WEBVTT

00:00:01.068 --> 00:00:03.431
So one of the most important solutions

00:00:03.431 --> 00:00:06.618
to the global challenge
posed by climate change

00:00:06.618 --> 00:00:10.161
lies right under our foot every day.

00:00:10.885 --> 00:00:12.585
It's soil.

00:00:12.585 --> 00:00:17.122
Soil's just the thin veil that covers
the surface of land,

00:00:17.410 --> 00:00:21.414
but it has the power to shape
our planet's destiny.

00:00:22.460 --> 00:00:25.912
See, a six foot or so of soil

00:00:25.912 --> 00:00:29.471
lose soil material that covers
the Earth's surface

00:00:29.471 --> 00:00:34.680
represents the difference between life
and lifelessness in the Earth system,

00:00:35.580 --> 00:00:39.291
and it can also help us
combat climate change

00:00:39.291 --> 00:00:42.600
and if we can only stop
treating it like dirt.

NOTE Paragraph

00:00:44.485 --> 00:00:46.461
Climate change is happening,

00:00:46.461 --> 00:00:48.978
the Earth's atmosphere is warming,

00:00:48.978 --> 00:00:52.310
because of an increasing amount
of greenhouse gases

00:00:52.310 --> 00:00:54.401
we keep releasing into the atmosphere.

00:00:54.401 --> 00:00:55.869
You all know that.

00:00:56.573 --> 00:00:59.006
But what I assume you might not have heard

00:00:59.006 --> 00:01:04.130
is that one of the most important things
our human society could do

00:01:04.130 --> 00:01:06.052
to address climate change

00:01:06.052 --> 00:01:08.652
lies right there in the soil.

NOTE Paragraph

00:01:10.046 --> 00:01:14.305
I'm a soil scientist who has
been studying soil since I was 18

00:01:14.305 --> 00:01:17.944
because I'm interested in unlocking
the secrets of soil

00:01:17.944 --> 00:01:23.300
and helping people understand this
really important climate change solution.

NOTE Paragraph

00:01:24.102 --> 00:01:26.056
So here are the facts about climate.

00:01:26.354 --> 00:01:30.057
The concentration of carbon dioxide
in the Earth's atmosphere

00:01:30.057 --> 00:01:32.356
has increased by 40 percent

00:01:32.356 --> 00:01:35.392
just in the last 150 years or so.

00:01:35.392 --> 00:01:40.602
Human actions are now releasing
9.4 billion metric tons of carbon

00:01:40.602 --> 00:01:42.649
into the atmosphere

00:01:42.649 --> 00:01:46.244
from activities such as
burning fossil fuels

00:01:46.244 --> 00:01:49.650
and intensive agricultural practices

00:01:49.650 --> 00:01:52.733
and other ways we change
the way we use land,

00:01:52.733 --> 00:01:55.255
including deforestation.

00:01:55.478 --> 00:02:00.976
But the concentration of carbon dioxide
that stays in the atmosphere

00:02:00.976 --> 00:02:04.693
is only increasing by about half of that,

00:02:04.693 --> 00:02:09.519
and that's because half of the carbon
we keep releasing into the atmosphere

00:02:09.519 --> 00:02:12.522
is currently being taken up
by land and the seas

00:02:12.522 --> 00:02:15.470
through a process we know
as carbon sequestration.

00:02:15.818 --> 00:02:21.042
So in essence, whatever consequence
you think we're facing

00:02:21.042 --> 00:02:23.016
from climate change right now,

00:02:23.016 --> 00:02:28.985
we're only experiencing the consequence
of 50 percent of our pollution,

00:02:29.348 --> 00:02:33.791
because the natural ecosystems
are bailing us out.

NOTE Paragraph

00:02:33.791 --> 00:02:36.195
But don't get too comfortable,

00:02:36.195 --> 00:02:40.974
because we have two major things
working against us right now.

