Онлайн семинар отдела гляциологии состоится 8 декабря, во вторник, в 11.00.
We kindly invite you to take part in the online seminar of the Department of Glaciology on December 8, Tuesday, at 11.00 (Moscow time)
VUB, Vrije Universiteit Brussel (Belgium)
Modelling the past and future evolution of Kara-Batkak glacier, Tien Shan, Kyrgyzstan
The worldwide loss of glaciers due to global warming is expected to continue and have far-reaching consequences for water availability, especially in High Mountain Asia, the region with the largest concentration of glaciers globally and one of the regions with the largest total ice mass loss during the last decades. Yet, due to access challenges and the lack of consistent long-term temporal and spatial information, it is also the region with the largest uncertainty regarding current and future ice volume assessments. This is precarious for water security assessments in the densely populated lowlands surrounding the high mountain ranges, where the glacier retreat since the end of the Little Ice Age has recently intensified. Continued in situ mass balance and ice thickness measurements are conducted for only a few glaciers in the region. One of these is Kara-Batkak glacier, located within the Terskey Ala-Too mountain range, part of the Kyrgyz Tien Shan.
As such, the aim of this work was to model the past and future evolution of Kara-Batkak glacier using the available data. The first part of the research consisted of the calibration of a time-dependent two-dimensional mass balance model of intermediate complexity, suitable for regions with limited available data. Despite the limited quality of the available data, the model performance was satisfying. Regarding the parameter values, the resulting tuned temperature gradient corresponded to the normal lapse rate in the free atmosphere. For the precipitation gradients and atmospheric flux parameters very low values were found, which were attributed to depletion of precipitable water, relatively high summer temperatures and small changes in albedo.
The second part of this study comprised the reconstruction of a historical climatic data series – based on meteorological station observations, global datasets and tree ring data – to drive the model since the end of the Little Ice Age. To simulate glacier retreat without the need for an ice-flow model, a glacier retreat parametrisation was added to the mass balance model. The results showed that the glacier was presumptively in steady state between the end of the 18th and 19th century, and that the Little Ice Age in the Terskey Ala-Too most likely ended towards the end of the 19th century. Lastly, the third part of the research encompassed future predictions for the retreat of Kara-Batkak glacier. For this, temperature and precipitation series under three future climate scenarios (RCP 2.6, RCP 4.5 and RCP 8.5) were constructed using projections by a reference Earth System model (CESM1-CAM5). Besides, a control dataset was added, representing a future climate with no further changes in temperature or precipitation compared to the last decade. As the results showed, almost the entire glacier is projected to disappear under RCP 8.5 and even under RCP 2.6 and the control scenario, the projected glacier retreat by the end of the 21st century is substantial.
Nevertheless, additional meteorological and topographical data could improve the model, and the results showed that for a better outcome regarding the past glacier retreat a more accurate representation of the Little Ice Age surface elevation of the glacier would be indispensable. As to the future evolution of Kara-Batkak glacier, additional projections of temperature and precipitation by other Earth System models would be needed to get a better idea of the entire range of uncertainty.
Meeting ID: 903 709 0909
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- During the presentation, all microphones will be muted so not to interfere with the presenter.
- If you have any questions, please use chat.
- At the end of the presentation (about 25-30 minutes) there will be an opportunity to ask questions.
Встреча будет проходить в формате видеоконференции Zoom.
Meeting ID: 903 709 0909
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