0:00:00.667,0:00:03.953
It may seem like we're all standing[br]on solid Earth right now,

0:00:03.977,0:00:05.350
but we're not.

0:00:05.753,0:00:10.150
The rocks and the dirt underneath us[br]are crisscrossed by tiny little fractures

0:00:10.174,0:00:11.573
and empty spaces.

0:00:11.597,0:00:16.526
And these empty spaces are filled[br]with astronomical quantities of microbes,

0:00:16.550,0:00:17.817
such as these ones.

0:00:18.866,0:00:22.229
The deepest that we found microbes[br]so far into the Earth

0:00:22.253,0:00:24.141
is five kilometers down.

0:00:24.165,0:00:26.321
So like, if you pointed[br]yourself at the ground

0:00:26.345,0:00:28.664
and took off running into the ground,

0:00:28.688,0:00:32.359
you could run an entire 5K race[br]and microbes would line your whole path.

0:00:33.044,0:00:35.568
So you may not have ever thought[br]about these microbes

0:00:35.592,0:00:37.282
that are deep inside Earth's crust,

0:00:37.306,0:00:40.268
but you probably thought[br]about the microbes living in our guts.

0:00:40.292,0:00:42.109
If you add up the gut microbiomes

0:00:42.133,0:00:44.974
of all the people[br]and all the animals on the planet,

0:00:44.998,0:00:48.907
collectively, this weighs[br]about 100,000 tons.

0:00:48.931,0:00:53.224
This is a huge biome that we carry[br]in our bellies every single day.

0:00:53.907,0:00:55.324
We should all be proud.

0:00:55.348,0:00:56.454
(Laughter)

0:00:56.478,0:01:00.350
But it pales in comparison[br]to the number of microbes

0:01:00.374,0:01:02.859
that are covering[br]the entire surface of the Earth,

0:01:02.883,0:01:05.714
like in our soils,[br]our rivers and our oceans.

0:01:05.738,0:01:09.611
Collectively, these weigh[br]about two billion tons.

0:01:10.174,0:01:12.770
But it turns out that the majority[br]of microbes on Earth

0:01:12.794,0:01:16.571
aren't even in oceans or our guts[br]or sewage treatment plants.

0:01:16.595,0:01:19.372
Most of them are actually[br]inside the Earth's crust.

0:01:19.396,0:01:23.245
So collectively,[br]these weigh 40 billion tons.

0:01:23.754,0:01:27.045
This is one of the biggest[br]biomes on the planet,

0:01:27.069,0:01:30.505
and we didn't even know it existed[br]until a few decades ago.

0:01:30.847,0:01:33.542
So the possibilities[br]for what life is like down there,

0:01:33.566,0:01:36.111
or what it might do for humans,

0:01:36.135,0:01:37.835
are limitless.

0:01:38.367,0:01:40.239
This is a map showing a red dot

0:01:40.263,0:01:43.621
for every place where we've gotten[br]pretty good deep subsurface samples

0:01:43.645,0:01:45.463
with modern microbiological methods,

0:01:45.487,0:01:46.870
and you may be impressed

0:01:46.894,0:01:49.204
that we're getting a pretty good[br]global coverage,

0:01:49.228,0:01:52.085
but actually, if you remember[br]that these are the only places

0:01:52.109,0:01:54.490
that we have samples from,[br]it looks a little worse.

0:01:54.514,0:01:56.323
If we were all in an alien spaceship,

0:01:56.347,0:02:00.006
trying to reconstruct the map of the globe[br]from only these samples,

0:02:00.030,0:02:02.352
we'd never be able to do it.

0:02:03.218,0:02:05.519
So people sometimes say to me,

0:02:05.543,0:02:09.059
"Yeah, there's a lot of microbes[br]in the subsurface, but ...

0:02:09.083,0:02:10.733
aren't they just kind of dormant?"

0:02:11.710,0:02:13.227
This is a good point.

