the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Persistent warming of the ground on the Earth’s Third Pole
Yuyang Wang
Jinzhi Ding
Shilong Piao
Abstract. A continuously increasing ground temperature in the Tibetan Plateau (TP) can result in permafrost degradation and impact regional climate through land-atmosphere interactions. However, systematic knowledge of spatiotemporal dynamics and regulatory mechanisms of ground temperature changes in the region is limited. Here, we quantify the thermal status and trends of both soil temperatures measured at depth and typical permafrost profile temperatures. We show that, shallow soil layers (0–40 cm) in most TP regions experienced significant warming from 1981 to 2021, with lower rates at greater depths. Ground surface warming trends aligned with air temperature, but the timing of the maximum warming trend was progressively delayed with depth. Cold seasons exhibited the largest warming trends for air and ground surface, while warm seasons saw greater warming trends at 5–40 cm soil depths. Regionally, warming trends were larger at sites with lower mean annual temperature and higher elevation. Out of the factors tested in addition to air temperature, only snow-cover days and downward longwave radiation were significantly related to the soil warming rate trends. Further analysis reveals that the persistent shallow ground temperature increase over decades is linked to the Atlantic Multidecadal Oscillation's warm phase, impacting near-surface air temperature through teleconnections. Additionally, we present spatially heterogeneous observations of continuous warming in permafrost profiles, which show intense warming in the surface layers, and minimal warming at 40 m depth. Permafrost profile warming magnitude and depth-dependent variation are influenced by local climate and elevation. This study provides a comprehensive view of persistent warming in the Tibetan Plateau across surface and deep layers.
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Yuyang Wang et al.
Status: open (until 08 Nov 2023)
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CC1: 'Comment on tc-2023-125', Zhiyong Ding, 06 Sep 2023
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In this paper, the author quantified the thermal status and trends of both soil temperatures measured at depth and typical permafrost profile temperatures on the Earth’s Third Pole. The topic selection has important research value. They show shallow soil layers in most study regions experienced significant warming from 1981 to 2021, with lower rates at greater depths. Moreover, the deep ground temperature variation at the typical permafrost borehole sites were also analyzed. This study provide a comprehensive understanding of the implications of recent variations in ground temperature across the Tibetan Plateau. However, there are still obvious drawbacks in this study. It is recommended to minor revision the manuscript before publication.
Major comments:
In the introduction section, after providing an overview of previous research, the authors should introduce the core scientific questions to be addressed in this study. Subsequently, they should outline the aspects from which this study intends to make improvements. Authors need to refine this part.
In the Discussion section, there have been previous studies on soil temperature in the Tibetan Plateau as well. The authors should extensively reference relevant literature and highlight the novel findings and innovations of this study.
Ground ice content is mentioned as a crucial element in the discussion but no information on ice content is provided in the analysis. The author needs to explain this.
The authors used some grid climate variables and other variables in attributing the increase in soil temperature. The resolution of these variables is relatively rough, and whether they match the soil temperature observed at the site. Before making correlation analysis, the author needs to first explore the reliability of these grid dataset.
The author believes that some atmospheric circulation plays an important role in the attribution of the interdecadal increase in soil temperature, but the mechanism behind it is not discussed enough. The author should add relevant references for further explanation.
Minor comments:
Some of the legends in the figures need more explanation, and the symbols used in the figures are not clearly described. The formatting of some figures and tables could be improved. For example, Figure 3 should give the literature source of the permafrost distribution map and indicate what figures (a)-(f) represent respectively. The color of soil at different depths in Figure 4 should be consistent with other figures in the paper. Some of the information in Figure 8 partially overlaps with previously published literature, and relevant references should be explicitly cited.
Some descriptions in the conclusion part lack support from data analysis and constitute speculative conclusions. These should be removed. For example, “The extent and variation of profile warming with depth are influenced by multiple factors, including local climate, lithology, and elevation”. The results regarding the lithology of the observation sites are not presented in the text.
The grammar and logical coherence of this article are still lacking. The authors should seek a native English-speaking scholar for comprehensive language refinement.
Citation: https://doi.org/10.5194/tc-2023-125-CC1
Yuyang Wang et al.
Yuyang Wang et al.
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