00:02:40.974 --> 00:02:45.958
One, unless we do something big

00:02:45.958 --> 00:02:47.705
and then fast,

00:02:47.705 --> 00:02:50.163
emissions will continue to rise.

00:02:50.163 --> 00:02:52.764
And second, the ability
of these natural ecosystems

00:02:52.764 --> 00:02:57.294
to take up carbon dioxide
from the atmosphere

00:02:57.294 --> 00:03:02.664
and sequester it in the natural habitats

00:03:02.664 --> 00:03:04.839
is currently getting compromised

00:03:04.839 --> 00:03:09.928
as they're experiencing serious
degradation because of human actions.

00:03:09.928 --> 00:03:11.959
So it's not entirely clear

00:03:11.959 --> 00:03:14.488
that we will continue to get bailed out
by these natural ecosystems

00:03:14.488 --> 00:03:20.909
if we continue on this
business-as-usual path that we've been.

00:03:21.427 --> 00:03:25.433
Here's where the soil comes in:

00:03:25.433 --> 00:03:28.568
there is about three thousand billion
metric tons of carbon in the soil.

00:03:28.568 --> 00:03:32.176
That's roughly about 315 times
the amount of carbon

00:03:32.176 --> 00:03:34.255
that we release into
the atmosphere currently,

00:03:34.255 --> 00:03:40.331
and there's twice more carbon in soil
than there is in vegetation and air.

00:03:40.331 --> 00:03:43.514
Think about that for a second.

00:03:43.514 --> 00:03:45.006
There's more carbon in soil

00:03:45.006 --> 00:03:48.679
than there is in all
of the world's vegetation,

00:03:48.679 --> 00:03:52.367
including the lush tropical rainforests
and the giant sequoias,

00:03:52.367 --> 00:03:56.393
the expansive grasslands,

00:03:56.393 --> 00:03:59.393
all of the cultivated systems,

00:03:59.393 --> 00:04:04.067
and every kind of flora you can imagine
on the face of the Earth,

00:04:04.261 --> 00:04:09.243
plus all the carbon that's currently
up in the atmosphere combined

00:04:09.243 --> 00:04:11.732
and then twice over.

00:04:11.898 --> 00:04:17.111
Hence, a very small change
in the amount of carbon stored in soil

00:04:17.111 --> 00:04:22.433
can make a big difference
in maintenance of the Earth's atmosphere.

NOTE Paragraph

00:04:22.797 --> 00:04:26.979
But soil's not just simply
a storage box for carbon though.

00:04:26.979 --> 00:04:29.922
It operates more like a bank account,

00:04:29.922 --> 00:04:33.549
and the amount of carbon
that's in soil at any given time

00:04:33.549 --> 00:04:37.464
is a function of the amount of carbon
coming in and out of the soil.

00:04:37.780 --> 00:04:41.925
Carbon comes into the soil
through the process of photosynthesis

00:04:41.925 --> 00:04:45.228
when green plants take carbon dioxide
from the atmosphere

00:04:45.228 --> 00:04:47.478
and use it to make their bodies,

00:04:47.478 --> 00:04:50.537
and upon death,
their bodies enter the soil.

00:04:50.834 --> 00:04:53.076
And carbon leaves the soil

00:04:53.076 --> 00:04:55.807
and goes right back up into the atmosphere

00:04:55.807 --> 00:05:00.535
when the bodies of those
formerly living organisms

00:05:00.535 --> 00:05:02.339
decay in soil by activity of microbes.

00:05:02.339 --> 00:05:06.537
See, decomposition releases
carbon dioxide into the atmosphere

00:05:06.537 --> 00:05:10.835
as well as other greenhouse gases
such as methane and nitrous oxide,

00:05:10.835 --> 00:05:16.774
but it also releases all the nutrients
we all need to survive.

NOTE Paragraph

00:05:16.774 --> 00:05:20.760
One of the things that makes soil
such a fundamental component

00:05:20.760 --> 00:05:23.648
of any climate change mitigation strategy

00:05:23.648 --> 00:05:28.190
is because it represents
a long-term storage of carbon.

