Century-Old Science Helps Confirm Global Warming

A new NASA and University of Tasmania study combined 135-plus-year-old measurements by the HMS Challenger (shown in the drawing above) of ocean temperatures with modern observations to get a picture of how the world's ocean has changed since the Challenger's voyage. The research reveals that warming of Earth can be clearly detected since 1873, with the ocean absorbing the majority of the heat.

The Royal Society of London's Challenger expedition, from 1872 to 1876, was the first global scientific survey of life beneath the ocean surface. Scientists also measured ocean temperatures, lowering thermometers hundreds of meters deep on ropes.

“Our research revealed warming of the planet can be clearly detected since 1873 and that our oceans continue to absorb the great majority of this heat,” said lead author Will Hobbs of the University of Tasmania's Institute for Marine and Antarctic Studies and the Australian Research Council's Centre of Excellence for Climate System Science.

The Challenger expedition measurements also revealed that thermal expansion of sea water caused by global warming contributed about 40 percent of the total sea level rise seen in tide gauges from 1873 to 1955. The remaining 60 percent was likely to have come from the melting of ice sheets and glaciers, NASA said. Prior to this research, climate models offered the only way to estimate the change before the 1950s.

More information is available on the University of Tasmania website.