Posts by Sarah Kai Zhen Toh

Research Shows How Climate Change Drives Glacier Retreat

Posted by on Feb 21, 2017 in All Posts, Featured Posts, Science | 0 comments

Research Shows How Climate Change Drives Glacier Retreat

Spread the News:ShareShrinking glaciers are oft-cited examples of the effects of anthropogenic climate change, providing dramatic imagery in different parts of the world. However, this has mostly been based on global aggregates of glacier extent. Differing opinions also exist about the best way to measure glacial change all over the world.  A recent study by Roe et al., published in Nature Geoscience, confirms that climate change has contributed to the shortening of numerous glaciers around the world, but the study is not immune to controversy surroundings the methods used. Using a combination of meteorological data and observations of glacier length, Roe et al. studied the influence of climate on 37 glaciers between 1880 and 2010. The glaciers were selected based on the continuity of length observations and the need for a wide geographical distribution. Glacier mass-balance records are a more direct measure of the effect of climate than glacier length as they measure the difference between the accumulation and ablation (sublimation or melting) of glacier ice. However, most mass-balance records do not extend for more than two decades, contributing to the previous lack of confirmation of the effect of climate change on individual glaciers around the world. The use of observations of glacier length helped to overcome this obstacle, but challenges were still encountered in obtaining long, continuous data sets, particularly for regions such as Asia and South America. In conversation with GlacierHub, Roe shared that many factors can affect the availability of continuous data sets. “For example, the collapse of the Soviet Union led to many glacier observation programs being abandoned,” he stated. An additional challenge arose from the variation in conditions experienced by each glacier. “Every glacier is a unique product of its local climate and landscape,” Roe shared, citing the example of maritime glaciers, which typically experience a large degree of wintertime accumulation variability. “This can mask the signal of a warming that, so far, has mainly impacted the summertime mass balance,” he added. Nevertheless, Roe et al. found that there was at least a 99% chance that a change in climate was needed to account for the retreat of 21 of the glaciers studied. “Even for the least statistically significant (Rabots Glacier in Sweden), there was still an 89% chance that its retreat required a climate change,” Roe said. As glaciers tend to have decadal responses to changes in climate, their retreat since 1880 is likely to be a result of twentieth-century temperature trends. They also act as amplifiers of local climate trends, providing strong signal-to-noise ratios that serve as strong evidence for the effects of anthropogenic climate change. For example, one of the glaciers included in the study, Hintereisferner in the Austrian Alps, retreated 2,800m since 1880, with a standard deviation (a measure of the deviation of values from the mean) of 130m. This value is small compared to the amount of retreat, providing a strong signal of change. “We hope that these results will lead to a stronger scientific consensus about the cause of glacier retreat. The last round of the Intergovernmental Panel on Climate Change was quite timid, concluding only that it was ‘likely’ that a ‘substantial’ part of glacier retreat was due to human-caused climate change,” Roe added. IPCC nomenclature would make it “very likely” (≥90%) that all but one of the glaciers in this study have retreated because of climate change, allowing for stronger conclusions to be drawn. Excitement about the results of this study was shared by Joerg Schaefer, professor at the Lamont-Doherty Earth Observatory: “Under Roe’s lead, the really smart glacier people find ways to explain this strange...

Read More

Roundup: Chemistry, Dams and Elevations

Posted by on Feb 13, 2017 in All Posts, Featured Posts, Roundup | 0 comments

Roundup: Chemistry, Dams and Elevations

Spread the News:ShareRoundup: Meltwater Chemistry, Hydroelectric Dams and Glacier Elevation   Diurnal Changes in the Chemistry of Glacier Meltwater From Chemosphere: “An evaluation of glacial meltwater chemistry is needed under recent dramatic glacier melting when water resources might be significantly impacted. This study investigated trace elements variation in the meltwater stream, and its related aquatic environmental information, at the Laohugou glacier basin (4260 m a.s.l.) at a remote location in northeast Tibetan Plateau… Results showed evident elements spatial difference on the glacier surface meltwater, as most of the elements showed increased concentration at the terminus compared to higher elevations sites… The accelerated diurnal and temporal snow-ice melting (with high runoff level) were correlated to increased elemental concentration, pH, EF (enrichment factor,the minimum factor by which the weight percent of mineral in is greater than the average occurrence of that mineral in the Earth’s crust) and elemental change mode, and thus this work is of great importance for evaluating the impacts of accelerated glacier melting to meltwater chemistry and downstream ecosystem in the northeast Tibetan Plateau.” Read more about it here.   Locals Oppose Dam Construction in the North Western Himalayas From the International Journal of Interdisciplinary and Multidisciplinary Studies: “Since early 1970s dam development projects witnessed severe opposition in India. The remote tribal groups and rural population rejected the idea of large scale displacement, land alienation, economic insecurity and endless suffering that came along with ‘development’ projects… In recent past the construction of hydroelectricity projects has faced severe opposition in the tribal regions in Himachal Pradesh. The locals in Kinnaur are facing numerous socio-economic and environmental consequences of these constructions in fragile Himalayan ecology… More than 30 hydro projects proposed in Lahaul & Spiti are also being challenged by the people in Chenab valley… The paper summarises the ongoing struggle and diverse implications added with climate change in the rural structures.” Read more about local opposition to these projects here.   Uneven Changes in Ice Sheet Elevation in West Antarctica From Geophysical Research Letters: “We combine measurements acquired by five satellite altimeter missions to obtain an uninterrupted record of ice sheet elevation change over the Amundsen Sea Embayment, West Antarctica, since 1992… Surface lowering has spread slowest (<6 km/yr) along the Pope, Smith, and Kohler (PSK) Glaciers, due to their small extent. Pine Island Glacier (PIG) is characterized by a continuous inland spreading of surface lowering, notably fast at rates of 13 to 15 km/yr along tributaries draining the southeastern lobe, possibly due to basal conditions or tributary geometry… Ice-dynamical imbalance across the sector has therefore been uneven during the satellite record.” Read more about the changes in ice sheet elevation here. Spread the...