00:05:28.190 --> 00:05:31.541
Carbon that would have lasted
maybe a year or two

00:05:31.541 --> 00:05:33.515
in decaying residue
if it was left on the surface

00:05:33.515 --> 00:05:35.346
can stay in soil for hundreds of years,
even thousands and more.

NOTE Paragraph

00:05:35.346 --> 00:05:43.112
Soil biogeochemists like me

00:05:43.112 --> 00:05:48.064
study exactly how the soil system
makes this possible,

00:05:48.263 --> 00:05:51.458
by locking away the carbon

00:05:51.458 --> 00:05:53.700
in physical association with minerals

00:05:53.700 --> 00:05:56.033
inside aggregates of soil minerals

00:05:56.033 --> 00:05:59.453
and formation of strong chemical bonds

00:05:59.453 --> 00:06:03.996
that bind the carbon
to the surfaces of the minerals.

00:06:04.250 --> 00:06:06.842
See, when carbon is entrapped in soil
in these kinds of associations

00:06:06.842 --> 00:06:10.168
with soil minerals,

00:06:10.168 --> 00:06:14.093
even the wiliest of the microbes
can't easily degrade it,

00:06:14.093 --> 00:06:17.079
and carbon that's not degrading fast

00:06:17.079 --> 00:06:21.158
is carbon that's not going back
into the atmosphere as greenhouse gases.

00:06:21.801 --> 00:06:24.484
But the benefit of carbon sequestration

00:06:24.484 --> 00:06:27.416
is not just limited
to climate change mitigation.

00:06:27.416 --> 00:06:30.023
Soil that stores large amounts of carbon

00:06:30.023 --> 00:06:34.003
is health, fertile, soft.

00:06:34.003 --> 00:06:35.569
It's malleable. It's workable.

00:06:35.569 --> 00:06:37.273
It makes it like a sponge.

00:06:37.273 --> 00:06:43.013
It can hold on to
a lot of water and nutrients.

00:06:43.312 --> 00:06:46.609
Healthy and fertile soils like this

00:06:46.609 --> 00:06:50.360
support the most dynamic, abundant,
and diverse habitat for living things

00:06:50.360 --> 00:06:56.104
that we know of anywhere
on the Earth system.

00:06:56.104 --> 00:07:02.172
It makes life possible for everything
from the tiniest of the microbes

00:07:02.172 --> 00:07:06.462
such as bacteria and fungi

00:07:06.462 --> 00:07:07.562
all the way to higher plants,

00:07:07.562 --> 00:07:12.043
and fulfills the food, feed,
and fiber needs for all animals,

00:07:12.043 --> 00:07:14.211
including you and I.

NOTE Paragraph

00:07:14.211 --> 00:07:18.251
So at this point, you would assume
that we should be treating soil

00:07:18.251 --> 00:07:21.129
like the precious resource that it is.

00:07:21.129 --> 00:07:23.118
Unfortunately, that's not the case.

00:07:23.118 --> 00:07:28.725
Soils around the world are experiencing
unprecedented rates of degradation

00:07:28.725 --> 00:07:31.519
through a variety of human actions

00:07:31.519 --> 00:07:34.163
that include deforestation,

00:07:34.163 --> 00:07:36.742
intensive agricultural production systems,

00:07:36.742 --> 00:07:38.708
overgrazing,

00:07:38.708 --> 00:07:41.711
excessive application
of agricultural chemicals,

00:07:41.711 --> 00:07:44.804
erosion, and similar things.

00:07:44.804 --> 00:07:50.572
Half of the world's soils
are currently considered degraded.

NOTE Paragraph

00:07:50.572 --> 00:07:54.167
Soil degradation is bad for many reasons,

00:07:54.167 --> 00:07:56.854
but let me just tell you a couple.

