If you think that the two photos above are depicting the same scene at different times of year, think again. The photo on the left, of the north face of Mount Abbot in the California’s Sierra Nevada Mountains, was actually taken in the summer of 1908, while the one on the right was taken this past August (after two years of drought). The contrast speaks volumes about the vulnerability of California’s snowpack, but take another look and you’ll see that it’s not just snow that missing. It’s ice. Because the photographer back in 1908 wasn’t really taking a photo of Mount Abbot. Instead, he was taking a photo of Abbot Glacier – that’s the big swath of ice in the very center of the image – and today that glacier is long gone.
It can be easy to dismiss these kinds of photos as nothing more than environmental P.R., but glacier “repeat photography” serves a very real scientific purpose. A glacier’s size is an indicator of how a given region’s temperature and snowpack have changed over long periods of time. If you can figure out how much your local glacier has retreated in past decades, you can start to figure out how much hotter and dryer things are likely to be in the future.
But the vast majority of the Earth’s glaciers go unmeasured any given year, for the simple reason that there are far more glaciers than there are climate scientists to measure them. Glaciers of The American West, a research program at Portland State University which catalogs and tracks glaciers in the lower 48, estimates that there are over 8,000 permanent ice features in the U.S. alone, not including Alaska. By comparison, the program has an on-again, off-again staff of around six. Satellite imagery helps, but that data can often be hard to interpret and only goes back to the 1970s. The result is a game of scientific whack-a-mole, with the researchers only able to go out and “ground truth” a small handful of glaciers any given year, during the brief season between spring and autumn snows.
That’s where repeat photos like this one come in, because it wasn’t actually taken by a scientist. Instead, I captured it myself using nothing more than a dinky point-and-shoot on a behalf of a citizen science program called the Alpine of the Americas project, which asks ordinary hikers to send in repeat photographs of glaciers, like Abbot Glacier, that would otherwise slip through the cracks. So far, they’ve only collected about hundred such photos, but the hope is that crowd-sourcing the efforts of the thousands of tourists who pass by such glaciers every year will offer researchers a level of granularity that has previously has proven elusive and – in the case of older photographs – allow them to peer back further in time. The result is a kind of tourist scavenger hunt combining history and science. The hiker gets the thrill of following in the footsteps of the Sierra’s earliest photographers, and the researchers get their much-needed data (plus the resulting time-lapse photo looks really cool).
And this isn’t just data for the sake of data. A growing body of research suggests that climate change has come in waves. Temperatures will rise for two or three decades, then level off, then rise further. And the glaciers in the photographs seems to follow suit, shrinking, then growing a little, then shrinking even more. So repeat photography acts like a regional thermometer. Or, in the case of Abbot Glacier, like the canary in the coal mine. You can pick your metaphor.
But more importantly, you can go take a photo. To get started, visit Alpine of the America’s webpage, and don’t forget to check out Glaciers of the American West, where you can find a cool interactive map of those 8,000 permanent ice-features, most of which – shocker – have never been properly photographed.