"It is difficult to get a man to understand something, when his salary depends on his not understanding it." - Upton Sinclair
Most of the willful ignorance peddled as climate skepticism fudges the evidence that global temperatures have risen. That, however, is far down the chain of causes. If I put a blanket on, I will retain more heat. How much heat, in how much time, depends on my temperature, the room's temperature, and how well the blanket insulates. But there is no arguing that I will retain more heat. The only question is, how fast?
The way that carbon dioxide (CO2) blankets the Earth is figurative, not literal. But there is a literal, everyday comparison to something that very few doubt: the workings of a microwave oven. We have turned the microwave on with us in the oven, and there is no timer.
Microwave ovens work by radiating their contents with microwave radiation, usually at 2.45 gigahertz (GHz)—a wavelength of 122 millimeters (4.80 in). At that wavelength, water molecules (per wiki) "rotate as they try to align themselves with the alternating electric field of the microwaves. Rotating molecules hit other molecules and put them into motion, thus dispersing energy. This energy, when dispersed as molecular vibration in solids and liquids (i.e., as both potential energy and kinetic energy of atoms), is heat." In a microwave, water has received energy from the microwave radiation, heats up, and re-radiates that heat to other nearby molecules of protein, carbohydrates, and fats.
Everything in the universe emits a spectrum of radiation, based on its temperature. It's called black body radiation. For a skin temperature of 80F, people emit peak radiation at a wavelength of 9.65 microns - which is how infrared optics work, by picking up that radiation and converting it to visible wavelengths. The surface of the sun is much hotter - about 10,000F, so its peak radiation is at about 1/2 micron. Earth absorbs radiation from the sun, heating it to a mean temperature of 60F, then re-radiates some of that energy.
While black body radiation has a clear peak, it is distributed along a range of wavelengths in a curve. Earth's peak radiation is at 10 microns, but emits some energy at higher and lower wavelengths: 95% of the energy is emitted between 6 and 60 microns. As it happens, CO2 absorbs radiation at 15 microns and re-radiates it: half goes out into space and half is re-radiated back to Earth, warming the planet. The more CO2 in the air, the more energy is retained.
That's how global warming works - the more CO2, the thicker the blanket and the warmer we get. Next: Who asked for this thicker blanket? Where did it come from?