China
Africa
Explore chapters and articles related to this topic
Climate Manifestations
Published in Gregory T. Haugan, The New Triple Constraints for Sustainable Projects, Programs, and Portfolios, 2016
The IPCC4 Report for snow and ice indicates just what one would expect: as the climate warms, snow cover and sea ice extent decreases, and glaciers and ice caps lose mass owing to dominance of summer melting over winter precipitation increases. This contributes to sea level rise. There is a projected reduction of sea ice in the twenty-first century in both the Arctic and Antarctic, with the projected reduction being accelerated in the Arctic, where summer sea ice cover is expected to disappear entirely in the latter part of the twenty-first century. Widespread increases in thaw depth over much of the permafrost regions are projected to occur in response to warming over the next century.
Load transfer of pile foundations in frozen and unfrozen soft clay
Published in International Journal of Geotechnical Engineering, 2020
Abdulghader A. Aldaeef, Mohammad T. Rayhani
Frozen ground may fail to maintain its frozen condition in confrontation of global warming. In warm permafrost, a small temperature increase may be sufficient to cause extensive thawing. In cold permafrost, temperature increase by couple of degrees may result in significant increase in active layer depth (annual thaw depth), which can promote significant thaw settlement and increase the potential frost heave upon freezing. The thaw settlement in ice-rich soils could be more disruptive and cause inclusive damage to the structures (Esch and Osterkamp 1990). Temperature record in high-latitude regions of earth has shown 0.6°C increase per decade over the last 30 years, which represent twice the global average (IPCC 2013). This normally would result in thawing the frozen ground and reduce the frozen depth (Brown and Romanovsky 2008). Lawrence and Slater (2005) used weather data to model permafrost area in the Northern Hemisphere under global warming impact predicting present-day permafrost as well as permafrost condition over the 21st century. The model showed that a reduction in near surface permafrost area from 12 to 10.5 million of Km2 has occurred between 1900 and 2000. Dramatic permafrost degradation was predicted by 2100 yielding 1 million km2 of near surface permafrost area.
Estimating methane emissions using vegetation mapping in the taiga–tundra boundary of a north-eastern Siberian lowland
Published in Tellus B: Chemical and Physical Meteorology, 2019
T. Morozumi, R. Shingubara, R. Suzuki, H. Kobayashi, S. Tei, S. Takano, R. Fan, M. Liang, T. C. Maximov, A. Sugimoto
We defined a 50-m monitoring transect, which was composed of a 100 × 50 m survey plot at site K (Fig. 2a) with local survey points distributed throughout a 10 × 10 km area of the Indigirka lowland (Fig. 1). At site K, the relative elevation from the lowest base level was measured using a surveying telescope (AT-B4, TOPCON, Tokyo, Japan) at every 2.5 m point along a 50 m transect on 31 July 2012, and in 5 m grids at 231 points over the 100 × 50 m survey plot on 14 July 2013. In addition, we measured seasonal thaw depth (i.e. active layer depth) using a metal rod, and estimated frost table height by subtracting the thaw depth from the relative elevation over the same survey plot. Volumetric soil moisture was also measured using a portable moisture sensor (Trime-Como, IMKO, Ettlingen, Germany) between the surface and a depth of 8 cm, by performing four observations at every 5 m points along the monitoring transect at site K in mid July 2012, 2014 and 2015, as well as at 70 local survey points distributed throughout the 10 × 10 km area in the Indigirka lowland in mid July 2014.