![]() The rate of tree growth can “respond to both precipitation and temperature – and will depend on the tree and where it is located”, explains Rojas. This allows them to analyse its rings without damaging the tree. Scientists can “ core” a tree to extract a cross-section through its trunk. Taken together, each ring indicates a year of a tree’s life. Each ring comprises a light and dark part – with the pale part signifying the fast growth of spring and early summer and the dark part indicating the slower growth of late summer and autumn. Take tree-rings, which provide a biological record of how a tree has added new layers of wood over time. Thus, the field of palaeoclimatology involves “disentangling” specific climate information, says Dr Rojas. ![]() Instead, they often reflect a combination of several. ![]() Clicking on an individual data point will reveal the period covered by the data, the site name and a link to NOAA’s reference webpage for further information.įor example, Cluett’s research analyses leaf waxes (the proxy) in ocean sediments (the archive) to reconstruct the climate of southern Greenland.Įach type of proxy is reflecting a change in conditions, but they are not simply capturing temperature or rainfall or some other single variable. Use the categories in the legend on the left to select a particular proxy or archive type, and the buttons in the top-right hand corner to zoom in and out. With its permission, Carbon Brief has mapped this data. NOAA holds an archive of more than 10,000 proxy datasets covering more than a dozen categories. Where in the world is proxy data found?įrom the ice sheets of Antarctica and the seabed of the Atlantic, to the boreal forests of Europe and corals of southeast Asia, proxy data is found across the Earth’s land and ocean. Urey described his discovery as “suddenly myself with a geologic thermometer in my hands”, explains Pearson. Extracting this information, thus provided information on the climate when the organisms were alive – going back many millions of years. Urey showed that the chemical composition of these shells (see the next section for more on isotopes) varied depending on the temperature of the water. “This method was pioneered by Harold Urey in the immediate post-war years and helped launch the entire field of palaeoclimatology.” In addition, Carbon Brief has produced an interactive map of the US National Oceanic and Atmospheric Administration (NOAA) archive of more than 10,000 proxy datasets. In this in-depth Q&A, Carbon Brief explores what proxy data is, the different types, how scientists draw climate data from them, and what they can tell us about the Earth’s climate in the past, present and future. It forms a fundamental part of the study of past climates, known as “palaeoclimatology”, while also helping underpin scientists’ understanding of how the climate will change in the future. In the same way that something “prehistoric” relates to a time before written history, proxy data provides an insight into the climate before dedicated records. This is known as “proxy data” – indirect records of climate imprinted on different parts of the biosphere. Tucked away in an assortment of unlikely places – from shells and stalactites to pollen and seal pelts – the natural world has recorded the ebb and flow of the climate for millions of years. This is a mere snapshot in time considering the hundreds of thousands of years that humans have roamed the planet.įortunately, the Earth has been keeping its own records. Put together over many years, these measurements provide a record of the Earth’s climate and how it is changing.īut even the world’s longest climate archive – the central England temperature record – only goes back to 1659. Across land, sea and sky, data is being gathered manually and automatically using a range of technologies, from the humble thermometer to the latest multi million-pound satellite. At any one moment in time, thousands of measurements are being taken of the world’s weather.
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