Water recycling for agricultural use is about to get a major boost through a massive reuse project in California that marks some first-evers.
“Starting as early as December, [Modesto] will sell its highly treated wastewater to struggling nearby farmers. When it’s up and running, Modesto’s experiment should be California’s largest wastewater-to-agriculture reuse project, and it will mark the first time recycled water flows through a federal canal,” Grist recently reported.
“The project will take tertiary-treated sewage from the cities of Modesto, Turlock and Ceres and route it through new pipelines into the Delta Mendota Canal, owned by the U.S. Bureau of Reclamation. From there, it will be purchased by Del Puerto Water District to irrigate crops on some 200 family farms along the west side of the San Joaquin Valley,” News Deeply explained.
The project, known as the North Valley Regional Recycled Water Program, is the “single largest recycled water conveyance project in the country and the first water project for the U.S. Bureau of Reclamation, the owner and operator of the Delta-Mendota Canal,” the Turlock Journalreported. The effort will bring waste-to-farm techniques to some of the nation’s most productive farmland….
After years of intense, record-setting drought across the U.S., particularly in the Great Plains and California, the country is now experiencing its lowest level of drought in the 17 years since the U.S. Drought Monitor began its weekly updates. Less than 5 percent of the U.S. was in some stage of drought as of May 4, the most recent update, compared to the 65 percent mired in drought in September 2012….
…The epicenters of drought were in the central and southern Plains states from 2011 to 2013 and California from 2012 to this winter. At the peak of its drought, more than half of California was experiencing “exceptional” drought conditions, the highest category. At the end of September 2011, more than 85 percent of Texas was in this category.
Both droughts were fueled by a combination of dry weather and repeated, sizzling heat waves. The exceptional heat that blanketed much of the central and eastern portions of the country in 2012 boosted it to the hottest year on record for the U.S., while California experienced back-to-back record-hot years during its drought.
That heat is probably the clearest link between climate change and droughts, as rising global temperatures fueled by increasing concentrations of greenhouse gases in the atmosphere tilt the odds in favor of record heat and away from record cold….
…Perhaps the clearest regional signals of climate change increasing drought are in the already arid Southwest, where droughts are expected to happen more often, last longer and be more intense than in the past. There is also some suggestion of more consecutive dry days for the Southern Plains, which could make it easier for that region to tip into drought…
Region could lose 30 percent of the snowpack it relies on for irrigation and drinking water—and potentially as much as 60 percent—over the next 30 years
Losses ahead could put farms, energy and drinking water at risk, a new study suggests
By Bob Berwyn, InsideClimate News Apr 27, 2017
The American West has already lost between 10 and 20 percent of its mountain snowpack since the early 1980s, and climate change is partly to blame, new research shows. If greenhouse gas emissions are not curtailed, the region could lose 30 percent of the snowpack it relies on for irrigation and drinking water—and potentially as much as 60 percent—over the next 30 years, the authors write.
The loss can’t be explained by natural climate variations alone, however it is consistent with model simulations that include both natural and human-caused changes, the study says. “These results add to the evidence of a human influence on climate that will have severe impacts on our water supply,” said Benjamin Santer, a Lawrence Livermore National Laboratory climate scientist and a co-author of the paper, published last week in Nature Communications….
The crippling wintertime droughts that struck California from 2013 to 2015, as well as this year’s unusually wet California winter, appear to be associated with the same phenomenon: a distinctive wave pattern that emerges in the upper atmosphere and circles the globe. …Scientists at the National Center for Atmospheric Research (NCAR) found in a recent study that the persistent high-pressure ridge off the west coast of North America that blocked storms from coming onshore during the winters of 2013-14 and 2014-15 was associated with the wave pattern, which they call wavenumber-5. Follow-up work showed that wavenumber-5 emerged again this winter but with its high- and low-pressure features in a different position, allowing drenching storms from the Pacific to make landfall.
…The slow-moving Rossby waves at times become almost stationary. When they do, the result can be persistent weather patterns that often lead to droughts, floods, and heat waves. Wavenumber-5 often has this stationary quality when it emerges during the northern winter, and, as a result, is associated with a greater likelihood of persistent extreme events.
…The new research indicates that the wave pattern may provide an additional source of predictability that sometimes may be more important than the impacts of sea surface temperature changes. First, however, scientists need to better understand why and when the wave pattern emerges.
