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According to a new study in Nature, the Northern Hemisphere has experienced considerably larger variations in precipitation during the past twelve centuries than in the twentieth century. Researchers from Sweden, Germany, and Switzerland have found that climate models overestimated the increase in wet and dry extremes as temperatures increased during the twentieth century. The new results will enable us to improve the accuracy of climate models and to better predict future precipitation changes.
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The researchers reconstructed changes in water availability by statistically analysing evidence for changes in precipitation and drought. To do this the researchers compiled hundreds of records of precipitation change across the Northern Hemisphere from archives including tree-rings, speleothems, lake sediments, and historical records. This is the first hemispheric-scale assessment of how a key societal resource – water availability – has fluctuated over the past twelve centuries.
To investigate the links between temperature and precipitation variations, the researchers compared their reconstructed precipitation variations with a temperature reconstruction which also was developed by the team. They conclude that it is possible to see clear correlations between variations in temperature and precipitation only in a few specific regions. For instance, during both the relatively warm twelfth century, and the relatively cold fifteenth century, drought was observed to be most widespread in the Northern Hemisphere.
“The study shows the importance of placing recent precipitation changes in a millennium-long perspective. Actual measurements of precipitation are too short to tell if the observed changes today fall outside the range of natural variability. Instrumental measurements are also too short to test the ability of state-of-the-art climate models to predict which regions of the hemisphere will get drier, or wetter, with global warming”, says Charpentier Ljungqvist.
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originally posted by: carewemust
Is this one of the rare un-biased studies that doesn't attempt to blame humans for disturbing the weather patterns? If so, kudos to this team of scientists!