[FreeFull]

The problem is that the Sun is significantly brighter now than it used to be back then, so the amount of heating from the same amount of methane/co2 is proportionally more now too

[edge17]

What does that mean that "the sun is brighter"?

[pfdietz]

Since the Sun settled onto the Main Sequence after its formation, it has gradually brightened. It is now 30% brighter than it was then.

The brightening is caused by accumulation of helium ash in the Sun's core. This causes the core's equilibrium state to be denser and hotter, with more energy being produced.

In another billion years or so, this will drive the Earth into a runaway greenhouse effect. The oceans will evaporate and the hydrogen will be lost to space. Not long after, the Earth will be a dead planet devoid of any life, even microorganisms. You sometimes see statements about how when the Sun expands into a red giant it will destroy life on Earth, but the Earth will have long been lifeless by that time.

[rawling]

https://www.forbes.com/sites/startswithabang/2018/08/28/our-...

[dtech]

The sun is literally shining brighter, in that it produces more energy

[sampo]

> What does that mean that "the sun is brighter"?

Sun has been getting about 8% brighter (8% more energy output) every 1 billion years.

[whinvik]

Don't know how HN hivemind works but there's nothing in this question that should lead to downvotes.

[whiplash451]

Don’t know why you got downvoted.

The article linked by one of your commenters is super interesting (assuming it is correct).

[Mountain_Skies]

Sunspot cycles are sometimes mentioned as a possible factor in climate change, especially by those skeptical of human generated causes. The downvoters might have mistaken the comment as being related to this instead of being a different solar variable.