<title>Abstract</title> Rapid shifts in fire regimes around the world raise critical questions about the rising impact of fire on climate, policy, and planetary health in the coming decades. To quantify these impacts, global climate modelling is needed to project how future fire regimes may evolve. One set of future fire estimates are included in the Shared Socioeconomic Pathway (SSP) scenarios that represent how emissions evolve under a range of socioeconomic trajectories the world could take. Yet, a critical component for fire science is missing: no SSP scenario includes the impacts of human-driven climate change on the fire regime. The result of not including how changes in temperature, precipitation, and vegetation alter future fire properties is that, globally, fire emissions are projected to decrease over this century under all SSP scenarios. An alternate set of estimates are a subsection of the Coupled Model Intercomparison Project Phase Six climate models that explicitly represent how fire responds to a warming world. Combining this novel dataset with the SSPs produces a harmonized set of fire emission projections that incorporates both climate and socioeconomic activity modulation. Comparison reveals a robust increase in global fire emissions when additionally accounting for the climate feedback on fire activity, determined primarily by increasing extra-tropical fires. A complementary statistical modelling-based approach identified fire drivers across scenarios: climate drives changes outside the tropics with increasing influence in higher forcing scenarios, while human and vegetation drivers are more important within the tropics and at lower forcing scenarios. We diagnose how updated fire emissions alter projections of end-of-century changes in atmospheric fire-aerosol burden and aerosol radiative forcing in two Earth System models. Large extra-tropical increases in fire-aerosol concentrations were predicted in both models, increasing pollution exposure and nutrient deposition to sensitive ecosystems. However, the predicted climate forcing diverged: one model predicts a large aerosol cooling effect (-0.5 to -0.9 Wm-2) while the second predicts a much smaller negative forcing (-0.1 to -0.2 Wm-2). Understanding how increasing fire activity impacts climate therefore relies not only on robust emission projections but also on a much deeper understanding of how fire is an integrated Earth System component and how best to replicate its myriad interactions within models.