Posts Tagged "tibetan plateau"

Tibetan Plateau Shows Warming Slowdown

Posted by on Nov 17, 2016 in All Posts, Featured Posts, Science | 0 comments

Tibetan Plateau Shows Warming Slowdown

Spread the News:ShareFrom 2001 to 2014, climate scientists observed a “hiatus” or pause in global warming. It is an issue that has led to much discussion in the scientific community and among climate skeptics who see the trend as an indication that global warming does not exist. According to a paper published by Fyfe et al., the word “hiatus” is not fully accurate. Instead, instrument data shows a slowdown or deceleration (as opposed to a full halt) of global warming at the beginning of the 21st century. Glaciers are key in helping us understanding the global warming slowdown. In a recent article, Wenling An et al. describe how the glaciers of the Tibetan Plateau show evidence of the recent warming slowdown. Known as the “Roof of the World,” the Tibetan Plateau spans 1,565,000 square kilometers and is the origin of the Indus, Mekong, and Yangtze Rivers. Due to its large size and location near the tropics, the plateau is one of the most ecologically diverse alpine regions in the world. Therefore, the Tibetan Plateau’s response to climate change has been studied extensively, with researchers relying on both meteorological and paleoclimate data. Most studies to date have taken place in the more accessible eastern and central parts of the Tibetan Plateau, where there are a greater number of meteorological stations. Meanwhile, the northwestern part of the plateau remains remote and formidable. Thus, data gathered in the northwestern plateau continues to be sparse and collected during shorter timeframes. But the northwestern area has an important connection to the Asian monsoon season and mid-latitudes, recently prompting scientists to focus increased attention on gathering higher resolution data from the area. For one, the Tibetan Plateau plays an important role in the Asian monsoon season by acting as a heat source in the summer and a heat sink in the winter, according to an article by Hongxu Zhao and G.W.K. Moore. Interestingly, the new data collected by An et al. revealed that the eastern and northwestern parts of the plateau have experienced entirely different temperature trends since the beginning of the 21st century. The eastern part shows increased warming during that period, while the northwestern part shows no warming. In their research, An et al. describe the usefulness of using ice cores (drilled samples of ice from a glacier) to detect this phenomena in climate data. For example, ratios of stable isotopes (forms of the same element with a different number of neutrons) found in ice cores provide information that informs us about past climate conditions. Studies were done on ice cores taken from the Tibetan Plateau examining the relationship of a particular variation of the amount of an oxygen isotope (δ18O) with precipitation and air temperature. The precipitation on the plateau was captured within the ice core as snow, which then converted to ice. The data demonstrated a positive correlation. This means the higher the concentration of δ18O, the higher the temperature of the air when the water evaporated. In situations of higher δ18O, the research indicates that the air temperature was higher at the time the snow formed. Aside from temperature, the effect of seasonality and the precipitation amount were also examined to understand the relationship of the δ18O concentrations. Through statistical t-tests, An et al. concluded that seasonality and the precipitation amount did not have an effect on the concentration as temperature does. The results indicate that the temperature is the factor influencing the concentration of δ18O, rather than other factors. The authors of the study drilled ice cores at Chongce Glacier on the northwestern part of the Tibetan Plateau. They...

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Roundup: Tyrolean Iceman, Greenland Glaciers and Tibetan Melt

Posted by on Oct 17, 2016 in All Posts, Art/Culture, Featured Posts, News, Roundup, Science | 0 comments

