Penn State warmist Richard Alley: “Carbon dioxide is the biggest control knob on the global warming dial”

Geoscientists sail to Antarctica to study plate tectonics, glaciology and climate change

Dr. Richard Alley is a professor of glaciology from Pennsylvania State. “Carbon dioxide is the biggest control knob on the global warming dial,” said Alley who described how geoscientists use satellites and other geophysical tools to measure the changing thickness of Antarctica’s ice sheets, with an accuracy of “one-third of a potato chip.”   [Hey Richard:  How do you manage such astounding accuracy when you don't always know where the ice ends and the land begins?  Are you just assuming that the land down there somewhere below the ice isn't rising or falling?]

July 2012:  'Grand Canyon' Discovered Beneath Antarctic Ice : Discovery News

During a surveying trip across Antarctica, scientists discovered a rift six miles across and a mile deep.

So what is the size of the carbon dioxide control knob, and what are the relative sizes of the next 100 biggest control knobs?