The Response of Tropical Climate to Orbital, Ice Sheet, and Greenhouse Gas Forcing

Substantial changes in tropical climate during the Quaternary Period (i.e., the past 2.6 million years) have been reconstructed from a wide array of paleoclimate proxies. To understand the mechanisms that may be responsible for these changes, we employ a set of single-forcing simulations with a coupled atmosphere-ocean general circulation model and examine the tropical responses to changes in Earth's orbital parameters (i.e., perihelion date and axial tilt), ice sheet extent, and greenhouse gas concentration. Our analysis focuses specifically on changes in the width of the tropics, monsoon precipitation, and the position of the intertropical convergence zone. In addition to providing insight regarding paleoclimate variations, our analysis may illuminate some of the mechanisms involved in recent tropical climate trends.