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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.
Greenland ice burg
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.
Greenland glacier grooves
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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CU Boulder’s sun-gazing SORCE satellite, designed to last 5 years, turns 10
Jan 22nd
When a sun-gazing NASA satellite designed and built by the University of Colorado Boulder launched into space on Jan. 25, 2003, solar storms were raging.
A decade later, the four instruments onboard the Solar Radiation and Climate Experiment, or SORCE, have given scientists an unprecedented look at some of the most intense solar eruptions ever witnessed — including the notorious Halloween storms in October and November 2003 — as well as the anomalously quiet solar minimum that hushed the sun’s surface beginning in 2008 and, now, a new solar maximum that appears to be the least active in a century.
CU’s SORCE satellite is 10 years old
“We were there to see it transform from a fairly normal solar cycle to a very low-activity solar cycle,” said Tom Woods, associate director of CU-Boulder’s Laboratory for Atmospheric and Space Physics, known as LASP, and principal investigator for SORCE. “Of course we couldn’t predict or know that, but it’s very exciting.”
The data generated by SORCE’s instruments, which were originally designed to operate for just five years, are downloaded twice a day with the help of CU-Boulder undergraduates working at LASP mission control. Scientists are now using that data to better understand how energy from the sun affects Earth’s climate. While human-produced greenhouse gases have been the dominant driver of climate change over the last several decades, the activity of the sun can either enhance or offset the resulting global warming.
“About 10 to 15 percent of the climate warming since 1970 is due to the sun,” Woods said. “That’s going to change now. Now that solar activity is low, the global warming trend could slow down some, but not nearly enough to offset the anthropogenic effects on global warming.”
The current, lackluster solar maximum is being compared to periods when astronomers observed very few sunspots in the early 19th century known as the Dalton Minimum and in the last half of the 17th century known as the Maunder Minimum. During the Maunder Minimum, which coincided with an era known as the Little Ice Age, temperatures in Europe were especially cool, with rivers and canals freezing during the winter across the continent and rapidly advancing glaciers destroying villages in the Swiss Alps.
The SORCE mission is also a critical contributor to the long-term record of total solar irradiance — the magnitude of the sun’s energy when it reaches the top of the Earth’s atmosphere — which stretches back to 1978, when the Nimbus-7 satellite was launched. The Total Irradiance Monitor, or TIM, instrument onboard SORCE is taking the most accurate and most precise measurements of total solar irradiance ever collected.
“The total solar irradiance provides nearly all the energy powering the Earth’s climate system, exceeding all other energy sources combined by 2,500 times,” said Greg Kopp, LASP senior research scientist and co-investigator responsible for the TIM instrument. “Any change in total irradiance can thus have large effects on our climate.”
Data from the SORCE mission have also begun a new record for measurements of visible and near-infrared light emitted from the sun. The solar spectral irradiance measurements are being made for the first time by the Spectral Irradiance Monitor, or SIM. Combined with other instruments onboard SORCE, scientists can now see all the wavelengths, including those in the ultraviolet range, emitted by the sun at once. This new way of seeing the sun has led to interesting discoveries, including that the energy emitted in some wavelengths of light vary out of phase with the sun’s overall activity, actually increasing as the number of sunspots decreases.
Now that SORCE has doubled its original life expectancy, LASP scientists are building new instruments to take over when SORCE gives out. A new TIM built at LASP launched on NASA’s Glory mission in 2011, but the satellite failed to make orbit. After the loss of Glory, CU-Boulder scientists, determined to avoid a gap in the record of total solar irradiance measurements, came up with a creative solution, repurposing a ground-based TIM to quickly make it space-worthy and then integrating it onto a U.S. Air Force satellite built by Ball Aerospace that is set to launch in August of this year.
“It’s important to have continuous measurements of solar irradiance since we’re looking for small changes in the sun’s output over decades and even centuries,” said Kopp. “Detecting such small changes using measurements disconnected in time would make this even more difficult.”
A new SIM instrument, also built at LASP, is scheduled to launch in 2016 on a National Oceanic and Atmospheric Administration satellite. But while SORCE is expected to continue functioning for at least another year, allowing for overlapping measurements with the TIM instrument launching in August, it’s uncertain if SORCE’s SIM instrument will still be running when its successor makes it to space in 2016.
“We’re definitely hoping and planning that SORCE lasts through this year,” Woods said. “But 2016 — I don’t think SORCE’s battery is going to last that long.”
During SORCE’s 10-year foray in space, the satellite also witnessed two rare transits of the planet Venus in front of the sun and another two less-infrequent transits by Mercury. When Venus, the larger of the two planets and the closer to Earth, blocked out part of the sun’s light, SORCE’s TIM instrument measured a corresponding drop in the amount of total solar irradiance. The measurements are now useful reference tools for astronomers hoping to discover planets around other stars by measuring a dip in a star’s light from a planetary transit.
In all, CU-Boulder has received about $120 million from NASA for the construction and operation of SORCE. But in 2008, LASP took the unusual step of returning $3 million in cost savings from the SORCE mission to NASA that resulted from the program’s efficient operations.
Researchers at LASP are planning to celebrate SORCE’s 10th birthday with cake, a science seminar and a write-up of the satellite’s top-10 accomplishments in NASA’s The Earth Observer magazine.
But while the decade mark is typically an important milestone for celebration here on Earth, the more appropriate milestone for SORCE may come in 2014 at the 11-year mark, the average length of a complete solar cycle
“Eleven years is special to us,” Woods said. “Instead of having a big science conference this year, we’re planning it for next January.”
For more information, visit LASP’s SORCE website at http://lasp.colorado.edu/sorce/index.htm.
A video of CU-Boulder researchers discussing the SORCE mission is available at http://www.colorado.edu/news/multimedia/cu-boulders-sun-gazing-satellite-turns-10-0.
Boulder police: Two Boulder police officers resign; internal investigation continues into elk incident
Jan 22nd
The two Boulder Police Department officers involved in the death of an elk on New Year’s Day have resigned their positions, effective immediately.
Sam Carter and Brent Curnow both turned in letters of resignation to Boulder Police Chief Mark Beckner. Chief Beckner has accepted their resignations.
Although both officers are no longer members of the police department, the internal personnel investigation into the circumstances and their behavior on Jan. 1 and Jan. 2, 2013 will continue.
Sam Carter (left) and Brent Curnow
Both officers faced termination for their actions on Jan. 1 and Jan. 2, 2013.
“The Boulder Police Department does not tolerate this kind of behavior,” said Chief Mark Beckner. “Police officers and other members of this department will be held accountable for their actions and behavior, and we want the community to know how seriously we take this breach of trust,” said Beckner.
The department hopes to complete its internal investigation quickly. In a separate criminal investigation, the Boulder County District Attorney’s Office charged Carter and Curnow with multiple crimes last Friday.
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