The following ECVs, included in this edition, are considered "fully monitored", such that they are observed and analyzed across much of the world, with a sufficiently long-term dataset that has peer-reviewed documentation: * Atmospheric Surface: air temperature, precipitation, air pressure, water vapor. * Atmospheric Upper Air: earth radiation budget, temperature, water vapor, cloud properties. * Atmospheric Composition: carbon dioxide, methane, ozone, nitrous oxide, chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, sulfur hexafluorides, perflurocarbons, aerosols. * Ocean Surface: temperature, salinity, sea level, sea ice, current, ocean color. * Ocean Subsurface: temperature, salinity. * Terrestrial: snow and ice cover, albedo. ...we have often commented that the State of the Climate series not only offers annual snapshots of the climate's state, but also of our capacity to monitor it.