Climate change could lead to a three-fold increase in groundwater loss from 2041 to 2080 in India as compared to the current rates, according to a recent study by the University of Michigan. This could occur despite expected increases in rainfall and potential reductions in irrigation as groundwater levels decline.
The study, titled Warming temperatures exacerbate groundwater depletion rates in India, published in the journal, Science Advances, focused on how rising temperatures are driving Indian farmers to intensify groundwater usage for irrigation, which poses a big threat to India’s food and water security, affecting over one-third of its 1.4 billion population and global food supplies.
The findings indicate a multi-dimensional crisis involving the intersection of climate change, agriculture, and water resources. Reduced water availability due to groundwater depletion and climate change is expected to reduce crop intensity and production, challenging India’s food security, which has implications for global food security, given that India is home to 18% of the worldwide population and is the second-largest producer of common cereal grains like rice and wheat.
The research team analysed groundwater data from thousands of wells and used remote-sensing data for crop water stress and weather data, including rainfall and temperature, from 2004 to 2013 in India. Their statistical analysis identified a direct link between rising temperatures and increased crop water stress.
Researchers found that higher temperatures directly create crop water stress during the monsoon and winter seasons. Warmer temperatures lead to greater water loss from crops through a process known as evapotranspiration. In simple terms, evapotranspiration is the loss of water from soil by evaporation and by transpiration from the plants. Even with a 1°C temperature increase, the study predicts a 5.9% rise in crop water stress during monsoon and a 3.5% increase during the winter season. The monsoon season is particularly vulnerable due to higher temperatures and increased radiative effects, leading to higher potential evapotranspiration.
The research suggested that groundwater depletion may expand to new regions in India, particularly in the northwest, southwest, and parts of central India, which is distressing as some of these areas are already experiencing groundwater depletion.
The study emphasised the urgent need for comprehensive policies and interventions, stating, “Water-saving strategies currently focused on northwest India must be extended to include south and central India to prevent farmers in these regions from losing their ability to irrigate. Without policies and interventions to conserve groundwater, warming temperatures will likely amplify India’s already existing groundwater depletion problem, further challenging India’s food and water security in the face of climate change.
Researchers found that both, unconsolidated and hard-rock aquifer systems in India are vulnerable to warming, though the monsoon’s effects are more pronounced in the former.
“Currently, most overexploitation of aquifers is concentrated in the northwest and south of India. However, our results suggest that overexploitation may expand to include aquifers in the southwest, the southern peninsula, and central India by 2050. Such an expansion is of concern because south and central India have hard rock aquifers that are more difficult to recharge and have less storage capacity than the alluvial aquifers found in northwest India,” the study noted. It emphasises the need for sustainable water management practices, including better irrigation techniques, the promotion of water conservation, and the adoption of drought-resistant crops to mitigate the impacts of climate change and ensure food and water security in India. It warns that the consequences of inaction could be disastrous, for India as well as global food supplies.