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Coral reefs protect coastlines from inundation and flooding and serve over 200 million people globally. Wave transformation has previously been studied on coral reef flats with limited focus on forereef zones where wave transformation is greatest during high‐energy conditions. This study investigates the role of forereef spur and groove (SaG) morphology in wave energy dissipation and transmission at the reef crest. Using XBeach on LiDAR‐derived bathymetry from One Tree Island in the southern Great Barrier Reef, we reproduced dissipation rates comparable to SaG field studies. We examined how wave energy dissipation differs between realistic bathymetry and those with SaG features removed, demonstrating an up to 40% decrease in dissipation when SaG features are absent. We then investigated changes to wave energy dissipation and wave transmission at the reef crest based on IPCC AR5 emission scenarios (RCP2.6 and RCP8.5) and a total disaster scenario (TD) for the year 2100. For RCP2.6, an increase in wave heights of 0.8 m and an increase in water level of 0.3 m resulted in a two‐fold increase in dissipation rates. For RCP8.5 and TD, with no increase in incident wave height, dissipation rates were 29% and 395% lower than RCP2.6. This resulted in increased wave transmission at the reef crest by 1.8 and 2.7 m for the RCP8.5‐ and TD based models, respectively, when compared to the RCP2.6‐based model. The results from our novel modeling approach of using long‐shore varying accurate bathymetry on forereefs show increased wave energy dissipation rates with implications for reducing coastal flooding and island inundation on reef‐lined coasts. Plain Language Summary: Coral reefs protect coastlines from floods and waves, benefiting over 200 million people globally. We studied how waves change over coral reefs, focusing on the forereef zone where wave transformation is most significant during high‐energy conditions. The shape of the forereef, specifically the long comb‐like grooves that cut through coral reefs, known as spur and grooves (SaG), modify wave energy transformation. Utilizing digital representation of waves over accurate reef shapes (known at bathymetry), we simulated wave dissipation rates comparable to real‐world SaG studies. By comparing high resolution, accurate bathymetry to smoothed bathymetry with SaG removed, we demonstrate a 40% decrease in wave energy dissipation. Next, we investigated how wave energy dissipation changes in different forereef environments. We considered low and high emission scenarios (RCP2.6 and RCP8.5) from the IPCC AR5 report and a total disaster scenario (TD) for the year 2100, considering changes to wave power, and water‐level. We found that models based on high‐emission scenarios (RCP 8.5) had decreased dissipation rates, resulting in more water passing the reef crest. Our study highlights the benefits of using accurate reef shapes in simulating wave energy dissipation on coral reefs. Accurate bathymetry can incorporate features such as SaG of different shapes, which increase wave dissipation. Key Points: Accurate bathymetry (<1 m) in forereef wave energy dissipation models can include features such as spurs and grooves (SaG)SaG increases forereef wave energy dissipation when compared to similar bathymetry without SaGForereef dissipation shifts from bed friction to wave breaking in modeled environmental conditions based on future climate projections [ABSTRACT FROM AUTHOR]

The Great Barrier Reef (GBR), Australia has a long history of palaeoenvironmental coral research. However, it can be logistically difficult to find the relevant research and records, which are often unpublished or exist as 'grey literature'. This hinders researchers' ability to efficiently assess the current state of coral core studies on the GBR and thus identify any key knowledge gaps. This study presents the Great Barrier Reef Coral Skeletal Records Database (GBRCD), which compiles 208 records from coral skeletal research conducted since the early 1990s. The database includes records from the Holocene, from ~8,000 years ago, to the present day; from the northern, central, and southern GBR from inshore and offshore locations. Massive Porites spp. coral records comprise the majority (92.5 %) of the database, and the remaining records are from Acropora , Isopora or Cyphastrea spp. The database includes 78 variables, with Sr/Ca, U/Ca and Ba/Ca the most frequently measured. Most records measure data over 10 or more years and are at monthly or lower resolution. The GBRCD is machine readable and easily searchable so users can find records relevant to their research, for example, by filtering for site names, time period, or coral type. It is publicly available as comma-separated values (CSV) data and metadata files with entries linked by the unique record ID and as Linked Paleo Data (LiPD) files. The GBRCD is publicly available from the NOAA National Center for Environmental Information's Paleoclimate Data Archive at https://doi.org/10.25921/hqxk-8h74 (Arzey et al. 2024). The collection and curation of existing GBR coral research provides researchers with the ability to analyse common proxies such as Sr/Ca across multiple locations and/or examine regional to reef scale trends. The database is also suitable for multi-proxy comparisons and combination or composite analyses to determine overarching changes recorded by the proxies. This database represents the first comprehensive compilation of coral records from the GBR. It enables the investigation of multiple environmental factors via various proxy systems for the GBR, northeastern Australia and potentially the broader Indo-Pacific. [ABSTRACT FROM AUTHOR]