0:02:13.251,0:02:18.101
Relative to a ficus plant or the measles[br]or my kid's guinea pigs,

0:02:18.125,0:02:21.156
these microbes probably[br]aren't doing much of anything at all.

0:02:21.180,0:02:25.006
We know that they have to be slow,[br]because there's so many of them.

0:02:25.030,0:02:27.720
If they all started dividing[br]at the rate of E. coli,

0:02:27.744,0:02:31.061
then they would double the entire[br]weight of the Earth, rocks included,

0:02:31.085,0:02:32.561
over a single night.

0:02:33.046,0:02:37.579
In fact, many of them probably haven't[br]even undergone a single cell division

0:02:37.603,0:02:39.736
since the time of ancient Egypt.

0:02:40.180,0:02:41.640
Which is just crazy.

0:02:41.664,0:02:47.242
Like, how do you wrap your head[br]around things that are so long-lived?

0:02:47.266,0:02:50.410
But I thought of an analogy[br]that I really love,

0:02:50.434,0:02:52.255
but it's weird and it's complicated.

0:02:52.279,0:02:54.450
So I hope that you can all[br]go there with me.

0:02:54.474,0:02:55.720
Alright, let's try it.

0:02:56.299,0:02:59.148
It's like trying to figure out[br]the life cycle of a tree ...

0:02:59.172,0:03:01.117
if you only lived for a day.

0:03:01.141,0:03:05.522
So like if human life span was only a day,[br]and we lived in winter,

0:03:05.546,0:03:07.171
then you would go your entire life

0:03:07.195,0:03:09.768
without ever seeing a tree[br]with a leaf on it.

0:03:09.792,0:03:11.847
And there would be so many[br]human generations

0:03:11.871,0:03:13.895
that would pass by within a single winter

0:03:13.919,0:03:16.315
that you may not even have access[br]to a history book

0:03:16.339,0:03:20.141
that says anything other than the fact[br]that trees are always lifeless sticks

0:03:20.165,0:03:21.696
that don't do anything.

0:03:21.720,0:03:23.379
Of course, this is ridiculous.

0:03:23.403,0:03:25.553
We know that trees[br]are just waiting for summer

0:03:25.577,0:03:26.926
so they can reactivate.

0:03:26.950,0:03:29.125
But if the human life span

0:03:29.149,0:03:32.228
were significantly shorter[br]than that of trees,

0:03:32.252,0:03:36.107
we might be completely oblivious[br]to this totally mundane fact.

0:03:36.879,0:03:41.807
So when we say that these deep[br]subsurface microbes are just dormant,

0:03:41.831,0:03:46.003
are we like people who die after a day,[br]trying to figure out how trees work?

0:03:46.601,0:03:48.491
What if these deep subsurface organisms

0:03:48.515,0:03:50.822
are just waiting[br]for their version of summer,

0:03:50.846,0:03:53.913
but our lives are too short[br]for us to see it?

0:03:54.784,0:03:58.324
If you take E. coli[br]and seal it up in a test tube,

0:03:58.348,0:03:59.690
with no food or nutrients,

0:03:59.714,0:04:02.182
and leave it there for months to years,

0:04:02.206,0:04:05.222
most of the cells die off, of course,[br]because they're starving.

0:04:05.246,0:04:07.552
But a few of the cells survive.

0:04:07.576,0:04:09.766
If you take these old surviving cells

0:04:09.790,0:04:12.657
and compete them,[br]also under starvation conditions,

0:04:12.681,0:04:15.855
against a new, fast-growing[br]culture of E. coli,

0:04:15.879,0:04:19.618
the grizzled old tough guys[br]beat out the squeaky clean upstarts

0:04:19.642,0:04:20.990
every single time.

0:04:21.339,0:04:25.942
So this is evidence there's actually[br]an evolutionary payoff

0:04:25.966,0:04:28.180
to being extraordinarily slow.

0:04:28.736,0:04:30.625
So it's possible

0:04:30.649,0:04:37.389
that maybe we should not equate[br]being slow with being unimportant.

