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Climate whiplash increased wildfires on California’s west coast about 8,000 years ago

ScienceDaily (December 8, 2022)

Titre : Climate whiplash increased wildfires on California’s west coast about 8,000 years ago

Climate change and its effects on our seasons, water resources, vegetation, and soil have already become clearly apparent. The rate and intensity of wildfires in semi-arid regions, such as those in the west of North America, already exceed those that might be expected in view of the historical records.

ScienceDaily (December 8, 2022)

Résumé
Researchers have been studying the effects of the sudden decrease in global temperatures that occurred about 8,200 years ago, the so-called 8.2-kiloyear event, with the help of mineral deposits present in White Moon Cave in Northern California. New indications show that oscillations between extreme wetness and aridity in California were closely linked with the occurrence of wildfires. The researchers have concluded that such events are likely to become more common in the face of human-induced climate change.

To be able to predict future scenarios, it is helpful to better understand the climate of the past. There are readily datable climate archives that reach back many thousands of years that preserve traces of chemical compounds. These compounds provide insight into continental and regional climatic changes and the prevailing environmental conditions. One of the most easily datable and detailed climate archives of this kind is provided by various forms of mineral deposits, known as speleothems, which accumulate in caves. Stalagmites are of particular interest in this connection because of their uniform growth pattern.

By analyzing the content of two novel marker substances, i.e., levoglucosan and lignin oxidation products (LOPs), in a stalagmite, the team of researchers from Mainz, Nashville, and Newcastle have been able to reconstruct fire activity and vegetation composition in the California Coast Range during the 8.2-kiloyear event. This cold phase lasted several hundred years. Evidence of the event was first detected in the analysis of pollen in early Holocene deposits in the Swiss Alps and later also in ice cores obtained in Greenland. The results of further studies indicate that precipitation rates in western North America at this time were much more variable than usual. Erratic climate-related swings of this type are characteristic of a phenomenon called climate whiplash. Many scientists share the opinion that we will see more climate whiplash events as a consequence of global warming.

Story Source  : Johannes Gutenberg Universitaet Mainz

Annonce (ScienceDaily)

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