What does salinity have to do with ocean currents and climate change?
NASA gave the command last week to power on its newest Earth-observing satellite, Aquarius. It may seem a somewhat peculiar measurement to make, but Aquarius, which launched in June 2011, will measure salinity across all the oceans every week. The data will undoubtedly help answer some of our most pressing questions about climate change. Why measure ocean salinity? The density of ocean water is determined by salinity and water temperature. Density drives the pattern of deep ocean currents, and ocean currents drive global climate. In recent decades, scientists have seen ocean salinity shift in ways that only climate change seems able to explain. Until now, salinity data came from slow-moving ships and a network of floating sensors that could only provide a limited global picture. Satellite technology changes that: From 400 miles (644 km) above Earth Aquarius' hypersensitive microwave radiometer can detect differences in ocean salinity to within a pinch of salt in a gallon of water. Let the science begin.