Posts tagged results
While 99 percent of Earth’s land ice is locked up in the Greenland and Antarctic ice sheets, the remaining ice in the world’s glaciers contributed just as much to sea rise as the two ice sheets combined from 2003 to 2009, says a new study led by Clark University and involving the University Colorado Boulder.
The new research found that all glacial regions lost mass from 2003 to 2009, with the biggest ice losses occurring in Arctic Canada, Alaska, coastal Greenland, the southern Andes and the Himalayas. The glaciers outside of the Greenland and Antarctic sheets lost an average of roughly 260 billion metric tons of ice annually during the study period, causing the oceans to rise 0.03 inches, or about 0.7 millimeters per year.
The study compared traditional ground measurements to satellite data from NASA’s Ice, Cloud and Land Elevation Satellite, or ICESat, and the Gravity Recovery and Climate Experiment, or GRACE, missions to estimate ice loss for glaciers in all regions of the planet.
“For the first time, we’ve been able to very precisely constrain how much these glaciers as a whole are contributing to sea rise,” said geography Assistant Professor Alex Gardner of Clark University in Worcester, Mass., lead study author. “These smaller ice bodies are currently losing about as much mass as the ice sheets.”
A paper on the subject is being published in the May 17 issue of the journal Science.
“Because the global glacier ice mass is relatively small in comparison with the huge ice sheets covering Greenland and Antarctica, people tend to not worry about it,” said CU-Boulder Professor Tad Pfeffer, a study co-author. “But it’s like a little bucket with a huge hole in the bottom: it may not last for very long, just a century or two, but while there’s ice in those glaciers, it’s a major contributor to sea level rise,” said Pfeffer, a glaciologist at CU-Boulder’s Institute of Arctic and Alpine Research
ICESat, which ceased operations in 2009, measured glacier changes using laser altimetry, which bounces laser pulses off the ice surface to determine changes in the height of ice cover. The GRACE satellite system, still operational, detects variations in Earth’s gravity field resulting from changes in the planet’s mass distribution, including ice displacements.
GRACE does not have a fine enough resolution and ICESat does not have sufficient sampling density to study small glaciers, but mass change estimates by the two satellite systems for large glaciated regions agree well, the scientists concluded.
“Because the two satellite techniques, ICESat and GRACE, are subject to completely different types of errors, the fact that their results are in such good agreement gives us increased confidence in those results,” said CU-Boulder physics Professor John Wahr, a study co-author and fellow at the university’s Cooperative Institute for Research in Environmental Sciences.
Ground-based estimates of glacier mass changes include measurements along a line from a glacier’s summit to its edge, which are extrapolated over a glacier’s entire area. Such measurements, while fairly accurate for individual glaciers, tend to cause scientists to overestimate ice loss when extrapolated over larger regions, including individual mountain ranges, according to the team.
Current estimates predict if all the glaciers in the world were to melt, they would raise sea level by about two feet. In contrast, an entire Greenland ice sheet melt would raise sea levels by about 20 feet, while if Antarctica lost its ice cover, sea levels would rise nearly 200 feet.
The study involved 16 researchers from 10 countries. In addition to Clark University and CU-Boulder, major research contributions came from the University of Michigan, the Scripps Institution of Oceanography in San Diego, Trent University in Ontario, Canada, and the University of Alaska Fairbanks.
Built by Ball Aerospace & Technologies in Boulder, NASA’s ICESat satellite was successfully operated from the CU-Boulder campus by a team made up primarily of undergraduates from its launch in 2003 to its demise in 2009 when the science payload failed. The students participated in the unusual decommissioning of a functioning satellite in 2010, bringing the craft into Earth re-entry to burn up. ICESat’s successor, ICESat-2, is slated for launch in 2016 by NASA.
-CU media release-
About four in five respondents reported satisfaction with their CU-Boulder education. A similar proportion would recommend CU-Boulder to a friend and nearly 98 percent of the seniors reported that their program of study met their educational goals.
The 2012 study is the latest edition of the senior survey, conducted 11 times since 1985 by CU-Boulder’s Office of Planning, Budget and Analysis, or PBA.
“The survey data clearly demonstrate that these students, from their perspective as seniors, judge the university in overwhelmingly positive terms,” said Michael Grant, CU-Boulder associate vice chancellor for undergraduate education. “CU-Boulder routinely invests a lot of time and energy in polling our senior students about their experiences, academic and otherwise, in order to continuously work toward improving those experiences.”
The online questionnaire was sent to 7,646 degree-seeking seniors and was completed by 2,890, or 38 percent, of the recipients. Comprising about 200 scaled items, plus four open-ended questions, the survey collected a massive amount of information including nearly 7,900 written comments.
The 2012 seniors’ ratings of CU-Boulder advising services were higher than those from any previous senior survey. The seniors’ satisfaction with numerous other CU-Boulder services, from libraries to information technology, was high and generally comparable to that of earlier cohorts.
“We use the survey results extensively to look at what’s popular and working well, to set goals to improve services, and even to pass along advice,” said Jim Davis Rosenthal, CU-Boulder director of orientation and director of the Office of Student Affairs Assessment. “Based on one of the survey questions, we are able to let incoming freshmen know what outgoing seniors wished they had gotten involved in. Other departments also use the results to encourage students to try opportunities they might not otherwise have considered. In a way, it’s like older siblings giving advice to their younger siblings.”
Large proportions of seniors said that if they were to start over at CU-Boulder, they would put more effort toward or spend more time on interacting with faculty (60 percent), career exploration (51 percent), and campus-related research projects, internships and applied experiences (45 percent).
Nearly two-thirds of seniors who expected to graduate by summer 2012 reported that their principal activity in fall 2012 was most likely to be paid employment, either full time (48 percent) or part time (15 percent). A combined 15 percent said they were most likely to be enrolled in graduate studies, professional school or other coursework. A combined 13 percent expected to go into military service, or pursue volunteer service, an internship, student teaching or travel.
The thousands of student comments included praise for various aspects of their major programs, suggestions for ways to enhance and improve major programs, and descriptions of ways in which their major program did or did not meet their educational goals.
