The HMS Challenger set sail 135 years ago. It was the world's first scientific survey of ocean life. But the HMS Challenger also studied ocean temperatures along the way by dropping thermometers attached to Italian hemp ropes hundreds of meters deep – an effort that has been used as a baseline for global warming in oceans since pre-industrial times.
Now, according to a new study, U.S. and Australian researchers have combined the work of the HMS Challenger with modern-era climate science models – and have some surprising results. The study found we may be significantly under-estimating global warming's impact and heat content in the oceans; and sea level rise from global warming seems to be split 60/40, with 40 percent coming from expansion of sea water caused by warming, and the remaining 60 percent coming from melting ice sheets and glaciers.
The U.S. and Australian researchers who re-examined the HMS Challenger thermometer readings in light of modern supercomputer climate models say it provides further confirmation of human-produced global warming over the past century.
"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 Dr. Will Hobbs, the study's lead author and a researcher at the University of Tasmania's Institute for Marine and Antarctic Studies. "Currently scientists estimate the oceans absorb more than 90 percent of the heat trapped by greenhouse gases, and we attribute the global warming to anthropogenic causes."
The HMS Challenger expedition ran from 1872 to 1876, and was the world's first global scientific survey of life beneath the ocean surface. But, while it wasn't part of its central research mission, the Challenger also dropped thermometers deep into the ocean at different points. More than a century later, researchers used state-of-the-art climate models to get a more accurate picture of how the world's oceans have changed since the Challenger's voyage. More
