Posts tagged Earth System Research Laboratory
Climate change could dry up Salt Lake City watersheds
Nov 1st
New study: Rising temperatures
challenge Salt Lake City’s water supply
challenge Salt Lake City’s water supply
In an example of the challenges water-strapped Western cities will face in a warming world, new research shows that every degree Fahrenheit of warming in the Salt Lake City region could mean a 1.8 to 6.5 percent drop in the annual flow of streams that provide water to the city.
By midcentury, warming Western temperatures may mean that some of the creeks and streams that help slake Salt Lake City’s thirst will dry up several weeks earlier in the summer and fall, according to the new paper, published today in the journal Earth Interactions. The findings may help regional planners make choices about long-term investments, including water storage and even land-protection policies.
Dell Creek in Parley’s Canyon, is a source of water for Salt Lake City. A new study shows how climate change is likely to affect the various creeks and streams that help slake Salt Lake City’s thirst.
“Many Western water suppliers are aware that climate change will have impacts, but they don’t have detailed information that can help them plan for the future,” said lead author Tim Bardsley, with NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder. “Because our research team included hydrologists, climate scientists and water utility experts, we could dig into the issues that mattered most to the operators responsible for making sure clean water flows through taps and sprinklers without interruption.”
Bardsley works for the CIRES Western Water Assessment, from the NOAA Colorado Basin River Forecast Center in Salt Lake City. For the new paper, he worked closely with colleagues from the city’s water utility, the National Center for Atmospheric Research (NCAR), NOAA’s Earth System Research Laboratory and the University of Utah.
The team relied on climate model projections of temperature and precipitation in the area, historical data analysis and a detailed understanding of the region from which the city utility obtains water. The study also used NOAA streamflow forecasting models that provide information for Salt Lake City’s current water operations and management.
The picture that emerged was similar, in some ways, to previous research on the water in the Interior West: Warmer temperatures alone will cause more of the region’s precipitation to fall as rain than snow, leading to earlier runoff and less water in creeks and streams in the late summer and fall.
“Many snow-dependent regions follow a consistent pattern in responding to warming, but it’s important to drill down further to understand the sensitivity of watersheds that matter for individual water supply systems,” said NCAR’s Andy Wood, a co-author.
The specifics in the new analysis—which creeks are likely to be impacted most and soonest, how water sources on the nearby western flank of the Wasatch Mountains and the more distant eastern flank will fare—are critical to water managers with Salt Lake City.
“We are using the findings of this sensitivity analysis to better understand the range of impacts we might experience under climate change scenarios,” said co-author Laura Briefer, water resources manager at the Salt Lake City Department of Public Utilities. “This is the kind of tool we need to help us adapt to a changing climate, anticipate future changes and make sound water-resource decisions.”
“Water emanating from our local Wasatch Mountains is the lifeblood of the Salt Lake Valley, and is vulnerable to the projected changes in climate,” said Salt Lake City Mayor Ralph Becker. “This study, along with other climate adaptation work Salt Lake City is doing, helps us plan to be a more resilient community in a time of climate change.”
Among the details in the new assessment:
- Temperatures are already rising in northern Utah, about 2 degrees Fahrenheit in the last century, and continue to climb. Summer temperatures have increased especially steeply and are expected to continue to do so. Increasing temperatures during the summer irrigation season may increase water demand.
- Every increase in a degree Fahrenheit means an average decrease of 3.8 percent in annual water flow from watersheds used by Salt Lake City. This means less water available from Salt Lake City’s watersheds in the future.
- Lower-elevation streams are more sensitive to increasing temperatures, especially from May through September, and city water experts may need to rely on less-sensitive, higher-elevation sources in late summer, or more water storage.
- Models tell an uncertain story about total future precipitation in the region, primarily because Utah is on the boundary of the Southwest (projected to dry) and the U.S. northern tier states (projected to get wetter).
- Overall, models suggest increased winter flows, when water demand is lower, and decreased summer flows when water demand peaks.
- Annual precipitation would need to increase by about 10 percent to counteract the stream-drying effect of a 5-degree increase in temperature.
- A 5-degree temperature increase would also mean that peak water flow in the western Wasatch creeks would occur two to four weeks earlier in the summer than it does today. This earlier stream runoff will make it more difficult to meet water demand as the summer irrigation season progresses.
Authors of the new paper, “Planning for an Uncertain Future: Climate Change Sensitivity Assessment Toward Adaptation Planning for Public Water Supply,” are Tim Bardsley, CIRES Western Water Assessment; Andrew Wood, NCAR and formerly of NOAA’s Colorado Basin River Forecast Center; Mike Hobbins, NOAA’s Earth System Research Laboratory, and formerly NOAA’s Colorado Basin River Forecast Center; Tracie Kirkham, Laura Briefer, and Jeff Niermeyer, Salt Lake City Department of Public Utilities, Salt Lake City, Utah; and Steven Burian, University of Utah, Salt Lake City.
Earth Interactions is jointly published by the American Geophysical Union, the American Meteorological Society and the Association of American Geographers.
CIRES is a joint institute of NOAA and CU-Boulder.
