Sea level rise is gonna get a whole lot realer
I was alarmed to recently learn that plenty of folks out there on the interwebz don't believe that the seas have risen, at all, for several centuries. Although, in hindsight, I shouldn't be surprised: after all, there's no shortage of climate change deniers out there, and sea level rise is very (although not completely) interconnected with climate change.
To be fair to those folks, it's true that – as they claim – the water level of various landmarks around the world, such as the Statue of Liberty, Plymouth Rock, and (in my own stomping ground of Sydney Harbour) Fort Denison, has not "visibly" risen since they were erected.
The fact, per the consensus of reputable scientists, is that the global average sea level has risen by 15-25cm (6-10") since 1900. Now, I'm willing to entertain the notion that, alright, for all practical purposes, that's not much. And that's just the average. So I consider it not unreasonable to concede that there are numerous places in the world today, where the sea level has barely, if at all, risen.
But.
Image source: PxHere.
The thing is, sea level rise lags behind global warming by several decades. So (if you'll excuse my hitting-rather-close-to-home choice of pun), what we've seen so far is just the tip of the iceberg. We've already locked in another 10-25cm (4-10") of sea level rise between now and 2050. And we're currently looking at a minimum 28-61cm (11-24") of sea level rise between now and 2100, and a minimum 40-95cm (16-38") of sea level rise between now and 2200. And those are the best-case scenarios, based: on the most conservative of scientists' conclusions; and on the world taking drastic action to reduce greenhouse gas emissions starting right now (a depressingly unlikely occurrence).
So, ok, perhaps sea level rise ain't gotten real yet for most people (although it sure has for some people). But I got news for y'all: it's gonna get a whole lot realer.
It's complicated
Sea level rise is, admittedly, one of the tricker symptoms of climate change to get your head around.
Firstly, it hasn't occurred – at least, not in most of the world – in as dramatic or as visible a manner as various other phenomena have. Glacial melting is clear as day, to anyone who is a local resident of, or a long-time vacationer to, one of the hotspots. Droughts, heatwaves and bushfires / wildfires have been noticeably increasing in both frequency and intensity, in North America, in Europe, and here in Australia (to name but a few places). Glaciers don't un-retreat, and charred countryside doesn't un-burn, when the tide goes out.
The only places in the world where the sea level rise merde (if you'll excuse my French) has already visibly hit the fan, are remote, impoverished, sparsely-populated, seldom-visited islands, particularly in the Pacific. So it's relatively easy, right now, for much of the world to feign blissful ignorance, if everything appears to still be cool and normal on the coastline down the road from your house.
Image source: PxHere.
Also, the amount of sea level rise that has occurred over the past century-and-a-bit is, historically speaking, quite modest. Sure, it's the most significant rise in the past 3,000 years. However, from around 20,000 years ago (at the end of the last ice age), until around the start of Classical Antiquity, the sea level rose by about 125m (400'). That's great ammunition for deniers to go around claiming: "sea levels have always risen and fallen naturally, whatever is happening now has nothing to do with human activity".
Secondly, although scientists unanimously agree that sea level rise is accelerating and that it will get pretty bad pretty soon, there is massive uncertainty as to exactly how much and when. As I said, a 28-61cm (11-24") sea level rise between now and 2100 is the best-case forecast. The current worst-case forecast is a 1.3-1.6m (4-5') sea level rise between now and 2100. There are numerous forecasts in between.
Apart from not realising that it's already happening, and not realising that it lags behind air temperature changes by several decades, most people also don't realise for just how insanely long the sea level is going to keep on rising, as a result of industrialised humanity's love affair with carbon. In this arena too, estimates vary quite widely. But we're looking at a best-case forecast of a 2-3m (6-10') sea level rise over the next 2,000 years, and a current worse-case forecast of a 19-22m (62-72') sea level rise over the next 2,000 years.
But that's not all. The thing is, all that carbon we've emitted lately, it just ain't going anywhere in a hurry, it's going to keep hanging around like a bad smell. As such, we're looking a a best-case forecast of a 6-7m (19-23') sea level rise over the next 10,000 years, and a current worst-case forecast of a 52m (170') sea level rise over the next 10,000 years.
Image source: Wallpaper Delight.
Get ready
The sea may have only barely perceptibly risen so far, but it's about to rise a whole lot more. It's going to happen soon enough, that it will have a real and devastating effect, not on your great-grandchildren, not on your grandchildren, but on your children (and mine) who have already been born. Even considering the best-case forecasts, the map of the world's coastlines will already be different by the end of this century; and it will be unrecognisable in millennia to come.