Palaeoclimatology, the study of past climates, plays an essential role in understanding long-term climate variability and predicting future climate change. Since direct instrumental records of climate extend back only about one and a half centuries, scientists rely on indirect evidence from natural archives to reconstruct past climates over hundreds, thousands, and even millions of years. These indirect pieces of evidence are known as palaeoclimatic proxies. Each source provides unique insights into temperature, precipitation, atmospheric composition, and environmental conditions of the past. The interpretation of these proxies allows us to reconstruct climatic patterns at local, regional, and global scales. The major sources of palaeoclimatic data include ice cores, tree rings, marine and lake sediments, corals, speleothems, pollen records, historical documents, and isotopic and geochemical analyses. Each of these proxies has its own strengths, limitations, and time scales of relevance, but together they create a coherent picture of Earth’s climatic history. One of the most reliable and widely studied sources of palaeoclimatic data is ice cores. Ice sheets in Antarctica, Greenland, and high mountain glaciers preserve layers of snow and ice accumulated over tens of thousands of years. Each layer traps bubbles of ancient atmosphere, dust particles, volcanic ash, and isotopic variations of oxygen and hydrogen. By analyzing the ratios of oxygen isotopes, scientists can infer past temperatures. The trapped gas bubbles provide direct records of greenhouse gas concentrations, such as carbon dioxide and methane, over glacial and interglacial cycles. Ice cores from Antarctica have extended the climate record back over 800,000 years, revealing a strong correlation between atmospheric carbon dioxide levels and global temperatures. They also preserve evidence of abrupt climate events, volcanic eruptions, and solar variability. Ice cores are therefore invaluable for understanding the links between greenhouse gases and temperature changes. Tree rings, or dendroclimatology, are another important proxy. Trees in temperate regions typically add one growth ring per year, and the width, density, and isotopic composition of these rings are influenced by climatic conditions such as temperature and rainfall. Wider rings may indicate favorable growing conditions with adequate warmth and moisture, whereas narrower rings suggest climatic stress such as drought or cold. Dendroclimatology offers high-resolution, annual to seasonal data, which can be cross-dated among living and dead trees to reconstruct long-term chronologies. Some tree-ring records extend back several thousand years, providing detailed insights into past droughts, floods, and temperature fluctuations. In particular, tree rings have been essential in reconstructing regional climate histories, such as the Medieval Warm Period and the Little Ice Age in Europe and North America. Sediments from oceans and lakes form another vast archive of palaeoclimate information. Marine sediments accumulate on the seafloor over millions of years, preserving microfossils, isotopes, and organic matter. For example, foraminifera, microscopic marine organisms with calcareous shells, incorporate oxygen isotopes that reflect seawater temperature and ice