0:00:00.984,0:00:03.207
So one of the most important solutions

0:00:03.231,0:00:06.507
to the global challenge[br]posed by climate change

0:00:06.531,0:00:09.961
lies right under our foot every day.

0:00:10.478,0:00:11.628
It's soil.

0:00:12.385,0:00:17.186
Soil's just the thin veil[br]that covers the surface of land,

0:00:17.210,0:00:21.214
but it has the power to shape[br]our planet's destiny.

0:00:22.260,0:00:25.759
See, a six foot or so of soil,

0:00:25.783,0:00:29.247
loose soil material[br]that covers the Earth's surface,

0:00:29.271,0:00:34.080
represents the difference between life[br]and lifelessness in the Earth system,

0:00:35.493,0:00:38.724
and it can also help us[br]combat climate change

0:00:38.748,0:00:42.057
if we can only stop treating it like dirt.

0:00:42.851,0:00:44.213
(Laughter)

0:00:44.237,0:00:46.212
Climate change is happening,

0:00:46.236,0:00:48.732
the Earth's atmosphere is warming,

0:00:48.756,0:00:51.868
because of the increasing amount[br]of greenhouse gases

0:00:51.892,0:00:54.185
we keep releasing into the atmosphere.

0:00:54.209,0:00:55.677
You all know that.

0:00:56.373,0:00:58.694
But what I assume you might not have heard

0:00:58.718,0:01:03.866
is that one of the most important things[br]our human society could do

0:01:03.890,0:01:05.592
to address climate change

0:01:05.616,0:01:07.598
lies right there in the soil.

0:01:09.846,0:01:14.081
I'm a soil scientist who has been[br]studying soil since I was 18,

0:01:14.105,0:01:17.806
because I'm interested in unlocking[br]the secrets of soil

0:01:17.830,0:01:22.711
and helping people understand this[br]really important climate-change solution.

0:01:23.782,0:01:26.027
So here are the facts about climate.

0:01:26.051,0:01:29.731
The concentration of carbon dioxide[br]in the Earth's atmosphere

0:01:29.755,0:01:32.132
has increased by 40 percent

0:01:32.156,0:01:34.926
just in the last 150 years or so.

0:01:34.950,0:01:40.870
Human actions are now releasing[br]9.4 billion metric tons of carbon

0:01:40.894,0:01:42.672
into the atmosphere,

0:01:42.696,0:01:46.020
from activities[br]such as burning fossil fuels

0:01:46.044,0:01:49.021
and intensive agricultural practices,

0:01:49.045,0:01:51.878
and other ways we change[br]the way we use land,

0:01:51.902,0:01:53.591
including deforestation.

0:01:55.254,0:02:00.636
But the concentration of carbon dioxide[br]that stays in the atmosphere

0:02:00.660,0:02:03.143
is only increasing by about half of that,

0:02:04.314,0:02:08.450
and that's because half of the carbon[br]we keep releasing into the atmosphere

0:02:08.474,0:02:12.178
is currently being taken up[br]by land and the seas

0:02:12.202,0:02:14.854
through a process we know[br]as carbon sequestration.

0:02:15.752,0:02:20.412
So in essence, whatever consequence[br]you think we're facing

0:02:20.436,0:02:22.704
from climate change right now,

0:02:22.728,0:02:28.084
we're only experiencing the consequence[br]of 50 percent of our pollution,

0:02:29.148,0:02:32.386
because the natural ecosystems[br]are bailing us out.

0:02:33.495,0:02:35.074
But don't get too comfortable,

0:02:35.995,0:02:39.630
because we have two major things[br]working against us right now.

0:02:40.710,0:02:45.671
One, unless we do something big,

0:02:45.695,0:02:47.614
and then fast,

0:02:47.638,0:02:49.472
emissions will continue to rise.

0:02:50.511,0:02:55.558
And second, the ability[br]of these natural ecosystems

0:02:55.582,0:02:58.510
to take up carbon dioxide[br]from the atmosphere

0:02:58.534,0:03:01.940
and sequester it in the natural habitats

0:03:01.964,0:03:03.877
is currently getting compromised,

0:03:03.901,0:03:08.646
as they're experiencing serious[br]degradation because of human actions.

0:03:09.616,0:03:11.735
So it's not entirely clear

0:03:11.759,0:03:15.703
that we will continue to get bailed out[br]by these natural ecosystems

0:03:15.727,0:03:19.505
if we continue on this[br]business-as-usual path that we've been.

