Biogeophysical Radiative Forcings of Large-Scale Afforestation in Europe Are Highly Localized and Dominated by Surface Albedo Change

Large-scale re-/afforestation projects afford sizable atmospheric CO2 removals yet questions loom surrounding their potentially offsetting biogeophysical radiative forcings. Forest area change alters not only the surface albedo but also heat, moisture, and momentum fluxes, which in turn modify the atmosphere's radiative, thermodynamical, and dynamical properties. These so-called radiative forcing “adjustments” have been little examined in re-/afforestation contexts, and many questions remain surrounding their relevance in relation to the instantaneous forcing from the surface albedo change—and whether they can affect Earth's radiative energy balance in regions remote from where the re-/afforestation occurs. Here, we quantified biogeophysical radiative forcings and adjustments from realistically scaled re-/afforestation in Europe at high spatial resolution and found that adjustments with high signal-to-noise were largely confined to only a few months and to the region of re-/afforestation. Adjustments were dominated by perturbed low-level clouds and rarely exceeded ±25% of the annual albedo change forcing.