Global warming delays the autumn date of foliar senescence (DFS) in recent decades, with positive implications for growing season length and therefore global carbon storage. However, warming-associated drought, leading to water limitation, may conversely stimulate earlier DFS. Using ground observations since 1940s and 34 years of satellite greenness data (1982‒2015) over the Northern Hemisphere (>30° N), we show the increased impact of drought on DFS. Earlier DFS is linked to decreased precipitation under warming and weaker drought resistance associated with various plant functional traits. For example, isohydric plants with strict regulation of water status may drop leaves fast during droughts. We derive an improved set of phenology models based on this influence and project earlier DFS by the end of the century, particularly at high latitudes (>50° N). Our results limit uncertainties in the later end of plant growth with warming, aiding estimation of carbon uptake of terrestrial ecosystems.

This work was funded by the Strategic Priority Research Programme of the Chinese Academy of Sciences (XDA19040103), the National Natural Science Foundation of China (42125101) and the CAS Interdisciplinary Innovation Team (JCTD-2020-05). J.P. and P.C. were funded by European Research Council Synergy grant ERC-SyG-2013-610028 IMBALANCE-P. J.P. was also financially supported by the Fundación Ramon Areces grant ELEMENTAL-CLIMATE, the Spanish Government grant 2013-610028 and the Catalan Government grant SGR 2017-1005.

10 pags.- 4 Figs. Under Licence CC BY 4.0

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