I believe it shows that human activities have little or no effect on whether the earth goes through a cooling or warming cycle. These and other samples taken from ice sheets have shown that there have been period of cooling and warming for millions of years, and that the 'wobbling' of the earth on its axis accounts for the sometimes dramatic shifts from cool to warm.
I doubt very seriously though, that you will see this info on the Nightly News; it doesn't fit their view of the global warming story.
It's based on Just Enough believable fact to keep your level of skepticism of "official" environmental information high!
A FUN Read!
I HOPE you're not prone to "Nightmares!"
Doc