Roundup: Tyrolean Iceman, Greenland Glaciers and Tibetan Melt

Spread the News:Share Roundup: Clues to Ötzi, Greenland Glaciers and Tibet   Tyrolean Iceman offers insights into Copper Age clothing. From Nature: “The attire of the Tyrolean Iceman, a 5,300-year-old natural mummy from the Ötzal Italian Alps, provides a surviving example of ancient manufacturing technologies. Research into his garments has however, been limited by ambiguity surrounding their source species. Here we present a targeted enrichment and sequencing of full mitochondrial genomes sampled from his clothes and quiver, which elucidates the species of production for nine fragments. Results indicate that the majority of the samples originate from domestic ungulate species (cattle, sheep and goat), whose recovered haplogroups are now at high frequency in today’s domestic populations. Intriguingly, the hat and quiver samples were produced from wild species, brown bear and roe deer respectively. Combined, these results suggest that Copper Age populations made considered choices of clothing material from both the wild and domestic populations available to them.” Learn more about the clothing of the Tyrolean Iceman here:   Early researchers of Greenland’s glaciers. From Exploring Greenland: “Christopher J. Ries sheds light on the disparate goals of three diverse groups that created geological knowledge in post-World War II Greenland: the civilian scientists of the US Geological Survey Military Branch working in northern Greenland, an international team of geologists of the Danish East Greenland Expeditions led by Danish geologist Lauge Koch working in eastern Greenland, and geologists of the Danish Geological Survey of Greenland working in western Greenland. Ries argues that the interdisciplinary American group’s ultimate mission was to enhance the ability of military units to operate in Arctic terrains, while the two mono-disciplinary Danish-led teams attempted to balance academic interests in mapping and interpreting the structure of bedrock against more prosaic pursuit of profitable minerals.” Read more about the early researchers of Greenland’s glaciers here:   Glacial melt of Tibetan Plateau exceeds USEPA guidelines. From the Journal of Hydrology: “Global warming has resulted in rapid glacier retreat on the Tibetan Plateau, and the impacts of glacier melting on downstream ecosystems remain largely unknown. Minor and trace elements in stream water draining Dongkemadi Glacier  were examined during the ablation season of 2013…Downstream increased concentrations and/or fluxes of some metals and metalloid (e.g. Cr, Cu and As) suggest potential environmental impacts. Discharge-normalized cation denudation rate (372 Σ∗meq+m−3) in the Dongkemadi Glacier basin is larger than those from alpine and polar glaciers, suggesting a stronger weathering of carbonate with greater abundance on the Tibetan Plateau in comparison to other mountain and polar glacial catchments. The maximum Fe concentration exceeds the USEPA guideline, and Al, Zn and Pb are close to or of the same order of magnitude as liminal values. This implies that the Tibetan Plateau may face a challenge of ecosystem health and environmental issue in a warming climate.” Learn more about the Tibetan Plateau here: Spread the...

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Slower Evaporation Rate Spurs Tibetan Lake Growth

Posted by on May 4, 2016 in All Posts, Featured Posts, Science, Uncategorized | 0 comments

Slower Evaporation Rate Spurs Tibetan Lake Growth

Spread the News:ShareA new study in the Journal of Hydrology uses a novel modelling technique that helps scientists understand the effect of evaporation on the expansion of lakes in the inner Tibetan Plateau. This research also has implications for the use of climate models on the Plateau. In addition, the work has broader significance for weather patterns beyond Tibet, due to the plateau’s influence on the atmospheric circulation of the Asian Monsoon system. The researchers focused on Nam Co Lake, the second largest of the more than one thousand lakes on the Tibetan Plateau. Unlike many lakes, which drain through rivers, this lake is in a closed basin, losing water only through evaporation. There is no bigger lake at a higher altitude than this body of water anywhere in the world. In fact, Nam Co Lake is expanding, and the researchers wanted to better understand why. Seeking a fresh approach, the researchers aimed to specify the role of evaporation in this expansion. Led by Ning Ma of the Institute of Tibetan Plateau Research, Chinese Academy of Sciences, they found that the expansion of Nam Co Lake is partly caused by decreased rates of evaporation, possibly due to declining wind speeds and decreased solar radiation. There have been many studies exploring the rapid expansion of lakes in the region since the 1990’s, but there is no agreement on the explanation for this phenomenon. Past studies have looked at increased glacial runoff or increased precipitation as the main drivers. But the authors of this study explain that to fully understand the expansion of this closed lake, evaporation, a factor often neglected by researchers, needs to be incorporated as well.  The authors indicate that evaporation in this lake, as in other lakes, depends on several factors: the radiation that reaches the lake’s surface, air temperature, wind speed, and the dryness of the air. In order to find which of these variables has the largest effect, the scientists correlated the average values of each with the evaporation rates over the lake. Wind speed, they concluded, was most plausible candidate. However, the lack of nearby weather stations and the mountainous landscape of the region pose an issue for the construction of accurate models which include wind speed. Because of this, the researchers used a different model than is usually employed during evaporation studies; this alternate method is called a complementary relationship lake evaporation (CRLE) model. The CRLE model did not include wind speed measurements, but the researchers can estimate this factor by including an air stability factor that includes variables for heat and moisture content. The study suggests that the ability to more accurately model the rates of evaporation without wind speed data is the key to counterbalancing the lack of meteorological observations in this area. Further, the need to examine the lake over decades can best be addressed by models, granted the lack of data from the weather stations in the region. Accurate models may be able to help those in the region better understand lake expansion. The Tibetan Plateau is of great regional importance because of the role it plays in the Asian Monsoon system. Simply put, the heat energy (which is affected by evaporation) from the plateau thermally regulates the monsoon circulation patterns. Changes in evaporation rates from lakes may have implications for the many areas affected by the Asian Monsoon. By providing an assessment of the CRLE model, which the authors argue provides a more accurate representation of evaporation, this study may aid in the understanding of the processes taking place in this critical, but rapidly changing, region.   Spread the...