One student wrote, “I feel that I am prepared to be an exceptional teacher after I graduate. The school had a lot to do with my preparedness.” Another wrote, “Excellent material, mostly great professors, and fantastic facilities all add up to a well-rounded education.”
The survey collects information on seniors’ satisfaction with their educational experiences at CU-Boulder and about their post-graduation plans. The survey’s findings are used primarily to provide systematic information for academic and service units to use in planning and improvement, and for use by prospective and current students, their advisers, and their families.
Preliminary results for the Seniors’ Future Plans Survey, which is separate from the comprehensive senior survey and which has been conducted each year since 2009, show a jump in full-time employment expectations. The initial data show that 54 percent of CU-Boulder seniors in 2013 expect full-time employment to be their principal activity after graduation, an increase from 48 percent in 2012. Expectations for part-time employment were reported by 15 percent of the 2013 seniors.
The 2012 questionnaire and comprehensive data from the senior survey, including summary reports from students in each of CU-Boulder’s schools and colleges and nearly 50 departments, are available athttp://www.colorado.edu/pba/surveys/senior/12/index.htm.
Outstanding winners of international competition, again
Two University of Colorado Boulder undergraduate student teams have been named among the 11 top winners from a field of 5,636 teams that entered the 2013 international Mathematical Contest in Modeling this spring.
Only 375 teams, or 6 percent of those entering the contest, were from the United States. The others were from Canada, China, Finland, Germany, Hong Kong, India, Indonesia, Ireland, Mexico, Malaysia, Singapore, South Korea, Sweden and the United Kingdom.
CU-Boulder had two teams designated as “Outstanding Winners” in 2012 as well, and has had a total of 13 Outstanding Winner designations since 2000.
“I don’t know any other university, from anywhere in the world, that has that track record,” said Anne Dougherty of CU-Boulder’s Department of Applied Mathematics. “This is a testament to our excellent students and exceptionally strong undergraduate program.”
One of the 2013 problems focused on developing an effective, feasible and cost-efficient strategy to meet projected water needs in a given country, while the other challenged students to develop the “ultimate brownie pan” to maximize heat distribution and cooking potential in an oven.
Results of the contest, which took place at the students’ home institutions Jan. 31-Feb. 4, were announced by the Consortium for Mathematics and its Applications on April 5.
One of the two CU-Boulder teams designated as an “Outstanding Winner” was comprised of students Gregory McQuie and David Thomas of aerospace engineering sciences, and Yueh-Ya Hsu of applied mathematics. The team also was awarded the Mathematical Association of America Award.
The other “Outstanding Winner” from CU-Boulder included students Christopher Aicher and Tracy Babb of applied mathematics, and Fiona Pigott, who is double-majoring in mechanical engineering and applied mathematics. The team also was presented with the Society for Industrial and Applied Mathematics Award.
Dougherty served as faculty adviser to both teams. Any undergraduate CU-Boulder student was welcome to participate.
A third team of CU-Boulder students entered the contest and was designated a “successful participant.” That team included students Runnan Lou of aerospace engineering, Weiming Zhang of applied mathematics and Xinyu Shen, who is double-majoring in math and physics.
According to the contest rules, the students had 96 hours to decide which of two problems to complete, research their problem, come up with a mathematical model, program a numerical model and write a report.
Official contest results are posted at http://www.comap.com/undergraduate/contests/mcm/contests/2013/results.
Astronomers targeting one of the brightest quasars glowing in the universe some 11 billion years ago say “sideline quasars” likely teamed up with it to heat abundant helium gas billions of years ago, preventing small galaxy formation.
CU-Boulder Professor Michael Shull and Research Associate David Syphers used the Hubble Space Telescope to look at the quasar — the brilliant core of an active galaxy that acted as a “lighthouse” for the observations — to better understand the conditions of the early universe. The scientists studied gaseous material between the telescope and the quasar with a $70 million ultraviolet spectrograph on Hubble designed by a team from CU-Boulder’s Center for Astrophysics and Space Astronomy.
During a time known as the “helium reionization era” some 11 billion years ago, blasts of ionizing radiation from black holes believed to be seated in the cores of quasars stripped electrons from primeval helium atoms, said Shull. The initial ionization that charged up the helium gas in the universe is thought to have occurred sometime shortly after the Big Bang.
“We think ‘sideline quasars’ located out of the telescope’s view reionized intergalactic helium gas from different directions, preventing it from gravitationally collapsing and forming new generations of stars,” he said. Shull likened the early universe to a hunk of Swiss cheese, where quasars cleared out zones of neutral helium gas in the intergalactic medium that were then “pierced” by UV observations from the space telescope.
The results of the new study also indicate the helium reionization era of the universe appears to have occurred later than thought, said Shull, a professor in CU-Boulder’s astrophysical and planetary sciences department. “We initially thought the helium reionization era took place about 12 billion years ago,” said Shull. “But now we think it more likely occurred in the 11 to 10 billion-year range, which was a surprise.”
A paper on the subject by Shull and Syphers was published online this week in the Astrophysical Journal.
The Cosmic Origins Spectrograph used for the quasar observations aboard Hubble was designed to probe the evolution of galaxies, stars and intergalactic matter. The COS team is led by CU Professor James Green of CASA and was installed on Hubble by astronauts during its final servicing mission in 2009. COS was built in an industrial partnership between CU and Ball Aerospace & Technologies Corp. of Boulder.
“While there are likely hundreds of millions of quasars in the universe, there are only a handful you can use for a study like this,” said Shull. Quasars are nuclei in the center of active galaxies that have “gone haywire” because of supermassive black holes that gorged themselves in the cores, he said. “For our purposes, they are just a really bright background light that allows us to see to the edge of the universe, like a headlight shining through fog.”
The universe is thought to have begun with the Big Bang that triggered a fireball of searing plasma that expanded and then become cool neutral gas at about 380,000 years, bringing on the “dark ages” when there was no light from stars or galaxies, said Shull. The dark ages were followed by a period of hydrogen reionization, then the formation of the first galaxies beginning about 13.5 billion years ago. The first galaxies era was followed by the rise of quasars some 2 billion years later, which led to the helium reionization era, he said.
