Once again, our climate models have betrayed us. Though scientists previously warned that melting Antarctic ice could raise global sea levels by a full meter by the end of the century, it seems those reports of our collective demise have been greatly exaggerated. Carbon Brief reports:
While some earlier studies, using different approaches, have posited that Antarctic ice sheets could add as much as a metre to sea levels by 2100, this new evidence suggests ice loss on this scale is “implausible”, the paper says.
The new findings show that for ice to be lost that quickly from Antarctica, one of two things would have to happen, says Payne. Either the glaciers would have to flow into the ocean at unrealistic rates, or rapid melting would have to be triggered over a much larger area of the ice sheet than current evidence suggests.
The paper also warns that melting Antarctic ice sheets will contribute to sea level rise, albeit at a much smaller rate—between 10 and 30 centimeters by 2100. That’s an order of magnitude smaller, but still worth paying attention to. There are other potential sources of sea level rise, too: melting continental glaciers, melting Arctic ice, and the simple fact that warmer water occupies more volume than colder water.
And let’s be clear about what we do know: Humans are emitting enormous quantities of gases that trap more of the sun’s heat in our atmosphere, which then leads to rising global surface temperatures. We can expect a hotter planet to have both less ice (and therefore more water) and warmer (and therefore more voluminous) water. From that, it’s not unreasonable to expect rising sea levels.
But this new study highlights the folly of calling climate science “settled” when we are constantly confounded by the specifics. The devil, as they say, is in the details. Our latest projections of Antarctica’s effect on our oceans are a fraction of what they were just a few years ago, and there’s no reason to expect that scientists won’t drastically revise those expectations yet again in the future as we continue to deepen our understanding of our immensely complex climate. It’s like this with virtually every macro-level natural process on earth, from trade winds to ocean currents to sea level rise to, yes, surface temperature changes. There are countless variables at work and complex feedback loops and relationships between those variables that frustrate any attempt to predict what comes next.
That doesn’t mean we have to disregard the threats posed by climate change, or scrap promising efforts to curb emissions. It does mean that the book isn’t closed on the science undergirding all of this, and the sooner greens understand the harm they do to their movement by overstating our ability to comprehend our climate, the better. We’ve said it before, but it bears repeating: Overconfident greens are the number one source of climate denialism.