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New Study on Drought by MacDonald Lab

I was the lead author on a new study of California drought based on using lake sediment records from the Sierra Nevada to look at how past climate warming has impacted the Pacific Ocean and California hydroclimate. This work took many years and was a real team effort between the MacDonald Lab’s graduate students and post-docs and Professor Katrina Moser and her team from the University of Western Ontario in Canada. Just like the stock market, past performance does not predict the future, but it can provide insights into what might occur with continued warming.   The article was published in Nature.com/Scientific Reports and is freely available to read and download at the Nature.com site –

MacDonald, G. M., Moser, K.A., Bloom, A. M., Potito, A.P., Porinchu, D.F., Holmquist, J.R., Hughes, J. and Kremenetski, K.V. 2016. Prolonged California aridity linked to climate warming and Pacific sea surface temperature. Nature.Com/Sci. Rep. 6, 33325; http://www.nature.com/articles/srep33325

Below is the Abstract for the article –

Abstract

California has experienced a dry 21st century capped by severe drought from 2012 through 2015 prompting questions about hydroclimatic sensitivity to anthropogenic climate change and implications for the future. We address these questions using a Holocene lake sediment record of hydrologic change from the Sierra Nevada Mountains coupled with marine sediment records from the Pacific. These data provide evidence of a persistent relationship between past climate warming, Pacific sea surface temperature (SST) shifts and centennial to millennial episodes of California aridity. The link is most evident during the thermal-maximum of the mid-Holocene (~8 to 3 ka; ka = 1,000 calendar years before present) and during the Medieval Climate Anomaly (MCA) (~1 ka to 0.7 ka). In both cases, climate warming corresponded with cooling of the eastern tropical Pacific despite differences in the factors producing increased radiative forcing. The magnitude of prolonged eastern Pacific cooling was modest, similar to observed La Niña excursions of 1o to 2 °C. Given differences with current radiative forcing it remains uncertain if the Pacific will react in a similar manner in the 21st century, but should it follow apparent past behavior more intense and prolonged aridity in California would result.

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