Climate News

Click here to visit the web page for this event.

Click here to watch Learn More About Climate's two newest films about Population, Consumption, Energy, and Solutions featuring Professor Al Bartlett.

Film Screening and Discussion of"Growthbusters: Hooked on Growth"

Monday, April 9

6:00-8:00 p.m.

Humanities Room 250, University of Colorado at Boulder

This documentary film examines the beliefs and behaviors preventing us from becoming a sustainable civilization. It takes a unique approach among modern environmental documentaries: Rather than dispensing facts about climate change; peak energy, food and water; and bio-diversity loss, it examines the cultural barriers that prevent us from acting rationally. It asks why population conversations are so difficult to have, and why a roaring economy is more important to us than a survivable planet. It explores our obsession with community growth and economic growth. Growthbusters holds up a mirror, encouraging us to examine the beliefs and behaviors we must leave behind, and the values we need to embrace, in order that our children can survive and thrive.

The film screening will be followed by a discussion with film's producer Dave Gardner and Dr. Al Bartlett.

Sponsored by the CU Environmental Center in conjunction with the Conference on World Affairs, April 9-13,www.colorado.edu/cwa/. This event is free and open to the public.

Location: http://www.colorado.edu/campusmap/map.html?bldg=HUMN


 

Click here to watch our film about the unprecedented mountain pine beetle epidemic featuring Professor Jeff Mitton.

March 27, 2012

Some populations of mountain pine beetles now produce two generations of tree-killing offspring annually, dramatically increasing the potential for bugs to kill lodgepole and ponderosa pine trees, CU-Boulder researchers have found.

Because of the extra annual generation of beetles, there could be up to 60 times as many beetles attacking trees in any given year, the study found. And in response to warmer temperatures at high elevations, pine beetles also are better able to survive and attack trees that haven't previously developed defenses.

This exponential increase in the beetle population might help explain the scope of the current beetle epidemic, which is the largest in history and extends from the Sangre de Cristo Mountains in New Mexico to the Yukon Territory near Alaska, according to Professor Jeffry Mitton and graduate student Scott Ferrenberg, both of the ecology and evolutionary biology department.

"This thing is immense," Mitton said. The duo's research, conducted in 2009 and 2010 at CU's Mountain Research Station, located about 25 miles west of Boulder, helps explain why.

"We followed them through the summer, and we saw something that had never been seen before," Mitton said. "Adults that were newly laid eggs two months before were going out and attacking trees" -- in the same year. Normally, mountain pine beetles spend a winter as larvae in trees before emerging as adults the following summer.

These effects may be particularly pronounced at higher elevations, where warmer temperatures have facilitated beetle attacks. In the last two decades at the Mountain Research Station, mean annual temperatures were 2.7 degrees Fahrenheit warmer than they were in the previous two decades.

Warmer temperatures gave the beetle larvae more spring days to grow to adulthood. The number of spring days above freezing temperatures increased by 15.1 in the last two decades, according to Mitton and Ferrenberg. Also, the number of days that were warm enough for the beetles to grow increased by 44 percent since 1970.

The Mountain Research Station site is about 10,000 feet in elevation, 1,000 feet higher than the beetles have historically thrived.

"While our study is limited in area, it was completed in a site that was characterized as climatically unsuitable for (mountain pine beetle) development by the U.S. Forest Service only three decades ago," they wrote in the study.

But in 25 years, the beetles have expanded their range 2,000 feet higher in elevation and 240 miles north in latitude in Canada, Mitton said.

April 5, 2012

A new study led by the University of Massachusetts Amherst and involving the University of Colorado Boulder proposes a simple new mechanism to explain the source of carbon that fed a series of extreme warming events on Earth about 50 million years ago called the Paleocene-Eocene Thermal Maximum, or PETM, as well as a sequence of similar, smaller warming events afterward.

“The standard hypothesis has been that the source of carbon was in the ocean in the form of frozen methane gas in ocean-floor sediments,” said lead study author Rob DeConto of the University of Massachusetts Amherst. “We are instead ascribing the carbon source to the continents in polar latitudes where permafrost can store massive amounts of carbon that can be released as CO2 when the permafrost thaws.”

