Multidecadal to multicentury scale collapses of Northern Hemisphere monsoons over the past millennium

Abstract

Late Holocene climate in western North America was punctuated by periods of extended aridity called megadroughts. These droughts have been linked to cool eastern tropical Pacific sea surface temperatures (SSTs). Here, we show both short-term and long-term climate variability over the last 1,500 y from annual band thickness and stable isotope speleothem data. Several megadroughts are evident, including a multicentury one, AD 1350–1650, herein referred to as Super Drought, which corresponds to the coldest period of the Little Ice Age. Synchronicity between southwestern North American, Chinese, and West African monsoon precipitation suggests the megadroughts were hemispheric in scale. Northern Hemisphere monsoon strength over the last millennium is positively correlated with Northern Hemisphere temperature and North Atlantic SST. The megadroughts are associated with cooler than average SST and Northern Hemisphere temperatures. Furthermore, the megadroughts, including the Super Drought, coincide with solar insolation minima, suggesting that solar forcing of sea surface and atmospheric temperatures may generate variations in the strength of Northern Hemisphere monsoons. Our findings seem to suggest stronger (wetter) Northern Hemisphere monsoons with increased warming.

A compilation of Western European terrestrial records 60–8 ka BP: towards an understanding of latitudinal climatic gradients

“…Voelker (2002) provided the first global compilation of marine and terrestrial sites, showing evidence of centennial-scale climatic change during the Last Glacial period. Since then, this evidence has been supported and extended by a number of high resolution records, such as Antarctic ice cores (EPICA, 2006), Cariaco Basin and Arabian Sea sediment cores (Deplazes et al, 2013), and Asian and American speleothems (Wang et al, 2001(Wang et al, , 2007Fleitmann et al, 2009;Asmerom et al, 2013). The deglacial period provides more records and accurate chronologies than earlier periods, and a comprehensive compilation of global proxy records is provided by Clark et al (2012) and Shakun et al (2012).…”

A record of wet glacial stages and dry interglacial stages over the last 560 kyr from a standing massive stalagmite in Carlsbad Cavern, New Mexico, USA

“…The cave has for decades been the site of research about the origin and nature of speleothems (e.g., Black, 1953;Thrailkill, 1968Thrailkill, , 1977Hill, 1973;Folk and Assereto, 1976;Gonzalez and Lohmann, 1988). More recently, stalagmites in the cave have been studied as records of climate change from the Last Glacial Maximum to the Holocene (Polyak and Asmerom 2001;Polyak et al, 2004;2012;Brook et al, 2006;Asmerom et al, 2013).…”

Placing the Common Era in a Holocene context: millennial to centennial patterns and trends in the hydroclimate of North America over the past 2000 years

“…Tree ring records have generated rich insight into annualto centennial-scale climate variability, but, with the exception of a small number of chronologies comprised of longlived individual series, most do not thoroughly preserve evidence of low-frequency (> 100 year) changes (Ault et al, 2013;Cook et al, 1995;Sheppard et al, 1997). New methods have improved the extraction of low-frequency signals (Cook et al, 2010), but a comparison of low-frequency changes during the Common Era and earlier portions of the Holocene requires focusing on different types of records that extend further in time than most tree ring chronologies.…”