If the Sun is growing bigger wouldn't that be a cause for global warming?
2 Answers
The Sun is gradually increasing, not rapidly. It's luminosity is increasing by 10% every 1 billion years, so for now, it's not a major deal.
The Sun isn't getting bigger as such, it is getting slowly hotter, but not enough to affect global warming.
Explanation:
The Sun is getting hotter by about 10% every billion years. The reason for this is that the Sun's core is much hotter than the layers above it. As heat rises from the core the outer layers get hotter. This means that the Sun is also getting brighter and emitting more energy into space.
In about 1 billion years time the Sun will be hot enough that Earth is no longer in the habitable zone. Mars will be in the habitable zone for some time after that.
Ultimately in about 6 billion years, the Sun will become a red giant and will consume Mercury, Venus and possibly Earth.
In terms of global warming, the increasing brightness of the Sun is too slow to have a noticeable effect. In a million years the Sun will only be 0.01% brighter than it is today.
In fact if the Sun goes through a low activity cycle where there are very few sunspots, it could cool down enough to cause a mini ice age as it did in the late 17th century.
