It's a military naval base in Scotland, and it's best known for

being home to the United Kingdom's four nuclear-armed submarines located here.

One submarine is always on patrol to provide a constant at-sea deterrent.

A recent report found that this area in red, which covers much of the base,

is at risk of flooding due to rising sea levels and storm surges.

If true, it would make flooding the biggest threat to the U.K.'s national security.

Behind me is the home of four Vanguard-class submarines.

They're armed with thermonuclear warheads, and together, 

they form the United Kingdom's nuclear deterrent.

The U.K. Ministry of Defence says their purpose is to discourage 

the most significant dangers to British national security.

But the deterrent may be under threat, not from an enemy nation

or a terrorist group, but from climate change.

No environmental disaster touches more people than flooding

and climate change projections indicate it's only going to get worse.  

Between 2000 and 2018, at least 255 million people were directly affected

by a large flooding event. The proportion of the global 

population affected by flooding increased by about 20 percent between 2000 and 2015.

That's 58 to 86 million more people experiencing the devastation of

everything they know going underwater.

Southeast Asia, home to many low-lying urban areas,

has the highest concentration of population exposed to floods by far.

Outside of Asia, the U.K. is one of the most vulnerable regions, 

with six million people at risk of floods.

Infrastructure is at risk too.

The U.K.'s Environment Agency recently stated that even if the country hits its net-zero targets by 2050,

summer temperatures will get up to 7.4˚C hotter, rainfall in winter will increase by 59%, 

and sea-level events that used to happen once every century

will be expected every year instead.  

The key issue that we all cumulatively face is climate change.

And in that sense, it poses the kinds of problems that past politics and past

military strategies seem unable to resolve.

Paul Dorfman is a senior research fellow at

University College London's energy institute and founder of the Nuclear Consulting Group.

He's written a report on the climate's impact on the U.K.'s nuclear military.

All of the models or predictions, all of the analysis, all of the data

has really begun to run hot.

It's good that people are taking notice, but it's bad that this new data, is showing us that we

really do need to get our act together.

According to the report, coastal flooding

frequency is estimated to increase by a factor of between 10 and more than

100 in several European locations.

One of those locations is Scotland.

Its mainland and numerous islands

make up more than eleven and a half thousand miles of coastline.

One small but important stretch of that coastline is located 25 miles

northwest of the city of Glasgow. Her Majesty's Naval Base Clyde, located

at Faslane, is the headquarters of the Royal Navy in Scotland,

as well as the home port for the U.K.'s nuclear deterrent fleet.

The base was first used during the second world war, but it was only when the U.S.

and the U.K. signed a missile systems agreement in the 1960s, during the height of the Cold War,

that it contained nuclear submarines.

So how has the U.K.'s nuclear deterrent

developed since then, and what is its relevance in today's world?

Professor Andrew Futter is Director of Research for Politics and International

Relations at the University of Leicester.

By the end of the 1950s, and particularly the 1960s, there was a move, certainly in

the U.K. to rely much more on submarines as the main way of deploying nuclear weapons.

Simply because submarines were seen as the most secure and safe way to house them.

If you have a nuclear-powered, very quiet, nuclear-powered submarine

on patrol hidden in the depths of the ocean somewhere,

it is very hard for an adversary to target it to strike it to knock it out.

Therefore, there is always the risk if somebody attacks you that you can retaliate.

I think Faslane and Scotland became a site of choice initially because

it would be used by the United States and their submarine force as a base in Europe.

But it has a number of very useful natural advantages.

It's very deep water.

There are a number of different ways to get out to the ocean very quickly, which makes

it very hard for an adversary that wants to track or find those submarines to do so.  

But some believe, the force's biggest adversary today is climate change.

This is an aerial map of a sea inlet called Gare Loch and HMNB Clyde.

The blue area is the current waterbody, but by 2050,

this additional area in red would also be below the water level.

This would mean that a number of fixed jetties, submarine infrastructures,

an oil depot and several other buildings would be below water.

Faslane is not the only Royal Navy base under threat.

Across Gare Loch is the Royal Naval Armaments Depot Coulport,

where they process and store nuclear warheads.

Some of the base's support facilities would be exposed to flooding by 2050.  

And there are more.

Sellafield on the Cumbrian coast is Europe's largest nuclear site and holds 

the world's biggest stockpile of untreated nuclear waste.

Next-generation nuclear-powered Dreadnaught

submarines are being built at a shipyard in Barrow-in-Furness.

The naval base Devonport Royal Dockyard is the Navy's sole nuclear repair and refueling facility.

And the Rosyth Dockyard on the east coast of Scotland is primarily used to

dismantle and decommission nuclear submarines.

The near term risk is not simply sea level rise

but a thing called storm surge, which is when certain atmospheric conditions happen.

It makes the sea level itself rise, and then rush on to the land.

The evidence is beginning to come in,

that these places are surprisingly vulnerable, and will be of no help at all.

