That graph is the leading image on the Solar activity and climate Wiki page. The temperature is modeled as a rate of change in degrees C, and the irradiance energy in W/m² is modeled in absolute value. The thick lines are averages. The total solar irradiance (TSI) data has large peaks and troughs after 1950. I mention this because the way the data is presented doesn't really tell the whole story, it's designed to not show correlation.
The TSI before 1970 is modeled on reconstruction analysis from this paper, extrapolating TSI based on the earth's magnetic flux. Interestingly that paper models TSI from 1700-1970 but this chart starts in 1880. That leaves out nearly 200 years of available data, which to me suggests cherry picking. Based on that paper TSI is high before 1880, while also other data sets suggests global temperatures were lower. Before 1880 anthropogenic CO2 emissions were low. This suggests that factors other than only TSI and CO2 play a role.
This paper, Long-term global temperature variations under total solar irradiance, cosmic rays, and volcanic activity, suggests that "there are combined effects of solar, cosmic rays, geophysical and human activity on climate change patterns. It should be noted that more detailed investigations of such complex interactions are necessary."
That graph is the leading image on the Solar activity and climate Wiki page. The temperature is modeled as a rate of change in degrees C, and the irradiance energy in W/m² is modeled in absolute value. The thick lines are averages. The total solar irradiance (TSI) data has large peaks and troughs after 1950. I mention this because the way the data is presented doesn't really tell the whole story, it's designed to show correlation.
The TSI before 1970 is modeled on reconstruction analysis from this paper, extrapolating TSI based on the earth's magnetic flux. Interestingly that paper models TSI from 1700-1970 but this chart starts in 1880. That leaves out nearly 200 years of available data, which to me suggests cherry picking. Based on that paper TSI is high before 1880, while also other data sets suggests global temperatures were lower. Before 1880 anthropogenic CO2 emissions were low. This suggests that factors other than only TSI and CO2 play a role.
This paper, Long-term global temperature variations under total solar irradiance, cosmic rays, and volcanic activity, suggests that "there are combined effects of solar, cosmic rays, geophysical and human activity on climate change patterns. It should be noted that more detailed investigations of such complex interactions are necessary."