Title: The early medieval warm epoch and its sequel
Abstract: Evidence has been accumulating in many fields of investigation pointing to a notably warm climate in many parts of the world, that lasted a few centuries around A.D. 1000–1200, and was followed by a decline of temperature levels till between 1500 and 1700 the coldest phase since the last ice age occurred. There has been some controversy as to whether this climatic variation was geeat enough to be significant in connection with the balance of Nature or the economy of Man. It is time to marshal the evidence and attempt a numerical assessment of the climatic values involved in some area for which there are enough data to permit it. This is attempted here and provides an illustration of how data from the realms of botany, historical document research and meteorology may be used to confirm, correct and amplify each other. Changes of prevailing temperature and rainfall in England between periods of 50–150 years duration around 1200 and around 1600 are found which, on all the evidence at present available, probably amounted to 1.2–1.4°C and 10% respectively. Changes in some reasons of the year may have exceeded these ranges of the annual mean. The changes indicated are small enough to account for earlier impressions in some quarters that there has been no significant change of climate in the last 2,500 years, yet they are big enough to be surprising in terms of previous meteorological knowledge and undoubtedly upsetting for the human economies of those times (and perhaps of any time). It is by quantitative assessment of climatic values for epochs, such as the one here treated, for which some sort of extreme character is indicated by reliably dated evidence, that palaeoclimatology may hope to progress. The time-scale of the epoch here studied appears similar to that of several earluer climatic oscillations of known importance to the history of the European fauna and flora, which for obvious reasons cannot be submitted to equally close meteorological analysis. It is essential that the geographical distribution of climatic values arrived at, should be examined (as is done here) for consistency and the possibility of a reasonable interpretation in terms of the condition of the wind and ocean circulations.
Publication Year: 1965
Publication Date: 1965-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 704
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