English: Estimated change in annual mean sea surface carbonate ion (CO₃^2-) between the pre-industrial period (1700s) and the present day (1990s). Calculated from fields of dissolved inorganic carbon and alkalinity from the Global Ocean Data Analysis Project climatology and temperature and salinity from the World Ocean Atlas (2005) climatology using Richard Zeebe's csys package. Δ CO₃^2- here is in mmol m^-3 of seawater. It is plotted here using a Mollweide projection (using MATLAB and the M_Map package). Note that the GLODAP climatology is missing data in certain oceanic provinces including the Arctic Ocean, the Caribbean Sea, the Mediterranean Sea and the Malay Archipelago.