Posts tagged National Science Foundation
Climate change: Big changes for big mammals
Jan 23rd
New CU-Boulder study shows differences
in mammal responses to climate change
in mammal responses to climate change
If you were a shrew snuffling around a North American forest, you would be 27 times less likely to respond to climate change than if you were a moose grazing nearby.
That is just one of the findings of a new University of Colorado Boulder assessment led by Assistant Professor Christy McCain that looked at more than 1,000 different scientific studies on North American mammal responses to human-caused climate change. The CU-Boulder team eventually selected 140 scientific papers containing population responses from 73 North American mammal species for their analysis.
Large mammals, like this elk, are threatened by climate change
The studies assessed by the team examined seven different responses to climate change by individual mammal species: local extinctions of species known as extirpations, range contractions, range shifts, changes in abundance, seasonal responses, body size and genetic diversity. The researchers used statistical models to uncover whether the responses of the 73 mammals to a changing climate were related to aspects of their physiology and behavior or the location of the study population.
The analysis showed only 52 percent of the mammal species responded as expected to climate change, while 7 percent responded the opposite of expectations and the remaining 41 percent had no detectable response. The two main traits tied to climate change responses in the CU-Boulder study were large mammal body size and restricted times during a 24-hour day when particular mammal species are active, she said.
A paper on the study by McCain and former CU-Boulder postdoctoral fellow Sarah King was published online Jan. 22 in the journal Global Change Biology. The National Science Foundation funded the study. King is currently a research associate at Colorado State University.
While body size was by far the best predictor for response to climate change — almost all of the largest mammals responded negatively — the new study also showed that mammals active only during the day or only at night were twice as likely to respond to climate change as mammals that had flexible activity times, she said.
“This is the first time anyone has identified specific traits that tell us which mammals are responding to climate change and which are not,” said McCain of CU-Boulder’s ecology and evolutionary biology department.
McCain said she and King were surprised by some of the findings. “Overall the study suggests our large, charismatic fauna — animals like foxes, elk, reindeer and bighorn sheep — may be at more risk from climate change,” she said. “The thinking that all animals will respond similarly and uniformly to temperature change is clearly not the case.”
The researchers also found that species with higher latitudinal and elevation ranges, like polar bears, American pikas and shadow chipmunks, were more likely to respond to climate change than mammals living lower in latitude and elevation. The ability of mammals to hibernate, burrow and nest was not a good predictor of whether a species responded to climate change or not. American pikas have been extirpated from some of their previously occupied sites in the West, as have shadow chipmunks, which are in decline in California’s Yosemite National Park.
One of the most intriguing study findings was that some small mammals may shelter from climate change by using a wider array of “micro-climates” available in the vegetation and soil, she said. McCain compared the findings with the events at the K-T boundary 66 million years ago when an asteroid smacked Earth, drastically changing the climate and killing off the big dinosaurs but sparing many of the small mammals that found suitable shelter underground to protect them from the cataclysmic event.
“I think the most fascinating thing about our study is that there may be certain traits like body size and activity behaviors that allow some smaller mammals to expand the range of temperature and humidity available to them,” said McCain, also a curator of vertebrate zoology at the University of Colorado Museum of Natural History. “These areas and conditions are not available to bigger mammals that live above the vegetation and experience only ambient temperatures.”
The new study builds on a growing body of global information documenting the shifting behaviors and environments of organisms like flowers, butterflies and birds in response to a warming world, said McCain.
“If we can determine which mammals are responding to climate change and the ones that are at risk of disappearing, then we can tailor conservation efforts more toward those individual species,” said McCain. “Hopefully, this potential loss or decline of our national iconic mammals will spur more people to curb climate impacts by reducing overuse of fossil fuels.”
For more information on the ecology and evolutionary biology department visit http://ebio.colorado.edu. For more information on the University of Colorado Museum of Natural History visit http://cumuseum-archive.colorado.edu/About/directory.html.
Climate change early warning system called for
Dec 3rd
A new National Research Council report calls for the development of an early warning system that could help society better anticipate sudden changes resulting from climate change and their impacts on society, says a University of Colorado Boulder faculty member who chaired the committee that produced the report.
Climate change has increased concern over possible large and rapid changes in the physical climate system, including Earth’s atmosphere, land surfaces and oceans, said Professor James White of CU-Boulder’s Institute of Arctic and Alpine Research and the chair of the National Research Council committee. Some abrupt changes and impacts already underway – including the loss of Arctic sea ice and increases in the extinction rates of marine and terrestrial species – and others could occur within a few decades or even years, said the committee.
“Research has helped us begin to distinguish more imminent threats from those that are less likely to happen this century,” said White, also a CU-Boulder professor in geological sciences. “Evaluating climate changes and impacts in terms of their potential magnitude and the likelihood they will occur will help policymakers and communities make informed decisions about how to prepare for or adapt to them.”
Other scenarios, such as the destabilization of the west Antarctic ice sheet, have potentially major consequences, but the probability of these changes occurring within the next century is not well understood, highlighting the need for more research, according to the committee.
In some cases, scientific understanding has progressed enough to determine whether certain high-impact climate changes are likely to happen within the next century. The report notes that a shutdown in the Atlantic Ocean circulation patterns or a rapid release of methane from high-latitude permafrost or undersea ice are now known to be unlikely this century, although these potential abrupt changes are still worrisome over longer time horizons.
But even changes in the physical climate system that happen gradually over many decades or centuries can cause abrupt ecological or socio-economic change once a “tipping point” is reached, the report adds. Relatively slow global sea-level rise could directly affect local infrastructure such as roads, airports, pipelines or subway systems if a sea wall or levee is breached. And slight increases in ocean acidity or surface temperatures could cross thresholds beyond which many species cannot survive, leading to rapid and irreversible changes in ecosystems that contribute to extinction events.