0:04:38.402,0:04:41.084
Maybe these out-of-sight,[br]out-of-mind microbes

0:04:41.108,0:04:43.315
could actually be helpful to humanity.

0:04:44.125,0:04:45.407
OK, so as far as we know,

0:04:45.431,0:04:47.537
there are two ways to do[br]subsurface living.

0:04:47.871,0:04:51.513
The first is to wait for food[br]to trickle down from the surface world,

0:04:51.537,0:04:56.045
like trying to eat the leftovers[br]of a picnic that happened 1,000 years ago.

0:04:56.069,0:04:58.093
Which is a crazy way to live,

0:04:58.117,0:05:01.275
but shockingly seems to work out[br]for a lot of microbes in Earth.

0:05:01.698,0:05:05.119
The other possibility[br]is for a microbe to just say,

0:05:05.143,0:05:07.618
"Nah, I don't need the surface world.

0:05:07.642,0:05:09.095
I'm good down here."

0:05:09.119,0:05:10.791
For microbes that go this route,

0:05:10.815,0:05:14.458
they have to get everything[br]that they need in order to survive

0:05:14.482,0:05:16.299
from inside the Earth.

0:05:18.205,0:05:20.661
Some things are actually[br]easier for them to get.

0:05:20.685,0:05:22.553
They're more abundant inside the Earth,

0:05:22.577,0:05:26.395
like water or nutrients,[br]like nitrogen and iron and phosphorus,

0:05:26.419,0:05:27.592
or places to live.

0:05:27.616,0:05:30.776
These are things that we literally[br]kill each other to get ahold of

0:05:30.800,0:05:32.014
up at the surface world.

0:05:32.038,0:05:35.569
But in the subsurface,[br]the problem is finding enough energy.

0:05:36.101,0:05:37.291
Up at the surface,

0:05:37.315,0:05:41.403
plants can chemically knit together[br]carbon dioxide molecules into yummy sugars

0:05:41.427,0:05:44.403
as fast as the sun's photons[br]hit their leaves.

0:05:44.427,0:05:46.955
But in the subsurface, of course,[br]there's no sunlight,

0:05:46.979,0:05:49.693
so this ecosystem has to solve the problem

0:05:49.717,0:05:52.982
of who is going to make the food[br]for everybody else.

0:05:53.416,0:05:57.291
The subsurface needs something[br]that's like a plant

0:05:57.315,0:05:59.102
but it breathes rocks.

0:05:59.641,0:06:02.776
Luckily, such a thing exists,

0:06:02.800,0:06:05.124
and it's called a chemolithoautotroph.

0:06:05.148,0:06:06.156
(Laughter)

0:06:06.180,0:06:10.204
Which is a microbe[br]that uses chemicals -- "chemo,"

0:06:10.228,0:06:12.458
from rocks -- "litho,"

0:06:12.482,0:06:15.244
to make food -- "autotroph."

0:06:15.268,0:06:17.926
And they can do this[br]with a ton of different elements.

0:06:17.950,0:06:21.783
They can do this with sulphur,[br]iron, manganese, nitrogen, carbon,

0:06:21.807,0:06:25.037
some of them can use[br]pure electrons, straight up.

0:06:25.530,0:06:27.942
Like, if you cut the end[br]off of an electrical cord,

0:06:27.966,0:06:29.875
they could breath it like a snorkel.

0:06:29.899,0:06:31.211
(Laughter)

0:06:31.235,0:06:32.736
These chemolithoautotrophs

0:06:32.760,0:06:35.395
take the energy that they get[br]from these processes

0:06:35.419,0:06:37.831
and use it to make food, like plants do.

0:06:37.855,0:06:40.658
But we know that plants do more[br]than just make food.

0:06:41.103,0:06:43.419
They also make a waste product, oxygen,

0:06:43.443,0:06:45.471
which we are 100 percent dependent upon.

0:06:45.992,0:06:49.277
But the waste product[br]that these chemolithoautotrophs make

0:06:49.301,0:06:51.268
is often in the form of minerals,

0:06:51.292,0:06:55.871
like rust or pyrite, like fool's gold,

0:06:55.895,0:06:57.895
or carminites, like limestone.

