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Transcript

Fresh Water – The Coming Scarcity · Talking Science

0:00
Right now, you are probably wearing clothes,
0:02
sitting in a building and digesting a meal that
0:06
was completely sustained by a resource that predates
0:09
human civilization. And we are, well, rapidly
0:13
running out of it. It is definitely a sobering
0:16
reality to wake up to. I mean, we live our daily
0:18
lives entirely dependent on these ancient systems
0:20
that most of us never even... thing to look at.
0:23
Which brings us to the really fascinating paradox
0:26
at the heart of today's deep dive. If you look
0:29
at a photograph of Earth from space, it does
0:32
not look like a world that is struggling for
0:34
water. Not at all. Right. It's a blue marble.
0:36
It looks like a planet that is just absolutely
0:39
drowning in water. I mean, oceans cover almost
0:41
three quarters of its surface. Yeah, exactly.
0:43
And yet fresh water like the kind we can actually
0:45
drink, the guy that grows our food and sustains
0:47
our cities, is one of the most incredibly scarce
0:49
and fiercely contested resources we have. It
0:52
really is. So reconciling those two facts is
0:55
our mission today. We're going to unpack where
0:56
all that water actually is, why our usable supply
1:00
is so astonishingly small. and how we actually
1:03
manage to survive on it. And I really want to
1:06
set a very clear, unhurried tone for us right
1:09
at the top here. You do not need to be a hydrologist
1:12
to understand what is happening here. Thank goodness.
1:15
Right. We are going to take this step by step.
1:17
We're going to follow the water together at a
1:19
comfortable pace and just really look at the
1:21
mechanics of why a planet literally covered in
1:25
oceans can still somehow run dry. I think to
1:29
really wrap our heads around the scarcity, we
1:31
first have to eliminate all the water that humanity
1:34
just can't easily use. Like start with those
1:36
global oceans and work our way all the way down
1:39
to the tiny. fraction we actually survive on.
1:41
Right. And when you lay the numbers out, they
1:43
are genuinely startling. Out of all the water
1:46
on Earth, the overwhelming majority of it, I'm
1:48
talking about 97 percent, is saltwater in the
1:51
oceans. 97 percent. So that is essentially just
1:53
off the table. Exactly. And I think sometimes
1:55
people wonder, why can't we just filter it easily?
1:59
Like, why is saltwater such a massive deal breaker
2:01
for agriculture and human consumption? Well,
2:05
it comes down to chemistry and energy. When salt
2:08
dissolves in water, it doesn't just float around
2:11
in there like sand. Right. You can't just scoop
2:13
it out. Exactly. It breaks down into ions. And
2:16
these are charged particles that bond very, very
2:19
tightly with the water molecules at a microscopic
2:22
level. Oh, wow. So to separate them, you have
2:24
to break those chemical bonds, which requires
2:27
just a tremendous amount of energy. What happens
2:30
if you just, I don't know, use it as is? Well,
2:32
if you pour salt water on a field of crops, the
2:35
salt actually pulls moisture out of the plant
2:38
roots through osmosis. Wait, really? Yeah. You
2:42
aren't watering the crops. You are literally
2:43
dehydrating them to death. So in its natural
2:46
state, that 97 % is totally useless to us. Okay,
2:50
so that leaves us with just 3 % of the planet's
2:53
water as fresh water. Which is already a massive
2:56
drop. It is. But it actually gets much tighter
2:58
than that, doesn't it? Much tighter. Because
3:00
most of that 3 % isn't available to us either.
3:03
The bulk of it is frozen solid. Like glaciers
3:05
and stuff. Yep. It's locked up in the great ice
3:08
sheets of Antarctica and Greenland and in mountain
3:11
glaciers all around the world. So we can't drink
3:14
that either. Unless we want to start, you know,
3:16
towing icebergs across the ocean. Which obviously
3:18
is not going to work. Right. So when you strip
3:20
away the salt water and you set aside all the
3:23
frozen water, the fresh water that is actually
3:25
liquid, reachable and usable, meaning, you know,
3:29
the water in our rivers or lakes and undergrounds
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comes to well under one percent. Of all the water
3:37
on the planet. Under 1%. That's our entire working
3:40
budget. Okay, let me try to visualize this. Because
3:42
numbers like that can be hard to grasp. Sure.