0:03:21.107,0:03:22.997
Here's where the soil comes in:

0:03:23.021,0:03:27.504
there is about three thousand billion[br]metric tons of carbon in the soil.

0:03:28.281,0:03:31.952
That's roughly about 315 times[br]the amount of carbon

0:03:31.976,0:03:34.677
that we release[br]into the atmosphere currently,

0:03:34.701,0:03:38.963
and there's twice more carbon in soil[br]than there is in vegetation and air.

0:03:40.091,0:03:42.362
Think about that for a second.

0:03:42.386,0:03:44.647
There's more carbon in soil

0:03:44.671,0:03:48.455
than there is in all[br]of the world's vegetation,

0:03:48.479,0:03:53.891
including the lush tropical rainforests[br]and the giant sequoias,

0:03:53.915,0:03:56.201
the expansive grasslands,

0:03:56.225,0:03:58.978
all of the cultivated systems,

0:03:59.002,0:04:02.628
and every kind of flora you can imagine[br]on the face of the Earth,

0:04:03.703,0:04:08.883
plus all the carbon that's currently[br]up in the atmosphere, combined,

0:04:08.907,0:04:10.383
and then twice over.

0:04:11.539,0:04:16.799
Hence, a very small change[br]in the amount of carbon stored in soil

0:04:16.823,0:04:20.864
can make a big difference[br]in maintenance of the Earth's atmosphere.

0:04:22.597,0:04:26.572
But soil's not just simply[br]a storage box for carbon, though.

0:04:26.596,0:04:29.554
It operates more like a bank account,

0:04:29.578,0:04:32.627
and the amount of carbon[br]that's in soil at any given time

0:04:32.651,0:04:36.395
is a function of the amount of carbon[br]coming in and out of the soil.

0:04:37.516,0:04:41.246
Carbon comes into the soil[br]through the process of photosynthesis,

0:04:41.270,0:04:44.445
when green plants take carbon dioxide[br]from the atmosphere

0:04:44.469,0:04:47.229
and use it to make their bodies,

0:04:47.253,0:04:49.872
and upon death,[br]their bodies enter the soil.

0:04:50.753,0:04:52.532
And carbon leaves the soil

0:04:52.556,0:04:55.464
and goes right back up into the atmosphere

0:04:55.488,0:04:58.258
when the bodies of those[br]formerly living organisms

0:04:58.282,0:05:01.099
decay in soil by the activity of microbes.

0:05:02.057,0:05:06.105
See, decomposition releases[br]carbon dioxide into the atmosphere,

0:05:06.129,0:05:10.611
as well as other greenhouse gases[br]such as methane and nitrous oxide,

0:05:10.635,0:05:15.103
but it also releases all the nutrients[br]we all need to survive.

0:05:16.359,0:05:20.765
One of the things that makes soil[br]such a fundamental component

0:05:20.789,0:05:23.677
of any climate-change mitigation strategy

0:05:23.701,0:05:27.447
is because it represents[br]a long-term storage of carbon.

0:05:27.910,0:05:31.038
Carbon that would have lasted[br]maybe a year or two

0:05:31.062,0:05:34.941
in decaying residue[br]if it was left on the surface

0:05:34.965,0:05:39.584
can stay in soil for hundreds of years,[br]even thousands and more.

0:05:40.568,0:05:43.213
Soil biogeochemists like me

0:05:43.237,0:05:47.949
study exactly how the soil system[br]makes this possible,

0:05:47.973,0:05:52.840
by locking away the carbon[br]in physical association with minerals,

0:05:52.864,0:05:55.777
inside aggregates of soil minerals,

0:05:55.801,0:05:59.319
and formation of strong chemical bonds

0:05:59.343,0:06:02.668
that bind the carbon[br]to the surfaces of the minerals.

0:06:04.050,0:06:06.531
See when carbon is entrapped in soil,

0:06:06.555,0:06:09.797
in these kinds of associations[br]with soil minerals,

0:06:09.821,0:06:13.837
even the wiliest of the microbes[br]can't easily degrade it,

0:06:13.861,0:06:16.409
and carbon that's not degrading fast

0:06:16.433,0:06:20.670
is carbon that's not going back[br]into the atmosphere as greenhouse gases.

0:06:21.601,0:06:23.760
But the benefit of carbon sequestration

0:06:23.784,0:06:26.982
is not just limited[br]to climate-change mitigation.

0:06:27.006,0:06:33.675
Soil that stores large amounts of carbon[br]is healthy, fertile, soft.

0:06:33.699,0:06:36.405
It's malleable. It's workable.

