Projected Drought Conditions over Southern Slope of the Central Himalaya Using CMIP6 Models

Sharma, Shankar; Hamal, Kalpana; Khadka, Nitesh; Ali, Munawar; Subedi, Madan; Hussain, Gulfam; Ehsan, Muhammad Fahad; Saeed, Sajjad; Dawadi, Binod

doi:10.1007/s41748-021-00254-1

Cited by 22 publications

(11 citation statements)

References 48 publications

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“…The drought severity (DS), tree density (TD), soil cation exchange capacity (CEC) and available water‐holding capacity (AWC) of soil were also introduced into the BRT models. The DS was measured by the sum of the SPEI‐3 values during the drought year(s) (Sharma et al., 2021). The TD was used to characterize the competitive pressure among individual trees in a forest stand (Crowther et al., 2015) and was derived from a global map of tree density (https://elischolar.library.yale.edu/yale_fes_data/1/).…”

Section: Methodsmentioning

confidence: 99%

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Enhanced growth resistance but no decline in growth resilience under long‐term extreme droughts

Wang,

Xu,

et al. 2023

Global Change Biology

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The frequency, intensity, and duration of extreme droughts, with devastating impacts on tree growth and survival, have increased with climate change over the past decades. Assessing growth resistance and resilience to drought is a crucial prerequisite for understanding the responses of forest functioning to drought events. However, the responses of growth resistance and resilience to extreme droughts with different durations across different climatic zones remain unclear. Here, we investigated the spatiotemporal patterns in growth resistance and resilience in response to extreme droughts with different durations during 1901–2015, relying on tree‐ring chronologies from 2389 forest stands over the mid‐ and high‐latitudinal Northern Hemisphere, species‐specific plant functional traits, and diverse climatic factors. The findings revealed that growth resistance and resilience under 1‐year droughts were higher in humid regions than in arid regions. Significant higher growth resistance was observed under 2‐year droughts than under 1‐year droughts in both arid and humid regions, while growth resilience did not show a significant difference. Temporally, tree growth became less resistant and resilient to 1‐year droughts in 1980–2015 than in 1901–1979 in both arid and humid regions. As drought duration lengthened, the predominant impacts of climatic factors on growth resistance and resilience weakened and instead foliar economic traits, plant hydraulic traits, and soil properties became much more important in both climatic regions; in addition, such trends were also observed temporally. Finally, we found that most of the Earth system models (ESMs) used in this study overestimated growth resistance and underestimated growth resilience under both 1‐year and 2‐year droughts. A comprehensive ecophysiological understanding of tree growth responses to longer and intensified drought events is urgently needed, and a specific emphasis should be placed on improving the performance of ESMs.

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Section: Methodsmentioning

confidence: 99%

“…The gridded CH was obtained from the global 1 km forest canopy height dataset (Simard et al, 2011) and available water-holding capacity (AWC) of soil were also introduced into the BRT models. The DS was measured by the sum of the SPEI-3 values during the drought year(s) (Sharma et al, 2021).…”

Section: Boosted Regression Trees Modelmentioning

confidence: 99%

Enhanced growth resistance but no decline in growth resilience under long‐term extreme droughts

Wang,

Xu,

et al. 2023

Global Change Biology

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“…Other methods for calculating PET are considered superior to the Thornthwaite method (e.g., Penman-Monteith); those methods require more variables (e.g., relative humidity) and thus are not adopted here. The Thornthwaite method has been used effectively for several drought and fire studies in Nepal (Hamal et al 2020b(Hamal et al , 2021Sharma et al 2021). Here, we considered three different timescales, monthly (SPEI-1), seasonal (SPEI-3, SPEI-6), and annual (SPEI-12), to compute the drought indices.…”

