An ice core is a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere.
As the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper, and an ice core contains ice formed over a range of years.
The length of the record depends on the depth of the ice core and varies from a few years up to 800 kyr (800,000 years) for the EPICA core. the shortest time period which can be accurately distinguished) depends on the amount of annual snowfall, and reduces with depth as the ice compacts under the weight of layers accumulating on top of it.
Upper layers of ice in a core correspond to a single year or sometimes a single season.
Deeper into the ice the layers thin and annual layers become indistinguishable.
schwit1 shares an article from The Hill: The Air Force announced on Friday that it has lost thousands of records belonging to the service's inspector general due to a database crash.
"We estimate we've lost information for 100,000 cases dating back to 2004," Air Force spokeswoman Ann Stefanek told The Hill in an email.
"The database crashed and there is no data..." The database, called the Automated Case Tracking System (ACTS), holds all records related to IG complaints, investigations, appeals and Freedom of Information Act requests....
"We also use ACTS to track congressional/constituent inquiries." The Air Force said they were "aggressively" trying to recover the data, adding that they had no evidence of malicious intent.
Ice cores contain an abundance of information about climate.
Inclusions in the snow of each year remain in the ice, such as wind-blown dust, ash, pollen, bubbles of atmospheric gas and radioactive substances.