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As the planet warms faster, more species will be increasingly at risk
Apr 21st
The Earth’s climate zones are shifting at an accelerating pace, says a new study led by a scientist at the CU’s Cooperative Institute for Research in Environmental Sciences.
The acceleration of change means that the species inhabiting each zone have less time to adapt to the climatic changes, said lead author Irina Mahlstein, a CIRES scientist who works at NOAA’s Earth System Research Laboratory in Boulder, Colo. “The warmer the climate gets, the faster the climate zones are shifting. This could make it harder for plants and animals to adjust.”
The study is the first to look at the accelerating pace of the shifting of climate zones, which are areas of the Earth defined by annual and seasonal cycles of temperature and precipitation, as well as temperature and precipitation thresholds of plant species. Over 30 different climate zones are found on Earth; examples include the equatorial monsoonal zone, the polar tundra zone and cold arid desert zone.
“A shift in the climate zone is probably a better measure of ‘reality’ for living systems, more so than changing temperature by a degree or precipitation by a centimeter,” said Mahlstein.
The scientists used climate model simulations and a well-known ecosystem classification scheme to look at the shifts between climate zones over a two-century period, 1900 to 2098. The team found that for an initial 3.6 degrees Fahrenheit of warming, about 5 percent of Earth’s land area shifts to a new climate zone.
The models show that the pace of change quickens for the next 3.6 F of warming as an additional 10 percent of the land area shifts to a new climate zone. The paper was published online in the journal Nature Climate Change on April 21.
Certain regions of the globe, such as northern middle and high latitudes, will undergo more changes than other regions, such as the tropics, the scientists found. In the tropics, mountainous regions will experience bigger changes than low-altitude areas.
In the coming century, the findings suggest that frost climates — the coldest climate zone of the planet — will largely decrease. In general, dry regions in different areas of the globe will increase, and a large fraction of land area will change from cool summers to hot summers, according to the study.
The scientists also investigated whether temperature or precipitation had a greater impact on how much of the land area changed zones. “We found that temperature is the main factor, at least through the end of this century,” said Mahlstein.
John Daniel at the NOAA Earth System Research Laboratory and Susan Solomon at the Massachusetts Institute of Technology co-authored the study.
-CU press release
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CU-NOAA study shows summer climate change, mostly warming
Nov 15th
Analysis of 90 years of observational data has revealed that summer climates in regions across the globe are changing — mostly, but not always, warming –according to a new study led by a scientist from the Cooperative Institute for Research in Environmental Sciences headquartered at the University of Colorado Boulder.
“It is the first time that we show on a local scale that there are significant changes in summer temperatures,” said lead author CIRES scientist Irina Mahlstein. “This result shows us that we are experiencing a new summer climate regime in some regions.”
The technique, which reveals location-by-location temperature changes rather than global averages, could yield valuable insights into changes in ecosystems on a regional scale. Because the methodology relies on detecting temperatures outside the expected norm, it is more relevant to understand changes to the animal and plant life of a particular region, which scientists would expect to show sensitivity to changes that lie outside of normal variability.
“If the summers are actually significantly different from the way that they used to be, it could affect ecosystems,” said Mahlstein, who works in the Chemical Sciences Division of the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory.
To identify potential temperature changes, the team used climate observations recorded from 1920 to 2010 from around the globe. The scientists termed the 30-year interval from 1920 to 1949 the “base period,” and then compared the base period to other 30-year test intervals starting every 10 years since 1930.
The comparison used statistics to assess whether the test interval differed from the base period beyond what would be expected due to yearly temperature variability for that geographical area.
Their analysis found that some changes began to appear as early as the 1960s, and the observed changes were more prevalent in tropical areas. In these regions, temperatures varied little throughout the years, so the scientists could more easily detect any changes that did occur, Mahlstein said.
The scientists found significant summer temperature changes in 40 percent of tropical areas and 20 percent of higher-latitude areas. In the majority of cases, the researchers observed warming summer temperatures, but in some cases they observed cooling summer temperatures.
“This study has applied a new approach to the question, ‘Has the temperature changed in local areas?’ ” Mahlstein said. The study is in press in the journal Geophysical Research Letters, a publication of the American Geophysical Union.
The study’s findings are consistent with other approaches used to answer the same question, such as modeling and analysis of trends, Mahlstein said. But this technique uses only observed data to come to the same result. “Looking at the graphs of our results, you can visibly see how things are changing,” she said.
In particular the scientists were able to look at the earlier time periods, note the temperature extremes, and observe that those values became more frequent in the later time periods. “You see how the extreme events of the past have become a normal event,” Mahlstein said.
The scientists used 90 years of data for their study, a little more than the average lifespan of a human being. So if inhabitants of those areas believe that summers have changed since they were younger, they can be confident it is not a figment of their imagination.
“We can actually say that these changes have happened in the lifetime of a person,” Mahlstein said.
Co-authors on the study were Gabriele Hegerl from the University of Edinburgh in Scotland and Susan Solomon from Massachusetts Institute of Technology.
CIRES is a joint institute of CU-Boulder and NOAA.
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