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South University of Science and Technology latest Nature!

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The Greenland Ice Sheet (GrIS) is currently the largest single contributor to global mass-induced sea level rise, largely due to the amplification of the Arctic on an increasingly warming planet. However, the processes of glacial water accumulation, storage and eventual release are still poorly understood.

On October 30, 2024, General Ran's team of Southern University of Science and Technology was inNaturemagazinePublished online entitled“Vertical bedrock shifts reveal summer water storage in Greenland ice sheet”The research paper,The study hairA considerable amount of summer meltwater is now temporarily buffered throughout the GrIS periphery, peaking in July and then gradually decreasing.

Increased meltwater runoff was the largest contributor (about 55%) to the mass loss of GrIS after 2000. On the way to the ocean, meltwater may be temporarily stored in surface lakes (on glaciers), snow layers (compressed snow layers) or ice caves (on glaciers), ice bedrock interfaces (under glaciers) or as groundwater. Most of this buffer water storage (BWS) is gradually released into the ocean before the start of the next melt season.BWS affects the evolution of ice sheets in several ways. In the inner accumulation zone, liquid water usually penetrates into the iron aquifer, where it refreezes or replenishes the molten iron aquifer. On the semi-impervious ice surface of the marginal ablation zone, meltwater enters the lakes and streams on the glacier, and finally flows into the ice sheet-bedrock interface through moraines and cracks.

In the subglacial environment, BWS causes a higher base water pressure, producing a temporary lubrication effect and acceleration of ice flow, especially at the beginning of the ice melting season. As the ice-melting season progresses, the accumulation of water forms an effective drainage system under the ice, reducing the pressure of the basal water.However, these drainage systems and glacier beds are highly uneven, and high base water pressure may persist if the drainage system is not hydraulically connected to the river.

In situ observations on GrIS are still too sparse to account for highly inhomogeneous (basal) water accumulation and flow in space and time. The ice-breaking radar detected the characteristics of the basement water, but the information of water volume and pressure was lacking. Satellite gravimetry quantifies water storage and release, but its relatively crude sampling prevents regionally resolved assessments of Greenland's hydrology.

Here, the author adopts a new method to quantify the spatial and temporal evolution of Greenland BWS: continuous monitoring of elastic vertical bedrock displacement through 22 Greenland GNSS network (GNET) stations. The results are derived from the quantification of the spatio-temporal behavior of the total water mass leaving the GrIS by analyzing the elastic deformation of the bedrock measured by the Global Navigation Satellite System (GNSS) site. During the melt season, the buffered meltwater allowed the bedrock close to the GNSS station to settle up to about 5mm. Regionally, meltwater storage varies from 4.5 weeks in the southeast to 9 weeks in other areas. The study also suggests that meltwater runoff simulated from regional climate models may contain systematic errors, requiring further scaling of about 20% in the warmest years.These results suggest that GNSS data are likely to constrain little-known hydrological processes in Greenland, providing a basis for improved predictions of future GrIS melt behavior and associated sea level rise.

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Chinese Academy of Sciences latest Nature!

University of Chinese Academy of Sciences Hu Ligang/Yin Yongguang Cooperation Latest PNAS

Chinese Academy of Sciences latest Nature!

University of Chinese Academy of Sciences Hu Ligang/Yin Yongguang Cooperation Latest PNAS