Editing IPCC:AR6/WGIII/Chapter-7 (section)

=== 7.2.4 Biophysical Effects and Short-lived Climate Forcers ===

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Despite new literature, general conclusions from the SRCCL and WGI-AR6 on biophysical effects and short-lived climate forcers remain the same. Changes in land conditions from land cover change or land management jointly affect water, energy, and aerosol fluxes (biophysical fluxes) as well as GHG fluxes (biogeochemical fluxes) exchanged between the land and atmosphere ( ''high agreement'' , ''robust evidence'' ) ( [[#Anderson--2011|Anderson et al. 2011]] ; [[#O’Halloran--2012|O’Halloran et al. 2012]] ; [[#Alkama--2016|Alkama and Cescatti 2016]] ; [[#Naudts--2016|Naudts et al. 2016]] ; [[#Erb--2017|Erb et al. 2017]] ). There is ''high confidence'' that changes in land condition do not just have local impacts but also have non-local impacts in adjacent and more distant areas ( [[#Pielke--2011|Pielke et al. 2011]] ; [[#Mahmood--2014|Mahmood et al. 2014]] ) which may contribute to surpassing climate tipping points ( [[#Nepstad--2008|Nepstad et al. 2008]] ; [[#Brando--2014|Brando et al. 2014]] ). Non-local impacts may occur through: GHG fluxes and subsequent changes in radiative transfer, changes in atmospheric chemistry, thermal, moisture and surface pressure gradients creating horizontal transport (advection) ( [[#de%20Vrese--2016|de Vrese et al. 2016]] ; [[#Davin--2010|Davin and de Noblet-Ducoudré 2010]] ) and vertical transport (convection and subsidence) ( [[#Devaraju--2018|Devaraju et al. 2018]] ). Although regional and global biophysical impacts emerge from model simulations ( [[#Davin--2010|Davin and de Noblet-Ducoudré 2010]] ; [[#de%20Vrese--2016|de Vrese et al. 2016]] ; [[#Devaraju--2018|Devaraju et al. 2018]] ), especially if the land condition has changed over large areas, there is ''very low agreement'' on the location, extent and characteristics of the non-local effects across models. Recent methodological advances, empirically confirmed changes in temperature and precipitation owing to distant changes in forest cover ( [[#Cohn--2019|Cohn et al. 2019]] ; [[#Meier--2021|Meier et al. 2021]] ).

Following changes in land conditions, CO 2 , CH 4 and N 2 O fluxes are quickly mixed into the atmosphere and dispersed, resulting in the biogeochemical effects being dominated by the biophysical effects at local scales ( ''high confidence'' ) (Y. [[#Li--2015|Li et al. 2015]] ; [[#Alkama--2016|Alkama and Cescatti 2016]] ). Afforestation/reforestation ( [[#Lejeune--2018|Lejeune et al. 2018]] ; [[#Strandberg--2019|Strandberg and Kjellström 2019]] ), urbanisation ( [[#Li--2013|Li and Bou-Zeid 2013]] ) and irrigation ( [[#Mueller--2016|Mueller et al. 2016]] and [[#Thiery--2017|Thiery et al. 2017]] ) modulate the likelihood, intensity, and duration of many extreme events including heatwaves ( ''high confidence'' ) and heavy precipitation events ( ''medium confidence'' ) ( [[#Haberlie--2015|Haberlie et al. 2015]] ). There is ''high confidence'' and ''high agreement'' that afforestation in the tropics ( [[#Perugini--2017|Perugini et al. 2017]] ), irrigation ( [[#Alter--2015|Alter et al. 2015]] ; [[#Mueller--2016|Mueller et al. 2016]] ) and urban greening result in local cooling, ''high agreement'' and ''medium confidence'' on the impact of tree growth form (deciduous vs evergreen) ( [[#Naudts--2016|Naudts et al. 2016]] ; [[#Luyssaert--2018|Luyssaert et al. 2018]] and [[#Schwaab--2020|Schwaab et al. 2020]] ), and ''low agreement'' on the impact of wood harvest, fertilisation, tillage, crop harvest, residue management, grazing, mowing, and fire management on the local climate.

Studies of biophysical effects have increased since AR5 reaching ''high agreement'' for the effects of changes in land condition on surface albedo ( [[#Leonardi--2015|Leonardi et al. 2015]] ). ''Low confidence'' remains in proposing specific changes in land conditions to achieve desired impacts on local, regional and global climates due to: a poor relationship between changes in surface albedo and changes in surface temperature ( [[#Davin--2010|Davin and de Noblet-Ducoudré 2010]] ), compensation and feedbacks among biophysical processes ( [[#Bonan--2016|Bonan 2016]] ; [[#Kalliokoski--2020|Kalliokoski et al. 2020]] ), climate and seasonal dependency of the biophysical effects ( [[#Bonan--2016|Bonan 2016]] ), omittance of short-lived chemical forcers ( [[#Unger--2014|Unger 2014]] ; [[#Kalliokoski--2020|Kalliokoski et al. 2020]] ), and study domains often being too small to document possible conflicts between local and non-local effects ( [[#Swann--2012|Swann et al. 2012]] ; [[#Hirsch--2018|Hirsch et al. 2018]] ).

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