By Star-Advertiser staff 
 
 
 
 COURTESY U.S. GEOLOGICAL SURVEY Lake Waiau, below the summit of Mauna Kea, has nearly disappeared since 2010. 
 
 
 
 Scientists at the Hawaiian Volcano Observatory say Lake Waiau, the tiny body of water just below Mauna Kea's summit has been shrinking at an alarming rate and has almost disappeared. 
 
 Since 2010, the lake has shrunk from about 1.2 to 1.7 acres to about .03 acres, 2 percent of its normal surface area, according to this week's Volcano Watch article. 
 
 The lake had been about 3 yards deep, but the water level is now less than a foot, meaning the water volume has shrunk to about 1 percent of its 2010 size, according to measurements by former University of Hawaii Hilo professor Donna Delparte. 
 
 Observatory scientists, Office of Mauna Kea Management rangers and state land and wildlife officials have been monitoring the disappearing water. But they are still trying to figure out why the lake is disappearing. 
 
 Scientists say, based on historical photographs and written reports, that a drop of this magnitude hasn't happened in the lake's recorded history. 
 
 Drought may be a factor in the water loss, the Volcano Watch article said. 
 
 "The Mauna Kea visitor center weather station shows very little precipitation for several consecutive months in early 2010, which may have been a trigger for the level drop that was sustained by low precipitation over the subsequent few years. The National Drought Mitigation Center shows that the drought across Hawaii intensified in early 2010," observatory scientists said. 
 
 But there could be other factors. 
 
 Lake Waiau is a "perched" water body, in which water is held in a depression by an impermeable substrate of layers of silty clay, interbedded with ash layers, and possibly permafrost, the article said. 
 
 Scientists are also wondering if the permafrost that surrounds the lake may have altered the water balance. 
 
 Scientists are asking residents with historical photographs of the lake to contact them by email at askHVO@usgs.gov. 
 
 "Given its cultural significance and its uniqueness, the disappearance of Lake Waiau would be a great loss for Hawaii. The future is far from certain for Lake Waiau, and DLNR (Department of Land and Natural Resources), rangers, and scientists will continue to watch this situation," the Volcano Watch article said. ||||| During the Last Glacial Maximum, large lakes (light blue) covered many of the now dry desert basins of Nevada, Oregon and California. Credit: Daniel Ibarra (Phys.org) —A new study by Stanford scientists solves a longstanding mystery of how ancient lakes in the western United States grew to such colossal sizes. 
 
 The research, published in the journal Geological Society of America Bulletin, found that the lakes were able to grow large – rivaling the Great Lakes – during the peak of the last Ice Age 21,000 years ago, a period known as the "Last Glacial Maximum," because evaporation rates were significantly lower than today. 
 
 "It was previously thought that the lakes grew because there was more rain and snowfall during this period of the Earth's history," said Daniel Ibarra, a graduate student in Stanford's Department of Environmental Earth System Science and the first author of the study. 
 
 More quantitative studies of past climate could help refine the computer models used by the Intergovernmental Panel on Climate Change (IPCC) to simulate Earth's atmospheric conditions under changing atmospheric conditions, said Kate Maher, assistant professor of geological and environmental sciences, who headed the project. 
 
 "The IPCC uses climate models to simulate past and future climate, so knowing that some of the models do a better job of simulating past changes gives us more confidence that we understand the physics involved," Maher said. "That can give us more confidence in the models we use to simulate future climate change." 
 
 During the Last Glacial Maximum (LGM), giant lakes covered large sections of California, Nevada, Oregon and Utah, including where Salt Lake City is today. Earth scientists have long been puzzled by how these ancient lakes, now completely dry, grew so large. The prevailing theory was there was more rain and snowfall during this time period. But recent evidence from paleoecology and climate model simulations indicates that precipitation rates were actually relatively low compared to later periods. 
 
 To resolve the discrepancy between computer models and the interpretation of geologic evidence, Ibarra collected more than 80 samples of tufa – a limestone created by the evaporation of mineralized water – from different locations around the edges of Lake Surprise, a moderate-sized fossil lake in Surprise Valley, California. 
 
