We know that the sun's output can vary by about 1 Watt per
square meter during a solar cycle. So try computing the
temperature with 1368 instead of 1367. Try again with 1366. How
much difference does that make? I get about 0.05 K (0.09 F).
That's a pretty small number. We'd be hard-pressed to get a
thermometer to record it. How about the albedo? I find about a 1
K change (0.9) for a 0.01 change in albedo. Such a change in
albedo (or to increase it by this much) is plausible for the
earth, though 0.10 would be a wild value, not expected by
anybody I know of. Quick sanity check ... why is the albedo so
much more important than solar term? Albedo multiplies the solar
constant. The natural variation is 1 Watt per square meter. The
0.01 change in albedo means a 13.67 Watt per square meter change
in energy entering the climate system, so we expect it to be
much larger. (project: why is it 19 times more important rather
than just 13.67?) The mean distance from the earth to the sun
does change -- on a long enough tim