The Brunt Ice Shelf in Antarctica. While this ice shelf is not part of the area most recently studied by Ferrigno, ice shelves like this are retreating across the Antarctic Peninsula. Credit: Charles Swithinbank, British Antarctic Survey.
If you want to see the effects of global warming, just look at how the maps of Antarctica are changing. That’s the advice of Jane Ferrigno, a US Geological Survey (USGS) researcher, who led a recently-published study of ice cover in an area known as Palmer Land.
“The most important pieces of evidence are the visible data, the satellite imagery, the aerial photographs, and the maps that we used to compile our map and report,” Ferrigno told Simple Climate. “The evidence is there for anyone to look at.”
The study of Palmer Land, is the latest in a series mapping West Antarctica. Previous USGS surveys of the Antarctic Peninsula, of which Palmer Land is the southern section, discovered that ice sheets had been retreating since the late 20th century. Ferrigno and her colleagues saw similar, and if anything more striking disappearance in their latest study. “We found that most, if not all, the ice fronts in the study area showed overall retreat,” she explained.
Because the Antarctic Peninsula is the furthest part of the continent from the south pole, it is the most susceptible to variations in temperature. Consequently, dramatic changes seen there are not representative of Antarctica as a whole. “Palmer Land is fairly representative of the Antarctic Peninsula, but not of the Antarctic continent as a whole,” Ferrigno explains. “Although there are changes occurring in other parts of Antarctic, it is not as dramatically visible.”
Ice-front retreat in part of the southern Antarctic Peninsula from 1947 (purple lines) through 1990 (blue lines), 1997 (green lines), 2002 (yellow lines) to 2009 (red lines). Credit: US Geological Survey
The study’s conclusions are based in part on maps drawn of the region as far back as 1949, and then satellite measurements since the 1970s. Despite the possibility of human error in the oldest maps Ferrigno says that the retreat in ice cover is “very clear”. “We evaluated the source materials we used and assigned an accuracy factor to each,” she explained. “Where possible, we cross checked the map information, the aerial photographic information, and the satellite information.”
She says that the 32-page report describing the work shows exactly how certain or uncertain all the measurements are, and the overall loss of ice is plain to see. Taken as a whole, the rapid retreat of ice does look to be a consequence of climate change. “I have been looking at historical and remotely sensed data of Antarctica for more than 30 years,” Ferrigno said. “The major changes in the ice shelves in the Antarctic Peninsula are recent, beginning about 20 years ago, with the change beginning in the north of the Peninsula. When I see this amount of ice melt, the evidence points to warming.”
While the polar regions are among the most affected by climate change, Ferrigno notes that other areas are also already being affected. “There have definitely been dramatic changes in both polar areas, but I have looked at glaciers in other parts of the Earth and found changes happening in many areas,” she said.
Ferrigno’s years researching icy climes have led her to view events such as these dispassionately. “As a scientist, I look at the evidence, and draw a conclusion,” she explains. “The Earth is always changing to a lesser or greater degree in one area or another – change is one of life’s constants.” However, the facts of the situation in Palmer Land can point in only one direction. “Right now, the evidence points to warming affecting the ice of the Antarctic Peninsula,” Ferrigno repeats.