3:44
If I'm picturing all the water on Earth as like
3:46
a large 100 -slice pizza. Okay, I like pizza.
3:50
Right, so 97 of those slices are completely covered
3:52
in salt, totally inedible. Yep. Two of those
3:54
slices are frozen solid in the freezer. So humanity,
3:58
with all of our industry and agriculture, is
4:01
essentially fighting over a single crumb that
4:04
fell off the crust of the very last slice. That
4:06
is exactly the scale we were talking about. It's
4:08
a single crumb. Every single farm that grows
4:11
your food, every factory that manufactures your
4:14
phone, and every city you rely on is drawing
4:17
from that tiny microscopic fraction of a fraction.
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It's staggering when you put it like that. So
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if humanity is surviving on less than 1 % of
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the world's water, the most obvious question
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is, where is it? Because when I think of freshwater,
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I immediately picture rivers and lakes. And that's
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what most people picture. But rivers and lakes
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are just a drop in the bucket of that 1%. Really?
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So where's the rest? A surprisingly massive share
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of our usable freshwater is completely hidden
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from view. It is stored deep underground in what
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are called aquifers. Okay, aquifers. If you're
4:52
listening to this and wondering what an aquifer
4:54
actually is, it's not... Like a giant underground
4:57
lake like you see in the movies, right? No, not
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at all. Think of an aquifer more like a giant
5:01
natural sponge made of rock beneath our feet.
5:03
Rock sponge. Right. It's composed of layers of
5:06
porous rock, gravel, and sand. And over incredibly
5:09
long periods of time, water trickles down from
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the staphis and saturates the tiny microscopic
5:15
spaces inside that rock. So how does the water
5:18
actually move through solid rock? That sounds
5:21
super counterintuitive to me. It's all about
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porosity and permeability. Even rock that looks
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totally solid to the naked eye, like sandstone,
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has tiny gaps between the grains. Oh, I see.
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And if those gaps are connected, water can slowly
5:34
seep through them, just driven by gravity. In
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many parts of the world, this groundwater is
5:39
drawn up to the surface through wells and bores,
5:41
acting as an absolute lifeline for agriculture
5:43
and drinking supplies. But there has to be a
5:46
catch here. A sponge sounds great, but it has
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to soak up that water from somewhere. I mean,
5:50
it has to rain, and that rain has to slowly filter
5:53
down through hundreds of feet of dirt and rock.
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And that takes time. These underground aquifers
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fill up extraordinarily slowly. Like how slowly?
6:00
We are talking about water trickling down over
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centuries, or in many cases, millennia. It's
6:05
an ancient savings account. Okay, wait, let me
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push back on that savings account idea for a
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second. Sure, go ahead. Because if it takes millennia
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to fill up... And we are pumping it out with
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these massive industrial pumps way faster than
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the rain can possibly replenish it. We aren't
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just using water, are we? We are literally mining
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it. Like we are extracting it the exact same
6:26
way we would extract coal or gold. Once we take
6:29
it out, it's effectively gone for our lifetimes.
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That is the precise reality of the situation.
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We are mining our water. And the consequences
6:37
of that are profound. I can imagine. When you
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pump water out of the pores of that underground
6:43
rock faster than it refills, the rock actually
6:46
starts to compress. Oh, because the water was
6:48
holding it up. Exactly. The land itself begins
6:51
to sink. It's a process called subsidence. In
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a number of major agricultural regions worldwide,
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the ground is literally dropping by inches every
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single year, and the water tables are falling
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deeper and deeper out of reach. That is terrifying.
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So we have this tiny fraction of water to begin
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with. We are pumping it out of these ancient
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underground sponges way faster than it can refill.
