The response of the general circulation of the atmosphere to increased CO2

How Earth’s surface climate will change in the future depends on the response of the general circulation of the atmosphere to increased CO2. The emergent response of the general circulation of the atmosphere to increased CO2 in state-of-the-art climate models involves a weakening and expansion of the Hadley cell and a strengthening and poleward shift of the extratropical jet stream and storm track. In this talk I will summarize theory and numerical experiments that support a causal connection between future changes in the general circulation of the atmosphere and moist physics. The theory focuses on the Clausius-Clapeyron scaling of specific humidity with warming and its impact on surface winds and turbulent surface heat exchange. The numerical simulations show that when the response of moist physics is disabled the response of the general circulation of the atmosphere to increased CO2 is insignificant.