Tropical south-western Pacific temperatures are of vital importance to the Great Barrier Reef (GBR), but the role of sea surface temperatures (SSTs) in the growth of the GBR since the Last Glacial Maximum remains largely unknown. Here we present records of Sr/Ca and δ(18)O for Last Glacial Maximum and deglacial corals that show a considerably steeper meridional SST gradient than the present day in the central GBR. We find a 1-2 °C larger temperature decrease between 17° and 20°S about 20,000 to 13,000 years ago. The result is best explained by the northward expansion of cooler subtropical waters due to a weakening of the South Pacific gyre and East Australian Current. Our findings indicate that the GBR experienced substantial meridional temperature change during the last deglaciation, and serve to explain anomalous deglacial drying of northeastern Australia. Overall, the GBR developed through significant SST change and may be more resilient than previously thought.

The approximately 10,000-year-long Last Glacial Maximum, before the termination of the last ice age, was the coldest period in Earth's recent climate history.sup.1. Relative to the Holocene epoch, atmospheric carbon dioxide was about 100 parts per million lower and tropical sea surface temperatures were about 3 to 5 degrees Celsius lower.sup.2,3. The Last Glacial Maximum began when global mean sea level (GMSL) abruptly dropped by about 40 metres around 31,000 years ago.sup.4 and was followed by about 10,000 years of rapid deglaciation into the Holocene.sup.1. The masses of the melting polar ice sheets and the change in ocean volume, and hence in GMSL, are primary constraints for climate models constructed to describe the transition between the Last Glacial Maximum and the Holocene, and future changes; but the rate, timing and magnitude of this transition remain uncertain. Here we show that sea level at the shelf edge of the Great Barrier Reef dropped by around 20 metres between 21,900 and 20,500 years ago, to -118 metres relative to the modern level. Our findings are based on recovered and radiometrically dated fossil corals and coralline algae assemblages, and represent relative sea level at the Great Barrier Reef, rather than GMSL. Subsequently, relative sea level rose at a rate of about 3.5 millimetres per year for around 4,000 years. The rise is consistent with the warming previously observed at 19,000 years ago.sup.1,5, but we now show that it occurred just after the 20-metre drop in relative sea level and the related increase in global ice volumes. The detailed structure of our record is robust because the Great Barrier Reef is remote from former ice sheets and tectonic activity. Relative sea level can be influenced by Earth's response to regional changes in ice and water loadings and may differ greatly from GMSL. Consequently, we used glacio-isostatic models to derive GMSL, and find that the Last Glacial Maximum culminated 20,500 years ago in a GMSL low of about -125 to -130 metres.Details of the drops in sea level associated with glaciation during the Last Glacial Maximum are revealed using a coral proxy from the Great Barrier Reef., Author(s): Yusuke Yokoyama [sup.1] [sup.2] [sup.3] , Tezer M. Esat [sup.4] [sup.5] , William G. Thompson [sup.6] , Alexander L. Thomas [sup.7] , Jody M. Webster [sup.8] , Yosuke Miyairi [...]