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Rising CO₂ levels reduced drought stress on plants on the Qinghai–Tibetan Plateau over the past four decades, but this benefit is largely cancelled out by warming that increases plant water demand, as revealed by ecological modelling and multi-source observations from 1979 to 2018.

Climate warming is advancing spring leaf unfolding, but it is also reducing the cold periods that many trees require to break winter dormancy. Here, the authors show that 7 of 12 current chilling models fail to account for the correct relationship between chilling accumulation and heat requirement, leading to substantial overestimates of the advance of spring phenology under climate change.

Climate change is increasing the frequency of flash droughts worldwide, posing threats to global ecosystems. This study suggests that flash droughts cause 1.5 times greater vegetation loss than conventional droughts and delay ecosystem recovery, with impacts intensifying over recent decades.

This study reports age-dependent negative correlations between temporal changes in maximal leaf area index and growing season length, indicating contrasting leaf acclimation strategies driving vegetation greening in young versus old deciduous broadleaf forests.

Cities serve as climate change laboratories for phenology studies. Here, the authors show that results of such studies should be interpreted with caution, as urban-rural phenology gaps are primarily driven by species composition differences rather than temperature differences.

Using satellite and carbon-flux data, the authors show that enhanced gross primary productivity in recent decades is driven primarily by increases in the rate, rather than the duration, of carbon uptake. They highlight asymmetric changes in productivity across seasons, which may worsen under climate change.

Climate warming causes earlier spring phenological events and higher risk of late spring frost damage. Here, the authors investigate the impact of late spring frosts on phenological events, finding that they delayed flowering by an average of 6 days across 640 species.

The authors combine 393,139 forest inventory plots with satellite data to understand the impact of biodiversity on the sensitivity of spring leaf-out dates to temperature (S_T). They show that high diversity significantly weakens S_T, a relationship that Earth system models largely fail to reproduce.

Despite overall warming, many regions in the Northern Hemisphere have been cooling in autumn. This cooling resulted in an increasing release of net CO₂ 2004–2018 as primary production decreased more than respiration in cooling and respiration increased more than production in warming areas.

Recent warming has significantly advanced leaf onset in the northern hemisphere. Here, the authors show asymmetric effects of daytime and nighttime temperature change on the timing of leaf onset.

The authors use long-term ground and satellite data to reveal the impact of drought on autumn date of foliar senescence (DFS). They link increased drought impacts to precipitation changes and plant functional traits and project earlier DFS by the end of the century, particularly at high latitudes.

The authors use tree-ring width data across the extratropical Northern Hemisphere to show that earlier growing season onsets lead to enhanced tree radial growth in cold humid but not in dry areas.

Cities can be used as natural laboratories for higher temperatures and CO₂ concentrations. Urban vegetation photosynthetic activity begins earlier, peaks earlier and ends later than in neighbouring rural areas.

Drivers of spatial differences in leaf phenology are not as widely studied as temporal differences. Here the authors show that the spatial variation of leaf unfolding in 8 deciduous tree species in Europe can be explained by local adaptation to long-term mean climate conditions.

Climate change may lead to changes in elevational patterns of vegetation activitities. Here, the authors analyze global remotely sensing data collected during 1982–2015 to investigate the spatio-temporal dynamics of the elevational gradient in vegetation activities.

Plant growing season increases under a warming climate, but it is not known whether this will alter plant exposure to frost days. Here Liu et al. investigate trends in the Northern Hemisphere over 30 years and find increased exposure to frost days in regions that have longer growing seasons.

Warming temperatures, shifting precipitation patterns and human activities on the Qinghai–Tibetan Plateau are impacting phenology, including advancing the start and delaying the end of the growing season. This Review examines the drivers, patterns and impacts of changing vegetation phenology across this region.

Rising pre-season daytime and night-time temperatures have contrasting effects on the timing of autumn-leaf senescence date in the Northern Hemisphere. Diurnal differences in drought stress may be the underlying mechanism.

Spring leaf unfolding has been occurring earlier in the year because of rising temperatures; however, long-term evidence in the field from 7 European tree species studied in 1,245 sites shows that this early unfolding effect is being reduced in recent years, possibly because the reducing chilling and/or insolation render trees less responsive to warming.

Earlier peak of vegetation activity across the Northern Hemisphere is mainly driven by enhanced early-season carbon uptake, impacted by an earlier onset of the growing season and higher temperature, based on an analysis of satellite observations and carbon flux measurements

An earlier spring phenology reduces daily carbon uptake rates during the early growing season, diminishing the potential gains in productivity from the extended duration during this period, based on an analysis integrating satellite and ground-based carbon flux data.