So, it probably comes from the sun¹. The sun didn't change its output much according to relevant science in the last few years, solar cycles notwithstanding. So, it must be related to the amount of energy not being reflected into space.
Which is where greenhouse gases come into play. The earth reflects a certain amount of energy it receives back into the vastness of space. The ratio of how much it reflects is affected by greenhouse gases.
Now, there are a lot of greenhouse gases. CO² is one of the least potent of all, but its sheer volume in the atmosphere - being increased by human emissions - makes it the most relevant actor here: https://www.epa.gov/ghgemissions/overview-greenhouse-gases
So, we're keeping more solar energy within earth's atmosphere. We can use that energy as solar energy, or as wind energy, or whatever we like, but as long as it is solar energy, the energy budget within earth's atmosphere won't change. We either have to reflect it back to space, or we'll suffer the same consequences as not using it as renewable energy².
That's it. This is just a collection of facts which are really obvious, but from my experience few people really consider in their threat model. I think not one fact I just posted is false, but I would really welcome to be educated where I am wrong.
¹ Energy generated on earth compared to energy received from the sun is almost negligible: the energy generated on Earth is roughly 0.0000000000054% of the energy received from the Sun (3.8 x 10^26 watts, compared to a ballpark around 10^15 watts of fossil + nuclear fuels combined).
² This is probably obvious, but by reducing greenhouse gases in absolute terms, we reduce the albedo of earth, which in turn means reflecting more energy into space. Right now, we're just focusing on reducing the 2nd derivative of greenhouse gas emissions. In 2023, we do nothing at all in terms of actively increasing the albedo, that is, reflecting energy back into space.