Source: The post Thirstwaves are reshaping climate and crop patterns has been created, based on the article “Rising evaporative demand spotlights India’s data and research gap” published in “The Hindu” on 24th June 2025
UPSC Syllabus Topic: GS Paper3- Environment
Context: The article explores thirstwaves, a newly identified climate phenomenon caused by rising atmospheric evaporative demand. These events are becoming more frequent and intense, especially during crop-growing seasons, raising concerns for agriculture and water availability in a warming world.
Thirstwaves and Evaporative Demand
- Definition and Origin: Thirstwaves refer to three or more consecutive days of high evaporative demand. The term was introduced by researchers Meetpal Kukal and Mike Hobbins. Their study showed that such events are increasing across the U.S.
- Climatic Drivers: Unlike heatwaves, thirstwaves are influenced by temperature, humidity, solar radiation, and wind speed. Global warming intensifies these combined factors, making the air more moisture-demanding.
- Agricultural Consequences: Evaporative demand controls water loss from plants, even when irrigation is adequate. Higher demand leads to increased moisture loss, leaving crops and soil drier, impacting crop health.
Measuring Evaporative Demand
- Standardised Short-Crop Evapotranspiration: This metric estimates water loss from a well-watered grass surface. It simplifies the complex interaction by assuming constant vegetation, making water use depend only on weather conditions.
- Indicators of Rising Demand: An increase in this measure means rising temperatures, lower humidity, faster winds, and more solar radiation. It is a core concept for irrigation planning.
- Historical Findings in India: A 1997 study found declining potential evapotranspiration in India over 30 years due to high humidity, despite rising temperatures. However, future warming is expected to override this effect, leading to higher evaporative demand.
Recent Regional Observations
- Changes in India’s Sub-Basins: A 2022 study found increased evapotranspiration in northern India, the Western and Eastern Himalayas, possibly from more vegetation or agricultural expansion.
- Data Limitations: There is no detailed data on extreme thirstwaves in India. Differences in crop and ecosystem sensitivity to demand remain understudied, creating a research gap.
- Need for Research: Kukal is collaborating with Indian scholars to study thirstwaves in South Asia, where societies are more climate-vulnerable. Their research could influence global food and water security strategies.
Policy and Adaptation Implications
- Unexpected Impact Zones: The worst thirstwaves occurred in areas without the highest demand, suggesting that current climate risk assessments may miss key regions.
- Global South Risks: South Asia’s agricultural dependence and climate exposure make it particularly vulnerable. Kukal’s work aims to improve regional readiness and resilience.
- Urgency of Awareness: Experts emphasize the need for monitoring, awareness, and policy focus. Educating farmers and water managers on thirstwaves is crucial for future preparedness.
Question for practice:
Discuss how rising evaporative demand and increasing thirstwaves impact agriculture and climate preparedness.
