It has been known for over 200 years that there is a relationship between the price of wheat and sunspots. William Hershel reported that finding to the Royal Society in 1801. (Herschel, W., 1801, Philosophical Transactions, 91, 265.)
It has recently been shown that there is a good correlation between solar cycle length and climate, as this chart shows.
Notice the dip in both solar and temperature from about 1940-1965. There is no such dip in graphs of CO2.
Graph adapted by Dr. Tim Patterson.from: Friis-Christensen, E., and K. Lassen, Science, 254, 698-700, 1991