The new view is supported by calculations estimating interactions of variables such as greenhouse gas levels, changes in the Earth’s tilt and orbit, ancient distributions of vegetation, and carbon stored in rocks and in frozen soil.  A paper on the subject appears in the April 5 issue of Nature.

While the amounts of carbon involved in the ancient soil-thaw scenarios were likely much greater than today, implications of the study appear dire for the long-term future as polar permafrost carbon deposits have begun to thaw due to burning fossil fuels, DeConto said. “Similar dynamics are at play today. Global warming is degrading permafrost in the north polar regions, thawing frozen organic matter, which will decay to release CO2 and methane into the atmosphere. This will only exacerbate future warming in a positive feedback loop.”  

He and colleagues at CU-Boulder, Yale, Penn State, the University of Urbino, Italy, and the University of Sheffield in England designed a model to account for the source, magnitude and timing of carbon release at the PETM and subsequent warm periods, which now appear to have been triggered by changes in the Earth’s orbit.

CU-Boulder researcher Kevin Schaefer, a Nature paper co-author, led a 2011 study showing up to two-thirds of Earth’s permafrost could disappear by 2200 as a result of warming temperatures, unleashing vast quantities of carbon into the atmosphere.

“We found in this new Nature study that changes in Earth’s orbit triggered massive releases of carbon dioxide and methane from thawing permafrost in Antarctica,” said Schaefer, a research associate at CU-Boulder’s National Snow and Ice Data Center, an arm of the Cooperative Institute for Research in Environmental Sciences. “If the Arctic permafrost thaws out, it will release carbon dioxide and methane into the atmosphere and amplify warming due to the burning of fossil fuels.”

Earth’s atmospheric temperature is a result of energy input from the sun minus what escapes back to space. CO2 in the atmosphere absorbs and traps heat that would otherwise return to space. The PETM was accompanied by a massive carbon input to the atmosphere, with ocean acidification, and was characterized by a global temperature rise of about 9 degrees Fahrenheit in a few thousand years, according to the study.

The research team used a new, high-precision geologic record from rocks in central Italy to show that the PETM and other warming events occurred during periods when Earth’s orbit around the sun was both highly eccentric and tilted. Orbit affects the amount, location and seasonality of solar radiation received on Earth, which in turn affects the seasons, particularly in polar latitudes, where permafrost and stored carbon can accumulate.

They then simulated climate-ecosystem-soil interactions, accounting for gradually rising greenhouse gases and polar temperatures plus the combined effects of changes in Earth’s orbit. Their results show that the magnitude and timing of the PETM and subsequent busts of warming can be explained by the orbitally triggered decomposition of organic carbon soil material in Antarctica and the area surrounding the Arctic.

The massive carbon reservoir at the poles had the potential to repeatedly release billions of tons carbon to the atmosphere-ocean system once a long-term warming threshold was reached just prior to the PETM,” DeConto and colleagues say. Until now, Antarctica, which today is covered by miles of ice, has not been recognized as an important player in such global carbon dynamics, according to the team.

In the past, Antarctica and high elevations adjacent to the Arctic region were suitable locations for massive carbon storage, according to the study. “During long-term warming, these environments eventually reached a climatic threshold,” with permafrost thaw and the sudden release of stored soil carbon triggered during the Earth’s highly eccentric orbits coupled with high tilt, according to the study.

Contact:

Janet Lathrop, UMass media relations, 413-545-0444
jlathrop@admin.umass.edu
Robert DeConto, 413-545-3426
deconto@geo.umass.edu
Kevin Schaefer, 303-492-8869
Kevin.schaefer@colorado.edu

Exploring Climate Connections between the Global Oceans and Climate, Ecosystems & Economy 

• Scientists will present talks on their cutting edge research
• Lessons that can be used in the classroom will be tied to the themes (both in science and computer labs)
• The nature and process of science will be explored

March 13, 2012

“You cannot sustain population growth. It’s not debatable,” says CU-Boulder Professor Emeritus Al Bartlett.  “It’s based on arithmetic.  It’s not debatable unless you want to debate arithmetic."
 