The radiation from the huge quasars heated the gas to 20,000 to 40,000 degrees Fahrenheit in intergalactic realms of the early universe, said Shull. “It is important to understand that if the helium gas is heated during the epoch of galaxy formation, it makes it harder for proto-galaxies to hang on to the bulk of their gas. In a sense, it’s like intergalactic global warming.”
The team is using COS to probe the “fossil record” of gases in the universe, including a structure known as the “cosmic web” believed to be made of long, narrow filaments of galaxies and intergalactic gas separated by enormous voids. Scientists theorize that a single cosmic web filament may stretch for hundreds of millions of light years, an eye-popping number considering that a single light-year is about 5.9 trillion miles.
COS breaks light into its individual components — similar to the way raindrops break sunlight into the colors of the rainbow — and reveals information about the temperature, density, velocity, distance and chemical composition of galaxies, stars and gas clouds.
For the study, Shull and Syphers used 4.5 hours of data from Hubble observations of the quasar, which has a catalog name of HS1700+6416. While some astronomers define quasars as feeding black holes, “We don’t know if these objects feed once, or feed several times,” Shull said. They are thought to survive only a few million years or perhaps a few hundred million years, a brief blink in time compared to the age of the universe, he said.
“Our own Milky Way has a dormant black hole in its center,” said Shull. “Who knows? Maybe our Milky Way used to be a quasar.”
The first quasar, short for “quasi-stellar radio source,” was discovered 50 years ago this month by Caltech astronomer Maarten Schmidt. The quasar he observed, 3C-273, is located roughly 2 billion years from Earth and is 40 times more luminous than an entire galaxy of 100 billion stars. That quasar is receding from Earth at 15 percent of the speed of light, with related winds blowing millions of miles per hour, said Shull.
Boulder police are still investigating an assault case from March 2, 2012, which took place at Conor O’Neill’s Pub, located at 1922 13th St. around 12:37 a.m. The suspect remains unidentified and police are asking the public for assistance.
The male victim was in the restroom when the male suspect tried to enter the stall. The two men pushed each other and at one point, the suspect attacked the victim with a beer bottle. The victim was taken to the hospital to be treated for his injuries which included a concussion, cuts to his head and face and wounds on his chest and arms from the beer bottle.
The suspect fled the bar, and the victim believes a friend of the suspect tried to detain the victim as the suspect got away. The suspect was seen running westbound across 13th St. and through a parking lot. Police were unable to locate him.
At the time of the assault, the Boulder Police Department released a composite sketch and a description of the suspect. The suspect has not yet been identified and police are publicizing the information again, hoping that a member of the public may recognize the suspect and contact police.
The sketch is attached. The suspect is described as:
· White male
· 21 – 29 years old
· 6’0 – 6’3” tall, weighing 180 – 200 pounds
· Build was described as “not toned”
· Short blonde hair which may have been bleached or highlighted
· Witnesses described him as a “surfer type”
· At the time of the assault, was wearing a light-colored shirt or white shirt with blue pinstripes
· May have been bleeding from his mouth, and may have had a cut over his left eye
The case number is 12-2846.
Anyone with information is asked to contact Detective Tom Dowd at 303-441-3385. Those who have information but wish to remain anonymous may contact the Northern Colorado Crime Stoppers at 1-800-222-TIPS (8477) or 1-800-444-3776. Tips can also be submitted through the Crime Stoppers website at www.crimeshurt.com. Those submitting tips through Crime Stoppers that lead to the arrest and filing of charges on a suspect(s) may be eligible for a cash reward of up to $1,000 from Crime Stoppers.
A team led by the University of Colorado Boulder looking for clues about why Earth did not warm as much as scientists expected between 2000 and 2010 now thinks the culprits are hiding in plain sight — dozens of volcanoes spewing sulfur dioxide.
The study results essentially exonerate Asia, including India and China, two countries that are estimated to have increased their industrial sulfur dioxide emissions by about 60 percent from 2000 to 2010 through coal burning, said lead study author Ryan Neely, who led the research as part of his CU-Boulder doctoral thesis. Small amounts of sulfur dioxide emissions from Earth’s surface eventually rise 12 to 20 miles into the stratospheric aerosol layer of the atmosphere, where chemical reactions create sulfuric acid and water particles that reflect sunlight back to space, cooling the planet.
Neely said previous observations suggest that increases in stratospheric aerosols since 2000 have counterbalanced as much as 25 percent of the warming scientists blame on human greenhouse gas emissions. “This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet,” said Neely, a researcher at the Cooperative Institute for Research in Environmental Sciences, a joint venture of CU-Boulder and the National Oceanic and Atmospheric Administration.
A paper on the subject was published online in Geophysical Research Letters, a publication of the American Geophysical Union. Co-authors include Professors Brian Toon and Jeffrey Thayer from CU-Boulder; Susan Solomon, a former NOAA scientist now at the Massachusetts Institute of Technology; Jean Paul Vernier from NASA’s Langley Research Center in Hampton, Va.; Catherine Alvarez, Karen Rosenlof and John Daniel from NOAA; and Jason English, Michael Mills and Charles Bardeen from the National Center for Atmospheric Research in Boulder.
The new project was undertaken in part to resolve conflicting results of two recent studies on the origins of the sulfur dioxide in the stratosphere, including a 2009 study led by the late David Hoffman of NOAA indicating aerosol increases in the stratosphere may have come from rising emissions of sulfur dioxide from India and China. In contrast, a 2011 study led by Vernier — who also provided essential observation data for the new GRL study — showed moderate volcanic eruptions play a role in increasing particulates in the stratosphere, Neely said.
The new GRL study also builds on a 2011 study led by Solomon showing stratospheric aerosols offset about a quarter of the greenhouse effect warming on Earth during the past decade, said Neely, also a postdoctoral fellow in NCAR’s Advanced Study Program.
The new study relies on long-term measurements of changes in the stratospheric aerosol layer’s “optical depth,” which is a measure of transparency, said Neely. Since 2000, the optical depth in the stratospheric aerosol layer has increased by about 4 to 7 percent, meaning it is slightly more opaque now than in previous years.
“The biggest implication here is that scientists need to pay more attention to small and moderate volcanic eruptions when trying to understand changes in Earth’s climate,” said Toon of CU-Boulder’s Department of Atmospheric and Oceanic Sciences. “But overall these eruptions are not going to counter the greenhouse effect. Emissions of volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gas emissions from human activity just continue to go up.”
