Climate Change and Earth-Ocean-Atmosphere Systems.
Luke Skinner is accepting applications for PhD students.
Luke Skinner is available for consultancy.
Marine Sediments and Millennial Climate Change
My research involves the reconstruction of rapid changes in deep-water circulation (i.e. rates and sourcing) during the late Quaternary using geochemical (e.g. Mg/Ca, stable isotopes) and sedimentological (e.g. granulometry) techniques. This work includes both the calibration and application of proxies, and aims to provide a geological basis for understanding our present climate. Some aspects of my research are outlined below. For more information go to my research home page.
Millennial Variability of Surface- and Deep-Water Temperature
Measurements of Mg/Ca ratios in benthic and planktonic foraminifera may provide information about past changes in surface- and bottom water temperature variability. Using this technique, it can be shown that Greenland temperature variability across 'Dansgaard-Oeschger' events has remained tightly coupled with the heat budget of both the surface- and the deep Northeast Atlantic, demonstrating a close link between the frontal systems in the North Atlantic and the export of relatively warm deep-water southwards.
Deep-Water Radiocarbon Variability and Millennial Climate Change
By measuring the radiocarbon age of bottom-dwelling foraminifera, and comparing this with the radiocarbon content of the contemporary atmosphere, it is possible to infer past changes in the exchange of carbon dioxide between the ocean and the atmosphere. Radiocarbon measurements from the deep North Atlantic have underlined the role of the overturning circulation in effecting rapid and intense changes in regional climate and carbon cycling across the Bolling-Allerod and the Younger Dryas events (~11-15,000 years BP), and new records from the deep Southern Ocean have confirmed an increase in the mean residence time of carbon dioxide dissolved in the deep glacial ocean.
The Marine Isotope Stage stratigraphy
On multi-millennial timescales the marine oxygen isotope record may provide a powerful stratigraphic reference of global relevance. However, given the variability of temperature and water-δ18O in the world's oceans (the distribution of which is controlled by the ocean circulation and hence climate), it need not be globally synchronous on 'sub-orbital' timescales. Deep-water temperature estimates across glacial Terminations, in different ocean basins, indicate that the development of our stratigraphic systems at the high temporal resolution that is now necessary is inherently bound up with the very climate changes that we use those stratigraphic systems to study. This presents a serious challenge that will have to be met if we are to make full use of the globally distributed high-resolution records that now exist, and if we are to eventually solve the 'mystery' of insolation- and carbon dioxide forcing on long-term climate evolution.