In a newly-released video, entitled “Population, Consumption, and Climate:  A Conversation with Al Bartlett,” the physics professor reprises themes from a talk on the arithmetic of population he first gave in 1969.  He has since delivered that well-known lecture more than 1,700 times to audiences worldwide.
 

Using an animation that shows bacteria doubling in number over a fixed period of time, Bartlett illustrates the arithmetic of steady growth and how quickly resources are depleted as growth continues.
 

“There will be limits,” states Bartlett.  We are approaching one such limit globally in petroleum. “New technologies in drilling for natural gas doesn’t change our supplies,” he points out.  “It doesn’t change the amount of oil or natural gas that’s in the ground.  What it does is let us use it up more rapidly.”
 

Bartlett goes on to explain that despite the fact that population growth rates in developing countries may be 3-4 times higher, the worst problem with population is in the United States because of our very high per capita demand for energy and resources.
 

“The average child born in the United States will have, over its lifetime, 10-20 times the impact on world resources as a child born in an underdeveloped nation,” he says.  “So we’ve got to address the problem at home” by learning to conserve and live within our means.
 

In addition to putting enormous strain on the earth’s natural resources, excessive consumption contributes to climate change because resource extraction, manufacturing and transportation produce a great deal of carbon dioxide.  And, according to Bartlett, “if any fraction of global warming can be attributed to the actions of humans, that’s all the proof you need to say the human population today is greater than the carrying capacity of the earth.”
 

Part of CU-Boulder’s “Learn More About Climate” initiative, which brings climate change-related information to communities across the state, “Population, Consumption, and Climate:  A Conversation with Al Bartlett” is the seventh in a series of videos that can be viewed at LearnMoreAboutClimate.colorado.edu — an online tool that localizes climate change through interviews with leading scientists and everyday Coloradans to explain how climate change is affecting our state.  The site also offers resources for teachers, students, policy makers and community members who want to learn more about this critical issue.    

Professor Emeritus Bartlett joined the faculty at CU-Boulder in 1950.  He continues to deliver his acclaimed lecture “Arithmetic, Population and Energy: Sustainability 101” to audiences in towns across Colorado. To view “Population, Consumption, and Climate:  A Conversation with Al Bartlett,” please visit LearnMoreAboutClimate.colorado.edu. 

Click here for a list of links related to climate, energy, and consumption.
 

In addition to our two new films, "Population Growth, Consumption, and Climate: A Conversation with Al Bartlett" and "Climate Change: Making Choices that Make A Difference," the websites below provide useful information about the speakers and topics covered.

Click on the links below for more information about population growth, climate, energy, and consumption.

POPULATION, CONSUMPTION, AND CLIMATE: A CONVERSATION ABOUT AL BARTLETT

About Al Bartlett: http://www.albartlett.org

Full Interview with Al Bartlett: http://vimeo.com/37014682

Related Links

• Al Bartlett's arithmetic, population, and energy presentation
• Al Bartlett's book, "The Essential Exponential" 
• CU-Boulder Population Center 
• NPR Story: "Visualizing How A Population Grows to 7 Billion" 
• The Population Connection 

CLIMATE CHANGE: MAKING CHOICES THAT MAKE A DIFFERENCE

About Max Boykoff: http://cires.colorado.edu/people/boykoff/

Full Interview with Max Boykoff: http://vimeo.com/37500836

Related Links

• Max Boykoff's new book, "Who Speaks for the Climate? Making Sense of Media Reporting on Climate Change"
•  "The New Carbon Economy: Constitution, Governance, and Contestation" edited by Peter Newell, Max Boykoff, and Emily Boyd
• Solar Energy International's "Solar in the Schools" Program
• The "Young Voices on Climate Change" project from author and illustrator Lynne Cherry
• The Global Learning and Observations to Benefit the Environment (GLOBE) science and education program

About Beth Osnes: http://theatredance.colorado.edu/?page_id=518 and http://centerwest.org/beth-osnes/

Full Interview with Beth Osnes: http://vimeo.com/37505865

Related Links:

