Corals record long-term Leeuwin current variability including Ningaloo Niño/Niña since 1795

Abstract

Variability of the Leeuwin current (LC) off Western Australia is a footprint of interannual and decadal climate variations in the tropical Indo-Pacific. La Niña events often result in a strengthened LC, high coastal sea levels and unusually warm sea surface temperatures (SSTs), termed Ningaloo Niño. The rarity of such extreme events and the response of the southeastern Indian Ocean to regional and remote climate forcing are poorly understood owing to the lack of long-term records. Here we use well-replicated coral SST records from within the path of the LC, together with a reconstruction of the El Niño-Southern Oscillation to hindcast historical SST and LC strength from 1795 to 2010. We show that interannual and decadal variations in SST and LC strength characterized the past 215 years and that the most extreme sea level and SST anomalies occurred post 1980. These recent events were unprecedented in severity and are likely aided by accelerated global ocean warming and sea-level rise.

δ<sup>11</sup>B as monitor of calcification site pH in marine calcifying organisms

“…The boron isotope composition ( 11 B) of biogenic CaCO3 ( 11 BCaCO3) has been primarily used as a palaeoceanographic proxy 40 for seawater pH Montagna et al, 2007;Palmer, 1998;Pearson et al, 2009;Penman and Hönisch, 2014;Rae et al, 2011;Saenger et al, 2013;Trotter et al, 2011;Vengosh et al, 1991;Zinke et al, 2014). Boron has a residence time in seawater of ca.…”

Evaluation of annual resolution coral geochemical records as climate proxies in the Great Barrier Reef of Australia

“…It is notable that while the geochemical records from 10AR2 are closely correlated with annual growth rates, they still record climatic change well, which suggests that the climatic significance of faster and steadier growing coral is independent of skeletal growth rate (Mitsuguchi et al 2003;Jones et al 2009). Therefore, such annual resolution coral records offer a potential approach to reconstructing past climate change (Dunbar et al 1994;Cole et al 2000;Zinke et al 2014). This is especially the case for research into climate change (2002) and Wei et al (2007) over long timescales, in which annual resolution sampling can save much time and expense, but still provides similar information to studies based on high-resolution sampling.…”

“…For example, coral samples such as 10AR2 are acceptable, while 10AR1 was not suitable. Second, replication from different coral colonies is very important as suggested and demonstrated in several recent studies (Lough 2004;DeLong et al 2013;Zinke et al 2014). Ideally, at least 2-3 coral cores from a reef location are necessary because coral records extracted from a single coral colony cannot be used to distinguish between climate signals and biologically induced noise.…”

“…Nevertheless, relative to the large quantity of high-resolution studies, annual to multi-year resolution coral-based studies are still relatively rare. In addition, of those coral-based studies undertaken at annual to pent-annual resolutions (Dunbar et al 1994;Cole et al 2000;Hendy et al 2002;Pelejero et al 2005;Calvo et al 2007;Linsley et al 2008;Abram et al 2009;Wei et al 2009;Deng et al 2013;Zinke et al 2014), few have focused on the replication of the lowresolution geochemical records of multiple coral cores. Some studies have evaluated the climatic significance of annual coral records averaged using monthly or sub-annual values from each year (Lough 2004;Smith et al 2006;Pfeiffer et al 2009).…”

Marine projections of warming and ocean acidification in the Australasian region

“…Some of the largest changes have been seen in the boundary currents along the east coast of Australia (Holbrook and Bindoff, 1997) where the warming has been 2 to 3 times faster than the global mean (Wu et al, 2012). The Leeuwin Current along the Western Australian Coast has also warmed, especially post-1980 (Zinke et al, 2014). For example, during the austral summer of 2010/2011 unprecedented temperatures were recorded along the Western Australian coast, with near-shore temperatures peaking about 5 K above average (Pearce and Feng, 2013).…”