Solar radiation varies by where on Earth you are located and the angle at which that radiation strikes us. The equatorial regions are hot, the polar regions are not, the sun is responsible for most of our heat. Solar radiation also varies according to what is happening on the sun, sunspot activity and the like.
Total world population = roughly 7 billion people. Total surface area of the world = 361 million square kilometers, total land surface = 148 million square kilometers. Number of people per square land kilometer = roughly 47. Earth receives 1336 watts of energy per square meter or 1336x10,000 watts from the sun per square kilometer.
What do you think has more impact on that square kilometer's climate, those 47 people or slight variations in that 13,360,000 watts of energy? I'm betting on the sun. See this Wall Street Journal article for some reputable scientific folks who are betting the same way I am.