The key to the new results was the combined use of two sophisticated computer models, including the Whole Atmosphere Community Climate Model, or WACCM, Version 3, developed by NCAR and which is widely used around the world by scientists to study the atmosphere. The team coupled WACCM with a second model, the Community Aerosol and Radiation Model for Atmosphere, or CARMA, which allows researchers to calculate properties of specific aerosols and which has been under development by a team led by Toon for the past several decades.
Neely said the team used the Janus supercomputer on campus to conduct seven computer “runs,” each simulating 10 years of atmospheric activity tied to both coal-burning activities in Asia and to emissions by volcanoes around the world. Each run took about a week of computer time using 192 processors, allowing the team to separate coal-burning pollution in Asia from aerosol contributions from moderate, global volcanic eruptions. The project would have taken a single computer processor roughly 25 years to complete, said Neely.
The scientists said 10-year climate data sets like the one gathered for the new study are not long enough to determine climate change trends. “This paper addresses a question of immediate relevance to our understanding of the human impact on climate,” said Neely. “It should interest those examining the sources of decadal climate variability, the global impact of local pollution and the role of volcanoes.”
While small and moderate volcanoes mask some of the human-caused warming of the planet, larger volcanoes can have a much bigger effect, said Toon. When Mount Pinatubo in the Philippines erupted in 1991, it emitted millions of tons of sulfur dioxide into the atmosphere that cooled the Earth slightly for the next several years.
The research for the new study was funded in part through a NOAA/ ESRL-CIRES Graduate Fellowship to Neely. The National Science Foundation and NASA also provided funding for the research project. The Janus supercomputer is supported by NSF and CU-Boulder and is a joint effort of CU-Boulder, CU Denver and NCAR.
The City of Boulder today released a 38-page report detailing the results of extensive research into the possibility of creating a city-owned and operated electric utility. The evaluation looked at a total of six options for meeting the community’s Energy Future goals. One is a baseline evaluation of staying with Xcel Energy with no change to the way it operates. The other five are options predicated on the city creating its own utility, which would be free from regulations that can limit innovation and customization.
The results show that there are several forms a new utility could take that don’t require trade-offs among the community’s core values. The Boulder community has said it wants cleaner and greener energy with rates and reliability comparable to or better than those provided by Xcel Energy. The community is also seeking more local control and a voice in decision-making, as well as an opportunity to enhance economic vitality by providing a test bed for emerging technology and a low-cost, high-reliability environment in which businesses can thrive.
When Boulder voters approved the continued exploration of a municipal utility in November 2011, they set limiting requirements in the Charter that must be met before City Council could proceed. These included provisions related to rates, revenue sufficiency and reliability, as well as plans to reduce greenhouse gas (GHG) emissions and increase renewable sources of energy.
Under some of the options analyzed, a municipal electric utility would meet the Charter metrics and have a high likelihood of being able to:
· Offer all three major customer classes (residential, commercial and industrial) lower rates than what they would pay Xcel, not just on day one, as required by the Charter, but on average over 20 years;
· Maintain or exceed current levels of system reliability and emergency response, and, if the community chose to, use future investments to enhance dependability;
· Reduce harmful greenhouse gas emissions by more than 50 percent from current levels and exceed the Kyoto Protocol target in year one;
· Obtain 54 percent or more of its electricity from renewable resources; and
· Create a model public electric utility with leading-edge innovations in reliability, energy efficiency, renewable energy, related economic development and customer service.
The report also examines the impact that a variety of stranded cost and acquisition cost rulings could have on rates and revenue requirements over 20 years.
The full memo, with all attachments, is available at www.boulderenergyfuture.com.
Process and Participation
“We are excited to share the results of this detailed analysis with City Council and our community. We believe the findings demonstrate that a municipal utility could be good for consumers, good for Boulder businesses and good for our planet,” said Heather Bailey, executive director of Energy Strategy and Electric Utility Development. “We look forward to an informed conversation over the next couple of month about how best to proceed.”
Bailey said she is especially grateful for the participation of more than 50 community members, many of whom have industry expertise, who donated their time to serve on working groups. These groups helped to ensure that a variety of perspectives was included and that all modeling was based on reasonable assumptions and data.
“This has been a community-wide review process, and this has greatly enhanced the quality and integrity of our report,” Bailey said. “I wish to thank everyone who has played a role in this direct way, as well as the countless members of the public who have shared their thoughts and concerns with me over the past year.”
An Xcel Energy Partnership Alternative?
While the city is committed to exploring ways to achieve “the electric utility of the future,” it has acknowledged that there might be ways to do so short of creating its own utility – in the form of a new partnership with the existing electric provider, Xcel Energy.
In December, the city released a paper that outlined a variety of ideas that could achieve the community’s goals if Xcel Energy is interested. The city has since spoken with officials from the current utility several times, asking them to identify which of the suggestions they would be willing to consider, as well as any innovative approaches the company might like to propose. Xcel officials have said they are open to a dialogue but have not yet come forward with specifics about what ideas they would like to discuss.
The framework for considering how the city should proceed includes the possibility of modeling an Xcel partnership option, when and if additional details become available. There are, in the analysis released today, also at least two options that might be achievable with the participation of a collaborative and willing energy partner.
“What we are looking to do is move beyond a 19th century approach to providing energy and create a forward-looking, innovative and consumer-friendly utility model that reduces our reliance on fossil fuels,” Bailey said. “Xcel Energy has served us for decades, and in many ways, done an admirable job. It is possible they could help us meet our objectives. We would welcome their involvement in a meaningful, timely and transparent discussion.”
Boulder City Council is scheduled to hear a presentation based on this memo and ask questions at a Study Session on Tuesday, Feb. 26. The session will be broadcast live on Comcast Channel 8 for Boulder viewers and online at www.boulderchannel8.com. A recording will also be available at the above website for later viewing. There is no opportunity for public comment at study sessions, but they are an excellent way to learn more about a topic and the staff’s work.
