No they don't. That is now science works at all.
We don't assume the planet is billions of years old. There's an abundance of evidence to substantiate the claim.
Of course you need to assume. You need assume the following at least,
1) You understand time, mind you time is a space in quantum physics calculation. And in relativity it is not even a stable quantity, speed is. You need to assume that time works in the past as it is now.
2) You need to assume that planet earth is in its current position all the times. Since you can't refute the presence of God, and by the assumption of God's existence, God can plug the earth in its current position any time He wishes. And in that case, you don't even how to apply your dating method.
3) Of course, we need to assume that everything shall work inside a sealed 3D space.
The above is close box or a paradigm for physics laws and the like to work. Physics law and science in general almost exclusively need a paradigm to work within.
Ice core samples are just a fraction of data available as to how we understand climate and the age of the Earth.
That's not the point, how much you understand ice age? or reverting of magnetic poies?
We understand a great deal about catastrophes. Even in our history it has been witnessed and documented. You're asking a bunch of baseless questions that we have amassed and extraordinary amount of evidence for.
Last heard is that we understand nothing about magnetic pole reverting. You over trusted human knowledge I must say.
Again, we understand it very well. Question is...How well do you understand catastrophe?
But it wasn't. First, outside your bible, we have no evidence "Noah" existed. That said, as we examine the world around us we have discovered no evidence to suggest a world wide flood in the time line spelled out by various creationist in this thread.
And what's your point? Various societies before, during, and after the supposed flood in your bible had their version of a flood myth. Why should believe the biblical "story" over another?
This is utter nonsense. Let's go with your assumption. See, we actually do know what flooding looks like. We've seen it before and know what to look for if this happened on a global scale as your bible explicitly states. We know what destruction and devastation looks like and there is absolutely no data to suggest that the story given actually happened.
Your assertion is totally moot and utterly nonsense by the assumption that we understand catastrophe well, while I already pointed out that we don't have a clue about what the pole change will cause, and we know almost nothing about how ice age is formed and disolved other than some hypothesis. Perhaps until next ice age comes we may be able to get more information.