Earth’s ICE RECORDSIce cores preserve climate history of million of years. Most of the ice cores are taken from the ice deposited in Antarctica and Greenland. Some interesting facts…
Ice cores have been preserved in US National Ice Core Library (NICL) in Denver Colorado.
- Oldest ice core record kept there is 420000 years old.
- In the library are ice cores collected and preserved from a single hole 3.6 kilometres.
- Total length of all the ice core samples preserved in the NICL is 20 kilometres.
Dust and chemicals trapped inside the ice samples can delineate the climatic conditions prevalent in the different times in the past. Climatic Histories upto 850000 years has been recreated.
How the age is determined??
Water like any other chemical contains normal oxygen 16 (O16)atom as well as a very small fraction of oxygen 18 (O18)atoms. Water evaporation is a function of temperature. At higher temperatures O18 water evaporates more along with O16 water which means when these vapors condense will be richer in O18 . From the ratios of hydrogen
O18 and O16, temperature can be deduced.
Similarly trapped CO2 inside the cores gives the CO2 levels at different times in the past.