City Council will discuss this issue again – and decide whether to move forward with the next steps related to the potential creation of a city electric utility – on April 16. This meeting will begin at 6 p.m. in Council Chambers at 1777 Broadway and will include a public hearing.
Opportunities for Public Feedback
Between now and council’s April 16 decision, the city is providing multiple ways for the community to provide input about the analysis and how council might move forward.
As always, council accepts correspondence on any issue of community interest. In addition, there is a comment form available for this specific initiative on the project website.
In addition, the city is offering the following unique opportunities:
· An online questionnaire that will be available at www.bouldercolorado.gov between Feb. 27 and March 27;
· A conference telephone call designed to focus on rates and reliability, two key concerns for the business community, from noon to 1 p.m. on Tuesday, March 12 (please register in advance at www.bouldercolorado.gov/energyfuture/businesscall);
· A community open house exploring the pros and cons of each of the modeled options from 6:30 to 8:30 p.m. on Wednesday, March 13, at the West Senior Center, 909 W. Arapahoe Ave.;
· Focused questions and examination of the options on the city’s new digital town hall platform, Inspire Boulder; and
· Presentations, by invitation, from Bailey or other members of the staff team to interested organizations and associations.
All input collected during the next couple of months will be shared with council in advance of the April 16 meeting.
CU-Boulder amphibian study shows how
biodiversity can protect against disease
The richer the assortment of amphibian species living in a pond, the more protection that community of frogs, toads and salamanders has against a parasitic infection that can cause severe deformities, including the growth of extra legs, according to a new study by the University of Colorado Boulder.
The findings, published Feb. 14 in the journal Nature, support the idea that greater biodiversity in larger-scale ecosystems, such as forests or grasslands, may also provide greater protection against diseases, including those that attack humans. For example, a larger number of mammal species in an area may curb cases of Lyme disease, while a larger number of bird species may slow the spread of West Nile virus.
“How biodiversity affects the risk of infectious diseases, including those of humans and wildlife, has become an increasingly important question,” said Pieter Johnson, an assistant professor in the Department of Ecology and Evolutionary Biology and lead author of the study. “But as it turns out, solidly testing these linkages with realistic experiments has proven very challenging in most systems.”
Researchers have struggled to design comprehensive studies that could illuminate the possible connection between disease transmission and the number of species living in complex ecosystems. Part of the problem is simply the enormous number of organisms that may need to be sampled and the vast areas over which those organisms may roam.
The new CU-Boulder study overcomes that problem by studying smaller, easier-to-sample ecosystems. Johnson and his team visited hundreds of ponds in California, recording the types of amphibians living there as well as the number of snails infected by the pathogen Ribeiroia ondatrae. Snails are an intermediate host used by the parasite during part of its life cycle.
“One of the great challenges in studying the diversity-disease link has been collecting data from enough replicate systems to differentiate the influence of diversity from background ‘noise,’ ” Johnson said. “By collecting data from hundreds of ponds and thousands of amphibian hosts, our group was able to provide a rigorous test of this hypothesis, which has relevance to a wide range of disease systems.”
Johnson’s team buttressed its field observations both with laboratory tests designed to measure how prone to infection each amphibian species is and by creating pond replicas outside using large plastic tubs stocked with tadpoles that were exposed to a known number of parasites. All of the experiments told the same story, Johnson said. Greater biodiversity reduced the number of successful amphibian infections and the number of deformed frogs.
In all, the CU-Boulder researchers spent three years sampling 345 wetlands and recording malformations — which include missing, misshapen or extra sets of hind legs — caused by parasitic infections in 24,215 amphibians. They also cataloged 17,516 snails. The results showed that ponds with half a dozen amphibian species had a 78 percent reduction in parasite transmission compared to ponds with just one amphibian species. The research team also set up experiments in the lab and outdoors using 40 artificial ponds, each stocked with 60 amphibians and 5,000 parasites.
The reason for the decline in parasitic infections as biodiversity increases is likely related to the fact that ponds add amphibian species in a predictable pattern, with the first species to appear being the most prone to infection and the later species to appear being the least prone. For example, the research team found that in a pond with just one type of amphibian, that amphibian was almost always the Pacific chorus frog, a creature that is able to rapidly reproduce and quickly colonize wetland habitats, but which is also especially vulnerable to infection and parasite-induced deformities.
On the other hand, the California tiger salamander was typically one of the last species to be added to a pond community and also one of the most resistant to parasitic infection. Therefore, in a pond with greater biodiversity, parasites have a higher chance of encountering an amphibian that is resistant to infection, lowering the overall success rate of transmission between infected snails and amphibians.
This same pattern — of less diverse communities being made up of species that are more susceptible to disease infection — may well play out in more complex ecosystems as well, Johnson said. That’s because species that disperse quickly across ecosystems appear to trade off the ability to quickly reproduce with the ability to develop disease resistance.
“This research reaches the surprising conclusion that the entire set of species in a community affects the susceptibility to disease,” said Doug Levey, program director in the National Science Foundation’s Division of Environmental Biology, which helped fund the research. “Biodiversity matters.”
The sheer magnitude of the recent study also reinforces the connection between deformed frogs and parasitic infection, Johnson said. Beginning in the mid-1990s reports of frogs with extra, missing or misshapen legs skyrocketed, attracting widespread attention in the media and motivating scientists to try to figure out the cause. Johnson was among the researchers who found evidence of a link between infection with Ribeiroia and frog deformities, though the apparent rise in reports of deformations, and its underlying cause, remains controversial.
While the new study has implications beyond parasitic infections in amphibians, it does not mean that an increase in biodiversity always results in a decrease in disease, Johnson cautioned. Other factors also affect rates of disease transmission. For example, a large number of mosquitoes hatching in a particular year will increase the risk of contracting West Nile virus, even if there has been an increase in the biodiversity of the bird population. Birds act as “reservoir hosts” for West Nile virus, harboring the pathogen indefinitely with no ill effects and passing the pathogen onto mosquitoes.
“Our results indicate that higher diversity reduces the success of pathogens in moving between hosts,” Johnson said. “Nonetheless, if infection pressure is high, for instance in a year with high abundance of vectors, there will still be a significant risk of disease; biodiversity will simply function to dampen transmission success.”
