You really are clueless aren't you.
The seasonal variation summer-winter is due to the *tilt* of the Earths spin axis which gradually precesses over a 26,000 year period.
The Earths orbit is also elliptical and at present Northern hemisphere winters (where there is a large sub-arctic landmass for snow to land on) roughly coincides with perihelion - the closest approach to the sun (around 4th Jan). This is the most favourable configuration for global mildness. Annual insolation at 60N is a good predictor of ice ages.
The ellipse itself precesses with a period of 21000 years relative to the sun. When the perihelion coincides with southern hemisphere winters then the northern hemisphere ends up colder with more ice & snow.
The complex interplay of evolution of the Earths orbital elements by perturbations from the other planets is what drives Milankovitch cycles of which this is about the shortest component. On a longer timescale the ellipticity can vary on geological timescales between 0 and 6%.
That sounds more like them justifying their new better experiment. There are multiple satellites monitoring TSI and the records they produce are pretty well all self consistent. Baseline errors and degradation of sensors in a hard vacuum UV environment are a worry.
It has to face to sun to measure it and that isn't a nice environment for precision calibrated sensors.
People who have a new better mousetrap are advertising the improvements they have made. The data we have since the late 70's rules out any hand waving dittohead science "explanations" that magically the sun brighter and noone noticed. The measurements are good enough to rule that out. Even sceptics like Baliunas and Soon admit these observational constraints.
And if anything the loss of sunspots and decrease in solar maximum activity which you allude to below should be making the Earth colder like it probably did during the Maunder minimum.
Utter rubbish. The present solar activity is lower than it has been in previous recent cyclees but it is by no means clear that it is abnormal yet. Solar cycles vary in length somewhat. There are three active regions on the sun at the moment and the Zurich sunspot number has been used for centuries to monitor their number in a systematic way.
Sunspot number has been well monitored since the invention of the telescope. And naked eye sunspots have been recorded by Chinese astronomers from antiquity (largely because it upset them to see the perfect sun disfigured).
I doubt they are doing anything meaningful when they extrapolate the field to zero like that. Time will tell - it isn't long to 2015. I shall be annoyed if the sun goes inactive I have an H-alpha scope.
Regards, Martin Brown