 The layered shorelines of California's Lake Surprise date back to the peak of the last Ice Age and provide a record of lake level changes over thousands of years. Credit: Anne Egger "The smaller lakes can tell you about the regional climate and can serve as a water gauge for the bigger lakes," Maher said. 
 
 By measuring the decay of radioactive carbon-14 and uranium in tufa samples, the team reconstructed the ancient shorelines of Lake Surprise at different times in the past. Their findings showed that at the height of the LGM, Lake Surprise had a surface area of about 390 square miles, roughly the size of San Francisco Bay. 
 
 With support from other laboratories at Stanford, Ibarra also used a mass spectrometer to precisely measure the amounts of two slightly different forms of oxygen in the tufa samples: oxygen-16 and the slightly heavier oxygen-18. Both isotopes of oxygen are present in water, but oxygen-18 water evaporates at a slower rate than oxygen-16 water. By knowing the ratio of oxygen-16 to oxygen-18 in the tufa samples, the scientists were able to calculate Lake Surprise's water balance through time. 
 
 Cooler temperatures 
 
 Their analyses revealed that 21,000 years ago, the evaporation rate at Lake Surprise was nearly 40 percent lower than today, with precipitation rates similar to the modern era. These results are consistent with previously run climate simulations that show Earth's climate was cooler during the LGM. 
 
 The cooler global temperatures would have reduced evaporation rates, allowing the lakes to gradually grow over time through inflows from streams and rivers. 
 
 "Lake Surprise is located in a closed basin. All streams flow into the lake, but there is no outflow. The only way for water to escape is through evaporation," Ibarra said. 
 
 The team's dating and isotope measurements also show that precipitation rates in the region increased for a brief period after the LGM. The tufa measurements indicated that Lake Surprise reached its largest size – around 530 square miles – 15,000 years ago. 
 
 Thus, the enormous lakes that once dotted the western United States initially grew large during the peak of the LGM due to reduced evaporation, but didn't reach their maximum sizes until several thousand years later, when rain and snowfall increased. 
 
 Knowledge about the past precipitation patterns of the region could be used to test the accuracy of the differing climate models scientists currently use to simulate global climate conditions. 
 
 "We can actually rank the models now," Ibarra said. "Our findings have implications for evaluating the models, and deciding which models successfully reproduced the past precipitation patterns we observe." 
 
 Explore further: Study of past climate change in Pacific Northwest lakes may presage future drought 
 
 More information: "Rise and fall of late Pleistocene pluvial lakes in response to reduced evaporation and precipitation: Evidence from Lake Surprise, California," Geological Society of America Bulletin, B31014.1, first published on June 2, 2014, DOI: 10.1130/B31014.1 ||||| Geoscientists have solved a decade-long mystery of how some of the large lakes that sit atop the Greenland ice sheet can completely drain billions of gallons of water in a matter of hours. 
 
 In 2006, Greenland's North Lake, a 2.2 square-mile (5.6 square kilometers) supraglacial meltwater lake, drained almost 12 billion gallons of water in less than two hours. In a study published two years later, researchers determined that this astonishing phenomenon is possible because giant hydro-fractures(water-driven cracks) can form directly beneath the lake basin and stretch down to the bed of the ice sheet, emptying the lake of water. But just how these fractures developed has been unknown — until now. 
 
 In the new study, published today (June 3) in the journal Nature, scientists using GPS technology discovered that the hydro-fractures form from tension-related stress caused by movements of the ice sheet. These movements are, in turn, triggered by the trickling meltwater. [See Gorgeous Images of Greenland's Supraglacial Lakes] 
 
 The new research may help scientists better understand how much the ice sheet is contributing to sea level rise, researchers say. 
 
 Most of Greenland's supraglacial lakes drain slowly when superficial streams route water into nearby, permanent crevasses or moulins (vertical conduits or shafts in a glacier). Fairly recently, however, satellite images showed that about 13 percent of the lakes drain quickly, emptying completely within 24 hours. 
 
