[Scott] Coming up on "Energy Switch," we'll look at sea level rise.

- The reality is today we're already seeing this incredible increase in high tide flooding, and this is very, very disruptive to people's lives and to economies, to ecosystems.

- True.

- Different countries can learn from successes as well as failures from their different mitigation efforts.

And then definitely the coastal population will be able to take informed decision.

[Scott] Next on "Energy Switch," sea level rise and potential solutions.

[Narrator] Funding for "Energy Switch" was provided in part by The University of Texas at Austin, leading research in energy and the environment for a better tomorrow.

What starts here changes the world.

[upbeat music] - I'm Scott Tinker, and I'm an energy scientist.

I work in the field, lead research, speak around the world, write articles, and make films about energy.

This show brings together leading experts on vital topics in energy and climate.

They may have different perspectives, but my goal is to learn, and illuminate, and bring diverging views together towards solutions.

Welcome to the "Energy Switch."

Sea level has been rising since the end of the last ice age when continental ice sheets began to melt.

In island nations in low-lying coastal areas, sea level rise is contributing, among other things, to high tide flooding and salt water encroaching into farmland and freshwater aquifers.

We'll talk about what the future could bring and ideas on how communities could adapt to sea level rise with Rachel Cleetus.

She's an economist and the policy director of the Climate and Energy program at the Union of Concerned Scientists, where she's an expert on sea level rise.

Susmita Dasgupta is a lead environmental economist for the World Bank.

Where she has conducted coastal area research in 14 countries across the developing world.

Next on "Energy Switch," we'll look at sea level rise and how we could adapt to it.

An important topic today, sea level rise.

Why should our viewers, why do they care about sea level rise?

- Sea level rise related dangers are too many.

We are expecting land loss, increase in coastal erosion, loss of critical wetlands like mangroves, progressive salinization of soil and water.

And all these are threats to population, assets and activities for all small island nations and hundreds of millions of people living on low elevation coastal areas.

To tell you the truth, I think that sea level rise is the big elephant now, which is in the room.

- Yeah.

Yeah, I like the way you described that.

And as a geologist who studied paleoclimate a lot, sea level has been rising for 15,000 years.

It's gonna keep rising, you know?

So adapting to that is important.

What would you add to that overview, Rachel?

- Yeah, as Susmita says, this is one of the most consequential impacts of climate change.

Sea levels have risen approximately since the industrial revolution began.

And unfortunately, even though the evidence is all around us already, it's still flying under the radar in terms of people preparing for this.

This is getting worse.

It's accelerating.

- Yeah.

Why do we say it's accelerating?

What are the data behind that?

- We have seen that from 3,000 years ago up to 1900, sea level was increasing and reducing slightly, but there was no significant trend.

But since 1900, sea level is rising steadily.

- Yeah.

- And it rose between six to 10 inches from 1900 to 2018.

I'm talking about global mean sea level.

[Scott] Yeah.

- And half of that change occurred from 1993 onwards.

Now we know exactly what are the factors, major factors.

One-third of sea level rise since 1993 can be explained by thermal expansion that the ocean expands in volume when the water warms, and then the melting of arctic and antarctic ice sheet is a major contributor.

And glaciers, other than polar ice sheets, are also melting and adding water to the ocean.

Going back to the paleoclimatic evidence from 21,000 years before, to 11,700 years before, warmed by four degrees centigrade, and sea level at that point rose by 280 feet.

- Yeah.

- But what was scary is, even when the warming stopped, and temperature reached its maximum and leveled off, still, sea level was rising because the polar ice sheets were melting.

And sea level kept on rising for 150 feet for a few next centuries, and then it stabilized at the modern level around 3,000 years ago, right?

So, what we are seeing is basically the tip of the iceberg.

[Scott] So to speak.

- So to speak, right?

- What's really important to recognize from what Susmita has said is we've already locked in.

We're already committed to a certain amount of sea level rise.

And the estimates from NOAA are that by 2050, we're going to see another 10 to 12 inches overall of sea level rise.

In some places, it's going to be more or less depending on land subsidence.

But the current estimates are, by the end of the century, we could see two to seven feet of sea level rise.

[Scott] That will be a massive acceleration.

- And a very, very profound change along our coastlines all over the world.

And the latest science on this is very sobering because it is showing that the Antarctic and Greenland ice sheets are more unstable than we had previously thought.