Read More

Large Populations of Jellyfish Found in West Antarctic Fjords

Posted by on Feb 7, 2017 in All Posts, Featured Posts, Science | 0 comments

Large Populations of Jellyfish Found in West Antarctic Fjords

Spread the News:ShareJellyfish can often be found in abundance in communities living in the benthic boundary layer, the water directly above the seafloor. The cold high-latitude systems surrounding the poles are no exception. A recent study published by Grange et al. in PLOS One reports on unusually high abundances of Ptychogastria polaris Allman in fjords in the glacier-rich West Antarctic Peninsula. P. polaris is a cold-water species that has been found in a variety of locations in the high latitudes of the Northern and Southern Hemisphere. It was first described in 1878 by A.G. Allman, based on a single specimen collected off East Greenland. Since then, it has been found to have a patchy, circumpolar distribution in Arctic and sub-Arctic areas, while only a few specimens have been documented in Antarctica. Between January and February 2010, Grange et al. conducted surveys of benthic megafauna in three subpolar fjords along the West Antarctic Peninsula – Andvord, Flandres and Barilari Bays. “Arctic fjords are heavily impacted by meltwater inputs and sedimentation that yield low seafloor abundance and biodiversity, so we wanted to see if that was also the case in the Antarctic,” Grange explained to GlacierHub. They analyzed live specimens, conducted photosurveys of the seafloor, and measured background environmental conditions to gain a better understanding of the distribution of P. polaris. Molecular analysis and DNA sequencing were also used to confirm the species identifications of specimens. P. polaris was found to be a common component of seafloor communities in both Andvord and Flandres Bays, but was absent in Barilari Bay. “We noted the conspicuous occurrence and high abundance of P. polaris,” Grange stated. She noted that the densities in these locations up to 400 times higher than previously recorded in northeast Greenland and the Barents Sea. These levels could be a result of higher productivity within the benthic boundary layer in the fjords. Reasons for this productivity include higher nutrient inputs that occur when the remains of sustained phytoplankton blooms sink to the ocean floor, or when macroalgae (large-celled algae such as seaweed) cascade down fjord walls, providing food sources that support larger populations of P. polaris. In addition, migrating Antarctic krill and baleen whales can transport nutrients to these regions in the form of feces and krill carcasses. P. polaris was also observed in smaller densities in the water column in all three bays. Although this species is known to undertake short swimming expeditions of up to fifteen seconds, these observations were relatively frequent, suggesting that P. polaris in Antarctica may behave differently from counterparts in Arctic and boreal environments. This could be driven by feeding opportunities, localized regions of turbulent mixing at the seafloor, or distinct circulation patterns, but further research is needed, according to Grange et al.   Both findings also suggest that P. polaris may form a link between pelagic (open water) and benthic food-webs within the region. For example, they may play an important role as ecological predators of benthic organisms like zooplankton, while providing food inputs to the seafloor when they die. This contributes to nutrient and energy transfers between the ecosystems, helping to integrate the dynamics of food-webs in different layers of the marine environment. This study was also the first to provide a phylogenetic (evolutionary history and relationship) analysis of the Ptychogastriidae family, to which P. polaris belongs. “We found relatively large genetic differentiation among P. polaris compared to that for other hydrozoan (the larger taxonomic class of organisms) species,” Grange explained. “This discovery may suggest the species contain multiple cryptic species (different species with identical physical forms) or an unusually high degree of sequence...

