Global warming: does the cause really matter that much?

I've been reading the Scietific Assessment report recently released by the White House (4 years late) on global warming and its effects on the US and North America.

And then there is this. an army scientist claims that global warming is due to the sun.

While I understand that there are implications whether "man" did it or "god" did it, what is NOT IN DISPUTE is that the atmosphere is warming and the effects are already evident.

So, as far as adaptation is concerned, does it matter? Even those who agree that humans are a significant factor in global warming, our ability to turn the process around, like we did with the ozone hole and banning CFCs, is much reduced, both for reasons of physics and geopolitics.

But squabbling over the human component of all this reduces our focus on identifying future changes and beginning to adapt/mitigate now. The outcomes are pretty predictable, whether it be due to industrialization or to s sun cycle.

Warming has occured before and humans adapated, and some didn't. But we have the ability to foresee the future on this one. Why ignore it?