• MOTHER: Caring for 7 Billion Film
• Beth Osnes Explains World Energy Justice
  

About Bernard Amadei:  https://mcedc.colorado.edu/amadei-biography

Related Links:

• Mortenson Center in Engineering for Developing Communities
• Mortenson Center Introduces Sustainable Housing Solution on Crow Reservation
• Crow Tribe Sustainable Housing Project Student Outreach, Exchange, and Training
• TED Talk: "Technology with a Soul" by Bernard Amadei 
• Engineers without Borders USA
• Engineers without Borders International

March 14, 2012

Long thought to produce only one generation of tree-killing offspring annually, some populations of mountain pine beetles now produce two generations per year, dramatically increasing the potential for the bugs to kill lodgepole and ponderosa pine trees, University of Colorado Boulder researchers have found.

Because of the extra annual generation of beetles, there could be up to 60 times as many beetles attacking trees in any given year, their study found. And in response to warmer temperatures at high elevations, pine beetles also are better able to survive and attack trees that haven’t previously developed defenses.

These are among the key findings of Jeffry Mitton, a CU-Boulder professor of ecology and evolutionary biology, and Scott Ferrenberg, a graduate student in that department. The study is being published this month in The American Naturalist.

This exponential increase in the beetle population might help to explain the scope of the current beetle epidemic, which is the largest in history and extends from the Sangre de Cristo Mountains in New Mexico to the Yukon Territory near Alaska.

“This thing is immense,” Mitton said. The duo’s research, conducted in 2009 and 2010 at CU’s Mountain Research Station, located about 25 miles west of Boulder, helps explain why.

“We followed them through the summer, and we saw something that had never been seen before,” Mitton said. “Adults that were newly laid eggs two months before were going out and attacking trees” -- in the same year. Normally, mountain pine beetles spend a winter as larvae in trees before emerging as adults the following summer.

These effects may be particularly pronounced at higher elevations, where warmer temperatures have facilitated beetle attacks. In the last two decades at the Mountain Research Station, mean annual temperatures were 2.7 degrees Fahrenheit warmer than they were in the previous two decades.

Warmer temperatures gave the beetle larvae more spring days to grow to adulthood. The number of spring days above freezing temperatures increased by 15.1 in the last two decades, Mitton and Ferrenberg report. Also, the number of days that were warm enough for the beetles to grow increased by 44 percent since 1970.

The Mountain Research Station site is about 10,000 feet in elevation, 1,000 feet higher than the beetles have historically thrived. In their study, Mitton and Ferrenberg emphasize this anomaly.

“While our study is limited in area, it was completed in a site that was characterized as climatically unsuitable for (mountain pine beetle) development by the U.S. Forest Service only three decades ago,” they write.

But in 25 years, the beetles have expanded their range 2,000 feet higher in elevation and 240 miles north in latitude in Canada, Mitton said.

Ferrenberg had the idea to monitor the beetles at higher elevations partly because trees at lower elevations have been attacked by beetles for centuries and have developed some defenses.

Lodgepole pines at higher elevations tended to have a lower density of resin ducts, which transport resin, the sole defense against beetles. The number of resin ducts in a tree can be a “marker” for whether a tree has a higher or lower resistance to a beetle attack, Ferrenberg said.
 

The trees at higher elevations had not faced the same intensity of beetle attacks as those at lower elevations until temperatures warmed, and they have not faced pressures of natural selection exerted by attacking beetles. “The trees in that area are somewhat naïve in their response,” Ferrenberg said.
 

These data help explain why westbound motorists emerging from the Eisenhower Tunnel on I-70 can look up, from 11,000 feet in elevation, and see beetle-killed trees. “We think we see some of the reason for the fact that this epidemic is so widespread,” Mitton said.
 

The research was funded by the U.S. Department of Energy.
 

More on this story will appear in the next edition of Colorado Arts and Sciences Magazine at http://artsandsciences.colorado.edu/magazine/

Contact:

Jeffry Mitton 303-492-8956

mitton@colorado.edu

Scott Ferrenberg, 303-492-8956

scott.ferrenberg@colorado.edu
 

MARCH 6TH TEACHER WORKSHOPS IN COLORADO SPRINGS

Meeting Materials

For those who attended the Science Hubs meeting, you can download meeting materials here.

