Potential role of the ocean thermostat in determining regional differences in coral reef bleaching events

Abstract

[1] Several negative feedback mechanisms have been proposed by others to explain the stability of maximum sea surface temperature (SST) in the western Pacific warm pool (WPWP). If these ''ocean thermostat'' mechanisms effectively suppress warming in the future, then coral reefs in this region should be less exposed to conditions that favor coral reef bleaching. In this study we look for regional differences in reef exposure and sensitivity to increasing SSTs by comparing reported coral reef bleaching events with observed and modeled SSTs of the last fifty years. Coral reefs within or near the WPWP have had fewer reported bleaching events relative to reefs in other regions. Analysis of SST data indicate that the warmest parts of the WPWP have warmed less than elsewhere in the tropical oceans, which supports the existence of thermostat mechanisms that act to depress warming beyond certain temperature thresholds. Citation: Kleypas, J. A., G. Danabasoglu, and J. M. Lough (2008), Potential role of the ocean thermostat in determining regional differences in coral reef bleaching events, Geophys. Res. Lett., 35, L03613,

Dimethylsulfide and Coral Bleaching: Links to Solar Radiation, Low Level Cloud and the Regulation of Seawater Temperatures and Climate in the Great Barrier Reef

“…Such a cloud cover-SST feedback occurs in the NE Pacific [22], and over coral reefs in the GBR [23], but it is not known whether DMS is implicated in these feedbacks. An increasing amount of evidence now suggests that a LLC climate feedback involving enhanced production of DMS a and other aerosols from coral reefs could occur in the GBR [18] [20], and indeed over reefs in the western Pacific warm pool (WPWP) [24] [25]. For example, air masses that travel over coral reefs in the southern GBR contain ammonium sulfate aerosols ( Figure 1) derived mainly from the oxidation of DMS a which are likely produced from the GBRs coral reefs [26].…”

Corals escape bleaching in regions that recently and historically experienced frequent thermal stress

“…Yet, regional differences in bleaching responses during past thermal events raise several questions: (i) did the differential response patterns result from regional differences in temperature and irradiance stress? (Mumby et al 2001;Kleypas et al 2008), (ii) did the different regions support different species, with different tolerances to elevated temperatures? (Loya et al 2001;van Woesik 2001) or (iii) did the regions, which support similar coral communities, adjust differently to thermal stress because of recent and/or historical circumstances?…”

“…The and 2005 bleaching events were used for the present analysis because they were the latest, most severe and the most extensively observed coral bleaching events on record. Although the Reefbase data have known uncertainties that stem from the multitude of data contributors, these data have been used to show useful regional stress patterns (Kleypas et al 2008;Maina et al 2008). The use of bleaching severity categories allowed for a more robust assessment of relative bleaching severity, because the surveyor only had to estimate an approximate range of bleaching severity, rather than estimate the per cent bleaching.…”

Temperature‐induced stress leads to bleaching in larger benthic foraminifera hosting endosymbiotic diatoms

“…Mean annual SSTs have increased by 0.3-0.4uC within the past two to three decades across the tropical region suitable for coral reef growth (Kleypas et al 2008). Annual SSTs in the Great Barrier Reef (GBR) reflect this global trend and have already risen by an average of 0.7uC within the last century (Lough 2001;Lough et al 2006).…”