Large global-scale vegetation sensitivity to daily rainfall variability

Area of Science:

• Climate Science
• Ecology
• Remote Sensing

Background:

• Global climate change is altering rainfall patterns, leading to less frequent but more intense rainfall events.
• The impact of these shifts in daily rainfall variability on terrestrial vegetation photosynthesis and growth remains largely uncertain, despite stable annual rainfall totals.

Purpose of the Study:

• To investigate the sensitivity of global vegetation photosynthesis and growth to daily rainfall variability, independent of annual rainfall amounts.
• To quantify the extent and magnitude of vegetation's response to changes in daily rainfall frequency and intensity.

Main Methods:

• Utilized satellite-based vegetation indices (e.g., NDVI, EVI) as proxies for photosynthesis and growth.
• Integrated field observations to validate satellite data.
• Analyzed the relationship between daily rainfall metrics (frequency, intensity) and vegetation indices across global vegetated land surfaces.

Main Results:

• Global annual-scale vegetation indices demonstrate significant sensitivity to the daily frequency and intensity of rainfall, irrespective of the total annual rainfall.
• Approximately 42% of vegetated land surfaces show sensitivity to daily rainfall variability.
• The impact of daily rainfall variability on vegetation is nearly as substantial as the impact of annual rainfall totals.

Conclusions:

• Daily rainfall variability is a critical factor influencing global vegetation photosynthesis and growth.
• Projected changes in wet-day frequency and intensity mirror those in annual rainfall, suggesting significant future impacts.
• These findings have crucial implications for understanding the global carbon cycle and ensuring food security under changing climate conditions.