1.  All presenter powerpoint files (zip file)
2.  Selected handouts

Some people noticed that the Evidence lesson plan has the old Colorado science standards on it -- this was due to a version error, and we are updating it.  You can access the Evidence lesson plan here:  http://learnmoreaboutclimate.colorado.edu/model-lessons/evidence-of-climate-change

Dr. Chris Ray mentioned the newly launched site on pika science that is not in the handouts.  That URL is:
http://cumuseum.colorado.edu/ScienceLIVE

Dr. Anne Gold included some resources in her first presentation that weren't on the handouts.  Those are:
1.  AAAS Strand Maps with concept maps of important topics in science and their interconnections, including climate:  http://strandmaps.nsdl.org
2.  AAAS Misconceptions study, outlining common misconceptions in various areas, including weather and climate:  http://assessment.aaas.org/topics
3.  Skeptical Science, a good source for sound information and explaining misinformation about various areas, including climate change:  http://skepticalscience.com
4.  Real Climate, another good resource for information about climate: http://realclimate.org

On the agenda:
* Is climate changing in Colorado?  How would we know?
* Climate and energy topics in the classroom
* The American Pika:  A model species for studying climate sensitivity
* Resources for teaching about climate and energy.
 

February 13, 2012

Equipped with specialized lasers and GPS technology, scientists at the National Center for Atmospheric Research are working with institutions including the University of Colorado Boulder to solve a critical wintertime weather mystery: how to accurately measure the amount of snow on the ground.

Transportation crews, water managers, and others who make vital safety decisions need precise measurements of how snow depth varies across wide areas. But traditional measuring devices such as snow gauges or yardsticks often are inadequate for capturing snow totals that can vary even within a single field or neighborhood.

Now scientists are finding that prototype devices that use light pulses, satellite signals, and other technologies offer the potential to almost instantly measure large areas of snow. In time, such devices might even provide a global picture of snow depth.

“We’ve been measuring rain accurately for centuries, but snow is much harder because of the way it’s affected by wind and sun and other factors,” says NCAR scientist Ethan Gutmann. “It looks like new technology will finally give us the ability to say exactly how much snow is on the ground.”

NCAR is conducting the research with several collaborating organizations, including CU-Boulder and the National Oceanic and Atmospheric Administration. The work is supported by NCAR’s sponsor, the National Science Foundation.

Emergency managers rely on snowfall measurements when mobilizing snow plows or deciding whether to shut down highways and airports during major storms. They also use snow totals when determining whether a region qualifies for disaster assistance. In mountainous areas, officials need accurate reports of snowpack depth to assess the threat of avalanches or floods, and to anticipate the amount of water available from spring and summer runoff.

More accurate measurements can also help meteorologists and hydrologists better understand snow physics and hydrological processes.

But traditional approaches to measuring snow can greatly underreport or overreport snow totals, especially in severe conditions. Snow gauges may miss almost a third of the snow in a windy storm, even when they are protected by specialized fencing designed to cut down on the wind’s impacts. Snow probes or yardsticks can reveal snow depth within limited areas. But such tools require numerous in-person measurements at different locations, a method that may not keep up with totals during heavy snowfalls.

Weather experts also sometimes monitor the amount of snow that collects on flat, white pieces of wood known as snow boards, but this is a time-intensive approach that requires people to check the boards and clear them off every few hours. The nation’s two largest volunteer efforts—The National Weather Service’s Cooperative Observer Program and the Community Collaborative Rain, Hail, and Snow Network—each involve thousands of participants nationwide using snow boards, but their reports are usually filed just once a day.

More recently, ultrasonic devices have been deployed in some of the world’s most wintry regions. Much like radar, these devices measure the length of time needed for a pulse of ultrasonic energy to bounce off the surface of the snow and return to the transmitter. However, the signal can be affected by shifting atmospheric conditions, including temperature, humidity, and winds.