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Roundup: Yaks, Snow Algae, and Slime Molds

Posted by on Apr 13, 2015 in All Posts, Featured Posts, Images, Roundup, Science, Uncategorized | 0 comments

Roundup: Yaks, Snow Algae, and Slime Molds

Spread the News:ShareHow do wild yaks respond to glacier melt and past exploitation? “To explore how mammals of extreme elevation respond to glacial recession and past harvest, we combined our fieldwork with remote sensing and used analyses of ~60 expeditions from 1850–1925 to represent baseline conditions for wildlife before heavy exploitation on the Tibetan Plateau. Focusing on endangered wild yaks (Bos mutus), we document female changes in habitat use across time whereupon they increasingly relied on steeper post-glacial terrain, and currently have a 20x greater dependence on winter snow patches than males. Our twin findings—that the sexes of a cold-adapted species respond differently to modern climate forcing and long-past exploitation—indicate that effective conservation planning will require knowledge of the interplay between past and future if we will assure persistence of the region’s biodiversity.” Read more about the article here.   Snow algae grows on glacier surface annually. “Snow algae in shallow ice cores (7 m long) from Yala Glacier in the Lang-tang region of Nepal were examined for potential use in ice-core dating. Ice-core samples taken at 5350 m a.s.l. in 1994 contained more than seven species of snow algae. In a vertical profile of the algal biomass, 11 distinct algal layers were observed. Seasonal observation in 1996 at the coring site indicated most algal growth occurred from late spring to late summer. Pit observation in 1991, 1992 and 1994 indicated that algal layer formation takes place annually.” Read more about the article here.   Slime mold preys on bacterium under snow. “Abundance and habitat requirements of nivicolous myxomycetes were surveyed over 4 yr at the northwestern Greater Caucasus ridge (Russia). An elevational transect spanning 3.66 km from 1 700 to 3 000 m a.s.l. was established at the summit Malaya Khatipara situated within the Teberda State Biosphere reserve. Between 2010 and 2013 1177 fructifications of nivicolous myxomycetes were recorded, with 700 of these determined to 44 species, varieties, and forms. Virtually all fructifications developed near or at the margin of a snow field. Abundance of myxomycete fructifications varied extremely between years, ranging from near zero to hundreds of colonies. At sites with known myxomycete occurrences 16 data loggers were installed in the years 2011 and 2012, measuring relative humidity and temperature at the soil surface. Together with weather data recorded on the nearby Klukhor pass and experiments with myxamoebae cultured on agar, these data explain the observed extreme fluctuations in myxomycete abundance.” Read more about the article here. Spread the...

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Roundup: Rock Avalanche, Melting Sound, Black Carbon

Posted by on Mar 23, 2015 in All Posts, Featured Posts, News, Roundup, Science | 0 comments

Roundup: Rock Avalanche, Melting Sound, Black Carbon

Spread the News:ShareLandslides on Glaciers “The chapter looks mainly at massive rock slope failures that generate high-speed, long- runout rock avalanches onto glaciers in high mountains, from subpolar through tropical latitudes. Drastic modifications of mountain landscapes and destructive impacts occur, and initiate other, longer-term hazards. Worst-case calamities are where mass flows continue into inhabited areas below the glaciers. Travel over glaciers can change landslide dynamics and amplify the speed and length of runout.” Read more about this chapter here.   Noise from Melting Glaciers “According to research accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union, the underwater noise levels are much louder than previously thought, which leads scientists to ask how the noise levels influence the behavior of harbor seals and whales in Alaska’s fjords.” Read more of this article.   Black Carbon in Tibetan Plateau “High temporal resolution measurements of black carbon (BC) and organic carbon (OC) covering the time period of 1956–2006 in an ice core over the southeastern Tibetan Plateau show a distinct seasonal dependence of BC and OC with higher respective concentrations but a lower OC / BC ratio in the non-monsoon season than during the summer monsoon. We use a global aerosol-climate model, in which BC emitted from different source regions can be explicitly tracked, to quantify BC source–receptor relationships between four Asian source regions and the southeastern Tibetan Plateau as a receptor.” Read the paper here.     Spread the...

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