Carbon Positive: The top layer of world’s oceans has warmed significantly since the early 1990s, consistent with the pattern of global warming, a new study shows. The results of a 15-year study up to 2008 by a research team led by the US National Oceanic and Atmospheric Administration (NOAA) found that temperatures in the top 700 metres of oceans worldwide increased significantly from 1993 to 2003 and continued to rise a lesser rate in the following five years. The scientists say it has been harder to …