0:06:36.977,0:06:39.460
It makes it like a sponge.

0:06:39.484,0:06:42.230
It can hold on to[br]a lot of water and nutrients.

0:06:43.112,0:06:45.676
Healthy and fertile soils like this

0:06:45.700,0:06:50.747
support the most dynamic, abundant,[br]and diverse habitat for living things

0:06:50.771,0:06:53.557
that we know of anywhere[br]on the Earth system.

0:06:55.483,0:07:01.630
It makes life possible for everything[br]from the tiniest of the microbes,

0:07:01.654,0:07:03.904
such as bacteria and fungi,

0:07:03.928,0:07:06.127
all the way to higher plants,

0:07:06.151,0:07:11.198
and fulfills the food, feed,[br]and fiber needs for all animals,

0:07:11.222,0:07:12.681
including you and I.

0:07:13.915,0:07:17.789
So at this point, you would assume[br]that we should be treating soil

0:07:17.813,0:07:19.836
like the precious resource that it is.

0:07:20.198,0:07:22.163
Unfortunately, that's not the case.

0:07:22.830,0:07:28.501
Soils around the world are experiencing[br]unprecedented rates of degradation

0:07:28.525,0:07:33.828
through a variety of human actions[br]that include deforestation,

0:07:33.852,0:07:36.627
intensive agricultural production systems,

0:07:36.651,0:07:37.960
overgrazing,

0:07:37.984,0:07:41.407
excessive application[br]of agricultural chemicals,

0:07:41.431,0:07:43.484
erosion and similar things.

0:07:45.318,0:07:48.945
Half of the world's soils[br]are currently considered degraded.

0:07:50.284,0:07:53.943
Soil degradation is bad for many reasons,

0:07:53.967,0:07:55.824
but let me just tell you a couple.

0:07:56.752,0:08:03.130
One, degraded soils have diminished[br]potential to support plant productivity,

0:08:03.154,0:08:06.012
and hence, by degrading soil,

0:08:06.036,0:08:11.955
we're compromising our own abilities[br]to provide the food and other resources

0:08:11.979,0:08:13.853
that we need for us

0:08:13.877,0:08:17.923
and every member of living things[br]on the face of the Earth.

0:08:19.478,0:08:20.628
And second,

0:08:22.043,0:08:26.820
soil use and degradation,[br]just in the last 200 years or so,

0:08:26.844,0:08:31.724
has released 12 times more carbon[br]into the atmosphere

0:08:31.748,0:08:35.305
compared to the rate at[br]which we're releasing carbon

0:08:35.329,0:08:37.105
into the atmosphere right now.

0:08:38.028,0:08:40.541
I'm afraid there's even more bad news.

0:08:40.565,0:08:43.764
This is a story of soils[br]at high latitudes.

0:08:44.504,0:08:47.362
Peatlands in polar environments

0:08:47.386,0:08:51.153
store about a third[br]of the global soil carbon reserves.

0:08:51.177,0:08:54.212
These peatlands have[br]a permanently frozen ground underneath,

0:08:54.236,0:08:55.724
the permafrost,

0:08:55.748,0:09:01.131
and the carbon was able to build up[br]in these soils over long periods of time

0:09:01.155,0:09:06.115
because even though plants are able[br]to photosynthesize during the short,

0:09:06.139,0:09:08.361
warm summer months,

0:09:08.385,0:09:12.147
the environment quickly[br]turns cold and dark,

0:09:12.171,0:09:15.964
and then microbes are not able[br]to efficiently break down the residue.

0:09:16.821,0:09:19.806
So the soil carbon bank[br]in these polar environments

0:09:19.830,0:09:22.885
built up over hundreds[br]of thousands of years.

0:09:24.001,0:09:27.593
But right now, with atmospheric warming,

0:09:27.617,0:09:30.949
the permafrost is thawing and draining.

0:09:31.845,0:09:34.746
And when permafrosts thaws and drains,

0:09:34.770,0:09:37.607
it makes it possible[br]for microbes to come in

0:09:37.631,0:09:40.823
and rather quickly[br]decompose all this carbon,

0:09:40.847,0:09:45.545
with the potential to release hundreds[br]of billions of metric tons of carbon

0:09:45.569,0:09:48.347
into the atmosphere[br]in the form of greenhouse gases.

0:09:49.145,0:09:53.200
And this release of additional[br]greenhouse gases into the atmosphere

0:09:53.224,0:09:56.175
will only contribute to further warming

0:09:56.199,0:09:59.832
that makes this predicament even worse,

0:09:59.856,0:10:04.986
as it starts a self-reinforcing[br]positive feedback loop

0:10:05.010,0:10:07.831
that could go on and on and on,

0:10:07.855,0:10:10.497
dramatically changing our climate future.