Further scientific research and enhanced monitoring of the climate, ecosystems and social systems may be able to provide information that a tipping point is imminent, allowing time for adaptation or possibly mitigation, or that a tipping point has recently occurred, the report says.
“Right now we don’t know what many of these thresholds are,” White said. “But with better information, we will be able to anticipate some major changes before they occur and help reduce the potential consequences.” The report identifies several research needs, such as identifying keystone species whose population decline due to an abrupt change would have cascading effects on ecosystems and ultimately on human provisions such as food supply.
If society hopes to anticipate tipping points in natural and human systems, an early warning system for abrupt changes needs to be developed, the report says. An effective system would need to include careful and vigilant monitoring, taking advantage of existing land and satellite systems and modifying them if necessary, or designing and implementing new systems when feasible. It would also need to be flexible and adaptive, regularly conducting and alternating between data collection, model testing and model predictions that suggest future data needs.
The study was sponsored by the National Oceanic and Atmospheric Administration, National Science Foundation, U.S. intelligence community, and the National Academies. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies. They are private, independent nonprofit institutions that provide science, technology, and health policy advice under a congressional charter granted to NAS in 1863. The National Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering.
For more information and a copy of the report visit http://national-academies.org. For more information on INSTAAR visithttp://instaar.colorado.edu.
CU-Boulder study: Spiral galaxies like Milky Way bigger than thought
Jun 27th
Let’s all fist bump: Spiral galaxies like our own Milky Way appear to be much larger and more massive than previously believed, according to a new University of Colorado Boulder study by researchers using the Hubble Space Telescope.
CU-Boulder Professor John Stocke, study leader, said new observations with Hubble’s $70 million Cosmic Origins Spectrograph, or COS, designed by CU-Boulder show that normal spiral galaxies are surrounded by halos of gas that can extend to over 1 million light-years in diameter. The current estimated diameter of the Milky Way, for example, is about 100,000 light-years. One light-year is roughly 6 trillion miles.
The material for galaxy halos detected by the CU-Boulder team originally was ejected from galaxies by exploding stars known as supernovae, a product of the star formation process, said Stocke of CU-Boulder’s astrophysical and planetary sciences department. “This gas is stored and then recycled through an extended galaxy halo, falling back onto the galaxies to reinvigorate a new generation of star formation,” he said. “In many ways this is the ‘missing link’ in galaxy evolution that we need to understand in detail in order to have a complete picture of the process.”
Stocke gave a presentation on the research June 27 at the University of Edinburgh’s Higgs Centre for Theoretical Physics in Scotland at a conference titled “Intergalactic Interactions.” The CU-Boulder research team also included professors Michael Shull and James Green and research associates Brian Keeney, Charles Danforth, David Syphers and Cynthia Froning, as well as University of Wisconsin-Madison Professor Blair Savage.
Building on earlier studies identifying oxygen-rich gas clouds around spiral galaxies by scientists at the Space Telescope Science Institute in Baltimore, the University of Massachusetts, Amherst College and the University of California, Santa Cruz, Stocke and his colleagues determined that such clouds contain almost as much mass as all the stars in their respective galaxies. “This was a big surprise,” said Stocke. “The new findings have significant consequences for how spiral galaxies change over time.”
In addition, the CU-Boulder team discovered giant reservoirs of gas estimated to be millions of degrees Fahrenheit that were enshrouding the spiral galaxies and halos under study. The halos of the spiral galaxies were relatively cool by comparison — just tens of thousands of degrees — said Stocke, also a member of CU-Boulder’s Center for Astrophysics and Space Astronomy, or CASA.
Shull, a professor in CU-Boulder’s astrophysical and planetary sciences department and a member of CASA, emphasized that the study of such “circumgalactic” gas is in its infancy. “But given the expected lifetime of COS on Hubble, perhaps another five years, it should be possible to confirm these early detections, elaborate on the results and scan other spiral galaxies in the universe,” he said.
Prior to the installation of COS on Hubble during NASA’s final servicing mission in May 2009, theoretical studies showed that spiral galaxies should possess about five times more gas than was being detected by astronomers. The new observations with the extremely sensitive COS are now much more in line with the theories, said Stocke.
The CU-Boulder team used distant quasars — the swirling centers of supermassive black holes — as “flashlights” to track ultraviolet light as it passed through the extended gas haloes of foreground galaxies, said Stocke. The light absorbed by the gas was broken down by the spectrograph, much like a prism does, into characteristic color “fingerprints” that revealed temperatures, densities, velocities, distances and chemical compositions of the gas clouds.
“This gas is way too diffuse to allow its detection by direct imaging, so spectroscopy is the way to go,” said Stocke. CU-Boulder’s Green led the design team for COS, which was built by Ball Aerospace & Technologies Corp. of Boulder for NASA.
While astronomers hope the Hubble Space Telescope keeps on chugging for years to come, there will be no more servicing missions. And the James Webb Space Telescope, touted to be Hubble’s successor beginning in late 2018, has no UV light-gathering capabilities, which will prevent astronomers from undertaking studies like those done with COS, said Green.
“Once Hubble ceases to function, we will lose the capability to study galaxy halos for perhaps a full generation of astronomers,” said Stocke. “But for now, we are fortunate to have both Hubble and its Cosmic Origins Spectrograph to help us answer some of the most pressing issues in cosmology.”
The study was supported by a NASA/Hubble Space Telescope contract to the Cosmic Origins Spectrograph science team, general NASA/Hubble Space Telescope observing grants to Stocke and a National Science Foundation grant to Keeney.
-CU-
[includeme src=”http://c1n.tv/boulder/media/bouldersponsors.html” frameborder=”0″ width=”670″ height=”300″]