00:07:56.854 --> 00:08:03.303
One, degraded soils have diminished
potential to support plant productivity,

00:08:03.303 --> 00:08:06.752
and hence, by degrading soil,

00:08:06.752 --> 00:08:12.179
we're compromising our own abilities
to provide the food and other resources

00:08:12.179 --> 00:08:15.429
that we need for us

00:08:15.429 --> 00:08:19.143
and every member of living things
on the face of the Earth.

00:08:19.678 --> 00:08:24.321
And second, soil use and degradation

00:08:24.321 --> 00:08:27.202
just in the last 200 years or so

00:08:27.202 --> 00:08:31.391
has released 12 times more carbon
into the atmosphere

00:08:31.391 --> 00:08:36.390
compared to the rate

00:08:36.390 --> 00:08:38.300
at which we're releasing carbon
into the atmosphere right now.

NOTE Paragraph

00:08:38.300 --> 00:08:40.765
I'm afraid there's even more bad news.

00:08:40.765 --> 00:08:44.301
This is a story of soils
at high latitudes.

00:08:44.301 --> 00:08:47.834
Peatlands in polar environments

00:08:47.834 --> 00:08:51.441
store about a third
of the global soil carbon reserves.

00:08:51.441 --> 00:08:55.898
These peatlands have a permanently
frozen ground underneath, permafrost,

00:08:55.898 --> 00:09:01.145
and the carbon was able to build up
in these soils over long periods of time

00:09:01.145 --> 00:09:05.443
because even though plants are able
to photosynthesize during the short,

00:09:05.443 --> 00:09:08.008
warm summer months,

00:09:08.008 --> 00:09:12.564
the environment quickly
turns cold and dark

00:09:12.783 --> 00:09:17.149
and then microbes are not able
to efficiently break down the residue.

00:09:17.149 --> 00:09:20.142
So the soil carbon bank
in these polar environments

00:09:20.142 --> 00:09:24.138
built up over hundreds
of thousands of years.

00:09:24.329 --> 00:09:28.014
But right now, with atmospheric warming,

00:09:28.014 --> 00:09:32.316
the permafrost is thawing and draining,

00:09:32.316 --> 00:09:34.970
and when permafrosts thaws and drains,

00:09:34.970 --> 00:09:37.570
it makes it possible
for microbes to come in

00:09:37.570 --> 00:09:41.120
and rather quickly
decompose all this carbon,

00:09:41.120 --> 00:09:45.068
with the potential to release
hundreds of billions of metric tons

00:09:45.068 --> 00:09:49.433
of carbon into the atmosphere
in the form of greenhouse gases.

00:09:49.433 --> 00:09:53.524
And this release of additional
greenhouse gases into the atmosphere

00:09:53.758 --> 00:09:56.590
will only contribute to further warming

00:09:56.590 --> 00:10:00.246
that makes this predicament even worse,

00:10:00.246 --> 00:10:03.082
as it starts a self-reinforcing
positive feedback loop

00:10:03.082 --> 00:10:08.126
that could go on and on and on,

00:10:08.126 --> 00:10:10.917
dramatically changing our climate future.

NOTE Paragraph

00:10:11.846 --> 00:10:16.402
Fortunately, I can also tell you
that there is a solution

00:10:16.402 --> 00:10:21.028
for these two wicked problems
of soil degradation and climate change.

00:10:21.248 --> 00:10:23.548
Just like we created these problems,

00:10:23.548 --> 00:10:25.504
we do know the solution,

00:10:25.504 --> 00:10:28.623
and the solution lies
in simultaneously working

00:10:28.623 --> 00:10:31.054
to address these two things together

00:10:31.054 --> 00:10:35.745
through what we call
climate-smart land management practices.

00:10:36.533 --> 00:10:38.131
What do I mean here?

00:10:38.131 --> 00:10:41.323
I mean managing land in a way that's smart

00:10:41.323 --> 00:10:45.470
about maximizing how much carbon
we store in soil.

