Stratospheric dynamics and chemistry can impact the tropospheric climate through changing radiatively active atmospheric constituents and stratosphere-troposphere interactions. The impact of stratospheric dynamics and chemistry on the Last Glacial Maximum (LGM) climate is not well-studied and remains an uncertain aspect of glacial-interglacial climate change. Here we perform coupled LGM simulations using the Community Earth System Model version 2 (CESM2), with a high-top atmosphere-the Whole Atmosphere Community Climate Model version 6 with a middle atmosphere chemistry mechanism (WACCM6ma). The CESM2(WACCM6ma) LGM simulations show a weaker stratospheric circulation than the preindustrial, 10%-35% less tropospheric ozone and 10%-50% more ozone in the lower stratosphere. These dynamical and chemical changes cause slightly more cooling (<5%) in LGM surface and tropospheric temperatures than parallel simulations using a low-top atmosphere without active chemistry. Results from our model suggest that stratospheric dynamics and chemistry may have little direct effect on the glacial-interglacial climate change.
