Patagonia, Chile. Left: September 18, 1986. Right: August 5, 2002. The 1986 image shows the region prior to a major retreat of the glaciers. The 2002 image shows a retreat of nearly 10 kilometers (6.2 miles) of the glacier on the left side. The smaller glacier on the right has receded more than 2 kilometers (1.2 miles). In front of the smaller glacier, two ribbon lakes have formed behind the debris left by the glacier's advance.

Wax Lake Delta, Louisiana. Left: January 13, 1983. Right: January 2, 2011. The delta, where the Atchafalaya River flows into the Gulf of Mexico, was formed by sediment following the construction of a canal through Wax Lake in 1941. Since Hurricane Katrina in 2005, the delta has served as a model for restoring wildlife habitat and protection against storm surge in the Mississippi River delta region.

Petermann Glacier, Greenland. Left: June 26, 2010. Right: August 13, 2010. An iceberg more than four times the size of Manhattan broke off the Petermann Glacier (the curved, nearly vertical stripe stretching up from the bottom right of the images) along the northwestern coast of Greenland. Warmer water below the floating ice and at the sea's surface were probably responsible for the break.

Wadi As-Sirhan, Saudi Arabia. Left: February 2, 1986. Right: February 12, 2004. Once so barren it could barely support the towns of Al'Isawiyah and Tubarjal (upper left of each image), a vast desert region gradually blossomed into crop-producing fields (green dots) by use of center-pivot irrigation. The system used here draws from an ancient aquifer containing water as much as 20,000 years old. Judicious use of water resources and climate-appropriate technology has improved food production without harming the environment.

The Yellow River Delta in China. Left: 2001. Right: 2009. The Yellow River is the second-longest river in China, and the sixth-longest in the world. It has been the cradle of Chinese civilization; but frequent devastating floods have also earned it the name of "China's Sorrow." Historical maps tell us that the river has undergone many dramatic changes in its course. Currently, the Yellow River ends in the Bohai Sea, yet its eastern terminus continues to oscillate from points north and south of the Shandong Peninsula. These images show the changes.

The Aral Sea, located in Kazakhstan and Uzbekistan in central Asia. Left: 2000. Middle: 2004. Right: 2009. Once one of the largest inland bodies of salty water in the world and the second largest sea in Asia, the Aral Sea has shrunk dramatically over the last 30 years. One of the main reasons is crop irrigation: water has been drawn off from the rivers that kept the Aral Sea filled. As the sea has shrunk, there have been noticeable changes in the local climate, contaminated dust storms, and the loss of drinking water and the local fishing industry. By the late 2000s, the Aral Sea had lost four fifths of its water volume.

Left: October 24, 2007. Right: December 23, 2011. A volcano erupted in the Red Sea in December 2011, apparently creating a new island. According to news reports, fishermen witnessed lava fountains reaching up to 30 meters (nearly 100 feet) high on December 19. By December 23, what looked like a new island had appeared. A thick plume can be seen in the 2011 image, dark near the bottom and light near the top, perhaps a mixture of volcanic ash and water vapor.

The La Escondida Mine, an open-pit mine in northern Chile, produces the most copper of any mine in the world — some 360 million metric tons per year. Its impact on the Atacama Desert environment can be seen by comparing the 1975 image, taken before mining began, with the 2008 picture.

The U.S. city of Boston in Massachusetts. Left: 1838 map. Right: Simulated natural color image taken by the ASTER instrument on September 7, 2001. Boston has grown dramatically since its original settlement in the 17th century. In 1838, downtown Boston was a peninsula, surrounded by several large islands and headlands across the Charles River. In the ensuing 170 years, much of Boston Harbor and the mouth of the Charles River were filled in to create buildable land.

Growth in the desert. Left: 1984. Right: 2007. These images show the increasing urban sprawl of Las Vegas, Nevada, and the shrinking of Lake Mead on the border of Nevada and Arizona. Rapid growth in Las Vegas has led to increased demand for water resources, while below-average rainfall has decreased the water levels in Lake Mead, which is the source of 90 percent of southern Nevada's water.