May 20, 2010 – Original Source: The Independent, Reuters, Xinhua
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 measure average ocean temperature change than surface air temperatures, but that being able to do so accurately now offers greater reliability for measuring global warming. Ocean temperature is more consistent over time than air temperatures, which show enormous variability.
Josh Willis, an oceanographer involved in the study, described the oceans as a heat reservoir which is absorbing 80 to 90 per cent of the planet’s warming.
The study, published in the journal Nature, is one of the most comprehensive yet done on marine temperature, with NASA, Britain’s Met Office, the University of Hamburg in Germany and the Meteorological Research Institute in Japan also contributing. Some uncertainty remains over the upper-ocean temperature record but the latest study removes a lot of the previous doubts over data, Peter Challenor of the National Oceanography Centre in Southampton said.
The sea temperature rise had also caused sea levels to rise as the warmer water expanded, the study found.
Meanwhile, surface waters in Lake Tanganyika, the second-oldest and second-deepest lake in the world, are now warmer than at any time in 1500 years, according to a study published online in the journal Nature Geoscience.