00:10:45.721 --> 00:10:47.823
And we can accomplish this

00:10:47.823 --> 00:10:49.046
by putting in place

00:10:49.046 --> 00:10:51.972
deep-rooted perennial plants,

00:10:51.972 --> 00:10:54.397
putting back forests whenever possible,

00:10:54.397 --> 00:10:58.853
reducing tillage and other disturbances
from agricultural practices,

00:10:58.853 --> 00:11:03.644
including optimizing the use
of agricultural chemicals and grazing

00:11:03.644 --> 00:11:07.262
and even adding carbon
to soil whenever possible

00:11:07.262 --> 00:11:12.075
from recycled resources such as compost
and even human waste.

NOTE Paragraph

00:11:12.977 --> 00:11:17.452
This kind of land stewardship
is not a radical idea.

00:11:17.452 --> 00:11:21.358
It's what made it possible
for fertile soils to be able

00:11:21.358 --> 00:11:25.807
to support human civilizations
since time immemorial.

00:11:25.807 --> 00:11:29.367
In fact, some are doing it just right now.

00:11:29.367 --> 00:11:34.501
There's a global effort underway
to accomplish exactly this goal.

00:11:34.711 --> 00:11:37.262
This effort that started in France

00:11:37.262 --> 00:11:39.805
is known as the "4 per mille" effort,

00:11:39.805 --> 00:11:43.501
and it sets an aspirational goal

00:11:43.501 --> 00:11:51.210
to increase the amount of carbon
stored in soil by 0.4 percent annually

00:11:51.210 --> 00:11:54.999
using the same kind of climate-smart
land management practices

00:11:54.999 --> 00:11:56.528
I mentioned earlier.

00:11:56.924 --> 00:12:00.369
And if this effort is fully successful,

00:12:00.369 --> 00:12:03.784
it can offset a third
of the global emissions

00:12:03.784 --> 00:12:06.855
of fossil-fuel derived carbon
into the atmosphere.

00:12:07.609 --> 00:12:11.172
But even if this effort
is not fully successful,

00:12:11.172 --> 00:12:14.903
but we just start heading
in that direction,

00:12:14.903 --> 00:12:19.470
we still end up with soils
that are healthier, more fertile,

00:12:19.470 --> 00:12:23.619
are able to produce all the food
and resources that we need

00:12:23.619 --> 00:12:25.954
for human populations and more,

00:12:25.954 --> 00:12:28.674
and also soils that are better capable

00:12:28.674 --> 00:12:31.928
of sequestering carbon dioxide
from the atmosphere

00:12:31.928 --> 00:12:35.173
and helping with
climate change mitigation.

NOTE Paragraph

00:12:35.721 --> 00:12:40.145
I'm pretty sure that's what politicians
call a win-win solution.

00:12:40.145 --> 00:12:43.719
And we all can have a role to play here.

00:12:43.719 --> 00:12:49.037
We can start by treating the soil
with the respect that it deserves:

00:12:49.037 --> 00:12:54.693
respect for its ability as the basis
of all life on Earth;

00:12:54.693 --> 00:12:58.630
respect for its ability to serve
as a carbon bank;

00:12:58.630 --> 00:13:03.401
and respect for its ability
to control our climate.

NOTE Paragraph

00:13:03.839 --> 00:13:05.442
And if we do so,

00:13:05.442 --> 00:13:07.919
we can then simultaneously address

00:13:07.919 --> 00:13:12.326
two of the most pressing
global challenges of our time:

00:13:12.326 --> 00:13:14.960
climate change and soil degradation.

00:13:14.960 --> 00:13:21.607
And in the process, we would be able
to provide food and nutritional security

00:13:21.607 --> 00:13:23.641
to our growing human family.

NOTE Paragraph

00:13:23.641 --> 00:13:24.999
Thank you.

NOTE Paragraph

00:13:24.999 --> 00:13:28.619
(Applause)