In the heart of California, at the Carnegie Institution for Science in Stanford, Lorenzo Rosa, a researcher at Biosphere Sciences and Engineering, has been delving into a critical yet often overlooked aspect of climate change: the impact of global warming on green water—soil moisture essential for rainfed agriculture. His latest study, published in the journal ‘Agricultural Water Management’ (which translates to ‘Agricultural Water Management’), paints a stark picture of the future if we fail to mitigate climate change effectively.
Rosa’s research focuses on green water scarcity (GWS), a term that refers to the insufficient rainfall to meet crop needs. Unlike blue water, which is surface and groundwater, green water is the moisture in the soil that plants rely on. As the planet warms, the distribution and availability of this vital resource are shifting, with profound implications for global food security.
The study projects the risks of GWS under two warming scenarios: 1.5°C and 3°C above pre-industrial levels. The findings are alarming. At baseline (1996–2005), 25% of global rainfed croplands, amounting to 183 million hectares, were classified as reliable, experiencing less than one month of GWS annually. However, with 1.5°C of global warming, this reliable category shrinks by 70 million hectares, and with 3°C warming, it contracts by a staggering 106 million hectares. This degradation could jeopardize food production for 0.8 billion people at 1.5°C and 1.2 billion at 3°C, with regions heavily reliant on rainfed systems bearing the brunt.
“Limiting warming to 1.5°C could preserve croplands that feed 400 million people,” Rosa emphasizes. This stark contrast underscores the urgency of climate mitigation efforts. The study reveals that 3°C warming doubles the spatial extent of severe GWS compared to 1.5°C, highlighting the nonlinear rise in agricultural risks with temperature.
The implications for the energy sector are significant. As food security becomes increasingly precarious, the demand for energy-intensive agricultural practices, such as irrigation and fertilizer production, may surge. This could lead to higher energy consumption and increased greenhouse gas emissions, creating a vicious cycle that exacerbates climate change. Moreover, the energy sector may face pressure to invest in sustainable and resilient agricultural technologies to mitigate these risks.
Rosa’s research calls for integrated water-resilient strategies, prioritizing soil moisture conservation, adaptive crop choices, and sustainable irrigation. These strategies could help stabilize rainfed agriculture in a warming world, ensuring food security for billions. For the energy sector, this means opportunities for innovation and investment in green technologies that support sustainable agriculture.
The study also underscores the need for a more nuanced understanding of water dynamics in agriculture. By bridging green water dynamics with climate targets, Rosa provides a roadmap for stabilizing rainfed agriculture. This could shape future developments in the field, driving research and investment towards more resilient and sustainable agricultural practices.
As the world grapples with the challenges of climate change, studies like Rosa’s serve as a wake-up call. They highlight the urgent need for action and the potential for innovation in creating a more sustainable future. For the energy sector, this means not just adapting to change but leading the way towards a more resilient and secure world.