CU-Boulder graduate students Dan Preston and Katie Richgels co-authored the study along with Jason Hoverman, a former postdoctoral researcher in Johnson’s lab who is now an assistant professor at Purdue. The research was funded by NSF, the National Geographic Society and the David and Lucile Packard Foundation.
To view photos and a video about the research, visit http://freshwatersillustrated.org/link/AmphibianDeformities.
Creeping climate change in the Southwest appears to be having a negative effect on pinyon pine reproduction, a finding with implications for wildlife species sharing the same woodland ecosystems, says a University of Colorado Boulder-led study.
The new study showed that pinyon pine seed cone production declined by an average of about 40 percent at nine study sites in New Mexico and northwestern Oklahoma over the past four decades, said CU-Boulder doctoral student Miranda Redmond, who led the study. The biggest declines in pinyon pine seed cone reproduction were at the higher elevation research sites experiencing more dramatic warming relative to lower elevations, said Redmond of CU’s ecology and evolutionary biology department.
“We are finding significant declines in pinyon pine cone production at many of our study sites,” said Redmond. “The biggest declines in cone production we measured were in areas with greater increases in temperatures over the past several decades during the March to October growing season.”
The cones in which the pinyon seeds are produced are initiated two years prior to seed maturity, and research suggests the environmental stimulus for cone initiation is unseasonably low temperatures during the late summer, said Redmond. Between 1969 and 2009, unseasonably low temperatures in late summer decreased in the study areas, likely inhibiting cone initiation and development.
The study is one of the first to examine the impact of climate change on tree species like pinyon pines that, instead of reproducing annually, shed vast quantities of cones every few years during synchronous, episodic occurrences known as “masting” events. Redmond said such masting in the pinyon pine appears to occur every three to seven years, resulting in massive “bumper crops” of cones covering the ground.
In the new Ecosphere study, the researchers compared two 10-year sequences of time. In addition to showing that total pinyon pine cone production during the 2003-2012 decade had declined from the 1969-1978 decade in the study areas, the team found the production of cones during masting events also declined during that period.
Some scientists believe masting events evolved to produce a big surplus of nut-carrying cones — far too many for wildlife species to consume in a season — making it more likely the nuts eventually will sprout into pinyon pine seedlings, she said. Others have suggested masting events occur during favorable climate conditions and/or to increase pollination efficiency. “Right now we really don’t know what drives them,” Redmond said.
“Across a range of forested ecosystems we are observing widespread mortality events due to stressors such as changing climate, drought, insects and fire,” said CU’s Barger. “This study provides evidence that increasing air temperatures may be influencing the ability of a common and iconic western U.S. tree, pinyon pine, to reproduce. We would predict that declines in pinyon pine cone production may impact the long-term viability of these tree populations.”
Wildlife biologists say pinyon-juniper woodlands are popular with scores of bird and mammal species ranging from black-chinned hummingbirds to black bears. A 2007 study by researchers at the University of Northern Arizona estimated that 150 Clark’s Nutcrackers cached roughly 5 million pinyon pine nuts in a single season, benefiting not only the birds themselves but also the pines whose nuts were distributed more widely for possible germination.
For the new study, Redmond revisited nine pinyon pine study sites scattered throughout New Mexico and Oklahoma that had been studied previously in 1978 by Forcella. Both Forcella and Redmond were able to document pinyon pine masting years by counting small, concave blemishes known as “abscission scars” on individual tree branches that appeared after the cones have been dropped, she said.
Since each year in the life of a pinyon pine tree is marked by a “whorl” — a single circle of branches extending around a tree trunk — the researchers were able to bracket pinyon pine reproductive activity in the nine study areas for the 1969-1978 decade and 2003-2012 decade, which were then compared.
Pinyon pines take three growing seasons, or about 26 months, to produce mature cones from the time of cone initiation. Low elevation conifers including pinyon pines grow in water-limited environments and have been shown to have higher cone output during cool and/or wet summers, said Redmond. In addition to the climate-warming trend under way in the Southwest, the 2002-03 drought caused significant mortality in pinyon pine forests, Redmond said.
“Miranda’s ideas and accompanying results will be of value to ecologists and land managers in the deserts of the Southwest and beyond,” said Forcella, now a research agronomist in the USDA’s Agricultural Research Service. “The work is evidence that the University of Colorado continues to cultivate a cadre of high-caliber graduate students for which it rightfully can take tremendous pride.”
Pinyon nuts, the Southwest’s only commercial source of edible pine seeds today, were dietary staples of indigenous Americans going back millennia.
For more information on CU-Boulder’s ecology and evolutionary biology department visit http://ebio.colorado.edu.
State to provide substantial assistance for county’s preventive approach to child welfare
Boulder County, Colo. – Boulder County will soon join in an expansion of a visionary approach to child welfare that stabilizes families and helps keep children safe. The Colorado Department of Human Services (CDHS) sent notification this week that in spring 2013 the state will begin providing assistance to the county in the form of training, coaching, technical assistance, and meetings to enhance the quality of the county’s Differential Response (DR) initiative.
Differential Response is an evidence-based approach to child welfare that involves identifying cases that are lower risk and partnering with the families to get them the help they need, rather than treating all cases in the same way. Boulder County has been using a more collaborative approach with families since 2009, and has seen tremendous success in its child welfare outcomes as a result.
“Children do best with their families when appropriate safety exists,” said Kit Thompson, director of the Family and Children Services Division of the Boulder County Department of Housing and Human Services. “What we’ve found is that by strengthening families, we give them the best chance to provide a safe, stable home for their children.”
Research indicates the Differential Response approach leads to families receiving more help sooner, which results in sustained child safety and improved family engagement. DR also helps ensure that families who need much closer attention in cases of abuse or neglect have those resources available to them.
The Colorado Consortium on Differential Response, a group of five counties in partnership with CDHS, has been working to implement DR across the state since 2010.
“Studying and implementing Differential Response allowed us to redefine the values and mission of our child protection work and challenged us to alter our daily thinking about how to collaborate with families, our community, and one another,” said Angela Lytle, Children Youth and Family Services division manager for the Arapahoe County Department of Human Services. Arapahoe County has seen tremendous success with Differential Response, and Lytle has been a strong advocate for expanding the practice statewide. “Congratulations to Colorado for demonstrating the courage to take this innovative work and expand it with diligence and fidelity to best meet the needs of Colorado families,” she said.
