Posts tagged changes
Volcanic aerosols, not pollutants, tamped down recent Earth warming, says CU study
Mar 1st
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.
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Healthy vending snacks on the rise
Feb 6th
Written by Ann Schimke on Feb 5th, 2013. | Copyright © EdNewsColorado.org
Jamie Marrufo, a senior at Greeley West High School, noticed right away that the vending machine in the student commons looked a little different when she got back from winter break.
One of the new vending machines offering healthier snacks in the Weld School District 6.
“I was like, ‘Where are the Snickers?’”
They were gone.
So were the rest of the candy bars as well as the fried potato and corn chips. In their place were baked chips, honey wheat pretzels, Chex Mix, beef jerky, granola bars, and pouches of trail mix, peanuts, almonds and sunflower seeds. The change was part of a district-wide vending machine makeover intended to offer snacks lower in fat, sugar and calories.
Although Marrufo, who buys snacks from the machine about twice a week, loves Snickers bars, she likes the new vending machine choices too.
“It’s healthy food,” she said. “I think it’s good.”
Her friend Aimee Veenendaal, a junior who doesn’t like candy, also approved of the changes.
“I actually like it because that’s basically what I eat…the healthier stuff.”
Weld County School District 6 launched the new snack vending program in early January with the help of a $157,329 grant from the Colorado Health Foundation. The grant paid for the district’s 16 food vending machines, a vending truck, the salary of a district vending employee for one year and marketing materials to promote the new program.
Jenna Schiffelbein, the district’s wellness specialist, said the impetus for the switch was feedback from a district-wide wellness assessment in 2011-12. With the exception of some nut products, the new vending snacks, which are accessible to students only at the district’s four high schools, all adhere to the district’s standards on fat and sugar content. In addition, each snack is coded with a red, yellow or green sticker indicating that, nutritionally speaking, it is “good,” “better,” or “best.”
The district has not changed the contents of its beverage vending machines as part of the new program, though Schiffelbein said that may come later. Currently, beverage machines in all Colorado districts are regulated by the state’s Healthy Beverages Policy standards, which prohibit soda from being sold to students.
Do your homework
- Colorado’s Healthy Beverage Policy standards
- Colorado law banning trans fat from school food, effective 9/1/13
- Resources for healthy vending programs from the Alliance for a Healthier Generation
- Colorado Legacy Foundation: School Nutrition Data Snapshot
- Colorado laws on “School Food Environment” from the National Association of State Boards of Education’s“State School Healthy Policy Database”
- Centers for Disease Control report: “Competitive Foods and Beverages in U.S. Schools: A State Policy Analysis”
Healthy vending programs increasing
Weld District 6 is part of a growing group of Colorado districts that have slimmed down their vending machine snacks in recent years. While there is no hard data on the number of districts that have launched healthy vending programs, school nutrition leaders agree that more and more districts are heading in this direction.
Denver Public Schools and Jeffco Public Schools launched healthy vending programs several years ago, Boulder Valley joined the club last year, and Adams 12 is currently in the process of making the switch.
Jane Brand, director of the Colorado Department of Education’s Office of School Nutrition, said a variety of factors have driven the change, including the USDA’s updated nutrition standards for school meals, which took effect last fall, and its new, long-awaited “Smart Snacks in Schools” proposal, which came out Feb. 1.
Greater awareness about health and wellness in schools and high-profile initiatives such as Michelle Obama’s “Let’s Move” campaign have also contributed to the push for healthier vending snacks, she said.
Naomi Steenson, director of Nutrition Services and Before and After School Enrichment in Adams 12, said, “It’s the right thing to do for the kids.”
The Jeffco experience
In Jeffco Public Schools, the largest district in the state, the vending program was revamped with healthier food in 2007-08 after a state audit found the district in violation of the federally-mandated “Competitive Foods” rule barring vending items from being sold when school meals are served. Linda Stoll, executive director of Food and Nutrition Services, said the district’s vending machines were supposed to be on timers that would disable them at the appropriate times, but because they lacked the technology the machines were always on.
As a result of the violation, the district launched a new vending bid process, specifying nutrition guidelines from the Alliance for a Healthier Generation, an organization focused on reducing childhood obesity. The guidelines use a common rule called the “35-10-35” standard, which stipulates that no more than 35 percent of a snack’s total calories can be from fat, no more than 10 percent can be from saturated and trans fat, and no more than 35 percent of a snack’s weight can be from sugar. Boulder Valley also uses these guidelines while Weld 6 uses a slightly stricter “30-10-35” standard.
In addition to a version of the 35-10-35 standard, some districts opt for additional parameters. For example, Boulder Valley also bans vending fare with non-nutritive sweeteners, hydrogenated or trans fat, artificial dyes, additives or preservatives. Jeffco prohibits high fructose corn syrup.
Not all snacks that met the letter of Jeffco’s standards were approved by Stoll. She vetoed MoonPies because she believed they were unhealthy though somehow they met the guidelines.
Stoll said she hopes the changes, which affected students in 17 high schools, have encouraged students to make healthier food choices.
“I’m sure kids miss Flamin’ Hot Cheetos but I haven’t heard a lot of complaints,” she said.
Impact on sales
While many food service directors expect some decline in sales after switching to healthier vending fare, it’s hard to quantify since individual schools often manage the day-to-day details of vending machines.
A vending machine containing healthier snacks at Greeley West High School.
At Fairview High School in Boulder, sales have dropped about 44 percent since new healthier vending snacks were introduced last winter. Still, school treasurer Ronda Pendergrass said the decrease may have nothing to do with a lack of interest in healthier choices. Instead, she believes it’s because the old machines weren’t properly programmed to be disabled during the school’s lunch periods until a few months into the 2011-12 school year. Thus, they racked up more sales than they should have.
Vending proceeds at Fairview benefit the athletics program, paying for sports equipment, signing parties for college-bound student athletes and some scholarships, said Pendergrass.
In Weld District 6, Nutrition Services Director Jeremy West said with the new vending selection in place, “Sales may dip a little bit. We do not have candy bars in there. We do not have gummy worms in there.”
Ultimately, West’s goal is for the new vending program is to break even, fully supporting itself after the grant funding is gone. Under the new program, 15 percent of vending sales will return to the schools that house the machines and 85 percent will go to the nutrition services department.
Ann Cooper, director of nutrition services for Boulder Valley School District (and an expert on EdNews Parent), said she’s not concerned about whether sales have dropped since the district switched to healthier vending items last winter.
“Our job is to serve kids full, healthy lunches…how much money we bring in in vending is not the priority.”
CU researchers say deep ice cores show past Greenland warm period may be ‘road map’ for continued warming of planet
Jan 23rd
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.
For more information on INSTAAR go to http://instaar.colorado.edu/. Additional information, photos and videos on NEEM can be found at http://www.neem.ku.dk.
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.
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