NASA - Images of Change

NASA - Images of Change

 - 279 images showing environmental changes over time

Pine Island Glacier calving, Antarctica
An iceberg estimated to be 35 by 20 kilometers (22 by 12 miles) separated from Antarctica's Pine Island Glacier between November 9 and 11, 2013. Such events happen about every five or six years but this iceberg, designated "B-31," is about 50 percent larger than its predecessors in this area. A team of scientists from Sheffield and Southampton universities will track the 700 square-kilometer chunk of ice and try to predict its path using satellite data.

Filchner Ice Shelf calving, Antarctica
The Filchner Ice Shelf, on the Antarctic coast facing the Atlantic Ocean, is the largest ice shelf by volume on Earth. In the austral winter of 1986, its front edge broke off, forming three large icebergs. This was a major, long-awaited calving. Ice shelves develop mainly from glaciers flowing slowly downhill toward the ocean. "Upstream" the ice shelf rests on land, and "downstream" it extends out into the sea. When a large piece calves, it does not drop and splash into the water, because the front of the ice shelf was already floating. In fact, the ocean's tides lift and drop the seagoing part of the ice shelf every day. The place where the floating part of the ice shelf connects to the part on land is called the "hinge" line, since the outer shelf swings up and down from it.

Ice melt, Ecuador
Atop the Cotopaxi Volcano — at 5,897 meters (19,347 feet), one of the tallest active volcanoes on Earth — sits the Cotopaxi Glacier. The glacier has considerable economic, social, and environmental importance. Its meltwaters provide fresh water and hydroelectric power to Ecuador’s capital city of Quito. But the glacier is melting and the rate has increased in recent years. The ice mass decreased 30 percent between 1956 and 1976 and another 38.5 percent between 1976 and 2006, a phenomenon tightly linked to global climate change. Comparing the 1986 and 2007 images reveals a notable reduction in the glacier at the volcano’s summit.

O'Higgins Glacier melt, Chile
Almost all the glaciers in the southern Patagonian ice field, in the south of Chile and Argentina, are melting. O'Higgins Glacier, which makes up a quarter of the ice field, is one of those that have changed the most. Its leading edge remained stable until the start of the twentieth century, when it began a retreat that measured 15 kilometers (about 9 miles) by 1995. Some 12 kilometers (over 7 miles) of ice were lost between 1945 and 1980 alone. While some of the reduction in the glacier’s thickness and area is due to the dynamics of the ice itself, global warming speeds up the rate of melting. In the 2007 satellite image, the glacier's retreat is quite visible relative to the 1973 image, when it extended several kilometers into O'Higgins Lake (purple-blue area).

Bear Glacier melt, Alaska
This series of images shows the shrinkage of Bear Glacier from 1980 to 2011. Warming in the region has caused less buildup of snow and therefore less material for glacial growth. As the glacier has receded, ice at the end of the glacier has broken off the main body, forming icebergs in the open water. The 2011 image shows considerable retreat of the glacier's "tongue."