Sex wanted free chat room - Oxygen isotopic ratios in the dating of ice cores
temperature correlation derived from recorded data. For example, he observed that if ice is sighted in 20 months of one decade and 22 months of the next decade, that second decade was about 0.1o C cooler than the first.By analyzing various clues to reports of drift ice, he applied this correlation to estimate temperatures back to 1591. 6 shows the variation in amount of polar ice seen from Iceland (Lamb, 1977.) Both illustrate the MWP and the LIA quite well.
From 1846 to present, detailed records have been kept in Iceland that show the number of months drift ice appeared along with the temperature.
Bergthrsson (1969) has estimated past north Atlantic temperatures using a drift ice vs.
Figure 1d (Mann, 2002) reveals this regional anomoly quite well. O16 isotopes in ice indicates the temperature of the snow at the time it was formed. Ice core data from Wyoming (Naftz et al., 1994) and Peru (Aber, 2000) also supports a warm period consistent with the MWP and a cool period consistent with the LIA.
Higher ratios of the heavier O18 oxygen isotope indicate the snow formed at a higher temperature while lower ratios indicate the snow formed at a cooler temperature. By studying the width of tree rings (dendrochronology) history of annual tree growth can be determined.
In colder times, arctic waters carry the ice southward while in warmer times the Gulf Stream dominates the Iceland area, keeping drift ice away.