Global Climate Responses to Anthropogenic Groundwater Exploitation

Abstract:

In this study, a groundwater exploitation scheme is incorporated into the earth system model, Community Earth System Model 1.2.0 (CESM1.2.0), which is called CESM1.2_GW, and the climatic responses to anthropogenic groundwater withdrawal are then investigated on global scale. The scheme models anthropogenic groundwater exploitation and consumption, which are then divided into agricultural irrigation, industrial use and domestic use. A group of 41-year ensemble groundwater exploitation simulations with six different initial conditions, and a group of ensemble control simulations without exploitation are conducted using the developed model CESM1.2_GW with water supplies and demands estimated. The results reveal that the groundwater exploitation and water consumption cause drying effects on soil moisture in deep layers and wetting effects in upper layers, along with a rapidly declining groundwater table in Central US, Haihe River Basin in China and Northern India and Pakistan where groundwater extraction are most severe in the world. The atmosphere also responds to anthropogenic groundwater exploitation. Cooling effects on lower troposphere appear in large areas of North China Plain and of Northern India and Pakistan. Increased precipitation occurs in Haihe River Basin due to increased evapotranspiration from irrigation. Decreased precipitation occurs in Northern India because water vapor here is taken away by monsoon anomalies induced by anthropogenic alteration of groundwater. The local reducing effects of anthropogenic groundwater exploitation on total terrestrial water storage evinces that water resource is unsustainable with the current high exploitation rate. Therefore, a balance between slow groundwater withdrawal and rapid human economic development must be achieved to maintain a sustainable water resource, especially in over-exploitation regions such as Central US, Northern China, India and Pakistan.