Warming waters are known to contribute to coral bleaching (SN Online: 10/8/15) and they take up more space than cooler waters, raising sea levels. While the top of the ocean is well studied, its depths are trickier to query. The researchers gathered 150 years of ocean temperature data in order to get a better picture of heat uptake from surface to seabed. They compiled temperature readings collected by everything from a 19th century sailing expedition of the HMS Challenger to modern automated ocean probes. The far-flung data sources, combined with computer simulations, created a timeline of ocean temperature changes, including cooling from volcanic eruptions and warming from fossil fuel emissions.