[frogjerk]

The figure shows that sunspot numbers rose in the first half of the 20th century, along with temperatures. The rise in solar activity in the early part of the century is though to be connected with an 80 year cycle of solar activity known as the Gleissman cycle. The temperature increase in the second half of the twentieth century does not seem to linked with sunspot numbers.

It sure does to me. Were talking overall trend here. Average number of sunspots went up and so did temperature.

Take a look at the graph where the number of sunspots stayed about an average of 80 (about 1940s-on). The surface temperature reflected this change. The number of sunspots hasn't receded to the early 1900's average level of 30 or so. This means the earth hasn't been able receive a cool sun's radiation for some time now.

[cogitator]

Look at the solar cycle length comment.