The instrumental temperature record shows fluctuations of the temperature of Earth's climate system. The global temperature datasets include land air temperatures and sea surface temperatures. Data are collected from thousands of meteorological stations around the globe and through satellite observations. The longest-running temperature record is the Central England temperature data series, that starts in 1659. The longest-running quasi-global record starts in 1850. In recent decades instruments more extensive sampling of ocean temperatures at various depths have begun allowing estimates of ocean heat content but these not form part of the global temperature datasets.