Could you imagine jumping from the
kitchen window and diving into water?
How much fun would that be?
Well, for some people, sure.
It seems unlikely, but it's not as crazy
as you might think.
Scientists predict that by 2050,
water levels
in 570 coastal cities worldwide
will rise by 0.5 m (1.6 ft),
threatening 800 million people.
In some cities,
the authorities have already responded
by building coastal walls for protection.
In other cities,
they are discussing the possibility
of making walls.
The climate crisis
is one of the biggest issues
facing humanity.
Ice sheets are melting
due to Earth's increasing temperature.
Because of that,
the sea level
is rising 4.8 mm (0.19 in) per year.
That seems such an insignificant number.
The problem is that ice melting
and the thermal expansion of ocean water
increase proportionally with temperature.
The more the planet continues to warm up,
the more the sea level will rise.
Climate scientists estimate that from 2040
to 2060, sea levels will rise 25 cm (9.8 in).
This could cause 100-year floods
on some coastlines,
and they could be
a near-annual occurence.
Now, imagine your daily routine with
25 cm (10 in) of water in your house,
at work, and on the street.
Rubber boots, anyone?
If all of our planet's
remaining small glaciers were to melt,
the sea level
would rise about 50 cm (19.7 in).
So, what would happen if
all of the ice sheets melt?
Well, there are three major
ice sheets on Earth.
One is in Greenland, and the other two
are in Antarctica,
known as the West
and the East Antarctic Ice Sheets.
The Greenland
and the West Antarctic Ice sheets
are melting and shrinking.
And, if they melt entirely,
the sea level
would be 12 m (39 ft) higher than it is now.
Much of our coastal cities
would be submerged.
So, you might want to save some money
for a comfy houseboat because
you would need one.
Thankfully, the East Antarctic,
the biggest of the three ice sheets,
is among the most stable.
It isn't gaining or losing mass.
Not yet.
If it did, though, the sea level would rise
another 53 m (174 ft)
for a total of 65 m (213 ft).
That would submerge
kilometers (miles) of coastal land,
and entire cities would disappear.
Maybe we would build floating cities,
and new generations of humans
might develop
bodies able to live under the water.
Yeah, right.
Before that happens,
let's just say we want to build walls
to protect our cities.
How much would they cost?
Well, it wouldn't be cheap, that's for sure.
The world's coastlines
are about 1.6 million km
(994,193 mi) long.
This is the same distance
as going to the Moon and back
twice
One estimation is that
approximately $400 billion,
just for the U.S.
Still, it would be cheaper than the $14.2
trillion in lost or damaged assets
projected to happen
by the end of the century.
More than 287 million people
could be exposed
to episodic coastal flooding
by the year 2100.
To put that in perspective,
Indonesia has a population
of around 273 million people.
You do the math.
Unfortunately, Indonesia is
also one of the countries most threatened
by rising sea levels
along with the United States,
northwestern Europe,
and large parts of Asia
like the Bay of Bengal, China,
and northern Australia.
Well, maybe we use traditional materials,
like rock or interlocking concrete units.
Or, we might build steel barriers
like the Maeslantkering
in the Netherlands.
This huge machine consists of two large
arms on each side of the waterway
that can be deployed when needed
to block it.
What we should keep in mind is that
these walls should work in balance
with the ecosystem and not disrupt it.
On this note,
there are also nature-based solutions
such as recreating dunes,
human-made reefs,
mangroves, or marshland
that would work just fine, if not better
than concrete walls.
Unfortunately,
nature-based solutions
don't seem to be the preferred option,
at least right now.
There are major plans all over the world
to start building the walls instead.
And we sure hope they'll work.
Otherwise, could you imagine how
awkward it would be if
New York's taxis were boats?
Well, that's a story for another What If.