This study uses a high-resolution global climate model to simulate future climate, with a particular focus on the Arctic and North Atlantic. The model projects a nearly ice-free Arctic by 2040. The paper also introduces a framework to diagnose deep-water formation (DWF) in the Labrador, Irminger, and Greenland Seas and to quantify their regional contributions to the Atlantic Meridional Overturning Circulation (AMOC), revealing how different ocean regions contribute to the weakening of AMOC in a warming climate.

Stratospheric aerosols from explosive volcanic eruptions are a major climate forcer. We compare the stratospheric aerosol forcing for the next phase of coordinated climate model experiments (CMIP7) against complementary datasets, such as observations of lunar eclipses, stellar extinction, and from satellites. We highlight the potential value of combining observational constraints from complementary datasets with the extensive CMIP7 volcanic emission inventory to refine future forcing data.

Injecting aerosol into the stratosphere has been suggested to rapidly cool the planet and counter climate change. Rival actors who oppose deployment may seek to counter stratospheric aerosol injection. Using a climate model, we investigate whether stratospheric aerosol removal could be hastened by injecting coarse aerosol which promote aerosol growth and gravitational settling. We find that this could be effective, reducing aerosol impacts by 30 % in simulations, and warrants further research.

Climate forcings, such as solar radiation or anthropogenic greenhouse gases, are required to run global climate model simulations. Stratospheric aerosols, which mostly originate from large volcanic eruptions, are a key natural forcing. In this paper, we document the stratospheric aerosol forcing dataset that will feed the next generation (CMIP7) of climate models. Our dataset is very different from its predecessor (CMIP6), which might affect simulations of the 1850–2021 climate.

Adding a layer of reflective particles high in the atmosphere is one suggested way of cooling the planet and reducing the impacts of climate change. This technique might be less logistically difficult in the high latitudes, because the material could be released at lower altitude there. Here, we use new simulations in three earth system models to assess how this form of intervention, High-Latitude Low-Altitude Stratospheric Aerosol Injection (HiLLA-SAI), would impact the global climate.