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This naturally brings a community to a breaking
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point, which brings us to a really critical concept,
7:18
which is water stress. Yes, water stress. So
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what does that actually mean in practice? A region
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is in a state of water stress when the demand
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for fresh water starts to bump up against or
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completely exceed the sustainable, renewable
7:33
supply. So if we're hitting that limit. What
7:35
is actually driving the massive demand? Because
7:38
when I think of wasting water, my mind immediately
7:40
goes to leaving the tap running while I brush
7:43
my teeth or, you know, taking a slightly too
7:45
long shower. Are our household habits really
7:47
the thing pushing the planet to the brink? It's
7:50
a very common misconception. I mean, obviously,
7:52
fixing a running tap is a good thing to do. Right.
7:54
Nobody's saying to waste water. Exactly. But
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household use is a tiny sliver of the pie. The
8:00
real immense pressure on our water systems comes
8:03
from agriculture. Growing our food. Exactly.
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Growing our food consumes the lion's share of
8:08
fresh water globally. Think about the concept
8:12
of virtual water. Virtual water. What is that?
8:15
It's the hidden water footprint of the things
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we consume. For example, to produce a single
8:20
cotton t -shirt, it takes thousands of liters
8:23
of water just to grow the cotton. Wow. For one
8:26
shirt? Yes. And a single steak. That requires
8:30
thousands of liters of water to grow the feed
8:32
that the cow eats over its entire lifetime. The
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sheer volume of hidden water on your dinner plate
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is astronomical. And it isn't just that demand
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is skyrocketing, right? Yeah. The supply itself
8:43
is being squeezed by outside factors at the same
8:46
time. Precisely. You have pollution, which can
8:48
completely spoil aquifers or rivers that would
8:51
otherwise be perfectly usable. Making our one
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crumb even smaller. Yep. And then crucially,
8:55
you have climate change. How does climate change
8:58
specifically alter the water supply? Does it
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just, I don't know, make things hotter so water
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evaporates faster? Well, evaporation is definitely
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part of it. A warmer atmosphere acts like a bigger
9:09
sponge. It holds more moisture, literally pulling
9:13
it out of the soil. But more importantly, climate
9:16
change actively shifts global atmospheric circulation.
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Okay, what does that mean for us? It means the
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bands of rainfall that have reliably watered
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our major agricultural zones for centuries are
9:27
physically moving. Oh, wow. Yeah. So regions
9:30
that are already dry are getting drier and the
9:33
droughts they experience are becoming longer
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and much harsher. So if we're trapped in the
9:38
zero sum game where agricultural demand is through
9:41
the roof, aquifers are being mined dry and rainfall
9:44
patterns are literally moving away from us. What
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does that actually look like in real life? Because
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we can't just legislate rain into existence.
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No, we certainly can't. If you want to see what
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this high stakes balancing act looks like in
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real time, look at Australia. Australia. Yeah.
9:58
It is the ultimate test case being the driest
10:01
inhabited continent on Earth. And the specific
10:04
focal point we should look at is a region called
10:06
the Murray -Darling Basin. What makes the Murray
10:08
-Darling Basin so critical to this? Well, it
10:11
is a massive network of interconnected rivers
10:13
located in the southeast of the country. It is
10:16
essentially Australia's food bowl. So they grow
10:19
everything there. Right. It produces a huge portion
10:21
of the entire nation's agricultural output. But
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it's not just farms. This river system sustains
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entire towns. It holds profound cultural significance
10:32
for Aboriginal communities who have ancient ties
10:34
to those waters. And it supports incredibly delicate,
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internationally recognized... wetland ecosystems.
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So you have all these different groups, corporate
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agriculture, small towns, indigenous communities,
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the environment itself, all relying on this one
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single river system. And that is exactly where
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the squeeze happens because they are all drinking
10:55
from the same finite, highly variable supply.
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In a dry year, there simply isn't enough water
11:00
to satisfy everyone. So how does the math work
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when there isn't enough? Who loses? Well, if
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you prioritize agriculture and allow farmers
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to pump enough water to keep their crops alive,
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the rivers themselves suffer immensely. The water
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levels drop so low that the flow stagnates. Algae
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blooms form, turning the water toxic. The wetlands
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completely dry out, and you see mass die -offs
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of native fish. That's awful. But if you do the
11:25
opposite. If you leave the water in the rivers
11:28
to protect the environment, then the farmers
11:30
don't have enough to irrigate. The crops fail.
