other overwhelming observable evidence like the on-going sea level rises every year, and that the oceans were the warmest on record too...
Like many Kiwi's, I live in coastal areas. I've spent my entire life a few hundred metres to a few K away. Right now I am actually about 7 k from the nearest shore.
Over Christmas I visited Opunake beach (very near where I grew up) for the first time in decades. I observed, quite plainly, that the sea was in the same place as last time I was there. If there were "observable" sea level rises over the last few decades, then I should've "observed" that, right?
I also visited other beaches along the Taranaki coast, including Patea beach; areas I spent almost every summer day (and many non-summer ones) during my childhood and teens. Areas with ancient wharfs which were built many decades ago, some even before electricity was common (and Patea was IIRC the 5th place in NZ to have electricity!). I observed that the water still reached the same levels in these places as when I remembered them, and indeed looking at the design of the wharfs, the same level as when they were built.
I recently visited Petone. Same thing with their wharf, built just a wee while ago (1907). Other beaches are the same as they were a long time ago, with the notable difference of the "shoreline 1840" markers a fair way inland on Wellington streets. These mark the old shoreine in 1840, but note it wasn't "global cooling" that moved the sea so far from where it used to be. it was largely (if my memory of history serves me right) a rather large upthrust of land from an earthquake that significantly altered the area, and a bit from "reclaimed land" as well. Mostly from the quake though.
Same for Titahi Bay, the Centenial Highway, the Pauatahinui Inlet - sea levels unchanged for as long as I've known them, and looking at the placements of very old boat sheds, boat ramps, and other constructions, the levels change with the tides, but no more. What his high tide today was high tide a hundred years ago.
So "observable" evidence is that the sea level has had no appreciable change in over 100 years. If you don't believe me, get on a plane and come over here. Plant a tree or two to offset the carbon of your flight like a good wee AGW-type, jetting around to prove how bad jetting around is... Er, anyway... If you want to observe it for yourself, get your arse over here and look for yourself.
I take most "global warming" stuff with a grain of salt, and given the observable levels of rise around me, a grain of salt would probably be enough to raise the sea much more than it has done in recent decades.
(One Wellington councilor did supposedly change his mind after a significant slip took out a chunk of the Hutt-Wellington rail line last year - but then I've always lived coastal, and I know that land erodes anyway, sometimes you get a big bit go in one storm (or even without the storm), sometimes you go decades without slips in a particular area - a slip during a storm is NOT proof or even evidence of global warming - I've been seeing them happen since the early 70's (when they were conclusive proof we were about to enter an ice age!).