Mapped: How ‘proxy’ data reveals the climate of the Earth’s distant past
At any one moment in time, thousands of measurements are being taken of the world’s weather. 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.
Put together over many years, these measurements provide a record of the Earth’s climate and how it is changing.
But even the world’s longest climate archive – the central England temperature record – only goes back to 1659. This is a mere snapshot in time considering the hundreds of thousands of years that humans have roamed the planet.
Fortunately, the Earth has been keeping its own records. 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 known as “proxy data” – indirect records of climate imprinted on different parts of the biosphere.
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. It, therefore, 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 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.
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.