Increasing sensitivity of dryland vegetation greenness to precipitation due to rising atmospheric CO2

Abstract

Water availability plays a critical role in shaping terrestrial ecosystems, particularly in low- and mid-latitude regions. The sensitivity of vegetation growth to precipitation strongly regulates global vegetation dynamics and their responses to drought, yet sensitivity changes in response to climate change remain poorly understood. Here we use long-term satellite observations combined with a dynamic statistical learning approach to examine changes in the sensitivity of vegetation greenness to precipitation over the past four decades. We observe a robust increase in precipitation sensitivity (0.624% yr−1) for drylands, and a decrease (−0.618% yr−1) for wet regions. Using model simulations, we show that the contrasting trends between dry and wet regions are caused by elevated atmospheric CO2 (eCO2). eCO2 universally decreases the precipitation sensitivity by reducing leaf-level transpiration, particularly in wet regions. However, in drylands, this leaf-level transpiration reduction is overridden at the canopy scale by a large proportional increase in leaf area. The increased sensitivity for global drylands implies a potential decrease in ecosystem stability and greater impacts of droughts in these vulnerable ecosystems under continued global change.

Rapid Indian ocean warming threatens Agricultural productivity in North America

“…The results suggested that the reduction in US GPP by TIO warming may be mainly attributed to less precipitation rather than higher temperature. It is also consistent with previous studies, which showed that vegetation activities over the US are mainly dependent on precipitation rather than temperature 22,23,24,25,26,27,28 .…”

Increased response of vegetation to soil moisture in the northern hemisphere drylands

“…CO 2 played the most important role in the θ SM increase, which is consistent with its fertilization effect on vegetation. Several studies have indicated that elevated CO 2 causes vegetation to conserve water so that limited water supports more plant growth in water-limited regions (Zhang et al, 2022). This also explained the decrease in the soil moisture with the increase in the NDVI, which was due to the increase in the global CO 2 concentration.…”

Climate Change and Rising CO2 Amplify the Impact of Land Use/Cover Change on Carbon Budget Differentially Across China

“…It would offset the effort of rising CO 2 in saving water and constraining photosynthesis in turn. The offset effect was proven to be more serious in semiarid and arid areas (Ukkola et al., 2016; Y. Zhang et al., 2022). This probably explains why drier northwestern China benefits less from rising CO 2 than northeastern China (Figures S10 and S13 in Supporting Information S1).…”