It is no doubt that the world’s climate has been changing in past and will continue to do so in the future. Climate has been thought of as the average weather condition over a long period of time.
Weather is the present atmospheric condition which includes temperature, precipitation, wind as well as humidity of a given geographical location. In the past, determining changes in climate was achieved by paleoclimatoligists through various ways such as analyzing tree rings, using clues from beneath the waters, studying underwater ‘cities’ as well as unlocking secrets in the ancient ice. The former will be of interest in this paper.
An adverse climatic change brings issues such as drought resulting to dire consequences. For instance in 1587 July 22, colonists from England who came to Roanoke the present Carolina disappeared. (D’alto 25). Efforts to try to establish their where about were futile.
It was till 1998 that some dendrologists studying tree rings came up with a possible explanation. According to D’alto 24 tree rings not only offer scientists with the opportunity to establish the age of a tree but also give insights on secrets of past climatic trends. Trees such as redwood, giant sequoias and some species of pine in Carolina have been used. Rings are added annually and the age can be determined by counting the number of rings.
It has been found that trees can live to hundred or some thousands years. The base line in determining climatic changes by using tree rings is by correlating the outer rings spacing of a tree and the National Weather Service records. A mathematical model is then created to help in calibration.
Analyzing this data yields Palmer Hydrological Drought Indices. An analysis of tree rings reveals a lot regarding climatic conditions. Thick rings depict that the climatic condition were favorable characterized with abundant rainfall, optimum temperature and generally good condition that fostered healthy growth.
On the other hand, when the rings are thin; this clearly shows that the conditions for tree growth were poor; characterized with lack of rainfall. According to Stahle and his collaborators, the rings of cypress are easily visible with naked eyes. However, the rings of some cypress back in 1587 were not present in some, while slimed down to some thousandth of a millimeter in others (D’alto 24). This thus seemed to be what sealed the fate of the colonialist arriving from England at the time. To accomplish the analysis, small portion of dead trees are sliced to provide samples for the study. For living tree, an increment borer is used to drill a thin hole into the trunk of the tree. After this a core sample a size of a straw is obtained with the help of a special spoon. It is worth noting that such drilling does not affect the growth of the tree in anyway.
Once in the laboratory the exposed bands are polished and measured to 1/100mm by use of a calibrated microscope. Then the widths are compared (D’alto 26). Patterns from various tree species are then correlated which help in creating an understanding of climatic changes. However there are other factors that affect this which include pest and diseases. The massive data is then summarized in a bar graph. This then is “assigns an absolute value to the narrowest band in each sample where the narrowest represents the driest period” (D’alto 27).
From the review of establishing climatic changes by studying tree rings, it offers scientist with a glimpse of what might have happened in the past.
D’alto, Nick. “Rings of Truth: Evidence of Weather Disasters found in Tree Rings Offers Clues to Historical Mysteries” Weatherwise, 1(5): 2005, 23-27.