Our Rapidly Changing Biosphere

Our Rapidly Changing Biosphere

– [Elliot] We’re here to talk
about the catalyst of change, last week we talked about
life on other planets. And the point of these lectures
is really to talk about some of the most important
scientific endeavors that are going on, that will
change the way that we live. So last week we talked
about life on other planets, and actually how life came
about, to some extent. And tonight we’ll talk about
the fast changing biosphere. So we have a really
interesting lecture discussing what’s happening to our current biosphere, how we can actually… What the impact of that’s
gonna be on our lives in the future, and also perhaps,
ways that we can actually have impact on it so that
some of the maybe, more dire impacts won’t happen. The lecture originally was
meant to have, continue our experiment with having
two lecturers, unfortunately due to unforeseen circumstances,
Rachel Gallery won’t be doing it, so Brian Enquist
will discuss in a second, has gallantly said that he’s
gonna take on this endeavor for us tonight. Brian Enquist is a
professor in the department of Ecology and Evolutionary
Biology, here at the University of Arizona, and he’s
broadly trained as both an ecologist and a biologist, a botanist. His lab investigates how climate
influences the physiology and functioning of plants. He has over 200 scientific
papers, that’s quite a bit, and over 35,000 citations,
meaning somebody else thought his work was very important. He recently published an
article, just this week in fact, on the importance of large
animals, and you’ll see that in part of his discussion. It was published in Nature
Communications, which is very prestigious in itself. I could be here all night
talking about his awards, but I’ll just mention two, he
won a Fullbright scholarship and was named one of the
Popular Science’s most brilliant 10 young scientists,
which is quite an honor. And he is also a fellow
of the Ecological Society of America, and the American Association for the Advancement of Science. So please join me in
welcoming Brian Enquist. (audience applauding) – [Brian] Great, thank
you Elliot, thank you. Thank you everyone. Is this on? Is this on? Yes, okay. Thank you very much, Elliot. I just want to just take
a moment and to thank the College of Science,
and to thank Elliot and the staff of the College of Science, for organizing this tremendous series. Not only is this a wonderful
venue to share the importance of science in society, but
also to kind of highlight just the amazing research that occurs here at the University of Arizona. So thank you to the College
of Science for this. (Everyone applauding) okay. So to get started, I’m
gonna talk about the future of the biosphere. So, by training I’m a
biologist, in particular my specialties are in
botany, I study plants, but I’m also an ecologist. And it’s tough being an
ecologist in the world today. And to pull out a quote from Aldo Leopold, in the Sand County Almanac,
“One of the penalties of an ecological education
is that one lives alone in a world of wounds. Much of the damage that
is inflicted in the land is quite invisible to laymen.” Now I’m just gonna give you one example. Did you know that we’re now
at the end of the decade on biodiversity. The United Nations
implemented, in 2010, a decade to study the importance of
biodiversity on the planet, the importance of
biodiversity, not in terms of just biology, but the
importance of biodiversity to our society and to the earth, and in particular the biosphere. Now we’re gonna be talking
about a lot of different terms and it’s always good when we start class, to start with some definitions,
in particular, biodiversity. So biodiversity is a term
that we use to describe the variety and variability
of life on Earth. And we apply our
understanding of biodiversity at all different levels of
biological organization, from the smallest scale,
from within the soil, and talk about microbes, all the way up to communities and ecosystems. And at the highest scale something that we call the biosphere. Now we can characterize biological
diversity, biodiversity, in terms of number of species,
different types of species, but also differences in
how those species function, that is the different roles
that they play on the planet. And we can also characterize
their relatedness to each other. Now the biosphere, is a
term that we use to describe the living skin of the planet. And you likely have heard
of our other spheres on the world, right? So we have the atmosphere,
the lithosphere in the world of rocks, the hydrosphere. And you’ve probably heard
a lot about climate change and how we’re changing the atmosphere. And climate change is also
changing the hydrosphere, changing the acidity of
the oceans, the temperature of the oceans. But you probably haven’t
heard how climate change is changing our biosphere. And that’s what I wanna
talk about tonight. Now in order to, kinda convey the work that I’m gonna
talk about, we have to kind of come up with some
kind of common metrics. And one of the metrics that
we use to connect aspects of biodiversity with the
biosphere, is something known as metabolism, something
actually you’re doing right now sitting there in your chair. Now metabolism is something
that all living things do, metabolism is the set of chemical
reactions within organisms within your cells, that’s
basically powering you. And we measure metabolism
in terms of energy. So metabolism is energy. It’s the ability then of life to do work. This talk is also about something known as the Great Acceleration. So acceleration, increasing
speed, the changes that we’re going through now
are not only obvious changes, but they’re accelerating
changes and they’re gonna continue to accelerate. This acceleration, ultimately,
is due to the success of humanity across the planet at large. Now this acceleration started
in the mid 20th century and it continues to this day. In this talk I’m gonna be
focusing on four aspects of the great acceleration. But I’m gonna focus on how
this great acceleration is influencing our biosphere. First aspect is metabolism,
