Steven Allison Earths original inhabitants and their role in combating climate change TED
Transcriber:
Microbes are everywhere.
They live in the air, the ocean,
the soil and on our bodies, lots of them.
But before you reach
for the hand sanitizer,
take a look at these beautiful
bacterial mats
in Yellowstone’s Grand Prismatic Spring.
They’re absolutely amazing
because they’ve somehow figured out
how to grow happily
at near boiling temperatures.
Ever since life on Earth began,
probably in a place like this,
microbes have kept planetary
chemical cycles in balance.
Today, humans are altering
that balance and changing the climate
by emitting greenhouse gases
into the atmosphere.
But microbes might be able
to help us with our climate problem.
After all, microbes are Earth’s original
and most adaptable inhabitants.
Now, I know that not everyone
is so enamored with microbes.
My biology students tell me
that they usually think of “pathogen”
when they hear the word “microbe”
and I know we’re in the middle
of a global viral pandemic.
But you should keep in mind that far less
than one percent of microbial diversity
is actually pathogenic to humans.
In fact, most of the microbes
we encounter are beneficial.
There are trillions
of bacteria, fungi and viruses
living in and on us right now,
more of them than human cells in the body.
They help us digest our food,
protect us from disease
and maybe even choose our mates.
Microbiologists call this assemblage
of tiny interlopers the human microbiome.
We now know that there are microbiomes
in basically every environment.
In the same way that they help
our human bodies stay healthy,
microbiomes in water, soil and air
are critical for planetary health.
For example, cyanobacteria in the ocean
carry out photosynthesis
and provide a large fraction
of the planet’s breathable oxygen.
Even though they’re tiny,
their green color can be seen
from outer space with satellites.
They may be harder to see,
but microbiomes in the soil
are just as important
as the human or ocean microbiome.
I think about soil
as a skin for the planet
that provides nutrients
to sustain crops and other plants.
As an ecologist and climate scientist,
I’ve been studying the microbes
that live in soil for 20 years now.
Just like we’ve seen
with the human microbiome,
cutting-edge techniques
in molecular biology,
especially DNA sequencing,
show that soil microbiomes
are extremely diverse
in their genes and life cycles.
Scientists are starting
to figure out how we can harness
the diversity of these
often invisible organisms
to solve global problems
like climate change and food insecurity.
Take agricultural crops, for example.
With climate change causing
more frequent heat waves and droughts,
crop plants may become stressed,
reducing yields
and threatening food security.
But microbes can help.
There are symbiotic fungi
called mycorrhiza
that grow out from plant roots
and into the soil
where they collect water and nutrients.
Then the plant and its
symbiotic fungus make a trade.
The fungus sends water and nutrients
into the plant roots
and the plant pays back the fungus
with sugars from photosynthesis.
To reduce stress on plants
from climate change,
farmers can inoculate the soil
with these beneficial fungi.
Land managers are also starting
to use the same approach
to help native plants
recolonize degraded soil
during habitat restoration.
So the next time you support
an environmental cause,
maybe through a nonprofit donation
or volunteer work,
remember, soil microbes
need conservation too.
The planet also relies on soil microbiomes
for other essential services.
Have you ever thought
about what happens to living things
like these leaves, mosses
and mushrooms when they die?
I’m not talking
about an existential crisis.
I’m talking about microbial decomposition.
Think about it like a type
of biological recycling
practiced by very diligent microbes.
They take dead bodies
and turn them into useful nutrients.
Without this essential service,
life on Earth would grind to a halt
because dead stuff would pile up,
depriving the next generation
of life forms of the raw materials
needed for growth.
Hundreds of researchers
funded by the US Department of Energy
are even trying to figure out
how to co-opt microbial decomposition
to produce sustainable biofuels
from wood, grasses
and other plant materials.
Fuels derived from plants and microbes
are part of the climate solution
because they don’t rely
on fossil carbon sources
like coal and oil.
At the same time, ecologists like me
are very concerned
about how climate change might affect
microbial recycling in the environment.
A warming climate
might speed up the process
and release more greenhouse gases
into the atmosphere.
A drier climate
might slow down the microbes
and leave plants starved
for essential nutrients.
Fortunately, there is reason for hope.
Microbes are super adaptable
because they can evolve very quickly.
