Global warming may enhance soil organic carbon (<em>SOC</em>) turnover and CO<sub>2</sub> release, potentially accelerating further warming in a positive feedback loop. The temperature sensitivity (<em>TS</em>) of soil respiration is a key determinant for the climate feedback of soils. However, it is uncertain how <em>TS</em> may change under continued warming due to potential microbial thermal acclimation and changes in substrate quality and availability. We examined <em>TS</em> in an incubation experiment using intact soil cores that had undergone 13 years (decadal) of <em>in situ</em> geothermal warming spanning a broad warming gradient of +0 °C to +75 °C.</p> <p>The observed loss of <em>SOC</em> stock (medians ± SE, kg C m<sup>-2</sup>) compared to ambient had increased with decadal warming, from -4.9 ± 2.4 % at +1–3 °C to -19.3 ± 1.5 % at +7–10 °C. Across incubation temperatures from 5 to 35 °C in the lab experiment, area-based <em>TS</em> generally declined with decadal warming intensity while <em>SOC</em>-normalized <em>TS</em> was similar across treatments. This suggests that <em>SOC</em> depletion rather than microbial thermal acclimation was the dominant control for reduced respiration rates with warming. <em>TS</em> showed variation with temperature range and was generally lower between the 5–15 °C and 25–35 °C incubation temperature changes and markedly higher in the 15–25 °C change. Best-fit standard field models for soil respiration (Van’t Hoff and Lloyd & Taylor models, R<sup>2</sup> = 0.842–0.929) failed to capture these shifts in <em>TS</em>, while a sigmoidal function closely captured the observed <em>TS</em> dynamics (R² = 0.970–0.998). Our study suggests that using fixed Q<sub>10</sub> <em>TS</em> values to upscale C budgets is inadequate. Although area-based respiration rates declined with warming, the observed decline in soil respiration with warming suggests a latent reduction of further <em>SOC</em> loss over time following prolonged exposure to warming.