CONUS forest carbon under climate x harvest x disturbance: a yield-curve factorial (2025-2125)

Projections of conterminous United States (CONUS) forest aboveground carbon from 2025 to 2125 under a full factorial of three drivers: climate (RCP4.5, RCP8.5), harvest (five removal intensities), and natural disturbance (off, observed, climate-amplified, and fire-only and insect-only amplification). Projections come from an FIA-anchored yield-curve engine run per state and summed to CONUS, on the OSC Cardinal cluster. Disturbance is parameterized from a raster-calibrated product (annual disturbance probability times expected severity, with fire and insect shares, keyed by forest-type group within ecoregion province; 98.8 percent of FIA plots matched a spatially explicit rate) and applied via an increment-preserving regrowth-aware recursion validated against Monte Carlo simulation (agreement 0.4 to 2.5 percent). A 150-replicate stochastic ensemble confirms the disturbance-timing variance is negligible at CONUS scale (about 0.1 percent). Key result: natural disturbance is the dominant control and reverses CONUS forest from a 34 to 35 percent carbon sink to a 14 to 16 percent source by 2125, roughly eight times the harvest effect and sixty times the direct climate effect; climate change acts mainly by amplifying fire and insect disturbance, split nationally 48 percent fire and 52 percent insect. All released values are state- or CONUS-level aggregates; no FIA true plot coordinates are included.