Read More

A Living Piece of History: An Outdoor Ice Rink in New Zealand

Posted by on Jan 24, 2017 in All Posts, Art/Culture, Featured Posts, Sports | 0 comments

A Living Piece of History: An Outdoor Ice Rink in New Zealand

Spread the News:ShareThe remains of an outdoor ice rink near Mount Harper/Mahaanui in New Zealand offer insight into the establishment, use and decline of what may have been the largest outdoor ice rink in the Southern hemisphere. The privately built rink on South Island was a popular social amenity from the 1930s to the 1950s, playing an important role in the development of ice hockey and skating in the country, as detailed in a heritage assessment carried out by Katharine Watson for New Zealand’s Department of Conservation (DOC). A combination of interviews, secondary sources and an archaeological survey were used to inform the history of the rink present in the assessment. Mt. Harper ice rink lies in the lee of the mountain (the side that is sheltered from the prevailing wind) that gives it its name, at the foot of the glacier-clad Southern Alps of New Zealand. It was built in the early 1930s by Wyndham Barker, the son of a minor member of the English gentry who lived in Canterbury and learned to ice skate while studying in Europe, as explained in the assessment. The rinks no longer contain any ice and some now contain vegetation, but the bunds (earth mounds) surrounding the ice rinks can still be seen. Many of the original buildings, such as the ticket office, toilet block, skate shed, a hut built to house the Barker’s cow, Sissy, and the Barker’s house are still standing. The rink was first built in the summer of 1931-1932 and was fed by water from a nearby stream. However, its original location was too exposed to the nor’westers (strong north-westerly winds that are characteristic of Canterbury in New Zealand), which rippled the ice. Barker subsequently moved the rink closer to Mt. Harper, building the rink by allowing controlled layers of ice to build up over many nights. The rink’s first major public season took place in the winter of 1934. A hydropower scheme was also installed in 1938 to power lights for skating at night, while allowing water to be sluiced onto the ice if necessary. “The whole landscape is really legible today, which is one of the things that makes it such a great place,” Watson explained to GlacierHub.  “These kinds of sites are very important records of the myriad ways in which human societies have used, interacted with, and taken advantage of seasonal ice over time,” added Rebecca Woods, a professor of the history of technology at the University of Toronto. “An archeological site like Barker’s rink would be a candidate for a cool virtual reality tour along the lines of a New York Times 360° video.” The potential of the site to tell the story of outdoor ice skating and ice hockey in New Zealand has been identified by the DOC. “The designation of the site as an Actively Conserved Historic Place recognizes this and entails a commitment to maintain the key buildings and structures in the expectation that despite being fairly isolated, the difficulty of access may change some time in the future,” shared Lizzy Sutcliffe, a representative from the DOC. The rink was subdivided over its first few years of use, with up to seven rinks existing in the 1940s. One reason for doing this was that the ice was not freezing well. It also allowed one of the rinks to be dedicated to ice hockey, which Barker was passionate about. In fact, he was an important figure in the history of ice hockey in New Zealand, establishing the Erewhorn Cup, an ice hockey tournament that persists to this day. “The main focus of the...

Read More

Roundup: Siberia, Serpentine and Seasonal Cycling

Posted by on Jan 16, 2017 in All Posts, Featured Posts, Roundup | 0 comments

Roundup: Siberia, Serpentine and Seasonal Cycling

Spread the News:ShareRoundup: Siberian Glaciers, Vegetation Succession and Sea Ice   Glaciers in Siberia During the Last Glacial Maximum From Palaeogeography, Palaeoclimatology, Palaeoecology: “It is generally assumed that during the global Last Glacial Maximum (gLGM, 18–24 ka BP) dry climatic conditions in NE Russia inhibited the growth of large ice caps and restricted glaciers to mountain ranges. However, recent evidence has been found to suggest that glacial summers in NE Russia were as warm as at present while glaciers were more extensive than today… We hypothesize that precipitation must have been relatively high in order to compensate for the high summer temperatures… Using a degree-day-modelling (DDM) approach, [we] find that precipitation during the gLGM was likely comparable to, or even exceeded, the modern average… Results imply that summer temperature, rather than aridity, limited glacier extent in the southern Pacific Sector of NE Russia during the gLGM.” Read more about the study here.     Plant Communities in the Italian Alps From Plant and Soil: “Initial stages of pedogenesis (soil formation) are particularly slow on serpentinite… Thus, a particularly slow plant primary succession should be observed on serpentinitic proglacial (in front of glaciers) areas..Ssoil-vegetation relationships in such environments should give important information on the development of the “serpentine syndrome” .Pure serpentinite supported strikingly different plant communities in comparison with the sites where the serpentinitic till was enriched by small quantities of sialic (rich in silica and aluminum) rocks. While on the former materials almost no change in plant species composition was observed in 190 years, four different species associations were developed with time on the other. Plant cover and biodiversity were much lower on pure serpentinite as well.” Read more about “serpentine syndrome” here.     Carbon Cycling and Sea Ice in Ryder Bay From Deep Sea Research Part II: Topical Studies in Oceanography: “The carbon cycle in seasonally sea-ice covered waters remains poorly understood due to both a lack of observational data and the complexity of the system… We observe a strong, asymmetric seasonal cycle in the carbonate system, driven by physical processes and primary production. In summer, melting glacial ice and sea ice and a reduction in mixing with deeper water reduce the concentration of dissolved organic carbon (DIC) in surface waters… In winter, mixing with deeper, carbon-rich water and net heterotrophy increase surface DIC concentrations… The variability observed in this study demonstrates that changes in mixing and sea-ice cover significantly affect carbon cycling in this dynamic environment.” Read more about carbon cycling in West Antarctica here.   Spread the...

Read More