No. 44: Mar-Apr 1986
Ice cores from the polar ice at Camp Century, in Greenland, have been analyzed for the presence of cosmic dust.
"It is concluded that on five occasions during the interval 20,000-14,000 years BP, cosmic dust mass concentrations in the solar system rose by one and two orders of magnitude above present day levels. Moreover if the particles found in these ice core samples are indicative of the particle size distribution which prevailed in the interplanetary medium at that time, then it may be concluded that the space number density of submicron sized particles must have uncreased by a factor of 105 or more. During these times the light transmission properties of the solar system would have been significantly altered resulting in major adverse effects to the earth's climate. Thus it is quite possible that these dust congestion episodes were responsible for the abrupt climatic variations which occurred toward the end of the last Ice Age."
Whence these interplanetary dust clouds? The author of this article ruled out terrestrial volcanism (an insufficient source of iridium) and encounters with asteroids and cometary tails (too infrequent to account for the long periods of high dust levels). Rather, the dust source may have been the same event that created the recently discovered dust ring between Mars and Jupiter, which is believed to be only a few tens of thousands of years old. The nature of the "event" is not specified.
(LaViolette, Paul A.; "Evidence of High Cosmic Dust Concentrations in Late Pleistocene Polar Ice (20,000-14,000 Years BP)," Meteoritics, 20:545, 1985.)
References. See our catalog volume The Sun and Solar System Debris for more on the flotsam and jetsam of outer space. This book is described here. Also see the following item on "icy meteors" which is also pertinent.