We’re just too dumb to understand. The idea that the sun affects our temperature is so primitive.
Recently there was the 10Be proxy study as cited in:
Beryllium 10 and climate (a Wattsupwiththat blog publication)
However, the 10Be proxy theory was promptly shot down with claims of unrepresentative sampling, and variation of deposition. That was subsequently backed up with claims of lack of statistical support from observation of sun-like stars. The solar irradiance theory ultimately being dismissed when correlation between sun-spot minima and ultraviolet irradiance was found to be a factor of three times to five times lower than expected to produce a significant global warming contribution based on present-day climate.
See: Climate: The Vanishing Solar Factor (a Space Daily publication)