I wonder if a sunspot might actually be created on the Sun, resulting in some instability that might produce more sunspots.
That is, assuming a very calm Sun has caused an acute ice age, if a spaceship could be launched with the equivalent of a 1,000MT nuclear bomb on board (the largest nuke ever built was the Tsar Bomba, at 100MT, though limited to only 50MT when tested).
Granted, the spaceship would not get very close to the Sun before melting, but the purpose of the nuke would be to create an immense magnetic field close (within millions of kilometers) to the Sun, with an electromagnetic pulse.
Doing so might create a “dent” in the magnetic field of the corona that might reverberate enough to affect the internal magnetic field of the Sun.
It's difficult to perceive the size of the Sun and the immense energy it unleashes every second. A million Earths can fit inside the Sun. The Sun's diameter is 1,000 X that of Earth. I would imagine a 1,000MT bomb would have the same effect as a grain of sand hitting Mt Everest.