Accurate climate reconstruction from fossil corals: The impact of seawater carbonate chemistry on the Sr/Ca, d18O and d11B of coral aragonite

热带珊瑚骨骼的化学成分反映了珊瑚生活时的海水温度和化学成分，化石珊瑚骨骼的分析为重建高分辨率(月度)气候记录提供了一条很好的途径。这些高分辨率记录对于了解过去全球气候的变化是必不可少的，例如研究过去厄尔尼诺现象的频率和严重性，以及测试预测21世纪气候变化的全球气候模型。然而，尽管存在这种可能性，但很明显，其他因素也影响珊瑚骨骼的化学成分，如果要准确地解释化石骨骼中记录的气候信息，这些影响需要得到解决。在这项研究中，我们将调查过去海水pH值的变化是否会影响珊瑚骨骼的化学成分。在最近的过去(在过去的500,000年中)，海水的酸碱值可能较高，反映出大气中二氧化碳水平较低。我们将在一定范围的海水pH范围内培养珊瑚，并确定pH如何影响骨骼化学。我们将开发一种方法来修正过去海水pH值的变化，使我们能够根据化石骨骼的化学物质准确地重建过去的海水温度。

The chemistry of tropical coral skeletons reflects the seawater temperature and chemistry at the time the coral lived and the analysis of fossil coral skeletons offers an excellent route to reconstruct high resolution (~monthly) climate records. These high resolution records are essential for understanding past changes in global climate e.g. for studying the frequency and severity of El Nino in the past, and for testing global climate models for predicting 21st century climate change.However, despite this potential, it is clear that other factors also affect the chemistry of coral skeletons and these influences need to be resolved if the climate information recorded in fossil skeletons is to be accurately interpreted. In this research we will investigate if past changes in seawater pH affect the chemistry of coral skeletons. Seawater pH was probably higher in the recent past (over the last 500,000 years), reflecting lower atmospheric CO2 levels. We will culture corals over a range of seawater pH and determine how pH affects skeletal chemistry. We will develop a methodology to correct for past variations in seawater pH, allowing us to reconstruct accurately past seawater temperatures from the chemistry of fossil skeletons.