There shouldn't be a way to get there from here

OK, here is how the National Academy of Sciences summarizes its recent report on global temperature over the centuries:

"There is sufficient evidence from tree rings, retreating glaciers, and other "proxies" to say with confidence that the last few decades of the 20th century were warmer than any comparable period in the last 400 years, according to a new National Research Council report. There is less confidence in reconstructions of surface temperatures from 1600 back to A.D. 900, and very little confidence in findings on average temperatures before then."

And here's how the Associated Press summarizes the same report:

"It has been 2,000 years and possibly much longer since the Earth has run such a fever.
The National Academy of Sciences, reaching that conclusion in a broad review of scientific work requested by Congress . . . ."

Scuse me?? !