As drought and water shortages become California’s new normal, more and more of the water that washes down drains and flushes down toilets is being cleaned and recycled for outdoor irrigation. But some public officials, taking cues from countries where water scarcity is a fact of life, want to take it further and make treated wastewater available for much more — even drinking. “This is a potential new source of water for California,” said former Assemblyman Rich Gordon. “We need to find water where we can.”
….Water recycling is more the norm in countries like Singapore, Israel, Saudi Arabia and Australia, which have long had water shortages. Israel reclaims about 80 percent of its wastewater, while Singapore reclaims almost 100 percent. The reclaimed water is extensively used to irrigate agricultural lands and recharge aquifers in Israel, while most of Singapore’s water is used for industrial purposes.
….To address the public perception issue, former Assemblyman Gordon was able to pass Assembly Bill 2022 last year. It enables water agencies in the state to distribute bottles of advanced purified recycled water for educational purposes….
A new approach for identifying the impacts of climate change and extreme weather on the variability of global and regional wheat production has been proposed by researchers. The study analyzed the effect of heat and water anomalies on crop losses over a 30-year period… [the study] finds that heat stress concurrent with drought or water excess can explain about 40% of the changes in wheat yields from one year to another.
….One finding is that in contrast to the common perception, water excess affects wheat production more than drought in several countries. Excessive precipitation and greater cloud cover, especially during sensitive development stages of the crop, are major contributors to reduced yields, as they help pests and disease proliferate and make it harder for the plants to get the oxygen and light they need….
M Zampieri, A Ceglar, F Dentener, A Toreti. Wheat yield loss attributable to heat waves, drought and water excess at the global, national and subnational scales. Environmental Research Letters, 2017; 12 (6): 064008 DOI: 10.1088/1748-9326/aa723b
The expansion of grasslands isn’t solely due to drought, but more complex climate factors are at work, both for modern Africans now and ancient Africans in the Pleistocene, suggests new research….
Researchers from the University of Utah have found a better way. By analyzing isotopes of oxygen preserved in herbivore teeth and tusks, they can quantify the aridity of the region and compare it to indicators of plant type and herbivore diet. The results show that, unexpectedly, no long-term drying trend was associated with the expansion of grasses and grazing herbivores. Instead, variability in climate events, such as rainfall timing, and interactions between plants and animals may have had more influence on our ancestors’ environment. This shows that the expansion of grasslands isn’t solely due to drought, but more complex climate factors are at work, both for modern Africans now and ancient Africans in the Pleistocene.
Scott A. Blumenthal, Naomi E. Levin, Francis H. Brown, Jean-Philip Brugal, Kendra L. Chritz, John M. Harris, Glynis E. Jehle, Thure E. Cerling. Aridity and hominin environments. Proceedings of the National Academy of Sciences, 2017; 201700597 DOI: 10.1073/pnas.1700597114
….Common sense dictates that we build water reserves during rainy years that will carry us through the lean years. While dams have been the reserve strategy in the past, recent experience has shown they have limitations…..UC Merced scientist Mohammad Safeeq has pointed to groundwater storage as a viable option, noting that California has enough unused groundwater storage capacity to hold 850 to 1,300 million-acre feet of water. This dwarfs the state’s current surface water storage capacity of 42 million-acre feet….
…Fortunately, …are currently researching and mapping areas with good recharge potential – areas with soil types that allow water to penetrate accompanied by a geologic makeup under the soil that filters and sends water to the aquifer.
Once special recharge sites are identified, we need to preserve or restore them. Here, progress is being made in both urban and in rural areas. For example, Santa Cruz and Butte Counties both have general plan language protecting important recharge sites from development.
…To get where we need to go, multi-benefit groundwater recharge projects must expand in number and scale. …working together, they can assure the ultimate success of California’s new Sustainable Groundwater Management Act….
The Earth’s rising temperature is expected to knock the global water cycle out of whack, but exactly how it will change is uncertain. Scientists, though, can look for clues as to what the future might bring in the major climate swings that have happened in the past.
A new study that does just that suggests that Earth’s rain belts could be pushed northward as the Northern Hemisphere heats up faster than the Southern Hemisphere. That shift would happen in concert with the longstanding expectation for already wet areas to see more rain and for dry ones to become more arid.
….These changes in rain distribution could have implications for future water resources, particularly in areas where water supplies are already stressed, such as the western U.S.and parts of Africa…
Biologists have shown what could be a startling drop in the amount of carbon stored in the Sierra Nevada mountains due to projected climate change and wildfire events.
….roughly half of all human-emitted carbon is absorbed by vegetation and the ocean, and is stored through natural processes — something that helps limit our actual carbon impact on the atmosphere. The problem is, as forests begin to change, due to global warming and large scale fires, the amount of forest carbon uptake will decrease, accelerating the amount of human-made carbon making its way into the atmosphere.
