China’s first successful sampling of ice core in Mongolia





China's first successful sampling of ice core in Mongolia
China’s first successful sampling of ice core in Mongolia

In collaboration with their colleagues from the ROK and Mongolia, CAS scientists achieved their first success in obtaining a 40.18m. specimen of ice core in the drilling operation from 5 to 25 June in an expedition to the (Hovd) Tsambagarav glacier in Altay Mountains of Mongolia.



The glacier is a Quaternary glacial relic, with a total area of more than 15km² and a thickness of 90-100m. It is the headstream of the Hovd River, the largest river in the Central Asian endorheic basin. According to experts, the glacier and its vicinity are an ideal theatre for probing the interaction of the Arctic water vapor with westerly wind.


The joint expedition was first contrived in 2007 and related agreement was discussed and signed in Lanzhou, capital of northwest China’s Gansu Province in April 2008.



The ice core-drilling project was first proposed by Prof. QIN Dahe, director of the State Key Laboratory for Cryosphere Science under the CAS Cold & Arid Regions Environmental and Engineering Research Institute. Its enforcement was under the leadership of its Prof. HOU Shugui from the Lab. This is the first successful attempt for Chinese scientists to obtain ice core samples from a foreign site except the polar areas.

Global Sea-Rise Levels By 2100 May Be Lower Than Some Predict





While the disintegrating Columbia Glacier in Alaska is adding to ocean levels this century, the total global sea rise by 2100 may be lower than some are anticipating, according to a new University of Colorado at Boulder study. Photo by Tad Pfeffer/University of Colorado
While the disintegrating Columbia Glacier in Alaska is adding to ocean levels this century, the total global sea rise by 2100 may be lower than some are anticipating, according to a new University of Colorado at Boulder study. Photo by Tad Pfeffer/University of Colorado

Despite projections by some scientists of global seas rising by 20 feet or more by the end of this century as a result of warming, a new University of Colorado at Boulder study concludes that global sea rise of much more than 6 feet is a near physical impossibility.



Tad Pfeffer, a fellow of CU-Boulder’s Institute of Arctic and Alpine Research and his colleagues made calculations using conservative, medium and extreme glaciological assumptions for sea rise expected from Greenland, Antarctica and the world’s smaller glaciers and ice caps — the three primary contributors to sea rise. The team concluded the most plausible scenario, when factoring in thermal expansion due to warming waters, will lead to a total sea level rise of roughly 3 to 6 feet by 2100.



A paper on the subject was published in the Sept. 5 issue of Science. Co-authors of the study were of the University of Montana’s Joel Harper and Shad O’Neel of the Scripps Institute of Oceanography at the University of California, San Diego. The study was funded by the National Science Foundation and a University of Colorado Faculty Fellowship.



“We consider glaciological conditions required for large sea level rise to occur by 2100 and conclude increases of 2 meters are physically untenable,” the team wrote in Science. “We find that a total sea level rise of about 2 meters by 2100 could occur under physically possible glaciological conditions but only if all variables are quickly accelerated to extremely high limits.”



“The gist of the study is that very simple, physical considerations show that some of the very large predictions of sea level rise are unlikely, because there is simply no way to move the ice or the water into the ocean that fast,” said Pfeffer.



The team began the study by postulating future sea level rise at about 2 meters by 2100 produced only by Greenland, said Pfeffer. Since rapid, unstable ice discharge into the ocean is restricted to Greenland glacier beds based below sea level, they identified and mapped all of the so-called outlet glacier “gates” on Greenland’s perimeter — bedrock bottlenecks most tightly constraining ice and water discharge.


“For Greenland alone to raise sea level by two meters by 2100, all of the outlet glaciers involved would need to move more than three times faster than the fastest outlet glaciers ever observed, or more than 70 times faster than they presently move,” said Pfeffer. “And they would have to start moving that fast today, not 10 years from now. It is a simple argument with no fancy physics.”



In Antarctica, the majority of ice entering the ocean comes from the Antarctic Peninsula and the Pine Island and Thwaites glaciers, said Pfeffer. Most of the marine-based ice in West Antarctica is held behind the Ross and Filcher-Ronne ice shelves, which Pfeffer’s team believes are unlikely to be removed by climate or oceanographic processes during the next century. The researchers used varying glacier velocities to calculate sea-rise contribution estimates from the Antarctic Peninsula, Pine Island and Thwaites glaciers.



