Cloud conundrums; satellites have spied strange plumes coming from the Soviet Arctic regions, including some rising from an island that served as a nuclear testing ground

Science News, March 28, 1987 by Stefi Weisburd

Cloud Conundrums

In 1810, a Russian industrialist namedJacob Sannikov stood on the New Siberian Islands in the East Siberian Sea, looked to the north and thought he had discovered a new continent.

Sannikov's sighting and similar reportsfrom 19th-century Arctic explorers fueled the belief of many geographers at the time (and of the U.S. Congress, which was eagerly financing Arctic expeditions) that a vast polar continent was just waiting to be conquered. Expeditions were mounted to search for Sannikov's Land. But it was never found, and two parties of explorers perished for their troubles.

Now, Pierre St. Amand, a consultant tothe Naval Weapons Center in China Lake, Calif., and a number of other scientists think these continental mirages could have been large plumes rising from the sea--similar to clouds recently spotted on satellite images of Bennett Island, which lies 150 kilometers to the north of the New Siberian Islands.

These Bennett Island plumes were firstdiscovered in infrared images from National Atmospheric and Oceanic Administration (NOAA) weather satellites. These cold clouds are hundreds of kilometers long and tens of kilometers wide, and appear to emerge from the sea, rising to altitudes of 1 to 2 kilometers, according to Michael Matson at NOAA's National Environmental Satellite, Data, and Information Service in Washington, D.C. More than 200 Bennett Island plumes have been spotted in random searches of NOAA imagery taken since 1973.

Most U.S. researchers who havethought about these plumes now suspect that they are caused by the escape of methane from the world's largest natural gas reservoir. But scientists are mystified by even more recently detected clouds that are lofted much higher into the atmosphere from an island on the other side of the Soviet Arctic. Partly because the island has been a Soviet nuclear testing site, some Western scientists have wondered whether these clouds are human-made.

In the Dec. 9 Eos, Matson reports thatclouds similar to those above Bennett Island have been seen on satellite imagery of the northern of two islands called Novaya Zemlya, which lie about 2,000 kilometers to the west of Bennett Island. So far, random searches of images of that region have turned up 12 plumes in a seven-year period.

When the first Bennett Islandplume was discovered in 1983, many scientists initially thought it had been spewed out by a volcano. But according to a number of researchers, the region has not experienced volcanism for nearly 80 million years. In a 1983 Eos article, Jurgen Kienle, Juan Roederer and Glenn Shaw of the Geophysical Institute at the University of Alaska in Fairbanks noted that the nearest known volcanic site lies 1,300 kilometers to the southwest, in Siberia, and last erupted in 1775. They write that the Geophysical Institute's seismic network could not find evidence for a volcano prior to the plume's appearance, and air samples taken at Barrow, on the northern end of Alaska, contained no traces of volcanic material.

The Air Force Technical ApplicationsCenter also found no evidence for volcanism from either its airborne sampling or its seismic network, according to an Air Force spokesman in Washington, D.C.

Moreover, Soviet scientists who investigatedthe Bennett Island region after learning about the plumes, presumably from U.S. sources, told U.S. researchers that they could find no evidence for a recent eruption. And according to Yevgeni Korotkevich, vice-president of the Geographical Society of the USSR, whose remarks were conveyed to SCIENCE NEWS by Yuri Kupin at the Novosti Press Agency, the Soviet expedition also "did not find any gas plumes. Apparently the vertical streaks [that we see on space] photographs represented a meteorological phenomenon, or could be associated with ice domes in those regions. They cannot be man-made.'

Back in the United States, researchersconsidered, and then discarded, a host of other possible sources, including Soviet cloud seeding experiments and burning coal beds. U.S. scientists investigating the Bennett Island plumes have now settled on the methane theory, which was suggested by geologist James Clarke at the U.S. Geological Survey in Reston, Va.

Clarke thinks the plumes are cloudsof water or ice and methane that has escaped from coal beds beneath the sea. He says the beds formed from the decay of plants during the last 4 million years, before the Siberian shelf was covered by a thick layer of permafrost and later inundated by the sea.

The permafrost layer is thought tocontain methane hydrates--ice-like compounds in which methane molecules are trapped in a cage formed by water molecules. Scientists believe that heat from the earth has been slowly melting the permafrost. Clarke suggests that as a result, pockets of methane gas build up near Bennett Island, and the methane is released explosively when a fault cracks through the overlying rocks and into the permafrost layer.

Clarke says the straight shoreline ofBennett Island suggests there is a fault there. Because methane is much lighter than air, he says, it probably shoots straight up into the atmosphere "like BBs coming from an air gun.'