Climate and stratospheric ozone during the mid-Holocene and Last Interglacial simulated by MRI-ESM2.0

The climates of the mid-Holocene (MH) and Last Interglacial (LIG) are characterised by warm periods caused by astronomical forcing and climate feedback. One potential feedback is variation in the stratospheric ozone, the influence of which would extend down to the troposphere, potentially affecting the climate. However, little is known about the role of changes in the stratospheric ozone during past warm interglacial periods. Here, we employ MRI-ESM2.0, an Earth system model with an interactive ozone model, and simulate the climate and atmospheric ozone during the MH and LIG. We show that the vertical and seasonal changes of stratospheric ozone in the LIG exhibited a stronger variation in the stratospheric ozone compared to that in the MH, indicating that both obliquity and precession forcings affect the stratospheric ozone distributions. We further show that ozone feedbacks decrease the surface air temperature by ∼ 0.35 and ∼ 0.25 K in the high-latitude regions of the northern hemisphere in MH and LIG, respectively, while the impact on the zonal mean surface air temperature around Antarctica is small. This is the opposite of the previous finding that implies the importance of ozone in southern hemisphere climates, indicating the need for further assessment of how dynamic ozone variations affect climate and atmospheric structures during past warm interglacial periods using multiple Earth system models.