For example, you may have heard
of pathogenic bacteria like staph
evolving antibiotic resistance.
Of course, that’s bad for us.
But the same evolutionary process
could also help microbes
adapt to climate change, which is good.
After all, microbes evolved long ago
to survive extreme conditions
like the hot springs of Yellowstone.
Just like our human cells,
each microbial cell contains a genome.
And just like our genomes,
microbial genomes
contain genes or DNA sequences
with instructions for growth and survival.
My colleagues and I have identified genes
that allow bacteria and fungi
to survive drought
and decompose dead plant material.
We’re currently doing experiments
to see how fast these genes evolve
and what kinds of genetic changes
make bacteria and fungi
more resistant to drought.
Some of our prior research
shows that microbes have the potential
to deal with climate change.
Microbiomes and the services they provide
could cope not just by evolving,
but also by shifting around
the dominant species of microbes.
Microbiomes are so diverse
that even if some of the species
die out with climate change,
others might survive and take their place,
allowing nature’s recycling to continue.
To test this idea, my colleagues and I
designed special cages
to contain microbiomes
from different habitats
in Southern California.
We sampled microbiomes from places
ranging from forested mountaintops
to hot deserts.
Each cage contained a microbiome
from one of these places
along with sterilized dead grass
for the microbes to use as a food source.
We then put the cages back
into the different habitats
so that the microbiomes experienced
pretty dramatic changes in climate.
We expected that the microbes
from the cooler places
would die out when we moved them
to the warm places like the hot desert,
and that they would lose their ability
to consume and recycle the nutrients
in the dead grass material.
But when we looked at the results,
I was really shocked.
The microbiomes were almost unfazed
by this massive climate difference.
There were some changes
in the dominant species,
but mountaintop microbes
decomposed dead grass just as well
as desert microbiomes
in the hot, dry climate.
This result tells us the microbiomes
have the ability to evolve
and shift to deal with really
dramatic climate changes.
Another way that soil microbiomes
can be part of the climate change solution
is by building healthy soil.
Many soil bacteria and fungi
ooze out sticky chemicals
to glue themselves onto soil surfaces.
The glue and the microbes
form these biofilms
that hold soil particles together.
This helps the soil resist erosion
and hold more water
that’s available for plants.
Microbes and their biofilms also play
a big role in soil carbon sequestration.
Many forms of carbon from plants,
like sugars, don’t last long in the soil
because they’re food for many organisms,
including the microbes.
But microbodies and biofilms
are made up of complex chemicals.
For example, many microbes
build cell walls for protection,
so the wall material has to be resistant
to biochemical attack.
When the microbes die, their corpses,
especially those cell walls,
can stick around for a really long time,
maybe even thousands of years.
In this way, soil acts a lot like
a bank vault for carbon.
More carbon in the bank
means healthier soil
and less greenhouse gas
buildup in the atmosphere.
Microbes are sort of
like the Federal Reserve.
They can take cash off the street
in the form of these plant sugars
and lock it away in a chemical vault
for long-term storage.
With the science of climate change
becoming more and more obvious every day,
we need to figure out
how to adapt, for sure.
Some scary outcomes,
like emerging microbial diseases,
are definitely something
we need to plan for.
But microbes can be a part
of the climate solution
if we figure out how to leverage
all that microbiome diversity.
To be honest, though, making sense
out of complex microbiomes
is still a big scientific challenge.
Their complexity
is both a blessing and a curse.
We’re only beginning to understand
all the strange and wonderful
microbial lifestyles
that have been evolving
since the origins of life on Earth.
This digital artwork
called “Microbes Reimagined”
does a great job of capturing
that sense of mystery.
But one thing we do know for sure
is that microbes are not just pathogens.
Our lives literally depend on them.
So next time you take a breath outside,
imagine all those
oxygen-spewing cyanobacteria
floating around in the ocean,
and when the time comes
and you draw in
that last and final breath,
take comfort in knowing
that soil microbes will be there
to turn your body into useful nutrients.
Even as we enjoy
these benefits of microbiomes,
climate change remains a potentially
existential threat to our well-being.
But dangerous climate change
is not inevitable, at least not yet.
With the right cutting-edge research,
diverse microbiomes
could become a big part of the solution
to our climate problem.
Thank you.