As discussed in the prior changelog entry, we are updating the three uncertainties below. Note that none of the metrics or uncertainty/decision relevance quantifications changed for any of these.

• New Aircraft Development
• Material Dispersion Technology
• Ground Infrastructure

When we first released this database, we made it available to the sunlight reflection community as soon as we felt that it could be a beneficial resource. But assessing this broad set of uncertainties is a large task, so since this initial release, we have also begun a slower process of improvement and expansion of the content. This has been based in part on the invaluable feedback we have received on framing, design, and content. Thank you to all those who have contributed!

We are working through the uncertainty entries one-by-one, taking several weeks in each case to expand our literature reviews, make new figures and quantitative assessments, and talk with relevant experts. This process aims to produce: sharper decision-relevance and uncertainty justifications, more robust explanations of each uncertainty and its sources, and a more complete list of relevant literature.

We are publishing these updates in batches rather than waiting for all of them to be finished. The four uncertainties listed below now have updated versions live. Any changes to the metric or decision relevance or uncertainty quantifications are listed below. Please let us know what you think here.

• Aerosol Size Distribution:
  • Old metric: ‘Radiative forcing per unit injection is wrong by a factor of 2 relative to the multi-model mean, due to difference in size distribution.'
    New Metric: ‘The global aerosol effective radius of stratospheric sulfate is >0.5 μm, under 21km 30°N/S injection at 5Tg annual injection’
• Stratospheric Transport of Aerosols
  • Title changed from ‘Aerosol Spatial Distribution’ to ‘Stratospheric Transport of Aerosols’
  • Old metric: ‘The average spatial pattern obtained in releasing a hypothetical passive tracer is outside the multi-model range.’
    New Metric: ‘The mean lifetime of a passive tracer injected at 21km and 30°N/S is less than 2 years.’
• Surface Air Quality
  • Old metric: ‘Direct impacts of SAI cause a sufficient net increase in PM2.5 and surface ozone to increase global annual mortality by 10,000.’
    New metric: ‘There is a 2% increase in mortality from PM2.5 and surface ozone under SAI relative to the no-SAI future, at 0.5°C global cooling.'
  • Degree of uncertainty changed from Low to Medium
• Volcanic Eruptions During Deployment
  • Old metric: 'Direct impacts of SAI cause a sufficient net increase in PM2.5 and surface ozone to increase global annual mortality by 10,000.'
    New metric: 'There is a 2% increase in mortality from PM2.5 and surface ozone under SAI relative to the no-SAI future, at 0.5°C global cooling.'

Today we're launching SAI Uncertainties, a comprehensive resource for exploring and understanding research uncertainties related to stratospheric aerosol injection. This database represents months of work synthesizing expert knowledge, literature review, and structured assessment frameworks.

Our goal is to provide researchers, policymakers, and stakeholders with a clear picture of what we know, what we don't know, and where research investments could have the greatest impact on reducing uncertainty. Each entry includes detailed metrics, contextual notes, and references to relevant literature.

• Browse uncertainties by type (physical, technical, social, governance), probability level, and potential consequences
• Detailed uncertainty pages with assessment metrics, expert notes, and literature references
• Full-text search and multi-faceted filtering to find relevant uncertainties quickly
• Responsive design optimized for desktop and mobile viewing
• Accessibility features including keyboard navigation and screen reader support

This is just the beginning. We'll be continuously updating the site with new uncertainties, refining assessments as new research emerges, and adding features based on user feedback. Check back regularly or follow our changelog to stay informed.