Again, this is the front edge of science, there's nothing baked in and certain about it.

But unfortunately, every new scientific study seems to be breaking in the wrong direction in terms of the risk.

And the challenge with ice sheet dynamics is, once these major ice sheets start to go, you can't turn back the clock.

You can't just turn back the dial.

You have these natural processes that just have feedback loops built in.

So we have to be very smart about both preparing, developing a more resilient coastline, but also sharply cutting our heat trapping emissions.

- You've been in many countries seeing these things for real.

So tell us about those.

What do those look like?

- A few years back, my team conducted a research on impacts of sea level rise on 84 developing countries and territories all over the world.

We found that 56 million people live now on land where elevation is less than one meter over sea level in terms of total population impacted, or you know, percentage of population impacted, East Asian Pacific region and Middle East North Africa region will be most impacted than other regions.

And the top countries are Vietnam, Egypt, Mauritania, Suriname, Guyana, French Guiana, Tunisia.

Let me see if my memory can give you everything.

- Yeah, you're doing good.

- --and Benin.

Not even including the island nations.

- It's incredible how vulnerable countries that are living with low incomes and in poverty are to everything.

You know, it's just unjust.

- It's an existential risk to small island nations for sure.

But well before places go underwater, there are all of these other hidden challenges.

The reality is, today we're already seeing this incredible increase in high tide flooding.

And this is very, very disruptive to people's lives and to economies, to ecosystems.

We're also seeing a lot of infrastructure that is just simply not built for the current reality, let alone going forward.

And in places like Florida, for example, the substrate is very porous.

So the water is coming up through the substrates and the real risk here is that it can contaminate fresh water aquifers.

And when that happens, that is very, very challenging.

- I'm glad that you raised that point, because this progressive salinization of water and soil is a huge problem in the Deltas right now.

For example, the Nile Delta, the Mekong Delta and the Ganges-Brahmaputra Delta are all reporting significant increase in salinity of water and soil in the coastal region.

And in Bangladesh where I worked, they have found considerable amount of river areas with salinity of above 10, 15, 20 parts per 1000.

To put the numbers in perspective, water is not portable if salinity exceeds one parts per 1000.

So, you know, we are trying to encourage rainwater harvesting.

It'll not cover the drinking water need, but still it can help.

- You can harvest some of it.

Yeah.

- And we are also looking into this small scale desalinization plants, because people cannot live without water.

- Have settlement patterns changed in the countries you've studied or not?

- To tell you the truth, it's very difficult to pinpoint what is causing changes in settlement pattern for any kind of settlement.

Couple of years back, we did conduct a study in neighboring areas of Bangladesh and India.

And what we found is in Bangladesh, our study area was in a remote area, and there we saw clear indication of working age male and female migrating out of the coastal areas.

Whereas, by contrast in India, the study area was very well connected with the city Calcutta, by railways and roads.

So we clearly saw that this migration out, migration incentive diminished in those areas because of well connectivity and the public assistance they were getting.

[Scott] Interesting.

- Even in hard hit areas.

- What we also recognize around the world is people are very attached to places.

They're attached to their communities, they're attached to the place they grew up.

[Scott] Sure.

- So they endure conditions that you would think, my God, shouldn't people get up and leave.

But people need a sense of agency over their future.

What are my choices?

Where am I gonna go?

What is gonna be the support offered?

And that's the piece that policy makers have to step up and deliver right now.

- One thing I must say, after working in developing countries, that if we release scientific information, people will not be able to understand.

So we need to repackage it.

And I would say this exchange of information need not be restricted to national boundaries.

Different countries can just learn from successes as well as failures from their different risk mitigation efforts, right?

And then definitely one section of the coastal population will be able to take informed decision.

And for others, you know, we have to think about, you know, training programs, skill built, so that, you know, they can move out.

The training programs can cater to training them with the host country language, or with skill in high demand sector there, and that will be of help.

- So education of what's possible, really, for many of these communities.

- Exactly.

And training of women is also very important because we have seen over and over again, that migrating households stabilize quickly if women also have a job.

- Sure.

How about in the U.S.?

You mentioned Florida, are there other areas?

- Louisiana, Texas, New Jersey, New York, South Carolina.

We've got about 311,000 homes and commercial properties at risk by 2045.

And that property is currently worth about $136 billion.

And that's today.

The reality is we're continuing to build in these areas.

If you look at a place like Miami, Miami-Dade, you have developers making all kinds of promises about flood-proofing buildings.