The team also used assessments of the world’s small glacier and ice cap contributions to sea level rise calculated by a CU-Boulder team and published in Science in July 2007. That study indicated small glaciers and ice caps contribute about 60 percent of the world’s ice to oceans at present, a percentage that is accelerating.



Considering all major sources of sea level rise, including Greenland, Antarctica, smaller glaciers and ice caps and the thermal expansion of water, the team’s most likely estimate of roughly 3 to 6 feet by 2100 is still potentially devastating to huge areas of the world in low-lying coastal areas, said Pfeffer.



Some scientists have theorized that continuing warming trends in Greenland and Antarctica could warm the Earth by 4 degrees F over the present by 2100. The last time that happened, roughly 125,000 years ago during the last interglacial period, glacier changes raised sea level by 12 to 20 feet or more. But the time scale is poorly constrained and may have required millennia, Pfeffer said.



“In my opinion, some of the research out there calling for 20 or 30 feet of sea rise by the end of the century is not backed up by solid glaciological evidence,” said Pfeffer.



Policymakers need to be able to predict sea level accurately if communities, cities and countries around the world are going to be able to plan effectively, Pfeffer said. “If we plan for 6 feet and only get 2 feet, for example, or visa versa, we could spend billions of dollars of resources solving the wrong problems.”

Climate Computer Modeling Heats Up





New advanced computing abilities will allow scientists to better understand the links between weather and climate. - Credit: NOAA
New advanced computing abilities will allow scientists to better understand the links between weather and climate. – Credit: NOAA

New “petascale” computer models lead to better understanding of weather-climate links



New “petascale” computer models depicting detailed climate dynamics, and building the foundation for the next generation of complex climate models, are in the offing.



Researchers at the University of Miami Rosenstiel School of Marine and Atmospheric Science (RSMAS), the National Center for Atmospheric Research (NCAR) in Boulder, Colo., the Center for Ocean-Land-Atmospheric Studies (COLA) in Calverton, Md., and the University of California at Berkeley are using a $1.4 million award from the National Science Foundation (NSF) to generate the new models.



The development of powerful supercomputers capable of analyzing decades of data in the blink of an eye marks a technological milestone, say the scientists, capable of bringing comprehensive changes to science, medicine, engineering, and businesses worldwide.



The speed of supercomputing is measured in how many calculations can be performed in a given second.



Petascale computers can make 1,000,000,000,000,000 calculations per second, a staggeringly high rate even when compared to supercomputers.



Although true “peta” processing is currently rare, the anticipated availability of petascale computing offers a golden opportunity for climate scientists to advance Earth system science and help to improve quality of life on the planet, the researchers believe.


“The limiting factor to more reliable climate predictions at higher resolution is not scientific ideas, but computational capacity to implement those ideas,” said Jay Fein, NSF program director in NSF’s Division of Atmospheric Sciences. “This project is an important step forward in providing the most useful scientifically-based climate change information to society for adapting to climate change.”



Researchers once had assumed that climate can be predicted independently of weather, that is, with weather having no impact on climate prediction. Now they’re finding that weather has a profound impact on climate, a result that’s integral to the drive to improve weather and climate predictions and climate change projections.



With this boost in computing capabilities, research team member Ben Kirtman, a meteorologist at RSMAS, has developed a novel weather and climate modeling strategy, or “interactive ensembles,” designed to isolate the interactions between weather and climate.



These interactive ensembles for weather and climate modeling are being applied to one of the nation’s premier climate change models, NCAR’s Community Climate System Model (CCSM), the current operational model used by NOAA’s climate forecast system (CFS).



The CCSM is also a community model used by hundreds of researchers, and is one of the climate models used in the Nobel Prize-winning International Panel on Climate Change (IPCC) assessments.



The research serves as a pilot program to prepare for the implementation of more intense computational systems, which currently remain a scientific and engineering challenge.



“This marks the first time that we will have the computational resources available to address these scientific challenges in a comprehensive manner,” said Kirtman. “The information from this project will serve as a cornerstone for petascale computing in our field, and help to advance the study of the interactions between weather and climate phenomena on a global scale.”