Boulder County will develop its own implementation plan for the DR expansion in partnership with the state and other counties currently involved in the pilot. Other counties in the expansion include Adams, Chaffee, Denver, La Plata, San Juan, Lincoln, Mesa, and Otero. A second round of counties will join the expansion in fall 2013.
We’ve all heard examples of animal altruism: Dogs caring for orphaned kittens, chimps sharing food or dolphins nudging injured mates to the surface. Now, a study led by the University of Colorado Boulder suggests some plants are altruistic too.
The researchers looked at corn, in which each fertilized seed contained two “siblings” — an embryo and a corresponding bit of tissue known as endosperm that feeds the embryo as the seed grows, said CU-Boulder Professor Pamela Diggle. They compared the growth and behavior of the embryos and endosperm in seeds sharing the same mother and father with the growth and behavior of embryos and endosperm that had genetically different parents.
“The results indicated embryos with the same mother and father as the endosperm in their seed weighed significantly more than embryos with the same mother but a different father,” said Diggle, a faculty member in CU-Boulder’s ecology and evolutionary biology department. “We found that endosperm that does not share the same father as the embryo does not hand over as much food — it appears to be acting less cooperatively.”
A paper on the subject was published during the week of Jan. 21 in the Proceedings of the National Academy of Sciences. Co-authors on the study included Chi-Chih Wu, a CU-Boulder doctoral student in the ecology and evolutionary biology department and Professor William “Ned” Friedman, a professor at Harvard University who helped conduct research on the project while a faculty member at CU-Boulder.
Diggle said it is fairly clear from previous research that plants can preferentially withhold nutrients from inferior offspring when resources are limited. “Our study is the first to specifically test the idea of cooperation among siblings in plants.”
“One of the most fundamental laws of nature is that if you are going to be an altruist, give it up to your closest relatives,” said Friedman. “Altruism only evolves if the benefactor is a close relative of the beneficiary. When the endosperm gives all of its food to the embryo and then dies, it doesn’t get more altruistic than that.”
In corn reproduction, male flowers at the top of the plants distribute pollen grains two at a time through individual tubes to tiny cobs on the stalks covered by strands known as silks in a process known as double fertilization. When the two pollen grains come in contact with an individual silk, they produce a seed containing an embryo and endosperm. Each embryo results in just a single kernel of corn, said Diggle.
The team took advantage of an extremely rare phenomenon in plants called “hetero-fertilization,” in which two different fathers sire individual corn kernels, said Diggle, currently a visiting professor at Harvard. The manipulation of corn plant genes that has been going on for millennia — resulting in the production of multicolored “Indian corn” cobs of various colors like red, purple, blue and yellow — helped the researchers in assessing the parentage of the kernels, she said.
Wu, who cultivated the corn and harvested more than 100 ears over a three-year period, removed, mapped and weighed every individual kernel out of each cob from the harvests. While the majority of kernels had an endosperm and embryo of the same color — an indication they shared the same mother and father — some had different colors for each, such as a purple outer kernel with yellow embryo.
Wu was searching for such rare kernels — far less than one in 100 — that had two different fathers as a way to assess cooperation between the embryo and endosperm. “It was very challenging and time-consuming research,” said Friedman. “It was like looking for a needle in a haystack, or in this case, a kernel in a silo.”
Endosperm — in the form of corn, rice, wheat and other crops — is critical to humans, providing about 70 percent of calories we consume annually worldwide. “The tissue in the seeds of flowering plants is what feeds the world,” said Friedman, who also directs the Arnold Arboretum at Harvard. “If flowering plants weren’t here, humans wouldn’t be here.”
CU researchers say deep ice cores show past Greenland warm period may be ‘road map’ for continued warming of planet0
A new study by an international team of scientists analyzing ice cores from the Greenland ice sheet going back in time more than 100,000 years indicates the last interglacial period may be a good analog for where the planet is headed in terms of increasing greenhouse gases and rising temperatures.
The new results from the NEEM deep ice core drilling project led by the University of Copenhagen and involving the University of Colorado Boulder show that between 130,000 and 115,000 years ago during the Eemian interglacial period, the climate in north Greenland rose to about 14 degrees Fahrenheit warmer than today. Despite the strong warming signal during the Eemian — a period when the seas were roughly 15 to 25 feet higher than today — the surface of the north Greenland ice sheet near the NEEM facility was only a few hundred yards lower than it is today, an indication to scientists it contributed less than half of the total sea rise at the time.
The NEEM project involves 300 scientists and students from 14 countries and is led by Professor Dorthe Dahl-Jensen, director of the University of Copenhagen’s Centre of Ice and Climate. CU-Boulder geological sciences professor and ice core expert Jim White is the lead U.S. investigator on the project. The National Science Foundation’s Division of Polar Programs funded the U.S. portion of the effort.
The new Nature findings showed that about 128,000 years ago, the surface elevation of ice near the NEEM site was more than 650 feet higher than present but the ice was starting to thin by about 2 inches per year. Between about 122,000 and 115,000 years ago, Greenland’s surface elevation remained stable at roughly 425 feet below the present level. Calculations indicate Greenland’s ice sheet volume was reduced by no more than 25 percent between 128,000 years ago and 122,000 years ago, said White.
A paper on the subject was published in the Jan. 24 issue of Nature.
“When we calculated how much ice melt from Greenland was contributing to global sea rise in the Eemian, we knew a large part of the sea rise back then must have come from Antarctica,” said White, director of CU-Boulder’s Institute of Arctic and Alpine Research. “A lot of us had been leaning in that direction for some time, but we now have evidence that confirms that the West Antarctic ice sheet was a dynamic and crucial player in global sea rise during the last interglacial period.”
Dahl-Jensen said the loss of ice mass on the Greenland ice sheet in the early part of the Eemian was likely similar to changes seen there by climate scientists in the past 10 years. Other studies have shown the temperatures above Greenland have been rising five times faster than the average global temperatures in recent years, and that Greenland has been losing more than 200 million tons of ice annually since 2003. The Greenland ice loss study was led by former CU-Boulder scientist Isabella Velicogna, who is currently a faculty member at the University of California, Irvine.