- What a surprise, right?

- And what they're saying is, you know, we've put the electricals higher up, we've got this envelope around the building, it's flood proof.

But what does that do for you when the street outside is completely flooded?

So here in the United States, what I would say is it's a microcosm of what's happening in the world.

People who have money and resources might be able to really invest in these expensive flood-proofing measures.

But for a lot of other people, they're enduring a very harsh situation.

[Scott] What infrastructure is the most vulnerable?

- It's roads, it's hospitals, it's bridges, it's power plants.

In some cases it's a combination of risks.

So we have things like wastewater, treatment plants and toxic facilities located in the coastal floodplain when they flood, all those toxics just flow into people's communities.

So, you get these compound risk factors.

And in the United States, for example, we've got a lot of military installations along our coastline.

- How much of this is related just for our viewers to the global problem versus local management of things, including withdrawal and river diversions, and building in places maybe we just shouldn't build?

- Well, there's no question land use and development patterns are exacerbating exposure to risk.

And the over-engineering of Delta floodplains is one of those challenges all over the world.

That said, sea level rise is happening at this fast rate that is taking all of that and making it much worse.

- Right.

So part of it is, and part of it's... - Yeah, so the land subsidence we're seeing in the Gulf Coast of the United States is clearly a combination of factors there.

But that shouldn't distract from the fact that we have to prepare.

You know, we have to prepare for what's coming.

And one of the big challenges that's coming our way is that many, many people through no fault of their own, are going to be forcibly displaced from some places.

[Scott] How does this affect insurability of coastal regions?

- I still think that sea level rise as the risk is flying under the radar in the real estate and the insurance market.

But we're seeing the leading edge with major insurance companies saying they won't offer new policies or exiting markets in places like Florida and California.

Many places are essentially becoming uninsurable because the risk is too high.

- What's sort of the macroeconomic effect of all this?

- I would say this is going to, in the years to come, have such significant impacts on economies because so much of our economic engines are tied to our coastlines.

To take an example, the real estate market is obviously exposed, but that's not just about individual homeowners, it's also about the mortgage lenders, it's about the insurance companies, it's the local property tax base that might get eroded, it is about the fact that as taxpayers, we also are on the hook through things like the National Flood Insurance Program, or other policies if there's a disaster.

So this will have really significant macroeconomic effects in the years to come.

- How do we harden coastlines?

Harden meaning, make them more resilient.

And what are some of the drawbacks to that?

- They can really provide predictable protection in densely populated areas, right?

And if space is limited, you can always get some core benefits.

You can combine the flood protection, storm protection function with recreational space, roads, buildings, car parking, designing everything within one multifunctional structure.

But the negatives are also quite a few.

First of all, it is costly to build and to maintain.

So it will not work for sparsely populated areas, but they need protection too.

You know, it has a tendency to lock in the path of development because as soon as it is built, development intensifies behind it, and then to protect those assets and population, government needs to make more investment.

And by design, these hard infrastructures disrupts the flow of water.

[Scott] Yeah.

- In some countries, you know, it changed, it disrupted the sedimentation pattern in such a way that the land outside, just outside the embankment has gone up, and the protected area is still deep down.

And if anything happens, if there is a flooding from local extreme rainfall, it is extremely difficult to drain that water.

- Yeah, yeah.

- The other piece around coastal infrastructure is pumps.

We're seeing places like Miami Beach and other places install these very, very expensive pumps.

And those kinds of systems as well have certain design specifications.

They're meant to last for a certain amount of sea level rise, they won't be able to continue beyond that.

And then you have to make a decision.

Is it a bigger and bigger system?

Or do you use that time, buy yourself some time, but during that time, use it to move people to safer areas instead of doubling down.

- What are some other alternatives?

- I work a lot with ecosystem-based protection, like reefs and mangroves.

And my work is very much centered on mangroves.

So mangroves help a lot because they work as obstacles during flooding from surges, and their aerial roots basically traps the organic matters and sediment.

So elevation of the land goes up, and their polluted water from rivers and streams go through this complex root system, you know, the nitrates and phosphates, and other pollutants get cleaned.

- So natural filter.

- Yeah, natural filter.

So the issue is and made in the environment can really benefit.

- Nice.

Would you call this a nature-based solution or what?

- Yeah, we call it nature-based solution these days.

But here we are talking about different alternatives as if one versus the other.

