---

New comparison of ocean temperatures reveals rise over the last century

April 02, 2012

Ocean robots used in Scripps-led study that traces ocean warming to late 19th century

A new study contrasting ocean temperature readings of the 1870s with temperatures of the modern seas reveals an upward trend of global ocean warming spanning at least 100 years.

The research led by Scripps Institution of Oceanography at UC San Diego physical oceanographer Dean Roemmich shows a .33-degree Celsius (.59-degree Fahrenheit) average increase in the upper portions of the ocean to 700 meters (2,300 feet) depth. The increase was largest at the ocean surface, .59-degree Celsius (1.1-degree Fahrenheit), decreasing to .12-degree Celsius (.22-degree Fahrenheit) at 900 meters (2,950 feet) depth.

The report is the first global comparison of temperature between the historic voyage of HMS Challenger (1872-1876) and modern data obtained by ocean-probing robots now continuously reporting temperatures via the global Argo program. Scientists have previously determined that nearly 90 percent of the excess heat added to Earth's climate system since the 1960s has been stored in the oceans. The new study, published in the April 1 advance online edition of Nature Climate Change and coauthored by John Gould of the United Kingdom-based National Oceanography Centre and John Gilson of Scripps Oceanography, pushes the ocean warming trend back much earlier.

"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."

Although the Challenger data set covers only some 300 temperature soundings (measurements from the sea surface down to the deep ocean) around the world, the information sets a baseline for temperature change in the world's oceans, which are now sampled continuously through Argo's unprecedented global coverage. Nearly 3,500 free-drifting profiling Argo floats each collect a temperature profile every 10 days.

Roemmich believes the new findings, a piece of a larger puzzle of understanding the earth's climate, help scientists to understand the longer record of sea-level rise, because the expansion of seawater due to warming is a significant contributor to rising sea level. Moreover, the 100-year timescale of ocean warming implies that the Earth's climate system as a whole has been gaining heat for at least that long.
###

Launched in 2000, the Argo program collects more than 100,000 temperature-salinity profiles per year across the world's oceans. To date, more than 1,000 research papers have been published using Argo's data set.

The Nature Climate Change study was supported by U.S. Argo through NOAA.

University of California - San Diego

Related Ocean Temperature Current Events and Ocean Temperature News Articles

The Asian Monsoon is Getting Predictable
For much of Asia, the pace of life is tuned to rhythms of monsoons. The summer rainy season is especially important for securing the water and food supplies for more than a billion people.

Ancient pool of warm water questions current climate models
A huge pool of warm water that stretched out from Indonesia over to Africa and South America four million years ago suggests climate models might be too conservative in forecasting tropical changes.

Profiting from climate change
The climate is getting warmer, and sea levels are rising - a threat to island nations. As a group of researchers lead by colleagues from the University of Bonn found out, at the same time, tiny single-cell organisms are spreading rapidly through the world's oceans, where they might be able to mitigate the consequences of climate change.

MBL scientists find 'bipolar' marine bacteria, refuting 'everything is everywhere' idea
In another blow to the "Everything is Everywhere" tenet of bacterial distribution in the ocean, scientists at the Marine Biological Laboratory (MBL) have found "bipolar" species of bacteria that occur in the Arctic and Antarctic, but nowhere else.

Projected sea-level rise may be underestimated
That sea level is rising faster than expected could mean that the Intergovernmental Panel on Climate Change's (IPCC) sea-level rise projections for the future may be biased low as well, their results suggest.

Scientists predict major shifts in Pacific ecosystems by 2100
What if you woke up every day to find that the closest grocery store had moved several miles farther away from your home? Over time, you would have to travel hundreds of extra miles to find essential food for yourself and your family.

Sea temperatures less sensitive to CO2 13 million years ago
In the modern global climate, higher levels of carbon dioxide (CO2) in the atmosphere are associated with rising ocean temperatures.

Elephant seal tracking reveals hidden lives of deep-diving animals
Researchers at the University of California, Santa Cruz, who pioneered the use of satellite tags to monitor the migrations of elephant seals have compiled one of the largest datasets available for any marine mammal species, revealing their movements and diving behavior at sea in unprecedented detail.

Growing risks from hatchery fish
A newly published collection of more than 20 studies by leading university scientists and government fishery researchers in Alaska, British Columbia, Washington, Oregon, California, Russia and Japan provides mounting evidence that salmon raised in man-made hatcheries can harm wild salmon through competition for food and habitat.

Earth's Energy Budget Remained Out of Balance Despite Unusually Low Solar Activity
A new NASA study underscores the fact that greenhouse gases generated by human activity -- not changes in solar activity -- are the primary force driving global warming.

---

More Ocean Temperature Current Events and Ocean Temperature News Articles

---