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And it's not just the farmer who hurts. The towns
11:35
that rely on agricultural commerce dry up, farm
11:38
workers lose their jobs, and the cost of food
11:41
nationwide spikes. It is a deeply painful economic
11:45
squeeze either way. It really is. Let me play
11:47
devil's advocate here for a second, though. Go
11:49
for it. Because when you lay it out like that,
11:51
it sounds like an administrative gridlock. Why
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can't the government just step in, look at the
11:56
science and make a definitive ruling? Just say,
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you know, environment first, everyone stop pumping.
12:01
Or people first, keep farming no matter what.
12:04
Why is it so complicated? Because neither of
12:06
those extremes results in a functioning society.
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You can't just decree a simple fix. If you bankrupt
12:11
the farming communities, the national food supply
12:14
chain collapses. People still have to eat. Exactly.
12:17
But if you destroy the river ecosystem, the water
12:20
source eventually turns into a toxic, salty ditch
12:23
and the agriculture dies anyway. Managing a basin
12:26
like this means constantly trying to balance
12:28
competing, deeply valid needs. It's a true zero
12:31
sum game. If the fish get the water, the almond
12:34
trees don't. Exactly. The Murray -Darling Basin
12:37
has been the subject of decades of incredibly
12:39
difficult, politically fraught negotiation. It
12:43
involves water markets where water rights are
12:45
bought and sold, government buybacks of water
12:47
allocations, and relying on incredibly complex
12:49
hydrology models. Sounds exhausting. It is a
12:52
grueling, agonizing process of compromise. There
12:55
is no magic solution that makes everyone happy.
12:58
Which naturally leads us to the biggest question
13:00
of this whole deep dive. How do we actually survive
13:03
this? Right. If there are no perfect Conflict
13:06
-free political solutions. We need practical
13:08
tools to prevent a total crisis. What is in our
13:12
survival toolkit to actually manage this stretched
13:14
resource? Well, the toolkit has several components,
13:16
but the biggest, most effective lever we have
13:18
is efficiency, particularly where we use the
13:21
most water in agriculture. Right, because if
13:23
agriculture is taking the lion's share, making
13:25
it even, I don't know, 5 % more efficient saves
13:28
more water than everyone in a city taking shorter
13:31
showers. Exactly. And a huge part of that is
13:34
revolutionizing how we irrigate. For a long time,
13:37
standard practice has been flood irrigation,
13:40
literally just flooding a field or using massive
13:43
sprayers. I see those sprayers all the time when
13:45
I drive past farms. Yeah. And when you spray
13:47
water wildly into the air in a hot climate, a
13:51
huge percentage of it just evaporates before
13:53
it ever even hits the dirt. That makes a lot
13:55
of sense. So what's the fix? The fix is transitioning
13:58
to drip irrigation. works of tubes to deliver
14:02
tiny amounts of water directly to the roots of
14:05
the plants exactly when they need it. So no evaporation.
14:08
Very little. It also means shifting away from
14:11
growing incredibly thirsty, water intensive crops
14:13
in the middle of a desert and planting crops
14:16
that are actually suited to the local climate.
14:18
That makes total sense. So if agriculture is
14:20
the big offender, cities must just be like a
14:23
drop in the bucket. Is there even a point in
14:26
urban areas overhauling their infrastructure
14:29
or are we just treating a symptom? Oh, it absolutely
14:31
matters because urban centers are incredibly
14:34
dense and demand a continuous, hyper -reliable
14:37
supply of highly treated water. Okay, fair point.
14:40
And right now, many cities waste a staggering
14:43
amount of it before it ever reaches a tap. How?
14:45
Like, where is it going? Aging infrastructure
14:48
means leaky underground pipes are silently bleeding
14:51
20 to 30 percent of a city's treated water right
14:54
back into the dirt. 20 to 30 percent? That's
14:56
huge. It is. Fixing those leaks is paramount.
15:00
Cities are also increasingly recycling wastewater,
15:02
treating it to a remarkably high standard and
15:05
using it for industry, parks, or even pumping
15:07
it back into aquifers to recharge them. Okay,
15:09
what about the technological fix that always
15:11
gets brought up? We started this whole conversation
15:14
by saying the Earth is drowning in saltwater.
