Differences between 'turning down the sun' and stratospheric sulfate injection

Abstract

Solar geoengineering refers to the idea of deliberately increasing Earth’s albedo to temporarily cool the planet while we cut emissions and remove greenhouse gases from the atmosphere. There are many ways this could be achieved, the most studied is stratospheric sulfate injection, which mimics what happens during a volcanic eruption. The increase in Earth’s albedo is not the only effect of stratospheric sulfate injection, yet many studies just reduce the solar constant (or ‘turn down the sun’) to simulate solar geoengineering. As part of the Geoengineering Model Intercomparison Project (GeoMIP), the G6sulfur and G6solar simulations reduce the warming from the high-tier emission scenario to the medium-tier emission scenario by adding a stratospheric sulfate aerosol layer (G6sulfur) or a uniform reduction in the solar constant (G6solar). By analysing the differences between these two simulations, we can isolate the climate impacts of stratospheric aerosol injection that arise independently from the increase in Earth’s albedo.

Contributors

• Mira Adhikari
• Emily Ball
• Matthew Henry
• Eunice Lo
• Carla Roesch
• With links to GitHub profiles / institution pages, etc.

What was done

Reproduce simple analysis figures for now on comparing changes in temperature and precipitation (and accounting for seasonality) between G6Solar and G6Sulfur, using UKESM model (only one available on Jasmin).

Outcomes

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About this repo

There are further README files in key directories.

Key files

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How to reproduce our outputs

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Repo structure

.
├── notebooks
│   ├── [...].ipynb
│   └── [...].ipynb
│           The Jupyter Notebooks that we created
│
├── code
│   ├── [...].py
│   └── [...].py
│           Any code (Python or otherwise) that we created that doesn't
│           sit within a Notebook
│
├── results
│   ├── [...].pdf
│   └── [...].png
│           The key figures that we produced
│
├── data
│   ├── raw_data
│   │       Any data we used that didn't come from JASMIN
│   │
│   └── processed_data
│           Any output data that we produced
│
├── environment.yml
└── environment_frozen.yml
        The libraries and versions that we used

Next steps for our project

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This template repo was created for the CMIP6 Data Hackathon by James Thomas and Will Seviour.