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| Titel |
Constraining the temperature history of the past millennium using early instrumental observations |
| VerfasserIn |
P. Brohan, R. Allan, E. Freeman, D. Wheeler, C. Wilkinson, F. Williamson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 8, no. 5 ; Nr. 8, no. 5 (2012-10-11), S.1551-1563 |
| Datensatznummer |
250005842
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| Publikation (Nr.) |
 copernicus.org/cp-8-1551-2012.pdf |
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| Zusammenfassung |
The current assessment that twentieth-century global temperature change is
unusual in the context of the last thousand years relies on estimates of
temperature changes from natural proxies (tree-rings, ice-cores, etc.) and
climate model simulations. Confidence in such estimates is limited by
difficulties in calibrating the proxies and systematic differences between
proxy reconstructions and model simulations. As the difference between the
estimates extends into the relatively recent period of the early nineteenth
century it is possible to compare them with a reliable instrumental estimate
of the temperature change over that period, provided that enough early
thermometer observations, covering a wide enough expanse of the world, can be
collected.
One organisation which systematically made observations and collected the
results was the English East India Company (EEIC), and their archives have
been preserved in the British Library. Inspection of those archives revealed
900 log-books of EEIC ships containing daily instrumental measurements of
temperature and pressure, and subjective estimates of wind speed and
direction, from voyages across the Atlantic and Indian Oceans between 1789
and 1834. Those records have been extracted and digitised, providing 273 000
new weather records offering an unprecedentedly detailed view of the weather
and climate of the late eighteenth and early nineteenth centuries.
The new thermometer observations demonstrate that the large-scale temperature
response to the Tambora eruption and the 1809 eruption was modest (perhaps
0.5 °C). This provides an out-of-sample validation for the proxy
reconstructions – supporting their use for longer-term climate
reconstructions. However, some of the climate model simulations in the CMIP5
ensemble show much larger volcanic effects than this – such simulations are
unlikely to be accurate in this respect. |
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