But we can also think about hybrid.

- Yeah, yeah.

- Right?

So, our research has shown that if we have mangroves on the fore shore area of embankments or dikes, then the cost of repair and maintenance goes down significantly.

- Blending these together is very logical and very sensible, and it adapts.

- Yes, there are quite a few location specific targeted adaptation measures that can help the coastal inhabitants to cope with today's sea level rise.

Or for the time being, let me just give you a specific example.

When my team was conducting a collaborative research with Bangladeshis, we found that sunflower is a crop that they can grow in saline coastal region.

And, you know, there is demand for edible oil all over the world.

- Yeah, I love that example where it's fit for local purpose and therefore the community, the local community and culture will maintain it and grow from it, and it adds another piece to their economy.

You know?

- Yes.

- This has been a great conversation.

You know, I wanna let you each kind of have a chance to provide some final thoughts.

What do we do to be the best prepared we can, and what does that future look like?

- I think one of the most important starting points is of course having the information and the science because that gives us very valuable metrics of the problem right now, how it's gonna get worse, and where it's gonna get worse and how much time we have so we can use that time well.

I think there's a lot of place-based indigenous knowledge that needs to be brought to bear because people have a very keen sense of their local environment and how it's changing.

We're going to have to galvanize the scale of resources that are needed.

So, for example, the U.N. is saying that on an annual basis, by 2030, we could need up to $340 billion for adaptation measures.

And that will only increase with time as these impacts worsen.

And then we absolutely have to make sharp cuts in our heat trapping emissions so we can invest in resilience as much as possible.

But we can't outrun this problem if we keep bumping heat trapping emissions into the atmosphere and worsening climate change.

And richer nations need to step up and help low and middle income countries who are on the front lines of this risk, even though they've contributed so little to the problem itself.

There's a real equity and justice element running through all of this.

It's not just about building resilience through engineering means, but building a more fair and just society.

- Sounds like you're very passionate about the social science side of this.

- You know, I came to this work first from a science lens thinking about numbers, and projections and sea level rise.

And then I had the fortune to go into communities and meet people on the ground.

And it really shifts your perspective about what these numbers actually mean.

The, just the profound human aspects of this challenge that we face.

So to me, we have a choice here.

We can have this kind of bleak unfolding of depopulation and disinvestment, or we could have a collective process where we make the right investments, we do it with innovation and engineering and social cohesion, and we actually thrive.

I think there is really hope for this livable future and we have to secure it.

This is the future we're leaving to our children and grandchildren.

[Scott] Yeah.

- I would like to conclude with three points.

- Okay.

- Number one, I think we have no other option but to adapt and developing technical baselines with historic data is an essential prerequisite for understanding vulnerabilities of different ecosystems and communities.

Number two, adaptation measures must be location specific because success of adaptation depends on local support.

And it may require a lot of government investment.

So policy makers must be reminded that what they're deciding today, will have a profound effect on the future trajectories of exposure and vulnerability.

Number three, there is no other way, you know, each investment must go through very hard cost-benefit calculation.

In some cases, subsidized adaptation may work, in other cases, subsidized retreat from the threatened areas is the only best option.

And like Rachel, I'm also optimist.

You know, I really believe that we can learn from one another, in the successes as well as failures.

Action however, must start now.

- Well, look, I've really enjoyed our visit and conversation.

I appreciate your care and your knowledge.

- Wonderful to be here, thank you.

[Scott] Low coastal areas, particularly in equatorial developing countries, are starting to feel the effects of sea level rise, increased high tide flooding and salinization of freshwater aquifers and of farmland.

Many coastal cities are also sinking, which aggravates the issue.

The U.S. government predicts another 10 to 12 inches of rise by 2050, which could put homes, power plants, water treatment, and other infrastructure here at risk.

To adapt, cities can look to today's successful strategies.

New infrastructure, like levees and pumps can be a solution.

But these are expensive to build and maintain, and may lure other development into at-risk areas.

Natural solutions also work like mangrove forests, or even allowing flooding in some areas.

When people are forced to migrate, training programs, especially for women, have proven to help them settle in new places.

A combination of engineered, natural and social adaptation strategies will likely be most effective.

♪ ♪ ♪ ♪ ♪ ♪ [Narrator] Funding for "Energy Switch" was provided in part by The University of Texas at Austin, leading research in energy and the environment for a better tomorrow.

What starts here changes the world.