0:06:58.680,0:07:05.283
So what we have are microbes[br]that are really, really slow, like rocks,

0:07:06.243,0:07:09.649
that get their energy from rocks,

0:07:09.673,0:07:12.870
that make as their waste[br]product other rocks.

0:07:13.268,0:07:17.089
So am I talking about biology[br]or am I talking about geology?

0:07:17.466,0:07:19.609
This stuff really blurs the lines.

0:07:19.633,0:07:20.637
(Laughter)

0:07:20.661,0:07:22.807
So if I'm going to do this thing,

0:07:22.831,0:07:26.149
and I'm going to be a biologist[br]who studies microbes

0:07:26.173,0:07:28.378
that kind of act like rocks,

0:07:28.402,0:07:31.776
then I should probably[br]start studying geology.

0:07:31.800,0:07:34.910
And what's the coolest part of geology?

0:07:35.292,0:07:36.460
Volcanoes.

0:07:36.484,0:07:37.735
(Laughter)

0:07:37.759,0:07:41.480
This is looking inside the crater[br]of Poás Volcano in Costa Rica.

0:07:41.854,0:07:45.632
Many volcanoes on Earth arise[br]because an oceanic tectonic plate

0:07:45.656,0:07:47.466
crashes into a continental plate.

0:07:47.490,0:07:49.403
As this oceanic plate subducts

0:07:49.427,0:07:51.792
or gets moved underneath[br]this continental plate,

0:07:51.816,0:07:54.657
things like water and carbon dioxide[br]and other materials

0:07:54.681,0:07:55.916
get squeezed out of it,

0:07:55.940,0:07:57.666
like ringing a wet washcloth.

0:07:58.382,0:08:02.064
So in this way, subduction zones[br]are like portals into the deep Earth,

0:08:02.088,0:08:05.849
where materials are exchanged between[br]the surface and the subsurface world.

0:08:05.873,0:08:08.901
So I was recently invited[br]by some of my colleagues in Costa Rica

0:08:08.925,0:08:12.028
to come and work with them[br]on some of the volcanoes.

0:08:12.052,0:08:16.650
And of course I said yes,[br]because, I mean, Costa Rica is beautiful,

0:08:16.674,0:08:19.954
but also because it sits on top[br]of one of these subduction zones.

0:08:20.478,0:08:23.272
We wanted to ask[br]the very specific question,

0:08:23.296,0:08:25.684
why is it that the carbon dioxide

0:08:25.708,0:08:28.684
that comes out of this deeply buried[br]oceanic tectonic plate

0:08:28.708,0:08:30.815
is only coming out of the volcanoes?

0:08:30.839,0:08:34.133
Why don't we see it distributed[br]throughout the entire subduction zone?

0:08:34.157,0:08:36.640
Do the microbes have something[br]to do with that?

0:08:36.664,0:08:40.287
So this is a picture of me[br]inside Poás Volcano,

0:08:40.311,0:08:42.495
along with my colleague[br]Donato Giovannelli.

0:08:42.519,0:08:46.121
That lake that we're standing next to[br]is made of pure battery acid.

0:08:46.145,0:08:49.867
I know this because we were measuring[br]the pH when this picture was taken.

0:08:50.362,0:08:53.093
And at some point while[br]we were working inside the crater,

0:08:53.117,0:08:57.696
I turned to my Costa Rican colleague[br]Carlos Ramírez and I said,

0:08:57.720,0:09:01.087
"Alright, if this thing[br]starts erupting right now,

0:09:01.111,0:09:02.844
what's our exit strategy?"

0:09:03.269,0:09:06.412
And he said, "Oh, yeah,[br]great question, it's totally easy.

0:09:06.436,0:09:09.514
Just turn around and enjoy the view."

0:09:09.538,0:09:10.831
(Laughter)

0:09:10.855,0:09:12.402
"Because it will be your last."

