1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 The influence of vegetation trait diversity on terrestrial energy and carbon budgets in Earth system modeling

Quantifying the surface energy and carbon budgets is crucial for projecting Earth’s 17 future climate. Earth system models typically simulate surface processes dependent 18 on plant functional types (PFTs), neglecting the spatial diversity of plant functional 19 characteristics (PFCs; e.g., chlorophyll content). Here, we showcase substantial 20 differences in modeled leaf optical properties and surface albedo between the PFT- and 21 PFC-based approaches, particularly in tropical and boreal forests. We advance the 22 canopy radiative transfer configuration in the Community Earth System Model with 23 PFC-based leaf optical properties. Our new configuration results in lower shortwave 24 surface albedo in the tropics but higher surface albedo in the boreal regions (>5 W 25 m−2 radiative flux differences), and a weaker tropical but stronger boreal carbon sink. 26 Through coupling to the atmosphere, the enhanced representation imprints atmospheric 27 processes leading to different temperature, cloud cover, and precipitation patterns. Our 28 findings highlight the necessity to transition beyond traditional PFT-based modeling 29 approaches.