Thirstwaves and Evaporative Demand

The concept of thirstwaves, developed by Meetpal Kukal and Mike Hobbins, refers to prolonged periods of increased atmospheric evaporative demand, which are becoming more frequent and intense due to global warming. This phenomenon affects how water leaves the land, impacting plants, crops, and trees, and is becoming a significant concern in agriculture, particularly in the U.S.

Key Findings from Research

• Researchers identified three or more contiguous days of intense evaporative demand as a thirstwave.
• The likelihood of having no thirstwaves during the growing season is significantly decreasing.
• Thirstwaves are influenced by temperature, humidity, solar radiation, and wind speed.
• Evaporative demand is measured using standardised short-crop evapotranspiration, which is crucial for determining water usage in irrigation.
• There is an observed increase in standardised short-crop evapotranspiration, indicating higher temperatures, lower humidity, and increased solar radiation and wind speeds.

Past and Future Trends

• Historical data from India showed a decrease in evaporation and potential evapotranspiration despite rising temperatures due to high humidity effects.
• Recent studies indicate an increase in actual evapotranspiration in regions like Northern India and the Himalayas, potentially due to increased vegetation or agricultural activity.

Implications and Future Research

• There is limited data on extreme thirstwaves in India, pointing to a need for more research on regional and crop-specific sensitivities to evaporative demand.
• The research aims to understand thirstwave behavior in the Global South, where the impact of climate change is more pronounced.
• Preliminary studies suggest that the worst thirstwaves may not occur in areas of highest evaporative demand, indicating a need for reevaluation of climate change strategies and mitigation efforts.

Experts emphasize the importance of tracking, measuring, and reporting thirstwaves to better manage water resources and inform farmers and water managers, which is crucial as the global climate continues to warm.