The specialized laser instruments under development at NCAR can correct for such problems. Once set up at a location, they can automatically measure snow depth across large areas. Unlike ultrasonic instruments, lasers rely on light pulses that are not affected by atmospheric conditions.

New tests by Gutmann indicate that a laser instrument installed high above treeline in the Rocky Mountains west of Boulder can measure 10 feet or more of snow with an accuracy as fine as half an inch or better. The instrument, in a little over an hour,  measures snow at more than 1,000 points across an area almost the size of a football field to produce a three-dimensional image of the snowpack and its variations in depth.

Gutmann’s next step, if he can secure the needed funding, will be to build and test a laser instrument that can measure snow over several square miles. Measuring such a large area would require a new instrument capable of taking over 12,000 measurements per second.

“If we’re successful, all of a sudden these types of instruments will reveal a continually updated picture of snow across an entire basin,” he says.

One limitation for the lasers, however, is the light pulses cannot penetrate through objects such as trees and buildings. This could require development of networks of low-cost laser installations that would each record snow depths within a confined area. Alternatively, future satellites equipped with such lasers might be capable of mapping the entire world from above.

Gutmann and Kristine Larson, a colleague at CU-Boulder, are also exploring how to use GPS sensors for snowfall measurements. GPS sensors record both satellite signals that reach them directly and signals that bounce off the ground. When there is snow on the ground, the GPS signal bounces off the snow with a different frequency than when it is bare soil, enabling scientists to determine how high the surface of the snow is above the ground.

Such units could be a cost-efficient way of measuring snow totals because meteorologists could tap into the existing global network of ground-based GPS receivers. However, researchers are seeking to fully understand how both the density of the snow and the roughness of its surface alter GPS signals.

“Our hope is to develop a set of high-tech tools that will enable officials to continually monitor snow depth, even during an intense storm,” Larson says. “While we still have our work cut out for us, the technology is very promising.”

“I think this technology has great potential to benefit emergency managers and other decision makers, as well as forecasters, “ Gutmann says.

The University Corporation for Atmospheric Research manages the National Center for Atmospheric Research under sponsorship by the National Science Foundation. Any opinions, findings and conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Scientific contacts:

Ethan Gutmann, NCAR Scientist
303-497-8283
gutmann@ucar.edu

Kristine Larson, CU Scientist
303-492-6583
kristinem.larson@gmail.com

From http://www.colorado.edu/news/releases/2012/02/08/cu-boulder-study-shows-global-glaciers-ice-caps-shedding-billions-tons-mass

February 8, 2012

Earth’s glaciers and ice caps outside of the regions of Greenland and Antarctica are shedding roughly 150 billion tons of ice annually, according to a new study led by the University of Colorado Boulder.

The research effort is the first comprehensive satellite study of the contribution of the world’s melting glaciers and ice caps to global sea level rise and indicates they are adding roughly 0.4 millimeters annually, said CU-Boulder physics Professor John Wahr, who helped lead the study. The measurements are important because the melting of the world’s glaciers and ice caps, along with Greenland and Antarctica, pose the greatest threat to sea level increases in the future, Wahr said.

The researchers used satellite measurements taken with the Gravity Recovery and Climate Experiment, or GRACE, a joint effort of NASA and Germany, to calculate that the world’s glaciers and ice caps had lost about 148 billion tons, or about 39 cubic miles of ice annually from 2003 to 2010.  The total does not count the mass from individual glacier and ice caps on the fringes of the Greenland and Antarctic ice sheets -- roughly an additional 80 billion tons.

“This is the first time anyone has looked at all of the mass loss from all of Earth’s glaciers and ice caps with GRACE,” said Wahr.  “The Earth is losing an incredible amount of ice to the oceans annually, and these new results will help us answer important questions in terms of both sea rise and how the planet’s cold regions are responding to global change.”

A paper on the subject is being published in the Feb. 9 online edition of the journal Nature.  The first author, Thomas Jacob, did his research at CU-Boulder and is now at the Bureau de Recherches Géologiques et Minières, in Orléans, France.  Other paper co-authors include Professor Tad Pfeffer of CU-Boulder’s Institute of Arctic and Alpine Research and Sean Swenson, a former CU-Boulder physics doctoral student who is now a researcher at the National Center for Atmospheric Research in Boulder.

