No, it's not true. Here's a 60-second explanation of global warming.
It's conservation of energy. Fourier asked in 1824: the earth receives a continuous stream of energy from the sun. Why doesn't it keep getting hotter and hotter?
The answer is that the earth also radiates heat into space. A warmer object radiates more heat, so the earth warms up to a temperature where the incoming solar energy and the outgoing thermal energy balance each other ("equilibrium temperature").
As long as the incoming energy and outgoing energy balance each other, the total amount of energy in the system (land, oceans, atmosphere) remains the same, and the climate remains stable.
Hasn't climate changed in the past? Yes: if the brightness of the sun changes, or if there's variations in the earth's orbit, or if the reflectiveness of the earth changes, or if volcanic activity changes the composition of the atmosphere, these can all affect the energy balance, and therefore make the equilibrium temperature higher or lower.
But we can measure all these things, and right now only one of them is changing dramatically: atmospheric composition. By digging up and burning vast quantities of fossil fuels, releasing fossil CO2 into the atmosphere, we've been acting like a giant super-volcano.
Tyndall reported in 1861 that carbon dioxide blocks thermal radiation. The CO2 molecules absorb thermal radiation and re-radiate it in all directions, so some of it goes back downward towards the earth.
You can measure this in a lab, as Tyndall did, by shining infrared through a vessel of CO2. You can see it in the atmosphere: we have satellite measurements showing that outgoing thermal radiation has declined since 1970.
So incoming energy > outgoing energy. Additional heat accumulates until a new, higher equilibrium temperature is reached.
It takes a long time for the actual temperature to catch up with the equilibrium temperature. (Tyndall: the atmosphere acts like a dam thrown across a stream, the water rises behind the dam until it reaches the top.) So even if we could stabilize the current CO2 level today, the temperature will continue to rise.
Novak's argument that CO2 molecules are too diluted to have a significant effect is incorrect. By reducing outgoing thermal radiation, the elevated CO2 level increases the equilibrium temperature at which incoming energy is balanced by outgoing thermal radiation. It has nothing to do with the temperature of the CO2 molecules themselves.
Because there's lots of random variation in temperature across the earth, what we see isn't a small uniform rise in temperature. Instead we see local or regional heat waves which are far hotter than in the past, like the 2003 heat wave in Europe which caused 70,000 premature deaths. For a more detailed view of the evidence of heat waves, see Hansen Sato Ruedy 2012. Figure 3 is especially remarkable.