While this research focuses on climate science, he said, by-products of the work are applicable to similar modeling challenges in other science and engineering fields, particularly the geosciences.

Ice Age lesson predicts a faster rise in sea level


If the lessons being learned by scientists about the demise of the last great North American ice sheet are correct, estimates of global sea level rise from a melting Greenland ice sheet may be seriously underestimated.



Writing this week (Aug. 31) in the journal Nature Geoscience, a team of researchers led by UW-Madison geologist Anders Carlson reports that sea level rise from greenhouse-induced warming of the Greenland ice sheet could be double or triple current estimates over the next century.



“We’re not talking about something catastrophic, but we could see a much bigger response in terms of sea level from the Greenland ice sheet over the next 100 years than what is currently predicted,” says Carlson, a UW-Madison professor of geology and geophysics. Carlson worked with an international team of researchers, including Allegra LeGrande from the NASA Center for Climate Systems at Columbia University, and colleagues at the Woods Hole Oceanographic Institution, the California Institute of Technology, University of British Columbia and University of New Hampshire.



Scientists have yet to agree on how much melting of the Greenland ice sheet – a terrestrial ice mass encompassing 1.7 million square kilometers – will contribute to changes in sea level. One reason, Carlson explains, is that in recorded history there is no precedent for the influence of climate change on a massive ice sheet.



“We’ve never seen an ice sheet disappear before, but here we have a record,” says Carlson of the new study that combined a powerful computer model with marine and terrestrial records to provide a snapshot of how fast ice sheets can melt and raise sea level in a warmer world.



Carlson and his group were able to draw on the lessons of the disappearance of the Laurentide ice sheet, the last great ice mass to cover much of the northern hemisphere. The Laurentide ice sheet, which encompassed large parts of what are now Canada and the United States, began to melt about 10,000 years ago in response to increased solar radiation in the northern hemisphere due to a cyclic change in the orientation of the Earth’s axis. It experienced two rapid pulses of melting – one 9,000 years ago and another 7,600 years ago – that caused global sea level to rise by more than half an inch per year.


Those pulses of melting, according to the new study, occurred when summer air temperatures were similar to what are predicted for Greenland by the end of this century, a finding the suggests estimates of global sea level rise due to a warming world climate may be seriously underestimated.



The most recent estimates of sea level rise due to melting of the Greenland ice sheet by the Intergovernmental Panel on Climate Change (IPCC) suggest a maximum sea level rise during the next 100 years of about 1 to 4 inches. That estimate, Carlson and his colleagues note, is based on limited data, mostly from the last decade, and contrasts sharply with results from computer models of future climate, casting doubt on current estimates of change in sea level due to melting ice sheets.



According to the new study, rising sea levels up to a third of an inch per year or one to two feet over the course of a century are possible.



Even slight rises in global sea level are problematic as a significant percentage of the world’s human population – hundreds of millions of people – lives in areas that can be affected by rising seas.



“For planning purposes, we should see the IPCC projections as conservative,” Carlson says. “We think this is a very low estimate of what the Greenland ice sheet will contribute to sea level.”



The authors of the new Nature Geoscience report were able to document the retreat of the Laurentide ice sheet and its contributions to changes in sea level by measuring how long rocks once covered by ice have been exposed to cosmic radiation, estimates of ice retreat based on radiocarbon dates from organic material as well as changes in ocean salinity.



In addition to Carlson and LeGrande, co-authors of the study, which was funded primarily by the National Science Foundation, are Gavin A. Schmidt of Columbia University, Delia W. Oppo of the Woods Hole Oceanographic Institution, Rosemarie E. Came of the California Institute of Technology, Faron S. Anslow of the University of British Columbia, Joseph M. Licciardi of the University of New Hampshire and Elizabeth A. Obbink of UW-Madison.