0:10:11.558,0:10:16.177
Fortunately, I can also tell you[br]that there is a solution

0:10:16.201,0:10:20.806
for these two wicked problems[br]of soil degradation and climate change.

0:10:20.830,0:10:23.218
Just like we created these problems,

0:10:23.242,0:10:25.446
we do know the solution,

0:10:25.470,0:10:28.344
and the solution lies[br]in simultaneously working

0:10:28.368,0:10:30.683
to address these two things together,

0:10:31.628,0:10:35.545
through what we call[br]climate-smart land management practices.

0:10:36.333,0:10:37.738
What do I mean here?

0:10:37.762,0:10:41.019
I mean managing land,[br]in a way that's smart,

0:10:41.043,0:10:44.190
about maximizing[br]how much carbon we store in soil.

0:10:45.521,0:10:47.334
And we can accomplish this

0:10:47.358,0:10:51.748
by putting in place[br]deep-rooted perennial plants,

0:10:51.772,0:10:54.122
putting back forests, whenever possible,

0:10:54.146,0:10:58.605
reducing tillage and other disturbances[br]from agricultural practices,

0:10:58.629,0:11:03.329
including optimizing the use[br]of agricultural chemicals and grazing

0:11:03.353,0:11:07.038
and even adding carbon to soil,[br]whenever possible,

0:11:07.062,0:11:11.333
from recycled resources[br]such as compost and even human waste.

0:11:12.721,0:11:16.269
This kind of land stewardship[br]is not a radical idea.

0:11:17.164,0:11:20.656
It's what made it possible[br]for fertile soils

0:11:20.680,0:11:24.722
to be able to support human civilizations[br]since time immemorial.

0:11:25.522,0:11:28.100
In fact, some are doing it just right now.

0:11:29.040,0:11:33.436
There's a global effort underway[br]to accomplish exactly this goal.

0:11:34.193,0:11:38.603
This effort that started in France[br]is known as the "4 per 1000" effort,

0:11:39.557,0:11:43.216
and it sets an aspirational goal

0:11:43.240,0:11:49.707
to increase the amount of carbon[br]stored in soil by 0.4 percent annually,

0:11:51.010,0:11:54.846
using the same kind of climate-smart[br]land management practices

0:11:54.870,0:11:56.020
I mentioned earlier.

0:11:56.748,0:11:59.240
And if this effort's fully successful,

0:12:00.169,0:12:03.560
it can offset a third[br]of the global emissions

0:12:03.584,0:12:06.366
of fossil-fuel derived carbon[br]into the atmosphere.

0:12:07.409,0:12:11.151
But even if this effort[br]is not fully successful,

0:12:11.175,0:12:14.565
but we just start heading[br]in that direction,

0:12:14.589,0:12:19.214
we still end up with soils[br]that are healthier, more fertile,

0:12:19.238,0:12:23.395
are able to produce all the food[br]and resources that we need

0:12:23.419,0:12:25.730
for human populations and more,

0:12:25.754,0:12:28.180
and also soils that are better capable

0:12:28.204,0:12:31.600
of sequestering carbon dioxide[br]from the atmosphere

0:12:31.624,0:12:34.378
and helping with[br]climate-change mitigation.

0:12:35.402,0:12:39.148
I'm pretty sure that's what politicians[br]call a win-win solution.

0:12:39.945,0:12:42.457
And we all can have a role to play here.

0:12:43.622,0:12:49.098
We can start by treating the soil[br]with the respect that it deserves:

0:12:49.122,0:12:54.424
respect for its ability[br]as the basis of all life on Earth,

0:12:54.448,0:12:58.406
respect for its ability to serve[br]as a carbon bank,

0:12:58.430,0:13:02.511
and respect for its ability[br]to control our climate.

0:13:03.591,0:13:05.171
And if we do so,

0:13:05.195,0:13:07.649
we can then simultaneously address

0:13:07.673,0:13:12.036
two of the most pressing[br]global challenges of our time:

0:13:12.060,0:13:14.696
climate change and soil degradation.

0:13:14.720,0:13:20.903
And in the process, we would be able[br]to provide food and nutritional security

0:13:20.927,0:13:22.783
to our growing human family.

0:13:23.441,0:13:24.592
Thank you.

0:13:24.616,0:13:29.238
(Applause)