The vast bog that helps fight climate change

To the untrained eye it looks like a vast expanse of empty moorland, but the Flow Country holds a secret.

Beneath the surface it contains more than double the carbon of all UK forests combined.

The huge area in the far north of Scotland acts as a giant sink, soaking up and storing carbon from the atmosphere.

It is a critical process in the fight against climate change.

In recognition of its global significance a team has been bidding to make it the planet's first peatland with world heritage status.

Assessors for Unesco have visited the 187,000 hectare (469,500 acres) site to see if it qualifies and a verdict is expected around the middle of next year.

Globally, the sites already on the list include Australia's Great Barrier Reef and Egypt's Historic Cairo.

About 400 small pool systems provide an important wildlife habitat

Volunteers use long extendable poles to probe the peat for depth measurements

Scotland's Flow Country stretches across Caithness and Sutherland but its intricate network of about 400 pool systems are only fully appreciated close up or from higher ground.

It is special because it contains the most extensive blanket bog system in the world.

It is called a blanket bog because the peat, which holds water, extends across both the hills and the glens.

Because it is so wet, plants do not decompose and release carbon dioxide back into the atmosphere.

Instead species like sphagnum moss fall below the water line forming the peat in layers which grow at a rate of about 1mm per year.

'Keep it in the ground'

The peatland has been building up for about 9,000 years and each metre of depth represents about a millennium.

In some places it is many metres from the surface to the bedrock.

But it has to be kept in good condition to prevent it from drying out which would release the carbon.

Prof Roxane Anderson describes the ecosystem as "globally important".

She says: "The best thing we can do for this very big stock of carbon is keep it in the ground."

A visitor centre was opened in 2015 so people can experience the flows

World heritage status is an internationally-recognised designation given to places of cultural, historical or scientific significance.

The idea of applying was first discussed back in 1988 but the serious work did not begin until 2010.

A formal bid was submitted by the UK government in February.

A designation would offer no further protection to the land, three-quarters of which is already covered by statutory designations like Sites of Special Scientific Interest.

The rest is protected through policy.

About 400 million tonnes of carbon is estimated to be contained within the flows.

Dr Steven Andrews, who has been leading the bid, says becoming the first peatland to be inscribed on the world heritage list would demonstrate how important such landscapes are.

"There are a number of opportunities we hope would arrive whether it be through restoration works, for training opportunities around that, for branding of produce."

He hopes it will encourage more tourists but added: "A peatland like the flow country can't be appreciated by just driving through it.

"You need to stop and you need to spend time. That's the way that you'll see the bird species, start to pick out the different sphagnum mosses and all the amazing biodiversity that's out there."