in sight for the drawdown of groundwater.
Nature exhausted
And for farmers who built their world on the High Plains Aquifer, the environmental fallout is increasingly painful. In the rural view, it is a problem that cannot be addressed by farmers alone without help from people in cities. All of the industrial agriculture is done with urban residents in mind — the people who consume the crops and cows that farmers grow.
“The world population is going to double. And we’re not going to be able to grow more farmland. We’re losing farming ground every day to development,” said Cody Powell, manager of 21st Century Equipment, the John Deere dealer in Burlington, an agricultural hub. “You take away farm ground for development, bring in more people. Who’s going to feed them? The only way to do that is to put water on crops.”
People in cities increasingly demand environmentally correct crops, which requires more water. “If they want natural grain-fed cattle, and non-GMO (genetically modified organism) crops — all that good stuff — it is going to take water,” he said.
A farmer can grow more by using pesticides and genetically modified seeds, he said. “With the same amount of water, you could get twice as much corn.”
He knows too well the perils of losing water. He grew up in southern Colorado’s Arkansas River Valley at a time when Aurora and other Front Range suburbs were buying up rights from farmers. This buy-up to slake growing suburban thirsts ended up killing agriculture across hundreds of thousands of once-irrigated acres.
And now when Powell goes back, he sees communities “overrun with thugs” near where his grandmother lived. “It makes me feel sick,” he said.
In eastern Colorado, the problem now is that few can afford to invest in high-efficiency water technology, such as irrigation drip tubes and tape installed underground to eliminate evaporation losses, and soil-sensor systems that let farmers irrigate only when absolutely necessary.
Federal programs to subsidize installation of this technology have withered. And the overpumping continues.
“The fear out here now is not that the aquifer is going to get ruined,” Powell said. “The fear is that the state is going to shut off wells.”
And prairie residents practically cringe to see the pipeline northeast of Wray that Colorado uses to convey groundwater away to Nebraska and Kansas to prevent future lawsuits.
The interstate compact was negotiated back when there was more water and far fewer people, they say.
“Now we just have weeds. We are feeling the effect of losing the water that Kansas is enjoying,” Scott said from her farmhouse. “It is robbing families of life. That’s what is happening to us. We should be entitled to the water underground.”
Past becomes future
The depletion means water scarcity increasingly dictates survival.
It is no surprise to historians. In the 1860s, John Wesley Powell’s surveys for the U.S. government warned that the land west of central Kansas was practically a desert. His report “On the Arid Lands of the Western United States” warned that the only way for people to live here would be by irrigating land. Otherwise, he wrote, the place could not support permanent communities. Tribes for centuries used the Great Plains seasonally as a hunting ground.
Settlers flocked in during the 19th century, initially relying on dryland farming. This led to massive soil erosion, culminating in the Dust Bowl environmental disaster of the 1930s.
Industrial irrigation took off during the 1960s, with tens of thousands of wells drilled through the 1980s.
But now, if people keep pumping, the dry-out will intensify, CSU senior research scientist Kevin Bestgen said.
“I appreciate it that people now are trying to reduce pumping. The reality is that the bucket they are pumping from does not refill. It is finite. And in order to allow recharge of that aquifer, farmers are going to have to get much more severe reductions in pumping levels. It has been going down and down and down,” he said. “People are getting what they can. This will turn out to be a tragedy. It is in the culture at this point. People want to grow corn now.”
Groundwater levels
The map shows the change in groundwater levels for various management districts in the Northern High Plains Basin over the last 10 years. The water level data is collected from wells in the areas. Click an area to see the changes in groundwater levels for 1-, 5- and 10-year periods.
Bruce Finley
Bruce Finley covers environment issues, the land air and water struggles shaping Colorado and the West. Finley grew up in Colorado, graduated from Stanford, then earned masters degrees in international relations as a Fulbright scholar in Britain and in journalism at Northwestern. He is also a lawyer and previously handled international news with on-site reporting in 40 countries.
Follow Bruce Finley @finleybruce
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Sponges, urban forests and air corridors: How nature can cool cities.
As China battles the twin challenges of rapid city growth and extreme weather, it is adopting a new tactic: Turning its cities into giant sponges.
LONDON, Sept 26 (Thomson Reuters Foundation) - As China battles the twin challenges of rapid city growth and extreme weather, it is adopting a new tactic: Turning its cities into giant sponges.
Thirty pilot cities in the country are trying to trap and hold more water to deal with problems from flooding and drought to extreme heat and pollution.
The effort, launched by Chinese President Xi Jinping, relies on a range of innovations, from green roofs on buildings to more urban wetlands. It is already being hailed as a bold step to solve some of the environmental problems plaguing the world’s most populous country.
“It’s a timely reminder that dealing with urban climate challenges requires a holistic approach,” said Sunandan Tiwari, a sustainable urban development expert at ICLEI - Local Governments for Sustainability, a global network of 1,500 cities, towns and regions.
PEOPLE AND WATER
Like many large urban areas, Chinese cities are grappling with both rapid urbanisation - more than half of the country’s population lives in urban areas - and extreme weather, such as severe floods, water shortages and heatwaves.
Both problems can leave more people at risk - but the sponge city effort, launched in 2015, aims to reduce the threats.
The pilot cities have been charged with finding ways to absorb, store, filter and purify rainwater, retain it within their boundaries, and release it for reuse when needed instead of channelling it away through sewers and tunnels.
