destroy homes and ruin livelihoods.

But how can the law help?

Can it help provide a solution?

You'll learn what lawmakers are doing to deal with this threat.

What is behind rising sea levels

and increasingly severe and unpredictable storms?

Can anyone be blamed?

Why those most affected are often least to blame...

and how the law can help them.

40% of people live within 100km of the coast

and one in ten of us live in coastal areas

that are less than 10m above sea level.

Sea levels are rising.

According to the United Nations,

recent rises are the fastest in nearly 3,000 years.

Rising seas and storms wash away the land, flood homes,

ruin drinking water supplies

and poison our crops.

It's driven by rising temperatures melting polar ice

and even expanding the water that is already there.

And scientists agree:

humans are the cause.

It's impossible to blame any one person,

country or company,

but it's clear the impact won't be fair.

Smaller island countries will be hardest hit,

but they often create very little pollution.

So, how can they get help?

Francesco Sindico, from the University of Strathclyde

and the Climate Change Litigation Initiative,

explained why this issue would take a long time to solve internationally.

It will be very difficult for international law

to operate at the same speed of national law,

where you have laws created by a parliament,

enforced by – for example – the police,

and judges that can take decisions.

That's not how international law works,

and because there are so many countries,

on such a very complex matters, often there is a compromise,

which means that things will be dealt with slowly.

Unlike national law,

international law doesn't have just one country making rules;

lots of countries are involved,

which means they take time to come to a compromise agreement.

So, how easy is it to find out who's responsible?

It is very difficult to pinpoint

a country or an actor responsible

for an island that may... or is already sinking.

The problem is climate change.

The emissions are coming from all over the world.

Having said that, in the last five to ten years,

there is a clearer understanding

that some countries and some private actors

are more responsible than others.

The nature of climate change makes it very hard to identify

who is responsible for something like a sinking island.

So, what have people done

to identify who is responsible, legally?

Five or ten years ago, a study called the Carbon Majors study

highlighted that the overwhelming majority

of the emissions – of the problem –

really comes from a handful of companies.

And individuals have used this study

to go in front of a judge and tell him or her:

'Look. Now, we know that there's a connection

between the problem – climate change –

and the activity of these companies.'

More research is being done into climate change.

Some campaigners use studies as evidence

to prove a company's responsibility.

And who are these campaigners?

We have children, literally,

going after the governments of the countries where they live.

At the same time, you also have elderly people

who are seeing their livelihood suffering because of climate change

and are using all sorts of law:

human rights – they're using international law

and they're using a number of very interesting,

even creative, new legal strategies.

A huge range of people are campaigning.

Children and the elderly are getting involved,

using human rights and international laws in creative ways.

So, that shows how hard it can be for the law

to protect a sinking island.

Now, let's take a look at the people

who are trying to live on these vanishing islands.

The entire Pacific region contributes

just 0.03% of total greenhouse gas emissions.

Seventeen-year-old Hereiti lives on Rarotonga,

one of the Cook Islands in the Pacific Ocean.

As a Polynesian person, I have a connection to it.

Since we first started voyaging across it,

it's been the lifeblood of our islands and our culture.

But with rising sea levels and pollution, I feel like that...

that history that we've had for thousands of years

might end up being lost.

Rising sea levels result in strong wave action and coastal flooding,

causing the coast to erode.

We're seeing a lot of coastal erosion happening

on all our islands here in the Cook Islands,

particularly around the northern islands

because there are low-lying atolls.

We might have to consider relocating to higher areas –

so, inland more – and abandon the coast.

But where do people like these go?

And how can the law help them?

We spoke to Simon Behrman,

a law professor from the University of Warwick.

He specialises in how the law helps refugees.

He explained the situation for people forced to move by climate change.

So, there's not much, in terms of laws,

that allow people to move from one country to another.

Some parts of the world have their own individual laws

that give some rights to people to enter for work visas,

but in the main the only recourse that people will have

are to some aspects of human rights law,

such as, for example, the right to life,

which may help people claim a right to live elsewhere.

People aren't allowed to move to another country due to climate change.

But human rights laws can help them try.

He explains the limits of refugee law.

But a refugee is defined in very narrow terms in international law.

Essentially, you have to prove that you have been persecuted

and that is why you have left your country of origin,

but obviously climate change – or the effects of climate change –

don't persecute people, and so as a result,

unfortunately, at the moment, people fleeing the effects of climate change

do not have access to the protection of international refugee law.

You can only be a refugee if you are being persecuted –

treated badly because of something like your gender, race or beliefs.

Climate change doesn't persecute.

So, what laws are being used to help?

The main route at the moment is to bring cases

related to the principle of non-refoulement.

This principle simply means that people cannot be sent back

to places where they face a serious risk of harm.

Lawyers are attempting to argue that in some parts of the world

the effects of climate change are so severe,

that sending people back there would violate that principle.

Without refugee status, lawyers are using 'non-refoulement' principles:

they ban sending people back into a dangerous place

where they are at risk of harm.

So, is this enough?

The numbers of climate refugees are estimated

to reach many tens of millions of people this century,

possibly many more than those displaced by wars and persecution.

Already, millions of people every year are having to leave their homes

because of climate change. Some entire countries,

such as certain Pacific island states,

are predicted to become completely uninhabitable

over the next ten to twenty years.

We have a responsibility to help these people.

Simon thinks the size of the problem means

the law around people forced out of their homes

due to climate crisis should change.

We've seen the scale of the problem for the law.

It's very hard to say who's responsible for a sinking island.

But we've seen that the law is changing to fix that.

And we've seen that lawyers are working to keep people

who are at risk safe in the future.