This study examines the response of the tropical atmospheric and oceanic circulation to increasing greenhouse gases using climate model experiments from the IPCC Fourth Assessment Report (AR4). The results show that the strength of the atmospheric overturning circulation decreases as the climate warms in all AR4 models, consistent with thermodynamic scaling arguments. The weakening is primarily in the zonally asymmetric (Walker) component rather than the zonal-mean (Hadley) component, leading to changes in the thermal structure and circulation of the tropical oceans. The weakening is associated with a decrease in strong updrafts and an increase in weak updrafts, though the robustness of this behavior across models is uncertain. As the climate warms, changes in both the atmospheric and ocean circulation over the tropical Pacific resemble "El Niño-like" conditions, but the mechanisms are distinct from those of El Niño. The Indian Ocean response to global warming resembles the Indian Ocean dipole mode. Model results are consistent with recent changes in sea level pressure since the mid-nineteenth century. The study uses climate model data to assess the robustness of the atmospheric circulation response to warming. It explores climate change simulations from 22 models integrated with projected changes in greenhouse gases and aerosols. The results show that all models project a weakening of the atmospheric overturning circulation, driven by changes in the atmospheric hydrologic cycle. The weakening is primarily in the Walker circulation rather than the Hadley circulation. The weakening impacts the thermodynamic and dynamic structure of the tropical oceans. The consistency of the circulation response is explained by thermodynamic and energetic arguments. The study also shows that the weakening of the Walker circulation is reflected in changes in sea level pressure, with a correlation between the relative changes in upward vertical velocity and dSLP across models. The weakening of the Walker circulation is also evident in the ensemble-mean precipitation response of the models. The response of the tropical ocean thermal structure and circulation to global warming is also examined, showing shoaling of the western equatorial Pacific thermocline and changes in the zonal surface currents. The study highlights the dominant role of atmospheric processes in the response of the Walker circulation to global warming. The results are consistent with recent observations of changes in the tropical Pacific Ocean circulation and the Walker circulation.This study examines the response of the tropical atmospheric and oceanic circulation to increasing greenhouse gases using climate model experiments from the IPCC Fourth Assessment Report (AR4). The results show that the strength of the atmospheric overturning circulation decreases as the climate warms in all AR4 models, consistent with thermodynamic scaling arguments. The weakening is primarily in the zonally asymmetric (Walker) component rather than the zonal-mean (Hadley) component, leading to changes in the thermal structure and circulation of the tropical oceans. The weakening is associated with a decrease in strong updrafts and an increase in weak updrafts, though the robustness of this behavior across models is uncertain. As the climate warms, changes in both the atmospheric and ocean circulation over the tropical Pacific resemble "El Niño-like" conditions, but the mechanisms are distinct from those of El Niño. The Indian Ocean response to global warming resembles the Indian Ocean dipole mode. Model results are consistent with recent changes in sea level pressure since the mid-nineteenth century. The study uses climate model data to assess the robustness of the atmospheric circulation response to warming. It explores climate change simulations from 22 models integrated with projected changes in greenhouse gases and aerosols. The results show that all models project a weakening of the atmospheric overturning circulation, driven by changes in the atmospheric hydrologic cycle. The weakening is primarily in the Walker circulation rather than the Hadley circulation. The weakening impacts the thermodynamic and dynamic structure of the tropical oceans. The consistency of the circulation response is explained by thermodynamic and energetic arguments. The study also shows that the weakening of the Walker circulation is reflected in changes in sea level pressure, with a correlation between the relative changes in upward vertical velocity and dSLP across models. The weakening of the Walker circulation is also evident in the ensemble-mean precipitation response of the models. The response of the tropical ocean thermal structure and circulation to global warming is also examined, showing shoaling of the western equatorial Pacific thermocline and changes in the zonal surface currents. The study highlights the dominant role of atmospheric processes in the response of the Walker circulation to global warming. The results are consistent with recent observations of changes in the tropical Pacific Ocean circulation and the Walker circulation.