Proxy (climate)
In the study of past climates ("paleoclimatology"), climate proxies are preserved physical, chemical, and even biological characteristics of the past that stand in for direct meteorological, climatological, and environmental measurements and enable scientists to reconstruct the climatic conditions over a longer fraction of the Earth's history. Reliable global records of climate only began in the 1880s, and proxies provide the only means for scientists to determine climatic patterns before record-keeping began.