The entire site is changed so don't bother freaking out over the old links not working. That's not the problem though, the problem is that climate change isn't in any of the new sections.
Here's something else that's weird and/or potentially disturbing though: as can be expected, the site has profiles on the previous presidents. Check out Obama's:
https://www.whitehouse.gov/1600/presidents/barackobama
It doesn't mention his actual presidency with a single word. It's like it's stuck in 2008. Maybe that's actually because you're not supposed to write a summary until after his presidency is over and that it might get changed now that it's ended, but who knows. Certainly would be a weird way of denying him his legacy if it stays like that.
EDIT: OK, I checked it out. It's simply retained from the old site.
https://obamawhitehouse.archives.gov/1600/presidents/barackobama
Will still be interesting to see if they bother updating it, though.