[Below is the original script. Some changes may have been made during the recording of this audio podcast.]
Ultimately, global warming can be blamed on the sun. It's the sun's light that bathes the Earth and then gets sent back towards space as heat. But some of that heat gets blocked by those pesky carbon dioxide molecules building up in the atmosphere—inexorably warming our planet.
So the sun's output has a lot to do with what we can expect climate-wise. After all, a decrease in solar output known as the Maunder Minimum helped freeze Europe for a few centuries.
For the last few years, the sun has been in a relatively quiet phase: there have been few sunspots, which are the markers of a powerful sun. Last year the number of sunspots dropped to a level not seen since the beginning of the 20th century.
So much for climate change contrarians attempts to blame the sun for global warming.
But now new sunspots are moving into view, and a new solar cycle seems to have dawned this past December, which NOAA and other experts expect to be one of the weaker cycles since the 1750s.
This small weakening of the sun, however, has been outpaced by the rapid increase in CO2 levels from all our fossil fuel burning and tree-cutting. A weaker sun might slow human-induced climate change slightly but when the sun eventually recovers force, global warming would heat up with even more of a vengeance.