Many of you will have seen different representations of the carbon cycle.
I tend to look and focus my research, and the research of my group, on the atmosphere-plant-soil
side of things. I don't work in the oceans, but it's important to acknowledge that the
atmosphere-ocean interface is an important part of the carbon cycle. So when I see this diagram,
I always hone in on the soil carbon part. You can see a big, white arrow going from a tree
down into the ground; and all of the white numbers in this representation of the global carbon cycle
are stocks, or pools, of carbon. So you can see 2,300 gigatonnes of carbon is stored in
the soil. People often think about growing more trees to store carbon above the ground in the
terrestrial biomass, and that is definitely an important part of our response to climate change.
But if you look closely to around the tree and the plant area, and you'll see that there's
550 gigatonnes of carbon stored in that above ground biomass. That's all across the planet.
The yellow numbers are the fluxes that are occurring of carbon moving from one pool to the
other. We've got 800 gigatonnes of carbon up into the atmosphere and we're constantly taking carbon
out of the atmosphere and putting it back in, not only through our burning of fossil fuels,
but also natural processes. Plants really are our allies in the fight against climate change because
they are continuously taking carbon dioxide out of the atmosphere and putting it together
inside their bodies, with sunlight and water and nutrients that they've got from the soil,
to create solid, stored carbon, the body of plants. And then there's four possible fates
for this solid carbon, which largely end up in it going back into a gaseous form:
so one, the plant can be burned; people and other animals can eat the plant; the plants
also break down these structures within their own bodies; and finally, as the plants die and decay,
they're eaten or partially eaten by bacteria and fungi. And it's this fourth pathway
that enables some of that carbon to not be returned to the atmosphere as carbon dioxide,
but instead to form soil carbon. The majority of soil carbon is at the surface of the soil.
You can see much darker carbon where the soil interacts with the atmosphere and also,
really, the crucially important role of plants in moving carbon down to deeper depths
in the soil. In many places, we've changed the way that we manage the land to actually
increase the amount of respiration that's occurring, so there's less photosynthesis
and more respiration. So we've altered that natural carbon cycle such that agricultural lands
are large emitters of greenhouse gases, and those emissions have almost doubled just since
1965. So while we talk a lot about keeping coal in the ground and keeping fossil fuels in the ground
and not opening up new mines, not many people are aware that we've also been mining soil carbon,
inadvertently, in the way that we manage the majority of our food producing landscapes.
Restoration of these degraded landscapes has the potential to store lots of carbon and particularly
in wetland soils, which is much of the focus of the work of my group at RMIT. And I want
to particularly introduce you to PEAT! This is a handful of extremely carbon rich soil. Peatlands
need water, they need to be wet. They are a type of wetland, they're a subset of wetland,
and to enable that balance between the carbon being fixed through photosynthesis and the carbon
then being respired and returned to the atmosphere by microbial respiration, water hinders that
breakdown of plant material. So peatlands need to stay wet to exist, and they also need not to have
a lot of tracks or drains or roads or physical disturbance through them. But in return, peatlands
provide, they also provide water. It might seem counter-intuitive; I'm saying on the one hand they
need water, and on the other hand they provide water, but it's true. This part of Australia is
really important hydrologically to this, our dry country, for a number of reasons.
You might be aware of our hydroelectricity generation, Snowy Hydro, and in Victoria we also
have a smaller hydroelectricity generated from Rocky Valley Dam, operated by AGL. That placement
of hydroelectricity in the Alps was very considered and strategic. These are high
rainfall and low evapotranspiration parts of our country, and so they're the ideal place
to be capturing and storing large amounts of water to generate hydroelectricity. So as well as that
important hydrologic role, peatlands also provide soil carbon sequestration. They provide a safe,
long-term storage for carbon. The tiny, little sphagnum mosses and the other shrubs and plants
that grow in the peatlands are just, you know, growing slowly each year, but they've been doing
so and storing that carbon in the soil in the build-up of peat for thousands of years. And what
we found is that Australian alpine peatlands, this one in particular that we're studying,
it's still forming peat and in fact it's a strong sink for carbon. This is an ecosystem
worth restoring, because it's doing some really important work for us. We're now
going to look at a more local example of carbon farming, where the Warrenbayne Farm Collective
in central Victoria is transitioning their family farm from a traditional Merino sheep enterprise
to a modern day carbon farm. The Warrenbayne Farm Collective is still farming sheep on this
property, but in a different way. Regenerative agriculture allows them to just switch the focus
a little, from a purely animal production focus to taking a whole systems, a whole landscape and
social ecological systems approach, and both grow sheep to eat as well as storing more carbon in the
soil. It's subtle changes; in the number of stock that are kept on the land, on the way stock are
managed and moved around the property. But after just 18 months, they're already starting to see
the results. And I'm going to leave you tonight with the Sustainable Development Goals. The
Sustainable Development Goals have been developed by the UN and taken on at all different levels
of society. So I've put a green circle around number two: zero hunger; number six: clean
water and sanitation; number thirteen: climate action. I'm sure, after tonight, you're very clear
on how soils relate to climate action and also number fifteen: life on land. These four goals
clearly are linked with soils and soil science. If we overlay the food system on top of those
circles with these red circles, you'll see that between food and soils, we have the majority
of the Sustainable Development Goals covered. So when you're thinking about climate action,
I hope that you will not ignore the possibilities right below your feet, and that you'll support
farmers who are doing so, and advocate to our governments to support both legislation and
practical action around storing more carbon in the soils, and enabling consumers to
make those supportive choices as well through a soil carbon certification scheme. And if you
want to learn more about any of these things, it would be fantastic to hear from you. Thanks!