A study of marine sponges has shown that global temperatures may have already risen faster and for longer than previously estimated, according to newly published research. A team lead by Australian scientists extracted ocean temperature records preserved in the calcium carbonate skeletons of long-lived Caribbean sclerosponges. The researchers found that industrial-era warming began in the mid-1860s, a date consistent with what could be expected from historical records but more than 70 years earlier than suggested by records from ship-based measurements of sea surface temperatures. University o…