Biogeochemical feedbacks on climate change are one of the largest sources of uncertainty in climate change projections of Earth System Models (ESMs). Current frameworks for evaluating biogeochemical feedbacks on climate change in ESMs lack an explicit consideration and quantification of the influence of nitrogen, an essential limiting nutrient to primary productivity, in the land and ocean spheres. In particular, the effect of atmospheric nitrogen deposition, which has increased dramatically over the historical period due to increasing gaseous nitrogen emissions from intensive nitrogen fertiliser use in agriculture as well as fossil fuel burning, is unclear. Here, we quantify the impact of atmospheric nitrogen deposition on biogeochemical feedbacks on climate change in idealized ESM simulations from CMIP6, extending the existing framework for quantifying the carbon-concentration and carbon-climate feedbacks for use in CMIP7. We show that intensifying atmospheric nitrogen deposition globally enhances CO2 sequestration and is a negative feedback over both land and ocean. However, the magnitude of this “carbon-nitrogen deposition” feedback is small relative to the significant reduction in the carbon-concentration feedback due to nitrogen limitation of primary productivity and CO2 fertilisation on land. Additionally, intensifying nitrogen deposition globally enhances soil emissions of nitrous oxide (N2O), a potent greenhouse gas. Altogether this work suggests that nitrogen deposition is expected to contribute only marginally to enhancing carbon sinks and mitigating climate change in the future.