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Is the Sun Responsible for Recent Warming?

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In a previous post , I pointed out that I find the notion of quantifying "consensus" to have limited value, but one value I admit it can have is to show areas of climate science about which practicing scientists no longer in actively debate in the literature. This allows us to understand what debates in popular discourse do not translate into debate among climate scientists. One of the most common objections to AGW I hear in popular circles is that warming is caused by the Sun, rather than human activity. The most common way I see this claim is with reference to solar variability in terms of total solar irradiance (TSI). Variability in TSI can be caused by two things: changes in solar output, like the 11-year solar cycle, or changes in the distance between the earth and the Sun. Variability in the Earth's orbit around the Sun, often referred to as orbital cycles, do not change the total amount of energy the Earth receives in a year, but they can change the distribution of...

Is There an Ongoing Debate about the Impact of Solar Variability on Climate?

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This is part 1 of  review of the claims in Connolly et al 2021. You can see part 2 here . A paper was published in 2021 arguing that scientists have been premature to rule out the possibility that the Sun is the dominant explanation for the current warming trend. One key element in this argument is that there is continued disagreement over the degree of solar variability in reconstructions of Total Solar Irradiance (TSI) since 1610.  Some reconstructions show "low solar variability," and if those are correct, then current warming may be best explained by anthropogenic forcings. However, if "high solar variability" reconstructions are correct, then solar variability may explain most of current warming. So Connolly et al argue that "the answer to our question 'How much has the Sun influenced Northern Hemisphere temperature trends?' depends substantially on which estimate of TSI we choose."[1] But is this correct? Connolly et al Figure 2 Figure 2 in h...