Thawing permafrost likely to boost global warming


Greenhouse gas emissions from previously frozen organic carbon in soil are seen as larger than previously believed



The thawing of permafrost in northern latitudes, which greatly increases microbial decomposition of carbon compounds in soil, will dominate other effects of warming in the region and could become a major force promoting the release of carbon dioxide and thus further warming, according to a new assessment in the September 2008 issue of BioScience. The study, by Edward A. G. Schuur of the University of Florida and an international team of coauthors, more than doubles previous estimates of the amount of carbon stored in the permafrost: the new figure is equivalent to twice the total amount of atmospheric carbon dioxide. The authors conclude that releases of the gas from melting permafrost could amount to roughly half those resulting from global land-use change during this century.


Schuur and his colleagues refine earlier assessments by considering complex processes that mix soil from different depths during melting and freezing of permafrost, which occur to some degree every year. They judge that over millennia, soil processes have buried and frozen over a trillion metric tons of organic compounds in the world’s vast permafrost regions. The relatively rapid warming now under way is bringing the organic material back into the ecosystem, in part by turning over soil. Some effects of permafrost thawing can be seen in Alaska and Siberia as dramatic subsidence features called thermokarsts.



Schuur and his colleagues acknowledge many difficulties in estimating carbon dioxide emissions from permafrost regions, which hold more carbon in the Arctic and boreal regions of the Northern Hemisphere than in the Southern Hemisphere. Data are limited, and emissions are influenced by the amount of surface water, topography, wildfires, snow cover, and other factors. Thawing, although believed to be critical, is hard to model accurately.



Some warming-related trends in Arctic regions, such as the encroachment of trees into tundra, may cause absorption of carbon dioxide and thus partly counter the effects of thawing permafrost. But Schuur and colleagues’ new assessment indicates that thawing is likely to dominate known countervailing trends.

Analysis of past glacial melting shows potential for increased Greenland ice melt and sea level rise


Researchers have yet to reach a consensus on how much and how quickly melting of the Greenland Ice Sheet will contribute to sea level rise. To shed light on this question, scientists at the University of Wisconsin and Columbia University’s Center for Climate Systems Research analyzed the disappearance of the Laurentide Ice Sheet, the last ice sheet to melt completely in the Northern Hemisphere and the closest example of what can be expected to happen to the Greenland Ice Sheet in the next century. Their findings show that sea level rise as a result of ice sheet melt can happen very rapidly. The study will be published online this week in Nature Geoscience.



“We have never seen an ice sheet retreat significantly or even disappear before, yet this may happen for the Greenland Ice Sheet in the coming centuries to millennia,” said Anders Carlson, the study’s lead author and assistant professor of geology and geophysics at the University of Wisconsin-Madison. “What we don’t know is the rate of melting of the Greenland Ice Sheet. The geologic data we compiled on the retreat history of the Laurentide Ice Sheet, however, gives us a window into how fast these large blocks of ice can melt and raise sea level.”



There are two challenges to determining the rate of melt for the Greenland Ice Sheet-a terrestrial ice mass covering more than 1.7 million km². The current rate of sea level rise is ~ 3 mm/year. In its Fourth Assessment Report, the Intergovernmental Panel on Climate Change (IPCC) indicated up to 59 cm of sea level rise, and stated that, if the observed contributions from the Greenland and Antarctic Ice Sheets between 1992 and 2003 were to increase in direct parallel with global average temperature change, the upper ranges of sea-level rise would increase by 10 to 20 cm. This prediction, however, is based on data collected in a very short period of time-mostly from the last decade-and is not enough to give a clearer idea about what might happen to the Greenland Ice Sheet.



The second challenge is that ice sheet modeling is still in its infancy, owing in part to the lack of observations of ice sheet decay, and therefore cannot accurately depict projected melt. To overcome these challenges, this study took a different approach to examining the potential for future changes to Greenland by exploring the last example of an ice sheet disappearance 9,000 years ago.



Analyzing geologic data and computer models, the team of researchers used terrestrial and marine records to reconstruct the demise of the Laurentide Ice Sheet, a land-based ice mass that covered much of North America, until its ultimate disappearance at around 6,500 years ago. The ice sheet, which once covered most of Canada and the upper reaches of the United States, had two intervals of rapid melting, the first around 9,000 years ago, and the second 7,500 years ago.


The researchers estimate that around the time of the first melting phase, the retreating ice sheet led to about approximately 7 meters of sea level rise at about 1.3 cm a year. The second phase accounts for around 5 meters of sea level rise at about 1.0 cm a year. These rates are comparable to evidence for global sea level rise for this interval derived from coral records.