The cities, including the capital Beijing, Shenzhen and Shanghai, receive funds and practical help to redesign their urban areas in a water-sensitive way, with the aim of turning 80 percent of China’s urban areas into sponges by 2030.
Flood control and water conservation, among other issues, are at the heart of the ambitious push.
But sponge cities have another benefit that looks set to become a major plus as urban areas in China and around the world get hotter: They can reduce the impact of heat waves, which are more pronounced in built-up areas, where concrete and asphalt trap heat.
Trees and other plants absorb water and then release it through evaporation. That creates a cooling effect, in the same way that sweat evaporating from skin cools people.
“Cooling is largely seen as a co-benefit of sponge cities. But with record temperatures in China and many parts of the world, it is becoming a key element in planning for climate-resilient cities,” said Boping Chen, China director at the Hamburg-based World Future Council, a think tank. GETTING HOTTER Shanghai, China’s most populous city with 24 million people, baked under a record high temperature of 40.9 degrees Celsius (105 degrees Fahrenheit) last July even as southern China was hit by torrential rain and floods.
Efforts to build sponge cities aim to deal with both problems - and improve life for city residents.
“It’s not just about limiting the damage of flooding, it’s also about coping with rising temperatures, improving urban bio-diversity, better public health and quality of life,” Tiwari, of ICLEI, told the Thomson Reuters Foundation.
Measures taken in sponge cities include covering buildings with green roofs and facades, and creating urban wetlands and trenches to filter run-off water that can be used to replenish aquifers, irrigate gardens and urban farms, flush toilets and clean homes.
The government has allocated each pilot city between 400 million yuan and 600 million yuan ($60 million to $90 million) each year for three consecutive years, and cities are encouraged to raise matching funds through public-private partnerships and other financial ventures, according to a 2017 study in the journal Water.
Lingang, in Shanghai’s Pudong district, has invested 800 million yuan in a 79 square km (30 square mile) area it hopes will become China’s largest sponge city - one that experts say could be a model for other cities lacking modern water infrastructure.
Lingang aims to cover rooftops with plants, create wetlands for rainwater storage, and create permeable pavements that store runoff water, allowing it to evaporate to moderate temperatures.
Shanghai also announced last year the construction of 400,000 square metres of rooftop gardens, alongside other measures to green the city.
“Many of the sponge cities have done really well but it is a long-term task that needs to be done in a systematic way,” said the World Future Council’s Chen.
FOREST CITIES
While China faces formidable financial and logistical challenges to creating sponge cities, Italian architect Stefano Boeri has plans to make “forest cities” in the country.
Boeri, who made headlines when he covered two residential tower blocks in Milan with 800 trees, 4,500 shrubs and 15,000 other plants, has won planning approval to build a forest city in Liuzhou in southern China. Conceived as a green metropolis, the city will house 30,000 people and all its buildings will be covered entirely with plants and trees, said Boeri, who declined to give a cost estimate for the project.
In total, Liuzhou’s forest city aims to host 40,000 trees and almost one million plants from more than 100 species, planted over buildings to improve air quality, decrease temperatures and contribute to biodiversity, Boeri said.
The city is expected to absorb almost 10,000 tons of carbon dioxide - the equivalent emissions of 2,000 passenger cars driven for a year - and 57 tons of pollutants per year. The greenery will also produce some 900 tons of oxygen every year, Boeri said.
He is working with botanists and engineers to create a high nutrient soil mixture able to retain water while still keeping weight to a minimum.
“Bringing forests into the city is one of the most radical and efficient ways to deal with climate change,” Boeri told the Thomson Reuters Foundation.
“We sometimes joke and say we’re building houses for trees,” he said.
To increase energy self-sufficiency, solar panels on the roofs will collect renewable energy to power the buildings, while geothermal energy - heat and cooling drawn from constant temperatures underground - will power air-conditioning, adding to the project’s green appeal.
Boeri also aims to build vertical forests, similar to the one in Milan, in Nanjing, Shanghai and Shenzhen in China and in other parts of the world.
NATURE AT WORK
While China’s sponge city programme is the most ambitious of its kind, urban planners have embraced nature-based solutions to heat and water worries in other parts of the world too.
The sponge city initiative takes inspiration from the North American concept of low-impact development, sustainable urban drainage systems in Europe and water sensitive urban design in Australia and New Zealand, all of which mimic nature’s water cycle.
The southern German city of Stuttgart, prone to high summer temperatures and air pollution, also has been a pioneer of using nature to adapt to climate change.
Officials there published a climate adaptation plan in 2012, but planners have been thinking about the valley city’s micro-climate as far back as 1938, according to Hans-Wolf Zirkwitz, head of Stuttgart’s Office for Environmental Protection.
“Even before we knew about climate change, our planning has been optimised with regards to the climate and improving air quality, because of our local climate conditions,” Zirkwitz told the Thomson Reuters Foundation in emailed comments.
City officials, for instance, have created green ventilation corridors to enable fresh air to sweep down from the city’s surrounding hills and building regulations that aim to keep these corridors free from new construction.
Thanks to a combination of mandatory building requirements and subsidies, the city of about 600,000 people also is a European green roof pioneer, with more than 60 percent of its area covered by greenery to absorb pollutants and reduce heat. ($1 = 6.6189 Chinese yuan renminbi) (Reporting by Astrid Zweynert @azweynert , Editing by Laurie Goering and Ros Russell.; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit news.trust.org)
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