The Earth is warmed by incoming solar radiation and cooled by radiating heat out into the cold of space - as summarised below. Taking the temperature of the Earth's surface is not a trivial task. The surface temperature as reported, sometimes alarmingly, is not the whole story.
The heating of the surface by the sun turns out to be a difficult thing to measure and predict.. But in the Climate Change debate this warming is relegated to a bit part.
The Earth’s surface radiates heat towards the cold of outer space. Some of this heat is ‘trapped’ by the atmosphere so the Earth is much warmer than it would otherwise be. Estimates have been made of by how much the Earth is warmed by its atmosphere which are generally accepted to be about 33⁰C.
This warming is called the ‘Greenhouse Effect’.
It is variations in the Greenhouse effect that underlie much of the climate debate.
Chapter 3 (pp 190-208) is devoted to the Warming side of the balancing act
Chapter 4 (pp 208-237) is devoted to the Cooling side of the balancing act
Chapter 5 (pp 234-242) considers if the warming or cooling question can be answered