“I was surprised to see that the model-in agreement with Anders’ data-showed the Laurentide Ice Sheet disappearing at 2.7 m/year,” said Allegra LeGrande, who led the computer modeling portion of this study and is a postdoctoral research scientist at the NASA Goddard Institute for Space Studies and the Center for Climate Systems Research at Columbia University. “This finding shows the potential for ice to disappear quickly, given the right push.”



The simulations of the Laurentide rapid melting episode show that the driving factors for the thinning of the ice sheet were increased solar radiation caused by a change in the earth’s orbit which increased summer temperatures. Similar temperature increases may occur over Greenland by the end of this century.



IPCC predictions for changes in sea level for the next century are mainly based on the expansion of the oceans through warming, accounting less for contributions from ice sheet melt. This analysis of the Laurentide Ice sheet finds that the ice sheet 9,000 years ago was under similar pressure to melt as the Greenland Ice Sheet will be by the year 2100, implying a greater potential for mass loss on Greenland and resulting sea level rise. (Although this finding should not be extrapolated for an absolute prediction in sea level rise over the next ten years.)



“The word ‘glacial’ used to imply that something was very slow,” said LeGrande. “This new evidence compiled from the past paired with our model for predicting future climate indicates that ‘glacial’ is anything but slow. Past ice sheets responded quickly to a changing climate, hinting at the potential for a similar response in the future.”



In an accompanying News and Views letter in Nature Geoscience, Mark Siddall, a researcher at Columbia’s Lamont-Doherty Earth Observatory, writes “Carlson and colleagues… show that the decay of the Laurentide ice sheet in the early Holocene was extremely fast during the periods they consider … Their work suggests that, in principle, future melt rates on the order of one metre per century are certainly not out of the question.”

Alpine lakes beginning to show effects of climate change





Results showed that in the 2000s alpine lakes became clearer, warmer, and mixed to deeper depths, relative to the 1990s. - Credit: Web Doodle,LLC
Results showed that in the 2000s alpine lakes became clearer, warmer, and mixed to deeper depths, relative to the 1990s. – Credit: Web Doodle,LLC

A recent study forecasts that increased climatic variability poses serious consequence for both the biodiversity and ecosystem function of high-elevation lakes.



David Schindler, world renowned ecologist, former University of Alberta graduate student Brian Parker and Rolf Vinebrooke, a professor in the Department of Biological Sciences, have shown that changes to the climate have also caused similar and concurrent changes in the features of alpine lakes, regardless of their ecological histories.



“Our demonstration of the environmental sensitivity of alpine lake ecosystems highlights both their vulnerability and usefulness as indicators of the effects of global warming and the predicted increases in climatic variability,” said Schindler.



The study, conducted during two climatically different groups of years between 1991and 2003, measured the physical, chemical, and biological attributes of two reference lakes and two experimentally restored alpine lakes in Banff National Park.



Results showed that in the 2000s-years with colder winter temperatures and higher winter snowfall, later snowmelt, shorter ice-free seasons and drier summers-alpine lakes became clearer, warmer, and mixed to deeper depths, relative to the 1990s. Further, phytoplankton biomass declined significantly in the lakes as a consequence of decreased nutrient availability


However, increased concentrations of dissolved organic carbon in lake water stimulated the appearance of small mixotrophic algal species which can acquire their nutrients through a mixture of plant- and animal-like behaviours. These beings thrive on the dissolved organic carbon, partially offsetting the decline in photosynthetic phytoplankton and increasing algal species richness.



The authors speculate that this change at the base of the aquatic food chain will have important effects on species higher in the food chain that depend on the algae for food.



“The climate regime in the 2000s altered the character and the function of high-elevation aquatic ecosystem,” said Schindler. “Forecasts of increased temperature and climatic variability in the future pose serious ramifications for both the biodiversity and ecosystem function of high-elevation lakes.”



While climate-driven aquatic changes have been observed from polar sites, less is known about the climatic sensitivity of alpine lakes and streams.



“The impacts of future change in climate on alpine ecosystems are particularly worrisome given that variation in climate is expected to be most pronounced at high elevations around the world.”