The intense melt in the vicinity of NEEM during the warm Eemian period was seen in the ice cores as layers of re-frozen meltwater. Such melt events during the last glacial period were rare by comparison, showing that the surface temperatures at the NEEM site were in a cold, nearly constant state back then. But on July 12, 2012, satellite images from NASA indicated 97 percent of Greenland’s ice sheet surface had thawed as a result of warming temperatures.
“We were quite shocked by the warm surface temperatures observed at the NEEM ice camp in July 2012,” said Dahl-Jensen. “It was raining at the top of the Greenland ice sheet, and just as during the Eemian period, meltwater formed subsurface ice layers. While this was an extreme event, the present warming over Greenland makes surface melt more likely, and the predicted warming over Greenland in the next 50-100 years will very likely be so strong that we will potentially have Eemian-like climate conditions.”
The Greenland ice core layers — formed over millennia by compressed snow — are being studied in detail using a suite of measurements, including stable water isotope analysis that reveals information about temperature and greenhouse gas levels and moisture changes back in time. Lasers are used to measure the water stable isotopes and atmospheric gas bubbles trapped in the ice cores to better understand past variations in climate on an annual basis — similar in some ways to a tree-ring record.
The results from the Nature study provide scientists with a “road map” of sorts to show where a warming Earth is headed in the future, said White. Of the nine hottest years on Earth on record, eight have come since the year 2000. In 2007 the Intergovernmental Panel on Climate Change concluded that temperatures on Earth could climb by as much as 11 degrees F by 2100.
Increasing amounts of carbon dioxide in the atmosphere from sources like vehicle exhaust and industrial pollution — which have risen from about 280 parts per million at the onset of the Industrial Revolution to 391 parts per million today — are helping to raise temperatures on Earth, with no end in sight, said White.
“Unfortunately, we have reached a point where there is so much carbon dioxide in the atmosphere it’s going to be difficult for us to further limit our impact on the planet,” White said. “Our kids and grandkids are definitely going to look back and shake their heads at the inaction of this country’s generation. We are burning the lion’s share of oil and natural gas to benefit our lifestyle, and punting the responsibility for it.”
In the past, Earth’s journey into and out of glacial periods is thought to be due in large part to variations in its orbit, tilt and rotation that change the amount of solar energy delivered to the planet, he said. But the anthropogenic warming on Earth today could override such episodic changes, perhaps even staving off an ice age, White said.
While three previous ice cores drilled in Greenland in the last 20 years recovered ice from the Eemian, the deepest layers were compressed and folded, making the data difficult to interpret. Although there was some folding of the lowest ice layers in the NEEM core, sophisticated ice-penetrating radar helped scientists sort out and interpret the individual layers to paint an accurate picture of the warming of Earth’s Northern Hemisphere as it emerged from the previous ice age, White said.
In addition to White, other CU-Boulder co-authors on the NEEM paper include INSTAAR scientist Bruce Vaughn and graduate student Tyler Jones of INSTAAR and CU-Boulder’s Environmental Studies Program.
“It’s a challenge being on the ice sheet, because we are out of our comfort zones and are working long, physical hours in an environment that is extremely cold and where the sun never sets,” Jones said. “Being a member of the research team allowed me to understand the ice core recovery process and the science behind it in terms of learning more about past climates and the implications for future climate change.”
Other nations involved in NEEM include Belgium, Canada, France, Germany, Iceland, Japan, Korea, the Netherlands, Sweden, Switzerland and the United Kingdom. Other U.S. institutions involved in the effort include Oregon State University, Penn State, the University of California, San Diego and Dartmouth College.
A video and a slide show on the project will be available on the CU-Boulder news site by clicking on the story headline at http://www.colorado.edu/news.
A team led by the University of Colorado Boulder has been awarded $9.2 million over five years from the U.S. Department of Energy to research modifying E. coli to produce biofuels such as gasoline.
“This is a fantastic opportunity to take what we have worked on for the past decade to the next level,” said team leader Ryan Gill, a fellow of CU-Boulder’s Renewable and Sustainable Energy Institute, or RASEI. “In this project, we will develop technologies that are orders of magnitude beyond where we are currently.”
The team is working with a non-pathogenic strain of E. coli. Among the microbe’s more than 4,000 genes, the team is searching for a small set and how it can be manipulated in a combination of on and off states to change the bacteria’s behavior.
“E. coli is not going to want to make your biofuel at all,” said Gill, who’s also a CU-Boulder associate professor of chemical and biological engineering. “It doesn’t do that naturally. It’s programmed with thousands of genes controlling how it replicates. We’re figuring out what control structure we need to rewire in the bug to make it do what we want, not what it wants.”
Included in the team are Rob Knight, CU-Boulder associate professor of chemistry and biochemistry; Pin-Ching Maness, principal scientist at DOE’s National Renewable Energy Laboratory, or NREL; and Adam Arkin, physical biosciences director at DOE’s Lawrence Berkeley National Laboratory.
The researchers hope to engineer the production of ethylene and isobutanol in the modified E. coli. The two compounds are widely used commodities that can be converted into gasoline among other chemicals.
The greatest challenge is harnessing an efficient and inexpensive process that competes with abundant and low-cost fossil fuels like oil, according to Gill.
“Microorganisms and their genomes are incredibly complex machines,” said Gill. “The first step alone — of pinpointing the part of the E. coli genome that can help us make biofuels or other chemicals on a cost-competitive basis — is a daunting challenge. Then we have to determine if the results we want will take one year or decades, $5 million or $500 million.”
The team will be able to simultaneously identify numerous E. coli genes and the results of turning these genes on or off using advanced technologies. Many of the technologies have been developed by the researchers’ own labs.
The grant is the first of its kind from the DOE’s Office of Biological and Environmental Research and was awarded to only seven other research groups including teams led by MIT, Purdue University and the J. Craig Venter Institute.
In 2011, CU’s Technology Transfer Office named Gill an inventor of the year. In 2005, Gill won a National Science Foundation CAREER Award as well as a National Institutes of Health K25 Career Development Award for genomics research and teaching.
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.