Why Sea Level Matters – Even if We’re Not Waterworld
Environmental textbooks like to emphasize that ours is a water world, driven by a complex hydrological system that both regulates global temperatures and nourishes the land. But that’s not the kind of water world I’m talking about.
I’m talking about Waterworld, the 1995 post-apocalyptic sci-fi movie starring Kevin Costner. It’s a bizarre film – and not just because its eco-friendly protagonist sports webbed toes and gills. Waterworld’s western parallels play out on a vast, post-apocalyptic ocean where the desert is made of water and all the horses are boats.
Costner plays The Mariner, a drifter whose very nature makes him unsuited for civilized life. The gruff nomad finds himself drawn into a woman’s quest to find Dryland, a mythic place in this distant future where the polar ice caps have melted and drowned all dry land.
Check out what the world will look like after the ice melts!
The good news is that scientists think it will take up to 5,000 years for all the ice on Earth to melt – not the mere 500 years it took in the movie universe.
The mechanics of sea level rise are fairly simple. Heat absorbed from the sun is warming ocean water. Warming water expands, its extra space contributing to higher sea levels while its heat melts smaller ice caps and glaciers.
Most of the Earth’s warming over the past 40 years has been hidden in the ocean, and that’s unsettling because it took scientists almost as long to figure that out. Meanwhile, the combination of atmospheric warming and ocean warming has helped global sea levels rise 1.0 – 2.5 millimeters per year over the last century.
At the same time, global warming patterns are expected to speed glacial melt and increase tropical sea temperatures. Sea levels are difficult to predict but could rise between 6 – 37 inches by 2100 … if Antarctica holds.
There’s a reason most research on sea level rise leads to the Antarctic. The continent, which is covered in snow and glacial ice, holds more than 800,000 years of climate history in its ice. With ice shelves extending off 75 percent of its coastline, Antarctica is the Big Boss for climate change.
Glaciologists agree that the Come-to-Jesus moment for sea level rise will happen when and if the West Antarctic Ice Sheet (WAIS) collapses. A marine ice sheet, the WAIS could become unstable if ocean warming trends continue. If this one ice sheet melts, it could raise sea levels more than three meters (about 10 feet).
Evidence from sediment samples in ice cores suggests the WAIS melted in previous interglacial periods. Keeping a watchful eye is not unreasonable, especially after the recent collapses of two major Antarctic ice shelves: The Larsen A in 1995 and the Larsen B in 2002. While studies have since shown the Larsen A previously melted and returned, they also concluded that the Larsen B Ice Shelf was a permanent fixture during previous warming cycles.
This begs the question: Is Waterworld even possible?
Nope! Melting polar ice caps will not drown the entire known world – but they would rewrite it. If the polar ice caps, land ice and glaciers all melted, the Earth’s sea level would rise more than 200 feet. Swaths of North America would disappear into the Atlantic and whole countries erased, but there would still be land.
While this isn’t exactly Waterworld-type ocean rise, it would devastate already at- risk coastal cities and upend today’s geopolitical structure.
And that’s kinda the point of the film.
For a film that doesn’t openly discuss ecology, Waterworld is surprisingly preachy. The reluctant hero is a man whose mutations enable him to live in harmony with the environment. The antagonists, pirates who cobbled together smoke-belching combustion engines, terrorize society from an old oil tanker called Exxon Valdez. Even its premise evolved with the idea that humans created ecological factors resulting in their own destruction.
“What was different about [Waterworld] was that it had to do with an ecological conflagration, a whole world covered in water because of human stupidity and greed,” said director Kevin Reynolds in a 1995 interview.
Scientists don’t expect Antarctica to melt any time soon. The continent, which is buried beneath feet of ice sheets, can survive warmer climates for some time before it gives way.
For now, Antarctica’s western ice sheet is safe. But should it fail in the future, we may well be on our way to the water world Kevin Reynolds and Peter Rader envisioned. And, as in the movie, it would be society’s destructive practices that caused it.