Description:

The trajectory of greenhouse gas emissions controls the extent of climate change over the coming decades and centuries. Earth system models (ESMs) that predict the evolution of global climate have traditionally used assumed concentrations of atmospheric greenhouse gasses as boundary forcing. This approach, however, neglects critical feedbacks that influence the rate at which natural systems can take up and store atmospheric carbon. A more comprehensive approach is to use greenhouse gas emissions to force ESMs, which requires explicitly simulating feedbacks among the atmosphere, land, and oceans. These feedbacks are critically important as the trajectory of emissions evolves over the coming decades and as natural carbon solutions – including human actions to enhance ocean carbon uptake or land carbon storage – are pursued to limit warming. In this session, we discuss climate variability and change in emissions-driven ESMs as well as comparison between ESMs and simpler climate models, and discuss future simulation needs to provide actionable climate predictions.