Examining debris on top of Earth’s icy white canvases
For a short time after a snowfall, glaciers are like blank white canvases. But it’s not long before the snowy surfaces are painted over with coats of dust, soot, ash, pollen, salt, sand, rocks, and other debris.
Nature has more than one paintbrush at its disposal. Winds blow in plumes of smoke and dust to coat surfaces with black, gray, metallic, even reddish or yellow tones. Volcanoes spew dark ash and tephra that can be millimeters to meters thick. And landslides and lahars slosh thick layers of soil, pulverized rock, muck, and sediment on the icy canvases.
This natural painting is an apt metaphor for the work of Kimberly Casey, a NASA glaciologist who once considered becoming an artist. After high school, she had scholarships for both science and art; she chose the former, but her artistic side has not disappeared. She continues to paint, draw, and take photographs, and those artistic skills and interests overlap with the ones she uses to explore new ground as a scientist. Casey is fascinated by the way the human eye perceives reality, and also intrigued by the deeper, hidden layers of meaning embedded in natural environments.
Casey is one of the first scientists to use satellite data to distinguish between the different types of debris—ranging from fine-grained aerosols, to bits of volcanic ash, to the large rocks and boulders—that end up on glaciers. After numerous expeditions to far-flung mountains, and years combing through satellite data at NASA’s Goddard Space Flight Center and the University of Oslo, she has something to show for it. Casey has produced satellite-derived maps of debris at key glaciers around the world. Her maps not only discriminate between dirty and clean ice; they describe the composition and source of the particulates and debris.
“People have made rudimentary maps of ice debris before, but there has been very little work to map the geochemical composition of particulates on ice with satellites,” she said. The techniques she is pioneering could help answer long-standing, controversial questions about the impact of climate change on glaciers.