Under scenario IS92a, the multi-model projection shows large decreases in pH and carbonate
ion concentrations throughout the world oceans (Orr et al., 2005; Figures 10.23 and 10.24).
Either the increased
concentration of free calcium
ions or their increased mobility (likely both, the researchers speculate) results in a decrease in the electrical resistance
throughout the material, which can be detected with a multimeter connected to electrodes embedded in the film.