Yeah I thought the Sun got bigger, and bigger as it's life cycle went on. Of coarse this aging is supposed to take place over "millions of years".
The Sun is mostly hydrogen and small fluctuations in the amount of energy emitted by the Sun can have a large impact on earth. The Sun will increase in size in about a billion years, before that total solar irradiance will incresase overall brightness, UV wavelengths and magnetic flux.
Aanthropogenically cause of global warming is a political theory and the solar variation theory is more a fact.