Argo

A system of buoys that record ocean temperatures to a depth of 6,500 feet helped scientists determine where the excess heat is stored.

The deep oceans have recently been soaking up much of the excess heat trapped under the ever-thickening blanket of greenhouse gases that humans pump into the atmosphere, according to a recent study.

The finding may help explain why the pace of global warming at the surface has slowed in recent years compared to the 1990s, a phenomenon that has left members of the climate science community scratching their heads.

"The warming at the surface hasn't stopped, but it has been less than most of the climate models have been predicting," David Pierce, a climate researcher with the Scripps Institution of Oceanography, explained to NBC News. "So the question is: Where is that extra heat going?"

Kevin Trenberth and colleagues at the National Center for Atmospheric Research reanalyzed ocean temperature records between 1958 and 2009. They found that about 30 percent of the extra heat has been absorbed by the oceans and mixed by winds and currents to a depth below about 2,300 feet.

Oceans are well-known to absorb more than 90 percent of the excess heat, but its presence in the deep ocean "is fairly new, it is not there throughout the record," Trenberth said during a teleconference with reporters on Thursday. "So the question is: What happened to produce this?"

To find out, the team used a model that accounts for variables including ocean temperature, surface evaporation, salinity, winds and currents, and tweaked the variables to determine what causes the warming at depth.

"It turns out there is a spectacular change in the surface winds which then get reflected in changing ocean currents that help to carry some of the warmer water down to this greater depth," Trenberth said. "This is especially true in the tropical Pacific Ocean and subtropics."

The change in winds and currents, he added, appears related to a pattern of climate variability called the Pacific Decadal Oscillation which in turn is related to the frequency and intensity of the El Niño/La Niña phenomenon, which impacts weather patterns around the world.

The oscillation shifted from a positive stage to a negative stage at the end of the extraordinarily large El Niño in 1997 and 1998. The negative stage of the oscillation is associated more with La Niñas, which is when the tropical Pacific Ocean is cooler and absorbs heat more readily, Trenberth explained.

"So, some of this heat may come back in the next El Niño event … but some of it is probably contributing to the warming of the overall planet, the warming of the oceans. … It means that the planet is really warming up faster than we might have otherwise expected," he said.

While this ocean mixing has been suggested by some of the models scientists use to simulate the global climate, the new study is the first to re-analyze the observational record to get at an answer, noted Pierce, who was not involved in the study.

This new work, he said, should compel the climate science community to incorporate the mixing into the full suite of models, which in turn could improve climate forecasts in the 5- to 10-year time frame most relevant to planning agencies.

"What people are getting more and more interested in is what's the actual trajectory going to be …this sort of exchange between the surface and the deep they found in this paper really affects the actual trajectory you'll see," explained Pierce.

For example, knowing when the Pacific Decadal Oscillation will switch back to the warm phase could benefit planners on the U.S. West Coast. That's because sea level rise there has been suppressed for the past two decades, Joshua Willis, a project scientist at NASA's Jet Propulsion Laboratory, noted during the teleconference.

"In California," he said, "I like to say we are running a sea level deficit of about 6 centimeters and over the next 10 or 20 years we'll probably make that up and then some."

The findings were reported online earlier this month in the journal Geophysical Research Letters. 

John Roach is a contributing writer for NBC News. To learn more about him, visit his website. 

The world's first moving images of a giant squid living in its natural habitat have been captured by a team of scientists more than half a mile below the surface of the Pacific Ocean.

The ghostly pictures of the 10-foot-long giant squid were recorded from a state-of–the-art submersible carrying a three-person team of Japanese zoologist Tsunemi Kubodera, a camera operator and the submersible’s pilot, who made around 100 dives during an expedition last summer.

Although small by giant squid standards – the largest ever caught measured 59 feet – it was the first time a live giant squid had been caught on video deep in the ocean.

Kubodera, from Japan's National Museum of Nature and Science, credited the success to the submersible’s silence and hi-tech lighting.

"A giant squid would never appear before a pool of light, that possibility is extremely slim", he told NBC News. "That's why we had to use lights that they wouldn't be able to detect. In fact, they're lights even humans wouldn't be able to see either."

“If you try to approach making a lot of noise, using bright lights, then the squid won't come anywhere near you," he added. “So we sat there in the pitch black, using a near-infrared light invisible even to the human eye, waiting for the giant to approach.''

'It was stunning'
On one dive in July 2012, near the Ogasawara islands, 620 miles south of Tokyo, they finally had their close encounter more than 2,000 feet down and followed the creature even deeper.

“This was the first time for me to see with my own eyes a giant squid swimming,'' Kubodera said. “It was stunning. I couldn't have dreamt that it would be so beautiful. It was such a wonderful creature.”

NHK/NEP/Discovery Channel via Reuters

A giant squid is seen in this video still talken near the Ogasawara Islands in July 2012.

The squid was missing its characteristic two longest tentacles – and scientists don’t know why. Marine biologists said if that pair of tentacles had been intact, the creature would probably have measured up to 23 feet long.

Kubodera’s deep-sea expedition was the culmination of a 10-year project by Japanese broadcaster NHK to capture pictures of the mysterious creature in its habitat. An  ultra-sensitive high-definition camera was developed to operate at the ocean depths, using special light that was invisible to the sensitive eyes of the giant squid.

NHK will air its video footage in Japan in a prime-time documentary entitled "Legends of the Deep: Giant Squid" on Jan. 13. It will also be shown on the Discovery Channel on Jan.  27.

Reuters contributed to this report.

More world stories from NBC News:

• 150 years old and still running late: London Tube reaches landmark
• Family escapes 'tornadoes of fire' by clinging to jetty for 3 hours
• Video: How happy is the only country to track happiness?
• Flag debate sparks rioting in Northern Ireland
• World's best frenemies: Karzai, Obama set for key talks
• Video: Death art encourages living to seize the day
• 10ft squid captured on film in natural habitat
• Experts: 'Horrible' sea level rise plausible by 2100

Follow World News from NBCNews.com on Twitter and Facebook