“Our simulations in the Sierra Nevada show that the mean amount of carbon loss from the forests under these projections could be as large as 663 teragrams,” said Hurteau. “That’s equal to about 73 percent of the total above ground carbon stock estimated in California vegetation in 2010.”
…The two factors that influence these findings are changes in climate and the likelihood of large scale forest fires. Because California is experiencing warmer and drier conditions due to global warming, certain tree species are not able to flourish across particular geographic regions like they once were. Less tree growth, means less carbon uptake in forests.
The study also shows that wildfires will play a big role in the reduction of stored carbon. And while many of these incidents will occur naturally, Hurteau says we are, in part, to blame for their significance….
…”We’ve been putting out fires for a hundred years, causing tree density to go way up. In the absence of fire that system has a lot more carbon stored in it,” explained Hurteau. “But, when you have these large fire events the amount of carbon stored in the system drops because it kills many of the trees. Whereas, in a forest that’s been maintained by regular forest fires, which is the natural ecological state, your total carbon at any given point in time can be lower but it stays more consistent.”
…Hurteau says researchers have identified strategies for reducing some of the fire risk by actively thinning forests to manage tree density and restoring surface fires. It’s an idea that seems counterproductive until you consider how volatile these ecosystems are due to the risk of large scale fires that end up destroying hundreds of thousands of acres.
…He says it’s not only for the benefit of nature but for all of us, since healthy ecosystems lead to cleaner, better regulated water flow to communities across the western United States.
Shuang Liang, Matthew D. Hurteau, Anthony LeRoy Westerling. Potential decline in carbon carrying capacity under projected climate-wildfire interactions in the Sierra Nevada. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-02686-0
By Jeannette E. Warnert April 5, 2017 University of California Division of Agriculture and Natural Resources Blog
The new publication, Adapting Forests to Climate Change, can be downloaded free from the UC ANR Catalog. It is the 25th in the Forest Stewardship series, developed to help forest landowners in California learn how to manage their land. It was written by Adrienne Marshall, a doctoral student at the University of Idaho; Susie Kocher, UC Cooperative Extension forestry and natural resources advisor; Amber Kerr, postdoctoral scholar with the UC John Muir Institute of the Environment; and Peter Stine, U.S. Forest Service.
The document provides specific recommendations for care of three common types of forest in California: mixed conifer, oak woodland and coastal redwood forests… see page 12 for specific management recommendations.
In the past, scientists typically avoided linking individual weather events to climate change, citing the challenges of teasing apart human influence from the natural variability of the weather. But that is changing.
…In a new study, published in this week’s issue of Proceedings of the National Academy of Sciences, Diffenbaugh and a group of current and former Stanford colleagues outline a four-step “framework” for testing whether global warming has contributed to record-setting weather events. The new paper is the latest in a burgeoning field of climate science called “extreme event attribution,” which combines statistical analyses of climate observations with increasingly powerful computer models to study the influence of climate change on individual extreme weather
….”Our results suggest that the world isn’t quite at the point where every record hot event has a detectable human fingerprint, but we are getting close,” Diffenbaugh said. For the driest and wettest events, the authors found that human influence on the atmosphere has increased the odds across approximately half of the area that has reliable observations.
….One high-profile test case was Arctic sea ice, which has declined by around 40 percent during the summer season over the past three decades. When the team members applied their framework to the record-low Arctic sea ice cover observed in September 2012, they found overwhelming statistical evidence that global warming contributed to the severity and probability of the 2012 sea ice measurements. “The trend in the Arctic has been really steep, and our results show that it would have been extremely unlikely to achieve the record-low sea ice extent without global warming,” Diffenbaugh said.
Noah S. Diffenbaugh, Deepti Singh, Justin S. Mankin, Daniel E. Horton, Daniel L. Swain, Danielle Touma, Allison Charland, Yunjie Liu, Matz Haugen, Michael Tsiang, Bala Rajaratnam. Quantifying the influence of global warming on unprecedented extreme climate events. Proceedings of the National Academy of Sciences, 2017; 201618082 DOI: 10.1073/pnas.1618082114
A team of Stanford and Columbia University researchers have found that U.S. grasslands may be more sensitive to atmospheric dryness than rainfall; their study suggests that scientists may have to look more to rising temperatures than precipitation in predicting plants’ response to global warming. Published on March 6 in Nature Geoscience, the researchers’ study examined 33 years of satellite data to understand grassland productivity in dry conditions. The timescale and quantity of data the team examined allows the study to inform predictive models of how environments will respond to droughts — which are likely to become more prevalent with rising temperatures around the globe. …”U.S. grasslands are way more sensitive to vapor pressure deficit (VPD), which is important. Because VPD is so tightly linked to temperature, we can predict that it’s going to keep going up in the future.”…
…We conclude that increases in vapour pressure deficit rather than changes in precipitation—both of which are expected impacts of climate change—will be a dominant influence on future grassland productivity.