paleoklima

Paleoklima, or paleoclimatology, is the scientific study of Earth's past climates. It seeks to reconstruct historical patterns of temperature, precipitation, and atmospheric composition over timescales ranging from thousands to hundreds of millions of years, and to understand the processes that drove climate change in the geological record.

Because direct measurements are available only for recent centuries, researchers rely on proxy data gathered from natural archives. Ice cores preserve ancient air, allowing reconstruction of past temperatures and greenhouse gas concentrations. Marine and lake sediments contain fossils and chemical isotopes, such as oxygen isotopes in carbonate shells, which relate to temperature and ice volume. Terrestrial records include tree rings, pollen assemblages, and cave speleothems, which reveal growing-season conditions and moisture. These data are dated using radiometric methods, magnetostratigraphy, or layer counting, and synthesized with statistical and modeling approaches to produce regional and global climate histories.

Paleoklima informs understanding of natural climate variability, orbital forcing, greenhouse gas cycles, and feedback mechanisms. It provides baselines for interpreting current climate change and tests climate models by comparing simulated and proxy-derived climates, including key intervals such as the last glacial maximum, the mid-Holocene, and various greenhouse periods in the Cenozoic and beyond.

Limitations include uneven geographic coverage, temporal resolution, and biases in proxies. Age models, calibration uncertainties, and diagenesis of materials can affect reconstructions. Despite these challenges, paleoklima integrates multiple lines of evidence to build robust pictures of Earth's climatic history.