"What impact will this have on climate change science?"

Not a lot, this is a non-story driven by right-wing science denial. Anyone with even a passing knowledge of the field knows we've moved beyond trying to prove anthropogenic climate change is happening and are now trying too understand how it is happening and the processes behind it.

Principal Scientific are a fringe group and the papers on their site are self-published and scientifically worthless, as they sort of admit themselves when they say in their front pages: "This is a PROM* Paper and subject to ongoing review" This means it's not peer reviewed and is therefore nothing more than an opinion.

For a more balanced view: Climate change: A guide for the perplexed

The hockey stick is discussed own more detail here: What evidence is there for the hockey stick?

Mind you, that's only part of the problem. Here's new paper on the sixth mass extinction published in an actual peer-reviewed journal: http://www.pnas.org/content/early/2017/07/05/1704949114.full.pdf