Palaeoclimatic data provides critical insight into Earth’s past climate, allowing scientists to understand long-term climate trends, natural variability, and the factors driving climate change. These data sources come from a variety of natural archives and proxies that record past environmental conditions. Palaeoclimatology relies on indirect evidence since direct meteorological measurements are only available for the last few centuries. Understanding the sources of palaeoclimatic data involves exploring biological, geological, and chemical records that preserve evidence of past climates over time scales ranging from thousands to millions of years. One of the primary sources of palaeoclimatic data is ice cores obtained from glaciers and ice sheets in regions such as Antarctica, Greenland, and high mountain glaciers. Ice cores contain trapped air bubbles that preserve ancient atmospheres, including greenhouse gas concentrations like carbon dioxide, methane, and nitrous oxide. The isotopic composition of oxygen (δ¹⁸O) and hydrogen (δD) in ice layers provides information about past temperatures, precipitation patterns, and even seasonal variations. Annual layers in ice cores can be counted to construct precise chronologies, sometimes extending back hundreds of thousands of years. These records are invaluable for correlating past climate events with geological and biological phenomena. Another significant source of palaeoclimatic data is sediment cores from lakes, oceans, and peat bogs. Marine sediments accumulate over millions of years and contain microfossils such as foraminifera, diatoms, and coccolithophores, whose shell composition and species distribution reflect historical ocean temperatures, salinity, and nutrient levels. Oxygen isotopes in the calcium carbonate shells of foraminifera are especially useful for reconstructing past sea surface temperatures and ice volume changes. Terrestrial sediments in lakes and bogs often contain pollen grains, plant macrofossils, and charcoal, providing insights into past vegetation, rainfall patterns, and fire frequency. The study of pollen, known as palynology, allows scientists to infer shifts in ecosystems, which are closely tied to climate conditions. Tree rings, or dendrochronology, are another critical palaeoclimatic source, particularly for reconstructing climate over the past several thousand years. Trees