0:09:12.426,0:09:13.561
(Laughter)

0:09:13.585,0:09:17.030
And it may sound like[br]he was being overly dramatic,

0:09:17.054,0:09:21.807
but 54 days after I was standing[br]next to that lake,

0:09:21.831,0:09:23.252
this happened.

0:09:23.276,0:09:24.434
Audience: Oh!

0:09:25.204,0:09:26.854
Freaking terrifying, right?

0:09:26.878,0:09:28.028
(Laughs)

0:09:28.934,0:09:33.287
This was the biggest eruption[br]this volcano had had in 60-some-odd years,

0:09:33.311,0:09:35.795
and not long after this video ends,

0:09:35.819,0:09:38.462
the camera that was taking[br]the video is obliterated

0:09:38.486,0:09:40.906
and the entire lake[br]that we had been sampling

0:09:40.930,0:09:42.330
vaporizes completely.

0:09:42.815,0:09:44.617
But I also want to be clear

0:09:44.641,0:09:47.141
that we were pretty sure[br]this was not going to happen

0:09:47.165,0:09:49.418
on the day that we were[br]actually in the volcano,

0:09:49.442,0:09:52.075
because Costa Rica monitors[br]its volcanoes very carefully

0:09:52.099,0:09:53.662
through the OVSICORI Institute,

0:09:53.686,0:09:56.892
and we had scientists from that institute[br]with us on that day.

0:09:56.916,0:10:00.006
But the fact that it erupted[br]illustrates perfectly

0:10:00.030,0:10:02.538
that if you want to look[br]for where carbon dioxide gas

0:10:02.562,0:10:04.426
is coming out of this oceanic plate,

0:10:04.450,0:10:07.553
then you should look no further[br]than the volcanoes themselves.

0:10:07.577,0:10:09.846
But if you go to Costa Rica,

0:10:09.870,0:10:12.330
you may notice that in addition[br]to these volcanoes

0:10:12.354,0:10:15.598
there are tons of cozy little hot springs[br]all over the place.

0:10:16.069,0:10:19.339
Some of the water in these hot springs[br]is actually bubbling up

0:10:19.363,0:10:21.664
from this deeply buried oceanic plate.

0:10:21.688,0:10:25.184
And our hypothesis was[br]that there should be carbon dioxide

0:10:25.208,0:10:26.387
bubbling up with it,

0:10:26.411,0:10:29.593
but something deep underground[br]was filtering it out.

0:10:29.617,0:10:33.799
So we spent two weeks[br]driving all around Costa Rica,

0:10:33.823,0:10:36.720
sampling every hot spring we could find --

0:10:36.744,0:10:38.418
it was awful, let me tell you --

0:10:38.442,0:10:44.078
and then, we spent the next two years[br]measuring and analyzing data.

0:10:44.102,0:10:47.911
And if you're not a scientist, I'll just[br]let you know that the big discoveries

0:10:47.935,0:10:50.768
don't really happen[br]when you're in a beautiful hot spring

0:10:50.792,0:10:51.943
or on a public stage,

0:10:51.967,0:10:54.490
they happen when you're hunched[br]over a messy computer

0:10:54.514,0:10:56.831
or you're troubleshooting[br]a difficult instrument,

0:10:56.855,0:10:58.593
or you're Skyping your colleagues

0:10:58.617,0:11:01.212
because you are completely[br]confused about your data.

0:11:01.236,0:11:04.567
Scientific discoveries,[br]kind of like deep subsurface microbes,

0:11:04.591,0:11:06.359
can be very, very slow.

0:11:07.267,0:11:10.616
But in our case,[br]this really paid off this one time.

0:11:10.640,0:11:14.918
We discovered that literally[br]tons of carbon dioxide

0:11:14.942,0:11:18.125
were coming out of this[br]deeply buried oceanic plate.