 "The images would show the lake there one day, and gone the next day," said first author of the new study, Laura Stevens, a glaciology doctoral candidate with the Massachusetts Institute of Technology/Woods Hole Oceanographic Institution (MIT-WHOI) Joint Program. "So we've known for the last 10 to 15 years that the water could disappear quickly." 
 
 A moulin, or crack, formed along the hydro-fracture through Greenland's North Lake basin continues to drain meltwater to the bed after the 2013 North Lake rapid drainage. Credit: Ian Joughin 
 
 The 2008 research, led by Stevens' co-author Sarah Das, a WHOI geological scientist, showed that temporary hydro-fractures could cause rapid lake drainage on an unprecedented scale. But that research was unable to determine what triggered the cracks in the first place. Two other, similar studies of different rapidly draining supraglacial lakes were also unable to identify what caused the hydro-fractures. 
 
 "The coverage of GPS stations was not dense enough," Stevens told Live Science. "This study goes beyond previous studies on the lakes, because we have 16 GPS stations, as opposed to one or four." 
 
 When meltwater in the summer drains to the bed from the ice surface through crevasses or moulins, it can cause the area within and around the lake basin to be "jacked up," Stevens said. Additionally, it can decrease the surface area of the ice-sheet bed that's in contact with the underlying bedrock, lubricating the bed and making it easier for the bed to move horizontally. 
 
 Placed around North Lake, the team's 16 GPS stations recorded these two types of movements — called uplift and slip — between 2011 and 2013. This provided an in-depth perspective on the meltwater injected into the bed before, during and after the yearly drainages. 
 
 "We found that before we get the main expression of the lake drainage, there is a period of time (about six to 12 hours) where uplift and slip increase," Stevens said. "That motion is enough to take the surface of the ice sheet and put portions of it in high tension that allows cracks to start forming." 
 
 The study provides a clearer picture of the amount and location of the meltwater that travels down to the ice-sheet bed, which could help scientists better understand how fast the ice sheet flows during the summer, Stevens said. 
 
 This is important because the inland ice that moves toward the coast gets funneled to so-called outlet glaciers, which are tonguelike protrusions that can break off to form icebergs that may drift off into the ocean and eventually melt. 
 
 "It's half of the equation of how the Greenland ice sheet contributes to sea level rise, with the other half being the years when the ice sheet melts quicker than the snow is deposited," Stevens said. 
 
 Follow Joseph Castroon Twitter. Follow us @livescience, Facebook& Google+. Original article on Live Science.
– Climate change, sinkholes, human water use—the reasons are many, but the result is the same: Lakes across the world have shrunk or disappeared completely, and in the Smithsonian, Sarah Zielinski tells their stories. Among them: It's called the Dead Sea, but it's technically a lake, and it's been around for millennia. Thanks to water diverted to businesses and homes, however, the balance between water entering and evaporating from the lake has been thrown off. Now, it's getting shallower, at a rate of about a meter yearly—though officials are working on the problem. Lake Waiau was seen by native Hawaiians as a sacred spot. Just 10 feet deep at its deepest, it started disappearing in 2010, and as of September, it was just a pond, less than a foot deep. The reason for the phenomenon, which US officials call "unprecedented in modern times," isn't known for certain; drought is among the possibilities. Florida's Scott Lake was the victim of a 2006 sinkhole; it was gone within two weeks, and it took some 32 tons of wildlife with it. The lake is slowly returning as clay and silt fill the sinkhole, but whether it will be back for good is an open question. Last year saw Chile's Lake Cachet 2, in the Andes, disappear in a night. The culprit here was climate change, which has caused the glacial lake's frequent disappearance and return. The Colonia glacier holds Lake Cachet 2 in place; when melting thins the glacier, a tunnel allows the water to escape. Lake Chad, which is found in Cameroon, Chad, Niger, and Nigeria, used to be the sixth-biggest lake in the world. Not anymore: Some 90% of its area is gone, thanks to a combination of familiar reasons—drought, human use, and climate change among them. That's caused a "local lack of water, crop failures, livestock deaths, collapsed fisheries, soil salinity, and increasing poverty throughout the region," the UN says. Images at Discover magazine show the changing lake. Click for Zielinski's full list.