Astronauts aboard the International Space Station (ISS) took this image of a major dust storm (image center and right) along the east side of the Aral Sea while passing over central Asia in the spring of 2007. The white, irregular lines along the bottom of the image are salt and clay deposits on the present coastline. The day that the ISS crew shot the image, winds were blowing from the west (lower left). The gray, puffy appearance is typical of dust clouds, allowing scientists to distinguish dust from fog and smog. The dust in this image is rising from the sea bed of the Aral Sea, from a point close to the middle of the original Aral Sea of 1950s and 1960s—at that time the fourth-largest inland sea on Earth. During the next several decades, heavy extraction of water from the main supply river, the Amu Dary’a, resulted in rapid shrinking of the sea. A similar dust storm was photographed in 1985, available through an ISS Aral Sea series. In that storm, dust blew from the Aral Sea’s eastern shore.
Dust storms have occurred over the Aral Sea region for thousands of years, but the half-century of drastic shrinking of the sea brought an important change in dust composition. By the time this photograph was taken, the dust included fertilizer and pesticide washed into the inland sea from the extensive cotton fields of the Amu Dary’a floodplain. Years of liberal application of agricultural chemicals resulted in concentration of these pollutants on the seabed, now exposed to the wind and transported hundreds of kilometers in a generally easterly direction. Research suggests that the remobilized chemicals are the cause of high rates of many diseases in the populations along the north, east, and southern margins of the Aral Sea.
Negative health effects were only one of the unexpected consequences of the shrinking of the sea, whose retreat made international news for many years due to the loss of the fishing industry and other significant ecological problems. Another negative consequence was the loss of the stabilizing influence of a large body of water on the region’s continental climate (cold winters combined with hot, dry summers). Large bodies of water cool down and heat up more gradually than land surfaces, so they moderate both extreme cold and extreme heat. Since the decline of the Aral Sea, summers have become shorter and hotter, and winters are longer; overall, the climate is drier. Frosts occur later in the spring and earlier in the fall, shortening the growing season.
Restoration efforts are underway for the North Aral Sea, which has been cut off from the South Aral Sea by a dam. In spring 2007, scientists announced that the North Aral Sea was refilling more rapidly than they originally expected.
The featured astronaut photograph ISS015-E-7874 was acquired May 12, 2007, by the Expedition 15 crew with a Kodak 760C digital camera fitted with a 180 mm lens. The image is provided by the ISS Crew Earth Observations experiment and the Image Science & Analysis Laboratory, Johnson Space Center. The image in this article has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth.
