Large global-scale vegetation sensitivity to daily rainfall variability

Authors: FELDMAN, A.F. - National Aeronautics And Space Administration (NASA); KONINGS, A.G. - Stanford University; GENTINE, P. - Columbia University; CATTRY, M. - Columbia University - New York; WANG, L. - Purdue University; SMITH, W.K. - University Of Arizona; Biederman, Joel; CHATTERJEE, A. - California Institute Of Technology; JOINER, J. - National Aeronautics And Space Administration (NASA) - Johnson Space Center; POULTER, B. - National Aeronautics Space Administration (NASA) - Jet Propulsion Laboratory

Submitted to: Nature
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2024
Publication Date: 12/17/2024
Citation: Feldman, A., Konings, A., Gentine, P., Cattry, M., Wang, L., Smith, W., Biederman, J.A., Chatterjee, A., Joiner, J., Poulter, B. 2024. Large global-scale vegetation sensitivity to daily rainfall variability. Nature. 636:380–384. https://doi.org/10.1038/s41586-024-08232-z.
DOI: https://doi.org/10.1038/s41586-024-08232-z

Interpretive Summary: In many parts of the world, rain storms are delivering greater rainfall amounts, but there are longer dry periods in between storms. It is unknown how this temporal repackaging of precipitation affects plant growth. Here we used several different data sources including satellite data and ground-based measurements to evaluate how plant growth is being affected rainfall temporal repackaging into fewer, larger storms. We find that about half of Earth’s surface is showing changes in plant growth due to rainfall repackaging. The differences in annual growth can be as much as 20-50% of the long-term average. Fewer, larger precipitation events tend to increase plant growth in arid regions, likely due to infiltration of water to greater depths, where it can be stored for longer in the root zone. We found negative impacts on plant growth in humid regions, where plants are adapted to frequent rainfall. Our results imply that as the hydrologic cycle intensifies under climate change, dryland regions may experience improved plant growth, while humid regions may see some inhibition.

Technical Abstract: Rainfall events are globally becoming less frequent but more intense under a changing climate, thereby shifting climatic conditions for terrestrial vegetation independent of annual rainfall totals1–3 . However, it remains uncertain how changes in daily rainfall variability are afecting global vegetation photosynthesis and growth3–17. Here we use several satellite-based vegetation indices and feld observations indicative of photosynthesis and growth, and fnd that global annual-scale vegetation indices are sensitive to the daily frequency and intensity of rainfall, independent of the total amount of rainfall per year. Specifcally, we fnd that satellite-based vegetation indices are sensitive to daily rainfall variability across 42'per cent of the vegetated land surfaces. On average, the sensitivity of vegetation to daily rainfall variability is almost as large (95'per cent) as the sensitivity of vegetation to annual rainfall totals. Moreover, we fnd that wet-day frequency and intensity are projected to change with similar magnitudes and spatial extents as annual rainfall changes. Overall, our fndings suggest that daily rainfall variability and its trends are afecting global vegetation photosynthesis, with potential implications for the carbon cycle and food security.