Global climate model simulations using high-obliquity (70¿), higher CO2 and CH4 but reduced O3 concentrations produce warm climate conditions for Archean boundary conditions (reduced solar forcing). Solar radiation under high-obliquity is distribution in such a way as to warm high latitudes and cool low-latitudes. Global mean air temperatures of approximately 280 ¿K are found with a 25% reduction in the solar forcing, 4760 ppmv CO2 and 25 ppmv CH4. High-obliquity could also explain why polar oceans on Mars may have occurred in its history. A substantial increase in the amount of insolation is accounted for if Mars had an obliquity of 70¿. ¿ 2001 American Geophysical Union