Figure 8.

Increase in COVID-19 cases listed in [46,53] in the spring as a function of solar irradiance from the Global Solar Atlas website [89], averaged over the year. Countries grouped as in Figure 6. New Zealand cases decreased, as also occurred in France (not shown). A few counties with 1–3 cases were excluded to reduce noise. GHI was estimated for the northernmost countries, which include Canada and those near the left axis, with labels, by assuming their lowest measured GHI value was 2. Russia, Sweden, and Finland, which are the three countries nearest to Siberian permafrost, all have high case increases for their GHI values. Similarly, Canada which has substantial permafrost has a large number of cases given its irradiance. Unlike Figure 7, a per day basis was not used, and only the April-to-June increase is shown.