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This edition of Green Room take a look at the emergence of shale gas as a energy source. Is it a saviour in the battle to secure supplies, or are the environmental costs too high? Also, what was the cause of a strange tidal surge around the shores of South-West England?

Anyone who follows stories on energy and climate change cannot help but notice how

As well as the US and Europe, China has recently

According to the US Energy Information Administration, , offering a geographical diverse source of possible energy.

Domestically, it says:

"The development of shale gas... has become a "game changer" for the US natural gas market."

At a time when there are growing concerns among nations about being left vulnerable to the potentially unstable supply of imports, shale gas does seem to offer, at the very least, a buffer to soften the blow of any sudden disruption in supplies.

But not everyone is convinced.

Some researchers have questioned the assertion that the gas is a "stepping stone" to a low-carbon future and energy security.

Instead, they say

Another US study suggested that shale gas drilling operations

In some cases, the concentrations were so high that

Another concern is the risk of minor earthquakes in the vicinity of drilling operations.

In North-West England, two minor quakes in the space of weeks prompted MPs to call for an inquiry about the safety of extracting the gas via "fracking" because a trial extraction plant had been operating in the area.

Responding to the concerns, the British Geological Survey said:

"Any process that injects pressurised water into rocks at depth will cause the rock to fracture and possibly produce earthquakes.

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"Typically, the earthquakes are too small to be felt, however, there are a number of examples of larger earthquakes occurring."

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Fracking involves injecting a mixture (including water and chemicals) under high pressure to break rock to release gas or oil locked in the material.

While environmentalists argue the process causes environmental damage, industry representatives say it is the only viable method currently available.

called on UK ministers should support plans to allow shale gas extraction to go ahead.

Yet, across the English Channel, Bloomberg reports that to extract gas and oil.

Permits that had been issued to companies to carry out exploration drilling have now been revoked.

'Mini tsunami'

Meanwhile, the shores of southern and western England experienced an "eerie" tidal surge at the end of June.

Videos posted on the web showed in a similar, but - admittedly, much smaller - fashion to the

Experts attributed the phenomenon to a underwater landslide on the continental shelf.

:

"Witnesses said the sudden movement around 200 miles out to sea caused the tide to suddenly shift by 50 metres, creating walls of water.

"The change in air pressure also generated static that left onlookers' hair standing on end in the extraordinary environmental events earlier today.

"There were even reports that the conditions caused fish to leap out of the water."

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