According to the Global Extreme Sea-Level Analysis, the magnitude and frequency of

extreme sea levels which cause storm surges and catastrophic flooding has accelerated worldwide.

A storm surge is an abnormal rise in water generated by, you guessed it, a storm.

And when a storm surge coincides with typical high tides,

it can result in huge storm tides reaching up to 20 feet or more.

But is this the case for Faslane, one of the most highly protected areas in the country?

I went to Brunel University to meet Dr. Phil Collins, an expert in geology & geotechnical

engineering to find out how serious the threat of flooding is to the naval base.

First of all, the storm surge threat is very real.

So if you get a large storm coming in, to some extent,

the pressure change will cause the sea level to rise up just on its own.

But then also the wave action as well compile water up into

shallow water areas like lochs. So it is a credible risk area.

Potentially more extreme storms, but almost certainly more storms.

You've done some research around  that area in the past many years ago.

Tell us a little bit about that area geologically.

If you go back 20,000 years or so ago, there was quite a large ice cap sitting on top of Scotland.

The weight of that is pushed down on the Earth's crust in the past.

And that now is reversing because the ice disappeared -the whole region

around Faslane has been moving upwards.

So when those ice sheets disappeared, you get this fairly rapid initial sea-level rise.

So that sea level is rising, the land is rising, and you get an interaction between the two.

Over the recent time, the balance between the land going up and the sea going up has changed.

And now the sea level is rising faster than the land, which is something that has worried quite a

lot of people because it was assumed that Scotland was going up and it would be safe, but it isn't.

So the predictions are that within the next 100 years or so, we've got somewhere between

probably about 30 centimeters to up to a meter of sea-level rise.

In terms of Faslane itself, the base is built

largely on a fairly low-lying area, but it already has quite a lot of existing flood infrastructure.

The engineering has taken a very pessimistic view on what might happen.

So they are engineered for earthquakes at a scale that we have very little evidence of

earthquakes like that for thousands of years.

They're also engineered for tsunami risk, and for storm surge risk.

Going forward, if sea level does rise by a meter, then that has to be reassessed.

Because obviously, if you've got a meter high,

increasing water, and then a storm surge on top, then areas that were safe are now exposed.

Is climate change the reason for these rising sea levels?

So we know a lot of glaciers are melting.

But on top of that, we've seen a documented increase in temperature

globally over about the last 150 years or so of about one and a half degrees centigrade

And that some of that heat goes into the ocean, and it causes the top of the ocean to expand.

And increases the sea level rise

We've got the two factors going on together and it's climate change.  

It's not just the U.K.'s military bases that are threatened by rising oceans and storm surges.

In the U.S., the Pentagon predicts there will be a 6-foot rise in global average sea levels.

The Pentagon has recently reported that

79 nuclear military bases will be affected by rising sea levels and frequent flooding.

This has played out in real-time when the nerve center of the U.S. nuclear deterrent

was submerged by floodwater, with recovery of the base to cost over $1 billion.

What's the current nuclear threat level?

I think there's there's a feeling that we're

entering into a more dangerous period in our nuclear history.

Russia remains whether it's said officially or not one of the main reasons for that deterrent

capability in the United Kingdom.

What's the current feeling around

the nuclear deterrent and nuclear weapons?

My gut instinct would say the British public or the U.K. public, probably split fairly evenly

between whether it's a good idea to retain nuclear weapons and the particular system that we have.

Britain is different to other countries,

where there is very little open debate about nuclear weapons.

There's virtually nothing in France, in Russia, China, some extent in the United States.

That leads on to something like

changing the infrastructure is going to be a political hot potato.

Yeah, I mean, it makes it something that is already

problematic because of the costs, even more so.

This would be another significant cost that would

have to be borne presumably by the Ministry of Defence,

at a time where there are big demands on lots of other conventional warfighting capabilities.

This is a prime ministerial decision that would have to involve

a number of other departments as well.

It would not be an easy thing to do.

And I think that's probably one of the reasons why this problem has not been given a lot of attention

because there's not a very easy one to solve.

There was a proposal for a very substantial

investment in the infrastructure on-site a few years ago.

So the likelihood of money being found to invest in either upgrading the existing infrastructure to

keep floods out or to replace it with higher grade infrastructure, that's very likely to be found.

We tend to think about the risk is happening tomorrow.

And really, what we're talking about is a progressive trend.

That may be going up until 2100.

So the infrastructure improvement doesn't happen have to happen now.

All of it, some of it will.

But some of it can be planned to be progressively built in over 20, 30, 50 years even.

It doesn't mean it's cheap, it doesn't mean that it's not technically challenging, 

but it is something that's much more manageable.

But do you think really this comes down to cost?

I think it's reasonably clear that cost is a huge driver.

The institute of mechanical engineers some time ago,

said that U.K. nuclear installations will be subject to either defense or abandonment.

So this isn't really a particularly new phenomenon.

So yes, cost is significant.

It is a complex debate.

But it's one that we need to face openly and with clear information.

And soon.