Spatiotemporal changes of permafrost in the Headwater Area of the Yellow River under a changing climate

Abstract

This article attempts to predict the spatiotemporal changes of permafrost in the Headwater Area of the Yellow River (HAYR) on the northeastern Qinghai‐Tibet Plateau, Southwest China by using field monitoring and numerical models. Permafrost in the HAYR is categorized into four types: low‐ and high‐ice‐content high‐plain permafrost and low‐ and high‐ice‐content alpine permafrost. According to these permafrost types, changes in permafrost temperature were calculated by coupling a geometric model with the soil thermal conduction model. Based on the calculation results, this paper evaluates the changes of permafrost in the HAYR over the past 50 years and predicts the change trends of permafrost in the HAYR under the scenarios of RCP2.6, RCP6.0, and RCP8.5 for possible climate change in 2050 and 2010 from the Intergovernmental Panel on Climate Change Fifth Assessment Report. The results show that (a) in the process of permafrost degradation, the same permafrost type at different degradation stages results in different modes and rates of increasing temperature. The response of permafrost to climate change differs in various degradation stages of permafrost; (b) from 1972 to 2012, the areal extent of permafrost degradation was 1,056 km2, resulting from a sharp air temperature increase after the 1980s. By 2050, the areal extent of permafrost degradation into seasonal frost is similar under the three scenarios of climate change. The areal extent of permafrost degradation is 2,224, 2,347, and 2,559 km2 or 7.5%, 7.9%, and 8.6% of the total area in the HAYR, respectively. In RCP2.6, the areal extent of permafrost degradation into seasonal frost by 2100 would be approximately 3,500 km2 greater than that by 2050. In RCP6.0, the areal extent of permafrost degradation by 2100 would be 10,000 km2 or 32.9% of the total area in the HAYR. In RCP8.5, the area of permafrost degradation by 2100 would be 18,492 km2 or 62.2% of the total area in the HAYR; (c) the active layer thickness (ALT) in the HAYR would increase significantly. The average of the ALT was 1.51 m by 1972 and 2.01 m by 2012, respectively. Under the RCP2.6, RCP6.0, and RCP8.5 scenarios, the basin‐wide average of ALT would be 2.21, 2.40, and 3.08 m by 2050 and 2.78, 4.07, and 4.39 m by 2100, respectively.

Streamflow Changes in the Headwater Area of Yellow River, NE Qinghai-Tibet Plateau during 1955–2040 and Their Implications

“…An increased baseflow and melting ground-ice would boost groundwater recharge and increase groundwater storage upon permafrost thaw (e.g., [10,[18][19][20][21][22][23]). With a catchment area of 21,000 km 2 , the Headwater Area of the Yellow River (HAYR, above the Huanghe'yan Hydrological Station) on the northeastern Qinghai-Tibet Plateau (QTP), with widespread discontinuous (~86%) permafrost [24][25][26], and under a persistently warming and slightly wetting climate, flow regimes of the Yellow River in the HAYR have shown no evident increasing trend in general as reported. Instead, the Yellow River flow showed a general trend of decline during 1955-2019, but the ratio of the Q Max /Q Min demonstrated a slightly increasing trend under permafrost degradation, in contrast to the observed streamflow shifts in other northern and alpine permafrost regions (e.g., [6,7,13,19]).…”

Changes in flow regimes of the Yellow River in the Headwater Area of the Yellow River on the northeastern Qinghai-Tibet Plateau, SW China during 1955-2040

“…In the HAYR, discontinuous, isolated, and sporadic permafrost presents and account for 86% of the catchment area above HHY near Madoi (Li et al, 2016;Wang et al, 2018;Sheng et al, 2020). Mean annual ground temperatures, generally measured at 10-25 m in depth, are higher than -2.0 ; permafrost thickness in the HAYR is generally less than 73 m according to borehole measurements (Luo et al, 2012), and; the average active layer thickness (ALT) in the HAYR varies from 1.8 -2.4 m (1980-2006) (Luo et al, 2014).…”

“…In recent decades, the HAYR has witnessed a marked climate warming and subsequent permafrost degradation (Jin et al, 2009(Jin et al, , 2011Luo et al, 2018). The ALT has increased at a rate of 1.2 cm yr -1 (1972-2012), and; by 2100, the ALT is projected to increase by 2.78-4.39 m and permafrost areal extent in the HAYR is projected to decrease by 7.5%-8.6% under varied carbon emission scenarios (Sheng et al, 2020).…”

“…With a catchment area of 2.1×10 4 km 2 , the Headwater Area of the Yellow River (HAYR, above the Huangheyan (HHY) Hydrological Station), located on the northeastern Qinghai-Tibet Plateau (QTP), with widespread discontinuous (86%) permafrost (Li et al, 2016;Wang et al, 2018;Sheng et al, 2020), and under a persistently warming and slightly wetting climate, flow regimes of the Yellow River (YR) in the HAYR showed no general increasing trend; instead, the YR flow showed a general trend of decline during 1955-2019, but the ratio of the Q Max /Q Min streamflow demonstrated an slightly increasing trend under permafrost degradation, which is inconsistent with the observed streamflow shifts in other northern and elevational permafrost regions (e.g., Qiu, 2012;Ge et al, 2013;Kurylyk et al, 2016;Bring et al, 2017).…”

Dynamic changes of land use/cover and landscape pattern in a typical alpine river basin of theQinghai‐TibetPlateau, China

“…The research of Duan et al (2021) on the relationship between the normalized difference vegetation index and climate change shows that different vegetation types on the Qinghai‐Tibet Plateau have great spatial differences in response to climate change. Through field testing and numerical simulation, Sheng et al (2020) found that the area of permafrost on the Qinghai‐Tibet Plateau decreased by more than 1000 km 2 due to the sharp rise in temperature after 1980, and the problem of desertification has become increasingly serious. In addition, the continuous distribution of the landscape index is of great significance to the environment of the biological community.…”