British climate scientists have published a new article in the journal Cryosphere announcing a new method of analyzing satellite imagery to distinguish between snow, rock, shadow, and clouds. Previous guesses put the amount of exposed rock in Antarctica at less than one percent. The new method nails that down to 0.18 percent, a huge improvement in accuracy.
The way snow, clouds, and rock look alike in satellite images has been a pain for mapping teams for a while, but this is especially a problem in Antarctica, where the entire continent is made of nothing but those very similar things.
Members of the British Antarctic Survey wrote a script that analyzed high-latitude imagery and parsed clouds from snow and rock. "This is the first automated methodology for the differentiation of snow and rock in Antarctica," the paper's authors wrote, "from which a new outcrop map of the entire Antarctic continent has been produced at higher and more consistent accuracies than existing data and techniques."
Automating the process was key. The best maps of Antarctica we had before were made from scientists viewing individual photographs and drawing areas of rock and ice by hand. Before those maps, the situation was even worse: Maps were made manually by cartographers exploring the Antarctic on the ground.
Greater accuracy in mapping is especially important for keeping tabs on climate change. The poles are critical players in the overall balance of global temperatures, so knowing exactly how much of the continent's ice has retreated and revealed rock is key. (Knowing how bad the situation is hasn't historically helped actually stop climate change, but at least we'll be able to see armageddon coming, right?)
Now that the automation is in place, new images from improved satellite cameras can be fed straight into it. Over time, this sets the groundwork for a constantly improving, much more accurate map of the continent. The team also made their script publicly available, so teams all over the world will be able to help build an accurate picture of Antarctic ice changes.