Vegetation-based climate mitigation in a warmer and greener World

Ramdane Alkama,Gregory Duveiller,Alessandro Cescatti,Shunlin Liang,Giacomo Grassi,Giovanni Forzieri

doi:10.1038/s41467-022-28305-9

Ramdane Alkama, Gregory Duveiller + Show 4 more

Open Access

https://doi.org/10.1038/s41467-022-28305-9

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Abstract

The mitigation potential of vegetation-driven biophysical effects is strongly influenced by the background climate and will therefore be influenced by global warming. Based on an ensemble of remote sensing datasets, here we first estimate the temperature sensitivities to changes in leaf area over the period 2003–2014 as a function of key environmental drivers. These sensitivities are then used to predict temperature changes induced by future leaf area dynamics under four scenarios. Results show that by 2100, under high-emission scenario, greening will likely mitigate land warming by 0.71 ± 0.40 °C, and 83% of such effect (0.59 ± 0.41 °C) is driven by the increase in plant carbon sequestration, while the remaining cooling (0.12 ± 0.05 °C) is due to biophysical land-atmosphere interactions. In addition, our results show a large potential of vegetation to reduce future land warming in the very-stringent scenario (35 ± 20% of the overall warming signal), whereas this effect is limited to 11 ± 6% under the high-emission scenario.

Highlights

The mitigation potential of vegetation-driven biophysical effects is strongly influenced by the background climate and will be influenced by global warming
To address the knowledge gap discussed in the introduction, here we use a combination of Earth observations and Earth system modelling to investigate the global biophysical impacts of future changes in leaf area index (LAI) on surface temperature (T) under different scenarios of climate warming and atmospheric CO2 concentration
We first use satellite retrievals to quantify the baseline (2003-2014) monthly sensitivity of T to LAI changes, as a function of the concurrent variations in snow cover, solar radiation, and evaporation rates. This baseline starts in 2003, which corresponds to the year of the first complete MODIS AQUA records of land surface temperature, used to derive air temperature in this study[25], and ends in 2014, the last year of the historical Coupled Model Intercomparison Project 6 (CMIP6)[26] simulations

Summary

Introduction

The mitigation potential of vegetation-driven biophysical effects is strongly influenced by the background climate and will be influenced by global warming. 1234567890():,; Earth system models (ESMs) project a progressive increase in leaf area index (LAI; the amount of leaf area per unit of ground area) in a large part of the planet over the 21st century[1] This emerging greening signal has been detected from satellites in the last three and half decades and attributed to the increase in atmospheric CO2, nitrogen deposition, climate change, and land cover change[2]. The net effect of vegetation and snow cover changes in boreal regions is still controversial[17,18] as model simulations have shown an opposite signal[4] Besides these differences, observational evidence and model experiments agree on the key role that background climate conditions play in the modulation of biophysical processes mediated by vegetation and, in particular, on the relative importance of radiative versus nonradiative processes[3,14]. The projected decline of key environmental drivers, like snow cover and soil moisture, are expected to influence substantially such land-atmosphere interactions as we move into future climate conditions[19]

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