Background Science

Speleothems have proven to be valuable multi-proxy climate archives (McDermott et al., 2004; Fairchild and Tremble, 2009), providing access to palaeoclimate records on timescales ranging from seasonal to millennial (e.g. Baker et al., 2010; Drysdale et al., 2010). Significant palaeoclimate variations recorded in speleothems include shifts of the Intertropical Convergence Zone (Cai et al., 2012), variations of the North Atlantic Oscillation (Trouet et al., 2009), glacial-interglacial transitions and Heinrich- and/or Dansgaard-Oeschger events (Spötl and Mangini, 2002). Furthermore, due to the extremely high precision of uranium-series dating methods, speleothems provide the opportunity to trace the leads and lags of global climate events as well as to provide detailed seasonal rainfall or temperature records (Henderson, 2006). Speleothems are well distributed worldwide and, in addition to recording local and regional climate variation, open the door for continental and inter-continental comparisons between spatially-separated speleothem records (e.g. McDermott et al., 1999; McDermott et al., 2011), as well as with other palaeoclimate archives (e.g. Boch et al., 2009; Trouet et al., 2009). Furthermore, speleothem-based proxies can be compared to climate forcing (e.g. local solar insolation) which can assist in the decryption of climate mechanisms (e.g. Neff et al., 2001).

Due to their potential as high-resolution climate archives, international research is now focusing on speleothems and the development of new speleothem-based proxies. Approaches to better reconstruct absolute palaeo-temperature and palaeo-rainfall records are highly sought after. Moreover, speleothem proxy records are currently being used to gain insights into other variations of climate such as changes in rainfall sources, seasonality, and precipitation regimes (e.g. Bar-Matthews et al., 1999; Fairchild et al., 2001; Baldini et al., 2002; Ayalon et al., 2002; Johnson et al., 2006; Spötl et al., 2006; Orland et al 2009; 2012). Speleothem proxy records can provide high quality calibration data for climate reconstructions and thereby increase the reliability of future climate models. It is therefore crucial that researchers improve the coverage of this terrestrial palaeoclimate archive, particularly at low latitudes where other terrestrial archives (e.g. ice cores) are sparse.

Recent cave monitoring and laboratory experiments have greatly improved our understanding of the mechanisms by which proxy data are incorporated into speleothems (e.g. Day & Henderson, 2011; Tremaine & Froelich, 2013; Rutlidge et al., 2014). Modelling efforts have also furthered our understanding of the controls on speleothem geochemistry (e.g. Dreybrodt & Scholz, 2011). These developments pave the way for more quantitative, nuanced interpretations of speleothem time-series, thus increasing the reliability of speleothem-based palaeo-climate reconstructions.