One of the most prominent arrows in the quiver of climate skeptics is the assertion a substantial portion of temperature increases experienced over the past century are related to increases in solar output and, and conversely, projected declines in solar output over the course of this century will help to substantially counteract projected temperature increases (see, this recent article, for example). A recent study by the U.K.’s Met Office puts the lie to the latter argument. The Met Office has published a nice summary of the study that would make a good reading in a teaching module that addresses the primary arguments of skeptics.
Among the takeaways of the summary:
- While solar output is slated to decline through 2100, this will have a de minimis impact on projected global surface temperatures, reducing projected temperature increases by only 0.08 °C;
- Even if solar output were to decline to below that seen in the Maunder Minimum during 1645-1715, a period in which solar activity was at its lowest observed level, this would only reduce projected temperature increases by 0.13.°C. However, there is only an 8% chance of solar output dropping to these levels;
- One caveat to the study is that it’s based on a single model; the use of multiple models would help to reduce uncertainties about these projections.