In the paper published in Journal of the Atmospheric Sciences, Branstator and Teng explored the physics of the wave pattern. Using a simplified computer model of the climate system to identify the essential physical processes, the pair found that wavenumber-5 forms when strong jet streams act as wave guides, tightening the otherwise meandering Rossby wave into the signature configuration of five highs and five lows.
“The jets act to focus the energy,” Branstator said. “When the jets are present, the energy is trapped and cannot escape.” But even when the jets are present, the wavenumber-5 pattern does not always form, indicating that other forces requiring study are also at play.
The scientists also searched specifically for what might have caused the wave pattern linked to the severe California drought to form. In the paper published in the Journal of Climate, the pair found that extremely heavy rainfall from December to February in certain regions of the tropical Pacific could double the probability that the extreme ridge associated with wavenumber-5 will form. The reason may have to do with the tropical rain heating parts of the upper atmosphere in such a way that favors the formation of the wavenumber-5 pattern.
Dust from as far away as the Gobi Desert in Asia is providing more nutrients than previously thought for plants, including giant sequoias, in California’s Sierra Nevada mountains, a team of scientists have found. The scientists found that dust from the Gobi Desert and the Central Valley of California contributed more phosphorus for plants in the Sierra Nevadas than bedrock weathering, which is breaking down of rock buried beneath the soil. Phosophorus is one of the basic elements that plants need to survive, and the Sierra Nevadas are considered a phosphorus-limited ecosystem.
…The study may help scientists predict the impacts of climate change which is expected to increase drought and create more desert conditions around the world, possibly including California. If that happens, based on these findings, scientists expect a lot more dust moving in the atmosphere, and likely bringing phosphorus and important nutrients to far flung mountainous ecosystems….
…The percentage of Asian dust ranged from 20 percent on average at the lowest elevation, to 45 percent on average at the highest elevation. The percentages were higher at the higher elevation sites because dust tends to travel high in the air stream and not fall unless it hits an object, such as a mountain. The researchers found that the amount of dust from Central Valley sources was greater at lower elevations compared to higher elevations. That was expected, but they also found that more Central Valley dust was entering higher elevations later in the dry season than just after the spring rains….
…The researchers believe their findings will hold true for other mountainous ecosystems around the world and have implications for predicting forest response to changes in climate and land use.
S. M. Aciego, C. S. Riebe, S. C. Hart, M. A. Blakowski, C. J. Carey, S. M. Aarons, N. C. Dove, J. K. Botthoff, K. W. W. Sims, E. L. Aronson. Dust outpaces bedrock in nutrient supply to montane forest ecosystems. Nature Communications, 2017; 8: 14800 DOI: 10.1038/ncomms14800
Note: Co-author, Dr. Chelsea Carey, is Point Blue’s Soil Ecologist.
Ecosystem collapse from extreme drought can be significantly hastened by pressures placed on drought-weakened vegetation by grazers and fungal pathogens, a new study finds. The study’s experimental evidence shows that the natural enemies of plants play a major role in lowering resilience to drought and preventing recovery afterward. The finding may be applicable to a wide range of ecosystems now threatened by climate-intensified drought, including marshes, mangroves, forests and grasslands….
Qiang He, Brian R. Silliman, Zezheng Liu, Baoshan Cui. Natural enemies govern ecosystem resilience in the face of extreme droughts. Ecology Letters, 2017; DOI: 10.1111/ele.12721
A new study has found that trees worldwide develop thicker bark when they live in fire-prone areas. The findings suggest that bark thickness could help predict which forests and savannas will survive a warmer climate in which wildfires are expected to increase in frequency….
…the study illustrates how climate change could create conditions that already-endangered ecosystems cannot withstand. “As periods of drought begin to be seen more frequently in tropical forests — the lungs of our planet — the risk that these ecosystems will burn increases,” said Coulson, who is familiar with the study but had no role in it.
“Because the species found there are not well-adapted to cope with fire, the consequences could be devastating,” he said. “[This] work highlights that the changes we are making to our climate can put ecosystems at risk to factors, such as fire, that they are poorly equipped to deal with.”
Adam F. A. Pellegrini, William R. L. Anderegg, C. E. Timothy Paine, William A. Hoffmann, Tyler Kartzinel, Sam S. Rabin, Douglas Sheil, Augusto C. Franco, Stephen W. Pacala. Convergence of bark investment according to fire and climate structures ecosystem vulnerability to future change. Ecology Letters, 2017; DOI: 10.1111/ele.12725
… if past weather patterns are fulfilled this year, experts say, Northern California’s winter — and long-term relief from years of drought — could be just around the corner for the state’s most important watershed. The Northern Sierra Nevada area has received more than 17 inches of precipitation through October and November, nearly 200% above average for the first two months of the water year, the state Department of Water Resources said.The southern portions of the Sierra Nevada, however, remain mired in drought and are only at 81% of average….