“The strength of GRACE is that it sees everything in the system,” said Wahr. “Even though we don’t have the resolution to look at individual glaciers, GRACE has proven to be an exceptional tool.”  Traditional estimates of Earth’s ice caps and glaciers have been made using ground-based measurements from relatively few glaciers to infer what all of the unmonitored glaciers around the world were doing, he said. Only a few hundred of the roughly 200,000 glaciers worldwide have been monitored for a decade or more.

Launched in 2002, two GRACE satellites whip around Earth in tandem 16 times a day at an altitude of about 300 miles, sensing subtle variations in Earth’s mass and gravitational pull. Separated by roughly 135 miles, the satellites measure changes in Earth’s gravity field caused by regional changes in the planet’s mass, including ice sheets, oceans and water stored in the soil and in underground aquifers.

A positive change in gravity during a satellite approach over Greenland, for example, tugs the lead GRACE satellite away from the trailing satellite, speeding it up and increasing the distance between the two. As the satellites straddle Greenland, the front satellite slows down and the trailing satellite speeds up. A sensitive ranging system allows researchers to measure the distance of the two satellites down to as small as 1 micron -- about 1/100 the width of a human hair -- and to calculate ice and water amounts from particular regions of interest around the globe using their gravity fields.

For the global glaciers and ice cap measurements, the study authors created separate “mascons,” large, ice-covered regions of Earth of various ovate-type shapes. Jacob and Wahr blanketed 20 regions of Earth with 175 mascons and calculated the estimated mass balance for each mascon.

The CU-led team also used GRACE data to calculate that the ice loss from both Greenland and Antarctica, including their peripheral ice caps and glaciers, was roughly 385 billion tons of ice annually. The total mass ice loss from Greenland, Antarctica and all Earth’s glaciers and ice caps from 2003 to 2010 was about 1,000 cubic miles, about eight times the water volume of Lake Erie, said Wahr.

“The total amount of ice lost to Earth’s oceans from 2003 to 2010 would cover the entire United States in about 1 and one-half feet of water,” said Wahr, also a fellow at the CU-headquartered Cooperative Institute for Research in Environmental Sciences.

The vast majority of climate scientists agree that human activities like pumping huge amounts of greenhouse gases in the atmosphere is warming the planet, an effect that is most pronounced in the polar regions.

One unexpected study result from GRACE was that the estimated ice loss from high Asia mountains -- including ranges like the Himalaya, the Pamir and the Tien Shan -- was only about 4 billion tons of ice annually.  Some previous ground-based estimates of ice loss in the high Asia mountains have ranged up to 50 billion tons annually, Wahr said.

“The GRACE results in this region really were a surprise,” said Wahr.  “One possible explanation is that previous estimates were based on measurements taken primarily from some of the lower, more accessible glaciers in Asia and were extrapolated to infer the behavior of higher glaciers.  But unlike the lower glaciers, many of the high glaciers would still be too cold to lose mass even in the presence of atmospheric warming.”

“What is still not clear is how these rates of melt may increase and how rapidly glaciers may shrink in the coming decades,” said Pfeffer, also a professor in CU-Boulder’s civil, environmental and architectural engineering department. “That makes it hard to project into the future.”

According to the GRACE data, total sea level rise from all land-based ice on Earth including Greenland and Antarctica was roughly 1.5 millimeters per year annually or about 12 millimeters, or one-half inch, from 2003 to 2010, said Wahr. The sea rise amount does not include the expansion of water due to warming, which is the second key sea-rise component and is roughly equal to melt totals, he said.

“One big question is how sea level rise is going to change in this century,” said Pfeffer. “If we could understand the physics more completely and perfect numerical models to simulate all of the processes controlling sea level -- especially glacier and ice sheet changes -- we would have a much better means to make predictions. But we are not quite there yet.”
 
Contact:

John Wahr, 303-492-8349

John.Wahr@colorado.edu

Tad Pfeffer, 303-492-3480

Tad.Pfeffer@colorado.edu