Meridional temperature gradients during the past 250 million years: Proxies versus Models

In this study, we investigate the meridional temperature gradients during the past 250 million years. We compare the differences between proxy data of oxygen isotopes and lithologic indicators and globally coupled atmosphere-ocean climate system model simulation results. Two climate models are employed, CESM1.2.2 and HadleyCM3. There are several significant differences between the model results and Scotese’s reconstruction and proxy data: 1) the tropical surface temperatures are usually higher in the model simulations than both Scotese’s reconstruction (Scotese 2016; Scotese et al. 2021) and proxy data (e.g., Huber and Caballero 2012, Song et al. 2019; Zhu et al. 2019), whereas the surface temperatures in high latitudes are usually lower; 2) the meridional temperature gradients in the model simulations are smaller in low latitudes but larger in the middle latitudes than Scotese’s reconstruction. These comparisons are helpful for paleoclimatology understanding and for future paleo-temperature reconstructions.