The findings, published in the journal Nature Climate Change, could help scientists better understand the Earth's record of sea-level rise, which is partly due to the expansion of water that happens as it heats up, the researchers said.
"Temperature is one of the most fundamental descriptors of the physical state of the ocean," lead study author Dean Roemmich, an oceanographer at the University of California, San Diego, said.
"Beyond simply knowing that the oceans are warming, the results will help us answer a few climate questions," Roemmich was quoted as saying by LiveScience.
The study is the first global comparison of temperature between the historic voyage of HMS Challenger between 1872 and 1876 and modern data obtained by ocean-probing robots.
During the four-year-long voyage, HMS Challenger sailed the world's oceans along a 69,000-nautical-mile track crossing the Atlantic, Indian and Pacific oceans. Scientists among the 200-member crew on board had taken 300 ocean-temperature profiles, or measurements at several depths in each spot, with pressure-protected thermometers.
Roemmich and his colleagues compared these temperatures with data from the modern-day Argo project, which uses 3,500 free-drifting floats to measure the temperature and salinity, or salt content, of the world's oceans every 10 days.
It showed a 1.1-degree Fahrenheit (0.59-degree Celsius) rise in temperatures at the ocean's surface over the last 135 years, a result corroborated by a large body of sea-surface temperature data that goes back more than 100 years. Read the full report here.
Source: Rediff News.
