Synergistic Satellite Assessment of Global Vegetation Health in Relation to ENSO‐Induced Droughts and Pluvials

Abstract

Under climate change, these climate oscillations will likely increase water cycle extremes, exacerbating risks to food insecurity globally (Funk et al., 2016) and the occurrence of natural disasters such as floods, droughts (Yoon et al., 2015) and wildfire (King et al., 2020). Despite the large body of prior research documenting ENSO related impacts on ecosystems and the environment, a great deal of uncertainty remains regarding the patterns and linkages of ENSO driven climate anomalies to drought and pluvial events, and how these events influence global ecosystems. Satellite-based studies for characterizing and monitoring of ENSO-induced droughts and pluvials over the globe, and their ecological impacts are still lacking but are needed for more effective environmental forecasts, timely onset detection, and early warning systems.

Interannual variability of spring fire in southern Nepal

“…Furthermore, the El Niño phase negatively impacts vegetation health (figure not shown); for instance, the NINO3 in winter and VHI in 2016 were + 2.63 and − 1.22, respectively, indicating that El Niño creates warm and dry conditions to produce the combustible fuel (Figures 4d and 6b). This is consistent with the El Niño impacts on vegetation health due to changes in the surface water inundation, soil moisture, and atmospheric moisture deficits (Du et al, 2021). Overall, these anomalous surface and atmospheric conditions during the El Niño phase provide favorable conditions for fire activities and spread.…”

Increased impact of the El Niño–Southern Oscillation on global vegetation under future warming environment

“…The vegetation area affected by ENSO might be low compared to previous studies 27 , 29 using correlation analysis. The higher influence of ENSO is related to the confounding factors (e.g., the SAM, the IOD and the NAO) which are not considered in the correlation analysis.…”

“…As the growth of trees depends on water availability 23 , ENSO-induced changes in the water cycle 24 – 26 may lead to impacts on vegetation cover. For instance, ENSO shows an impact on global growing-season normalized difference vegetation index (NDVI gs ) 27 , vegetation respiration 28 , vegetation health 29 , and plays an important role in altering the global crop production 30 , 31 . In particular, ENSO showed influences on tree-level ecophysiology via the impacts on regional water availability 32 and ENSO-induced drought and soil drying may cause leaf shedding, tree mortality, and slow recovery of forests 33 – 35 .…”