Section: Observational Datamentioning

confidence: 99%

Amplified drought trends in Nepal increase the potential for Himalayan wildfires

Pokharel

Sharma²,

Stuivenvolt-Allen³

et al. 2023

Climatic Change

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In spring 2021, Nepal underwent a record wildfire season in which active fires were detected at a rate 10 times greater than the 2002-2020 average. Prior to these major wildfire events, the country experienced a prolonged precipitation deficit and extreme drought during the post-monsoon period (starting in October 2020). An analysis using observational, reanalysis, and climate model ensemble data indicates that both climate variability and climate changeinduced severe drought conditions were at play. Further analysis of climate model outputs suggests the likely reoccurrence of drought conditions, thus favoring active wildfire seasons in Nepal throughout the twenty-first century. While the inter-model uncertainty is large and direct modeling of wildfire spread and suppression has not been completed, the demonstrated relationship between a drought index (the standardized precipitation and evapotranspiration index) and subsequent fire activity may offer actionable opportunities for forest managers to employ the monitoring and projection of climate anomalies at sub-seasonal to decadal timescales to inform their management strategies for Nepal's wildlands.

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“…Human-induced climate change has emerged globally in temperature and evapotranspiration increases and precipitation changes. These changes significantly impact hydrometeorological disasters, including droughts, floods, heat waves, and others (Cowherd et al, 2023;An et al, 2022;IPCC, 2021;Sharma et al, 2021;Separated & Nafung, 2021;Bazaz et al, 2018;Huo-Po et al, 2013). Drought is a complex and costly natural disaster that is difficult to monitor and define.…”

Section: Introductionmentioning

confidence: 99%

Future drought over Urmia Lake Basin under SSP scenarios: the relevance of snow melt

Habibi,

Babaeian,

Schöner

2024

Preprint

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Abstract. Snow melt is one of the sources of freshwater supply in the late spring and summer in the mountainous regions of Iran, especially in the Urmia Lake Basin (ULB). In this study, past and future droughts of Urmia Lake Basin (ULB) have been studied by analyzing three types of droughts: (i) precipitation-deficit based characterized by the Standardized Precipitation Index (SPI), (ii) precipitation-evapotranspiration based droughts characterized by the Standardized Precipitation and Evapotranspiration Index (SPEI) and (iii) those droughts forced additionally by snow melt using the Snowmelt and Rain Index (SMRI). While reanalysis data ERA5-land describes the past climate, bias-corrected CMIP6 ensemble serves as the data for the future climate. Contrary to the SPI drought index, an increasing trend has been projected both in snowmelt-based (SMRI trend -0.068 units/year) and evapotranspiration-based (SPEI trend -0.079 units/year) drought indices, both for the period 1995–2014 and significant at the 5 % level. This indicates that summer droughts in the ULB will increase in the future, particularly because of increasing evapotranspiration and less snowmelt, while precipitation changes play a minor role. Drought severity will generally increase from the near future (2021–2040) to the far future (2081–2100), particularly forced by snowmelt deficit under the SSP5-8.5 scenario for the far future. Under the present climate, the extent of drought-affected areas is similar for all three types of droughts. However, under future climate drought-affected areas forced by snowmelt deficit will increase from about 20 % in the near future (2021–2040) to 60 % in the far future (2081–2100), showing that snow melt plays a vital role in aggravating the drought over the Basin. A decrease in the Basin's drought trend in the 2080s and later can be seen both for SMRI and SPEI indices under SSP1-2.6, which may be due to the temperature effect on snowmelt and evapotranspiration from the reduction of greenhouse gas emissions in SSP1-2.6 scenario at the end of 21st century. Such a decrease in SMRI and SPEI drought indices can also be seen around the 2090s under the SSP2-4.5 scenario. Results also reveal that the mountainous areas of the Basin will experience much less drought compared to the lowlands (including the lake) and foothills.

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Projected Drought Conditions over Southern Slope of the Central Himalaya Using CMIP6 Models

Cited by 22 publications

References 48 publications

Enhanced growth resistance but no decline in growth resilience under long‐term extreme droughts

Enhanced growth resistance but no decline in growth resilience under long‐term extreme droughts

Amplified drought trends in Nepal increase the potential for Himalayan wildfires

Future drought over Urmia Lake Basin under SSP scenarios: the relevance of snow melt

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