Iceland is on the rise. I’m not talking about its economy, its military, or its soccer team. The country is literally rising. Like, it’s getting higher—and climate change is to blame.
The phenomenon is known as post-glacial rebound. As ice melts and water drains away from a glacier, pressure on that portion of the earth’s crust lessens. As a result, the ground rises.
“It’s like a trampoline,” says Kathleen Compton, a geodesist at the University of Arizona. (Geodesy is the branch of applied math that deals with the earth's size and shape.) “If you stand on it, the surface sags. When you hop off, the trampoline rebounds upward.”
Post-glacial rebound has been going on for at least 12,000 years, since ice from the last major glacial period began to melt. But in recent decades, parts of the earth have begun to rise faster than ever before. In their study published last week in the journal Geophysical Research Letters, Compton and her colleagues showed that each year, areas near Icelandic glaciers are rising around 0.08 inches faster than in the prior year. Overall, the fastest-moving areas are currently lifting 1.4 inches annually.
For the study, the researchers relied on 62 GPS receivers spread throughout the island. If you’re in the country and bored, you could try to find one. They look like white Frisbees sitting on top of tripods sunk into the bedrock. Here’s a map to help you.
For about two decades, the receivers have been communicating with satellites three or four times per minute. The satellites send the results on to the scientists daily. The raw data is just a long, long (long) series of numbers, but after running the information through two processing programs, there's a minute-by-minute record of precisely where the receiver is located in three-dimensional space.
This sort of research is challenging in other parts of the world, where particularly mushy parts of the earth’s crust are still rebounding strongly from the last ice age. That complicates efforts to isolate the effects of more recent, climate change–related melt. Iceland’s portion of the crust, however, shows very little of that leftover depression, so the researchers are confident the accelerated rise is attributable to climate change. Existing models also support the conclusion.
“Many scientists have modeled the relationship between the speed of the Icelandic ice caps melting and the rate of the earth’s rise, and our observations match that very closely,” says Compton.
I know what you’re thinking: “So what? Who cares if Icelanders are a few inches higher than they were 10 years ago?”
It’s a fair question, but remember this?
The Icelandic volcano Eyjafjallajökull, which erupted in 2010 and spewed 9.5 billion cubic feet of ash across Europe, disrupted air travel, food shipments, and even the Champions League soccer tournament, costing the global economy billions of dollars. Post-glacial rebound is going to make those seismic problems more frequent and severe. A 2013 study suggested that accelerated uplift from the loss of glaciers could increase the total volume of erupted material by approximately the size of the Eyjafjallajökull eruption every seven years.
But forget about the money and the inconvenience (and the liquid hot magma) for just a moment: Studies like Compton’s show that carbon emissions are literally changing the shape of the planet itself. That’s worth pondering.
There was a time when humans thought the earth, sky, and oceans were so big that there was nothing we puny beings could do to alter them. We now know that’s completely wrong. Pollution can initiate profound changes. Vast power like that comes with some serious responsibility. Studies like this show us that we’re not meeting those obligations.
onEarth provides reporting and analysis about environmental science, policy, and culture. All opinions expressed are those of the authors and do not necessarily reflect the policies or positions of NRDC. Learn more or follow us on Facebook and Twitter.
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