Are Ocean Levels And Temperatures On The Rise?
April 2, 2012

Are Ocean Levels And Temperatures On The Rise?

A new study has revealed a global warming and rising of the oceans. Contrasting ocean temperature readings from the 1870s with modern readings, this study reveals an upward rising trend spanning over 100 years.

Dan Roemmich, a Scripps Institution of Oceanography at UC San Diego physical oceanographer led the research. He found a .33 degree Celsius (.59-degree Fahrenheit) increase on average in the top portions of the ocean, down to 700 meters. Ocean surface temperatures, however, saw the largest amount of temperature rise at .59 degrees Celsius (1.1 degree Fahrenheit) and down to .12 degrees Celsius (.22 degree Fahrenheit) at 900 meters.

Roemmich´s study is the first to compare the temperature between the voyage of HMS Challenger (1872-1876) and data from modern day readings conducted by ocean-probing robots. These robots continuously report the ocean´s temperature thanks to the global Argo program. Scientists have long believed 90% of Earth´s excess heat in the climate system since the 1960s has been trapped and stored in the oceans.

Roemmich´s study, however, reports the warming trend began much sooner, as soon as 100 years ago. His report was co-authored by John Gould of the United Kingdom-based National Oceanography Centre and John Gilson of Scripps Oceanography. It was published on April 1, 2012, in an advance online edition of Nature Climate Change.

“The significance of the study is not only that we see a temperature difference that indicates warming on a global scale, but that the magnitude of the temperature change since the 1870s is twice that observed over the past 50 years,” said Roemmich, co-chairman of the International Argo Steering Team. “This implies that the time scale for the warming of the ocean is not just the last 50 years but at least the last 100 years.”

The data set captured by the Challenger in the 1800s only measured temperatures from 300 locations around the world. However, this relatively small sample sets a baseline for the world´s oceans temperature changes. This baseline is now measured against Argo´s continuous sampling, which measures at a larger scale than the Challenger. Nearly 3,500 free-drifting Argo floats continuously sample temperatures of the world´s oceans and report their findings every 10 days.

According to a press release by the Scripps Institute, the Argo program was launched in 2000 and collects more than 100,000 temperature-salinity profiles each year across the Earth´s ocean. The institute reports more than 1,000 research papers have been published using data from the Argo program.

According to Scripps, Roemmich believes his new findings will provide a small piece to the large puzzle that is the Earth´s climate. The information recorded in his study should help scientists understand the long record of sea-level rising. As seawater expands due to warming, so too does the sea level, and these measurements have been corroborated with previous research. Furthermore, Roemmich´s findings also provide evidence of a longer global warming trend expanding over 100 years, more than scientists had previously thought.