0:11:18.149,0:11:20.498
And the thing that was keeping[br]them underground

0:11:20.522,0:11:23.517
and keeping it from being released[br]out into the atmosphere

0:11:23.541,0:11:25.101
was that deep underground,

0:11:25.125,0:11:29.109
underneath all the adorable sloths[br]and toucans of Costa Rica,

0:11:29.133,0:11:30.933
were chemolithoautotrophs.

0:11:31.338,0:11:34.839
These microbes and the chemical processes[br]that were happening around them

0:11:34.863,0:11:37.615
were converting this carbon dioxide[br]into carbonate mineral

0:11:37.639,0:11:39.567
and locking it up underground.

0:11:39.591,0:11:41.885
Which makes you wonder:

0:11:41.909,0:11:45.410
If these subsurface processes[br]are so good at sucking up

0:11:45.434,0:11:48.015
all the carbon dioxide[br]coming from below them,

0:11:48.039,0:11:50.499
could they also help us[br]with a little carbon problem

0:11:50.523,0:11:52.688
we've got going on up at the surface?

0:11:53.006,0:11:57.331
Humans are releasing enough[br]carbon dioxide into our atmosphere

0:11:57.355,0:12:00.329
that we are decreasing[br]the ability of our planet

0:12:00.353,0:12:02.353
to support life as we know it.

0:12:02.704,0:12:05.136
And scientists and engineers[br]and entrepreneurs

0:12:05.160,0:12:07.664
are working on methods[br]to pull carbon dioxide

0:12:07.688,0:12:08.981
out of these point sources,

0:12:09.005,0:12:11.323
so that they're not released[br]into the atmosphere.

0:12:11.347,0:12:12.998
And they need to put it somewhere.

0:12:13.022,0:12:14.199
So for this reason,

0:12:14.223,0:12:17.561
we need to keep studying places[br]where this carbon might be stored,

0:12:17.585,0:12:19.879
possibly in the subsurface,

0:12:19.903,0:12:22.546
to know what's going to happen to it[br]when it goes there.

0:12:22.570,0:12:26.037
Will these deep subsurface microbes[br]be a problem because they're too slow

0:12:26.061,0:12:27.942
to actually keep anything down there?

0:12:27.966,0:12:29.374
Or will they be helpful

0:12:29.398,0:12:33.188
because they'll help convert this stuff[br]to solid carbonate minerals?

0:12:33.712,0:12:36.132
If we can make such a big breakthrough

0:12:36.156,0:12:38.542
just from one study[br]that we did in Costa Rica,

0:12:38.566,0:12:41.533
then imagine what else[br]is waiting to be discovered down there.

0:12:41.891,0:12:47.556
This new field of geo-bio-chemistry,[br]or deep subsurface biology,

0:12:47.580,0:12:49.121
or whatever you want to call it,

0:12:49.145,0:12:50.982
is going to have huge implications,

0:12:51.006,0:12:53.379
not just for mitigating climate change,

0:12:53.403,0:12:57.275
but possibly for understanding[br]how life and Earth have coevolved,

0:12:57.613,0:13:02.311
or finding new products that are useful[br]for industrial or medical applications.

0:13:02.335,0:13:04.597
Maybe even predicting earthquakes

0:13:04.621,0:13:06.819
or finding life outside our planet.

0:13:06.843,0:13:09.969
It could even help us understand[br]the origin of life itself.

0:13:10.827,0:13:13.652
Fortunately, I don't have[br]to do this by myself.

0:13:13.962,0:13:17.287
I have amazing colleagues[br]all over the world

0:13:17.311,0:13:20.603
who are cracking into the mysteries[br]of this deep subsurface world.

0:13:21.831,0:13:26.641
And it may seem like life[br]buried deep within the Earth's crust

0:13:26.665,0:13:30.639
is so far away from our daily experiences[br]that it's kind of irrelevant.

0:13:31.363,0:13:35.051
But the truth is that this weird slow life

0:13:35.075,0:13:38.600
may actually have the answers[br]to some of the greatest mysteries

0:13:38.624,0:13:39.774
of life on Earth.

0:13:40.225,0:13:41.376
Thank you.

0:13:41.400,0:13:46.444
(Applause)