On Nov. 3, the U.S. Drought Monitor reported that about a quarter of California was out of drought conditions, the best outlook the state has had since spring 2013, when 64% of the state was considered in “moderate drought” or worse. The U.S. Drought Monitor relies heavily on precipitation levels and soil moisture to assess conditions, state water officials said. Because Northern California’s soil was essentially a dried sponge last year, much of the El Niño rains were soaked up instead of trickling into rivers, streams and reservoirs. But this year the soil is in better condition, so a larger portion of the fall and winter snowpack that melts next spring could end up in reservoirs….
The picture in Southern California, however, remains bleak. A bark beetle infestation that took hold in the southern and central Sierra Nevada during the drought has killed more than 100 million trees and is moving north, increasing the danger of wildfire….
Long-term experiment in Yosemite shows managing fires can help make forest more resilient to fire
October 24, 2016 UC Berkeley ScienceDaily
An unprecedented 40-year experiment in a 40,000-acre valley of Yosemite National Park strongly supports the idea that managing fire, rather than suppressing it, makes wilderness areas more resilient to fire, with the added benefit of increased water availability and resistance to drought….
…”When fire is not suppressed, you get all these benefits: increased stream flow, increased downstream water availability, increased soil moisture, which improves habitat for the plants within the watershed. And it increases the drought resistance of the remaining trees and also increases the fire resilience because you have created these natural firebreaks,” said Gabrielle Boisramé, a graduate student in UC Berkeley’s Department of Civil and Environmental Engineering and first author of the study….
…”We know that forests are deep-rooted and that they have a large leaf area, which means they are both thirsty and able to get to water resources,” Thompson said. “So if fire removes 20 percent of that demand from the landscape, that frees up some of the water to do different things, from recharging groundwater resources to supporting different kinds of vegetation, and it could start to move into the surface water supplies as stream flow.”…
Gabrielle Boisramé, Sally Thompson, Brandon Collins, Scott Stephens. Managed Wildfire Effects on Forest Resilience and Water in the Sierra Nevada. Ecosystems, 2016; DOI: 10.1007/s10021-016-0048-1
As a multiyear drought grinds on in the Southwestern United States, many wonder about the impact of global climate change on more frequent and longer dry spells. As humans emit more carbon dioxide into the atmosphere, how will water supply for people, farms, and forests be affected? A new study from the University of California, Irvine and the University of Washington shows that water conserved by plants under high CO2 conditions compensates for much of the effect of warmer temperatures, retaining more water on land than predicted in commonly used drought assessments.
According to the study published this week in the Proceedings of the National Academy of Sciences, the implications of plants needing less water with more CO2 in the environment changes assumptions of climate change impacts on agriculture, water resources, wildfire risk, and plant growth.
The study compares current drought indices with ones that take into account changes in plant water use. Reduced precipitation will increase droughts across southern North America, southern Europe and northeastern South America. But the results show that in Central Africa and temperate Asia—including China, the Middle East, East Asia and most of Russia—water conservation by plants will largely counteract the parching due to climate change. “This study confirms that drought will intensify in many regions in the future,” said coauthor James Randerson, UCI professor of Earth system science. “It also shows that plant water needs will have an important influence on water availability, and this part of the equation has been neglected in many drought and hydrology studies.”…
Global climate models already account for these changes in plant growth. But many estimates of future drought use today’s standard indices, like the Palmer Drought Severity Index, which only consider atmospheric variables such as future temperature, humidity and precipitation. “New satellite observations and improvements in our understanding hydrological cycle have led to significant advances in our ability to model changes in soil moisture,” said Randerson. “Unfortunately, using proxy estimates of drought stress can give us misleading results because they ignore well-established principles from plant physiology.”
Is this good news for climate change? Although the drying may be less extreme than in some current estimates, droughts will certainly increase, researchers said, and other aspects of climate change could have severe effects on vegetation. “There’s a lot we don’t know, especially about hot droughts,” Swann said. The same drought at a higher temperature might have more severe impacts, she noted, or might make plants more stressed and susceptible to pests. “Even if droughts are not extremely more prevalent or frequent, they may be more deadly when they do happen,” she said.