15:16
So let's talk about desalination. Ah, desalination.
15:19
For anyone unfamiliar, desalination is the process
15:23
of removing the salt from seawater to make it
15:26
fresh and drinkable. Why isn't this the ultimate
15:29
silver bullet for us? Because of the physics
15:31
we talked about earlier. To get the salt out,
15:33
modern desalination plants use a process called
15:36
reverse osmosis. Avert osmosis. Right. They take
15:39
ocean water and use... Like, it keeps you alive
15:42
this month, but the math eventually crushes you.
15:44
It's great to have in your wallet for severe
15:46
drought emergency, but you really don't want
15:49
to try and live off it every single day. Exactly.
15:51
You do not want to be paying the high interest
15:54
energy costs of desalination every day if you
15:56
can avoid it. For wealthy coastal cities, it
15:59
provides an incredible drought -proof backstop,
16:03
but it is a backstop, not a cheap cure -all.
16:06
Right. You can't exactly use desalinated water
16:09
to affordably grow cheap crops. The mask just
16:12
doesn't work. So we have agricultural efficiency,
16:14
we have plugging the leaks in urban infrastructure,
16:17
and we have desalination as our emergency credit
16:19
card. What ties all of this together? The final
16:22
tool is the unglamorous but absolutely vital
16:25
foundation of everything, which is just good
16:27
management. The paperwork and the data. The paperwork,
16:30
the science, the metering. You cannot manage
16:32
what you do not measure. It means rigorously
16:35
monitoring exactly how much water is in the aquifers,
16:38
deciding transparently and fairly how it gets
16:41
shared among all those competing interests we
16:43
talked about, and aggressively protecting the
16:45
health of the rivers so they don't turn into
16:47
toxic dead zones. None of that really makes for
16:49
flashy headlines, does it? No, but those management
16:52
practices are exactly how water scarce regions
16:55
keep from collapsing. So as we bring this deep
16:58
dive to a close. What is the core takeaway for
17:01
you as the listener? How do we synthesize all
17:04
of this? I think the most important thing is
17:06
to avoid alarmism, but completely reject complacency.
17:09
The water cycle is a closed loop. Meaning it
17:12
doesn't leave the planet. Right. Water evaporates.
17:15
It forms clouds. It falls as rain. Freshwater
17:18
is not magically vanishing into space. The total
17:21
amount of water on Earth remains basically the
17:24
exact same. You're just moving around or getting
17:26
harder to access. Exactly. The freshwater available
17:29
to us at any given time and in our specific locations
17:31
is limited, it is unevenly distributed, and it
17:35
is being stretched incredibly thin by rising
17:37
demand and shifting climates. But it's not hopeless.
17:40
Not at all. The situation is entirely solvable.
17:43
We have the tools. We just discussed them. Efficiency,
17:46
smart technology, and sensible sharing. The challenge
17:49
isn't that we are running out of water on a blue
17:51
planet. The challenge is learning how to wisely
17:54
manage a precious, thinly spread resource. And
17:57
managing it wisely really does start with simply
18:00
appreciating how rare and mechanically fascinating
18:03
it actually is. So to you, the listener, the
18:06
next time you turn on your tap in the kitchen,
18:08
just remember the physics and the journey behind
18:11
that water. You are accessing a microscopic...
18:15
precious fraction of a massive blue planet. It
18:18
really does completely change your perspective
18:20
when you see the hidden systems behind it. It
18:22
really does. And I want to leave you with one
18:24
final unhurried thought to mull over as you go
18:26
about the rest of your day. We talked earlier
18:28
about how much of the water we rely on for agriculture
18:30
is pumped from those deep hidden aquifers, the
18:33
giant underground layers of rock that took millennia
18:36
to fill. Fossil water. Exactly. That means we
18:39
are effectively using fossil water. When you
18:42
sit down to eat dinner tonight, consider that
18:44
the food on your plate might have been grown
18:45
using water that fell as rain thousands of years
18:48
before human civilization even began. We are
18:51
currently eating into that ancient inheritance,
18:53
and the question we all have to face is, what
18:56
happens to our global food supply when that ancient
18:58
irreplaceable well finally runs dry?