Have the oceans been HIDING the true scale of global warming? Nasa warns heat hasn't disappeared, it's just been buried in the sea

Scientists looked at a layer of the oceans between 300 and 1,000ft
They found it has been accumulating more heat than first thought
Study looked at direct ocean temperature data for more accurate results
Previous attempts to explain the temperature trends have relied heavily on climate model results which are less able to deal with short-term data

By ELLIE ZOLFAGHARIFARD FOR DAILYMAIL.COM

PUBLISHED: 23:05 GMT, 9 July 2015 | UPDATED: 23:13 GMT, 9 July 2015

Powerful winds in the Pacific and Indian oceans are hiding the effects of global warming.

This is according to a new report that claims the so-called 'pause' in climate change never took place – scientists just haven't been digging deep enough.

The pause refers to the fact that the temperature of Earth's surface has increased by just 0.06°C in the past 15 years.

A new report claims the so-called 'pause' in climate change never took place – scientists just haven't been digging deep enough. Temperature data from the global ocean (2003-2012) at four depths shows the warmest water at depths of about 330-660 feet

It has been used by some groups as evidence that climate change is not happening.

HOW OCEANS CAN BURY HEAT

Scientists claim one of the causes of the‘plateau’ in sea-surface temperature is a change in the exchange of ocean water.

They believe this exchange is occurring between warm, surface waters and cold, deep waters – as if the warming is ‘hiding’ underwater.

Easterly trade winds of the Pacific Ocean have increased significantly over the past two decades and as a result are blowing higher volumes of warm surface sea water to deeper depths.

Stronger trade winds blowing from South America to Australia have had the net effect of cooling surface temperatures by a global average of between 0.1°C and 0.2°C,

This would be enough to account for the apparent hiatus in global average temperatures over the past 15 years.

The warm water won’t hide below the surface forever: scientists believe that it may re-emerge later or affect other climate indicators, such as sea level or ocean circulation.

But the Nasa study claims the planet's extra heat has spent the last 10 years sinking into the depths of equatorial waters.

Scientists have found a specific layer of the Indian and Pacific oceans between 300 and 1,000ft (100 and 300 metres) below the surface has been accumulating more heat than previously recognised.

The team, which included Veronica Nieves, Josh Willis and Bill Patzert of Nasa's Jet Propulsion Laboratory, also found the movement of warm water affected surface temperatures.

During the 20th century, as greenhouse gas concentrations increased and trapped more heat energy on Earth, global surface temperatures also increased.

However, in the 21st century, this pattern seemed to change temporarily.

'Greenhouse gases continued to trap extra heat, but for about 10 years starting in the early 2000s, global average surface temperature stopped climbing, and even cooled a bit,' said Willis.

In the study, researchers looked at direct ocean temperature measurements, including observations from a global network of about 3,500 ocean temperature probes known as the Argo array.

These measurements show temperatures below the surface have been increasing.

The Pacific Ocean is main source of the subsurface warm water found in the study, though some of that water now has been pushed to the Indian Ocean.

Since 2003, unusually strong trade winds and other climatic features have been piling up warm water in the upper 1,000 feet of the western Pacific, pinning it against Asia and Australia.

'The western Pacific got so warm that some of the warm water is leaking into the Indian Ocean through the Indonesian archipelago,' said Nieves, the lead author of the study.

This schematic shows from a separate study shows the trends in temperature and ocean atmosphere circulation in the Pacific over the past two decades. Colour shading shows observed temperature trends (°C per decade) during 1992-2011 at the sea surface

The movement of the warm Pacific water westward pulled heat away from the surface waters of the central and eastern Pacific, which resulted in unusually cool surface temperatures during the last decade.

Because the air temperature over the ocean is closely related to the ocean temperature, this provides a plausible explanation for the global cooling trend in surface temperature.

Cooler surface temperatures are also related to a long-lived climatic pattern called the Pacific Decadal Oscillation, which moves in a 20 to 30 year cycle.

It has been in a cool phase during the entire time surface temperatures showed cooling, bringing cooler-than-normal water to the eastern Pacific and warmer water to the western side.

There currently are signs the pattern may be changing to the opposite phase, with observations showing warmer-than-usual water in the eastern Pacific.

WHAT IS THE 'GLOBAL WARMING PAUSE'?

The global average temperature has risen only slightly since 1998 – which is surprising, considering scientific climate models predicted considerable warming due to rising greenhouse gas emissions.

Some people used this apparent contradiction to question climate change per se – or at least the harm potential caused by greenhouse gases – as well as the validity of the climate models.

Meanwhile, the majority of climate researchers continued to emphasise that the short-term ‘warming hiatus’ could largely be explained on the basis of current scientific understanding and did not contradict longer term warming.

Recently, researchers have been looking into the possible causes of the warming hiatus over the past few years.

In one study, ETH Zurich concluded that two important factors are equally responsible for the hiatus. One of the important reasons is natural climate fluctuations, of which the weather phenomena El Niño and La Niña in the Pacific are the most important, they claim.

According to the study, the second important reason for the warming hiatus is that radiation from the sun has been weaker than predicted in the past few years.

'Given the fact the Pacific Decadal Oscillation seems to be shifting to a warm phase, ocean heating in the Pacific will definitely drive a major surge in global surface warming,' Nieves said.

Previous attempts to explain the global surface temperature cooling trend have relied more heavily on climate model results or a combination of modelling and observations.

These, Nasa says, are better at simulating long-term impacts over many decades and centuries.

The latest study relied on observations, which are better for showing shorter-term changes over 10 to 20 years.

In shorter time spans, natural variations such as the recent slowdown in global surface temperature trends can have larger regional impacts on climate than human-caused warming.

Pauses of a decade or more in Earth's average surface temperature warming have happened before in modern times, with one occurring between the mid-1940s and late 1970s.

'In the long term, there is robust evidence of unabated global warming,' Nieves said.

The new study used ocean temperature measurements from a global array of 3,500 Argo floats and other ocean sensors

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