To: Brumar89 who wrote (78060 ) 7/6/2017 12:59:40 PM From: Brumar89 1 RecommendationRecommended By
Read Replies (1) | Respond to The Historical Southwest U.S. Climate: 3.2°C Warmer During Medieval Times Millar et al., 2006 “The paleoclimate modeled for Whitewing [Sierra Nevada, CA ] during the Medieval period was significantly warmer and slightly drier than present . Medieval mean annual minimum temperature was warmer than current by 3.2°C Scuderi, 1993 “Long-term trends in the temperature reconstruction are indicative of a 125-year periodicity that may be linked to solar activity as reflected in radiocarbon and auroral records. The results indicate that both the warm intervals during the Medieval Warm Epoch (A.D. 800 to 1200) and the cold intervals during the Little Ice Age (A.D. 1200 to 1900) are closely associated with the 125-year [solar activity] period .”Medieval Drought Lasted Hundreds Of Years And Was Much More Sever e Whitehouse et al., 2010 “Paleoclimatic and model data indicate increased temperatures in western North America [~AD 900–1300] of approximately 1?°C over the long-term mean. This was a period of extensive and persistent aridity over western North America. Paleoclimatic evidence suggests drought in the mid-12th century far exceeded the severity, duration, and extent of subsequent droughts .”Kirby et al., 2014 Cook et al., 2010 Scientists: Natural Variability Dominates In Southwestern U.S. Drought Cheng et al., 2016 the net effect of climate change has made agricultural drought less likely, and that the current severe impacts of drought on California’s agriculture has not been substantially caused by long-term climate changes .” Prein et al., 2016 “Projected changes of a poleward extension of the subtropical dry zones simulated by climate models and the corresponding decrease of precipitation in the U.S. Southwest have not been found in observations to date because of the large natural climate variability .” Seager et al., 2015 “The causes of the California drought during November to April winters of 2011/12 to 2013/14 are analyzed using observations and ensemble simulations with seven atmosphere models forced by observed SSTs. …[T]he precipitation deficit during the drought was dominated by natural variability , a conclusion framed by discussion of differences between observed and modeled tropical SST trends.” Diaz and Wahl, 2015 “An analysis of the October 2013–September 2014 precipitation in the western United States and in particular over the California–Nevada region suggests this anomalously dry season, while extreme, is not unprecedented in comparison with the approximately 120-yr-long instrumental record of water year (WY; October–September) totals and in comparison with a 407-yr WY precipitation reconstruction dating back to 1571. Over this longer period, nine other years are known or estimated to have been nearly as dry or drier than WY 2014 . The 3-yr deficit for WYs 2012–14, which in California exceeded the annual mean precipitation, is more extreme but also not unprecedented, occurring three other times over the past approximate 440 years in the reconstruction.”
