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No, We're Not Headed For a New Ice Age
purkinje writes "Unusual calm in the solar cycle — called a solar activity minimum — has sparked claims that the Sun will cool the Earth, leading us into a new ice age. While Europe did experience a Little Ice Age during a solar activity minimum three centuries ago, the connection between sunspots and climate is a lot more complicated, and it's unlikely this change in the Sun's activity will cool Earth down — or even affect the climate at all. Plus, any cooling that might come from this would be less than the global warming that's been going on. So don't pull out that parka yet; a new ice age seems more than unlikely."
This is because people are bad at quantitative analysis. Look, solar irradiance averages about 1366 W/m^2 and a has a variation of about 1 W/m^2 (using a one-year moving average). That's 0.073%. If the Earth's temperature was entirely determined by solar irradiance, then the temperature variation would be about 0.2 C. That is, you'd see an 11-year temperature cycle corresponding to the solar output cycle with temperatures varying +/- 0.1 C from the average over the course of this cycle.
There. A tiny bit of research on the Internet and some math and you too can put bounds on how much influence sunspot cycles have on Earth's temperature.
And yes, climate scientists are familiar with this. The sun has been kind of important to climate science since Arrhenius figured out the greenhouse effect in 1896 and used the Stefan-Boltzmann law to estimate the Earth's temperature dependence on CO2.