Actually science does take into account the output of the sun.

This shows some of the factors that scientists look at and how the lower sun output in recent years has not cooled our planet.

https://www.skepticalscience.com/solar-activity-sunspots-global-warming.htm

Over the last 35 years the sun has shown a cooling trend. However global temperatures continue to increase. If the sun's energy is decreasing while the Earth is warming, then the sun can't be the main control of the temperature.