Irrigation and warming drive the decreases in surface albedo over High Mountain Asia

Maina, Fadji Zaouna; Kumar, Sujay V.; Gangodagamage, C.

doi:10.1038/s41598-022-20564-2

Cited by 8 publications

(3 citation statements)

References 71 publications

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“…The reduction of albedo when changing from annual agriculture to sheltered agriculture can be explained by considering that there are materials used in greenhouse structures capable of absorbing large amounts of solar radiation, but, in counterpart, increasing the heat island effect [39]. In the case of a change from annual agriculture to irrigation agriculture, the decrease in albedo is explained by the increase in soil moisture and the constant greening of the cover [47,48].…”

Section: Discussionmentioning

confidence: 99%

Deforestation and Its Effect on Surface Albedo and Weather Patterns

et al. 2023

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Deforestation is an important environmental problem and a key promoter of regional climate change through modifying the surface albedo. The objective of this research was to characterize the impact of deforestation and land use changes on surface albedo (α) and climate patterns in a tropical highland region of Mexico, between the years 2014 and 2021. The main land cover types are coniferous forests (CF), oak and gallery woodlands (OGW), and annual agriculture (AA), which represent more than 88% of the regional territory. We used 2014 and 2021 Landsat 8 OLI images with topographic and atmospheric correction in order to develop an inventory of albedo values for each land cover type in both time scenarios. Albedo images were generated by using the equation proposed by Liang in 2001, which is based on the reflectance of the bands 2, 3, 4, 5, and 7. Differences in albedo values were calculated between the years 2014 and 2021, and those differences were correlated with variations in climate parameters, for which we used climate data derived from the WRF model. In addition, the different land use changes found were classified in terms of triggers for increasing or decreasing surface albedo. We used the Mann–Whitney U Test to compare the 2021 − 2014 climatic deviations in two samples: Sample A, which included sites without albedo change in 2021; and Sample B, including sites with albedo change in 2021. Results showed that between 2014 and 2021, at least 38 events of land use change or deforestation occurred, with albedo increments between 1 and 11%, which triggered an average increment of 2.16% (p < 0.01; Mann–Whitney U Test) of the regional surface albedo in comparison to the 2014 scenario. In this period, the albedo for CF, OGW, and AA also increased significantly (p < 0.001; Mann–Whitney U Test) by +79, +12, and +9%, respectively. In addition, the regional albedo increment was found to be significant and negatively correlated (p < 0.01 Spearman’s coefficient) with relative humidity (RH), maximum temperature (Tmax), and minimum temperature (Tmin), and correlated (p < 0.01) positively with diurnal temperature range (DTR). The Mann–Whitney U Test revealed that 2021 climatic variations in Sample B sites are statistically different (p < 0.05) to 2021 climatic variations in Sample A sites, which demonstrates that albedo changes are linked to a decrease in minimum temperature and relative humidity and an increase in DTR. Conversion of CF and OGW into AA, perennial agriculture (PA), or grassland (GR) always yielded an albedo increment, whilst the conversion of AA to irrigation agriculture (IA) or PA triggered a decrease in albedo, and finally, the pass from GR or AA to protected agriculture (PA) caused albedo to increase or decrease, depending on the greenhouse covers materials. Reducing deforestation of CF and OGW, conversion of AA or GR into PA, and selecting adequate greenhouse covers could help to mitigate regional climate change.

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Section: Discussionmentioning

confidence: 99%

Deforestation and Its Effect on Surface Albedo and Weather Patterns

et al. 2023

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“…Precipitation can alter surface albedo, and a decrease in surface albedo results in an increase of absorption of solar radiation at the surface. This, in turn, influences the balance of surface heat flux (Maina et al., 2022). Surface horizontal temperature gradients resulting from changes in aerosol concentration affect sensible heat transfer from the surface to the atmosphere and may influence local circulation and precipitation (e.g., Vendrasco et al., 2009).…”

Section: Introductionmentioning

confidence: 99%

Rain‐Induced Surface Sensible Heat Flux Reduces Monsoonal Rainfall Over India

Zhou,

Ray,

Tan

et al. 2024

Geophysical Research Letters

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Precipitation can induce a surface sensible heat flux since the raindrops are generally cooler than the surface. This precipitation‐induced sensible heat flux (QP) is typically ignored in models. However, during heavy rainfall, QP can be large and may not be negligible such as over India during the summer monsoon season. We provide the first results of incorporating QP in a simulation that shows ∼2% (∼5%) reduction in precipitation over India compared to the simulation without QP during a monsoonal active phase in 2017 (2018). This reduction was primarily due to a reduction in vertical advection of moisture. Additionally, QP modified the spatial distribution of precipitation with 40% of the geographical area encountering alterations of at least 20% in precipitation. This change in precipitation distribution across the region can have important implications for regional agriculture and irrigation practices. Changes in the partitioning of surface heat flux components due to QP is also discussed.

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“…highest greening rates on Earth, altering the water and energy balances 20,22,23 . This moisture-induced greening, triggered by irrigation, decreases in snow, and increases in precipitation affect the surface albedo and hence the climate system and the water resources 21,24 .…”

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confidence: 99%

Irrigation-driven groundwater depletion in the Ganges-Brahmaputra basin decreases the streamflow in the Bay of Bengal

Maina,

Getirana,

Kumar

et al. 2024

Commun Earth Environ

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Ganges and Brahmaputra, two of Asia’s most prominent rivers, have a crucial role in Southeast Asia’s geopolitics and economy and are home to one of the world’s biggest marine ecosystems. Irrigation-driven groundwater depletion and climate change affect the Ganges-Brahmaputra’s hydrology, threatening the stability of the Bay of Bengal. Here, we quantify, using results from a land reanalysis, the impacts of a changing climate and intensive irrigation on the surface water flowing into the Bay of Bengal. The effects of such activities mostly occurring in the Ganges basin, either intensified or lessened depending on the area by the climatic conditions, decrease freshwater flow into the bay by up to 1200 m3/s/year. While the increase in precipitation in the Ganges basin reduces the effects of groundwater depletion on the streamflow, the decrease in precipitation and the snowmelt decline in the Brahmaputra basin exacerbate streamflow reduction due to groundwater depletion at the delta.

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Irrigation and warming drive the decreases in surface albedo over High Mountain Asia

Cited by 8 publications

References 71 publications

Deforestation and Its Effect on Surface Albedo and Weather Patterns

Deforestation and Its Effect on Surface Albedo and Weather Patterns

Rain‐Induced Surface Sensible Heat Flux Reduces Monsoonal Rainfall Over India

Irrigation-driven groundwater depletion in the Ganges-Brahmaputra basin decreases the streamflow in the Bay of Bengal

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