our common measure that’s gonna allow us
to assess future worlds, what our biosphere may
look like in the future. The second I’m gonna be
focusing on aspects of climate and climate change, but in
particular how metabolism and climate change is
influencing species on the planet and also the responsive
ecosystems on the planet. And to do that we’re gonna be
focusing also on biodiversity, how biodiversity then
is going to be changing. And lastly, what’s gonna be
happening to our biosphere? And I’m gonna be focusing
on something known as the megabiota, the largest
plants and animals on the planet. So we’re now living in an era
known as the Anthropocene. The increasing human
domination of the planet. We can characterize the
Anthropocene as something known as the Great Acceleration,
and I can characterize this great acceleration in a
series of different graphs. So let’s look at several
different measures of human activity on the planet,
going back about 250 years. And here are all the graphs. On the x axis is years
going back to the 1700s to present day, and the y
axis is a change in something associated with humanity on the planet. Population has increased,
the gross domestic product, our economy has increased,
race of investment, how much energy we use
on the planet, the amount of fertilizer that we use in the planet. How much water is needed,
how much paper is produced, our rates of transportation,
telecommunications and the rise of international tourism. Now if you look at these
curves, they all have the same shape, accelerating change. It’s not stopping. And that acceleration is
not just in human systems, that impact is on the planet
and our planetary systems. So if we look at earth
system trends, carbon dioxide in our atmosphere, nitrous
oxide, methane, ozone levels, the surface temperature
is increasing, the oceans are getting more acidic,
the harvesting of fish, the loss of tropical forest,
how much land on the planet is used for agriculture. The overall degradation of the
biosphere, all accelerating. This acceleration really
started to ramp up around 1950, approximately. So metabolism. All right, so this a class, right? I can ask you questions,
I expect a response. What is driving this acceleration? What underlies this acceleration? Anybody? (crowd talking at same time) Very good. (crowd chuckling) The number of people. But that’s partial credit. What else? (crowd chattering) Technology. The what? – [Man In Audience] Energy consumption. – [Woman In Audience] The
human need for domination. (crowd laughing) – All right, we’re gonna have
to go to the introductory lecture on this one. I heard a little bit. Partial credit. It’s you per capita metabolic demand. Okay? It’s the number of people,
times, the demand per person. Now we can make this a
little bit more complicated, if we’re gonna keep this in
metabolic units, energy units, we can parse out our per
capita metabolic demand in terms of how much
energy it costs you to keep your biology alive,
basically how much you have to ingest a day to keep
your metabolism going, times, what we’re gonna call
our extended metabolism. Basically to keep you
happy and here, right? Our way of living. So biological metabolism
and extended metabolism. Okay. In biology we can characterize
the variation in metabolism by something known as Kleiber’s
Law, actually named after Max Kleiber, an American
animal physiologist here in 1938. And actually this graph is
Kleiber’s original publication from 1938, we would probably
plot things a little differently now, but what
this relationship shows is that if you go from the
smallest organisms up to the largest organisms, there
is a very simple mathematical relationship that describes
your biological metabolic needs. That is, is you go from
small things to big things, big things just require more
energy, they have more cells, they’re bigger, they eat more. You have a bigger dog, you feed the dog more dog food, all right. But we can characterize
that mathematically, and if you notice on this
graph from Kleiber, we have a man and a woman, and it turns
out that your metabolic rate is approximately a 100 watts,
that’s what you need to live and survive, a 100 watts. And so to give you an idea,
this is the old light bulb, all right, 60 watts. This is the one, unlike the
LEDs that make you look orange apparently.
(audience laughing) Here’s you, 120 watts. Each one of you, 120 watts
glowing in the audience. So next question, where does
all that energy come from? – [Man 2 In Audience] The sun. – Very good. The sun. That powers you. And here’s the chemical
equation for that reaction. How that energy gets to
you is through plants, photosynthesis, that
is powering everything in the biosphere. But, in order for photosynthesis
to proceed, carbon dioxide, remember, comes into the
plant via photosynthesis, plants create sugar with that
carbon, but to do that process takes a little bit of energy. And when you calculate what that is. So that’s how much energy
then, is happening associated with photosynthesis, about 39
kilojoules per gram of carbon. Now that’s at one scale, the leaf. We can also measure, now,
photosynthesis on the scale of a planet. Thanks to remote sensing,
satellite data, we can now measure the metabolism of
the biosphere and this is the metabolism of the
earth right here, in terms of photosynthesis in the
oceans, the aquatic landscapes, but also in terrestrial environment. And as you can see,
this is a dynamic earth, we have the advancement
of snow in the winter, retreat of snow during the
summer, but we can then see, basically this breathing
dynamic biosphere, associated with the seasonality of the earth. We can also show the metabolism
of the earth a little bit differently, to give you
a new view of metabolism. And what we can do is estimate
exactly how much energy is being passed through the
biosphere, through metabolism. And it turns out that the
energy flow through the land is about 150 TW, which is a
150 million million watts. And here’s the energy
flow through the ocean, about 120 million watts, 120
TW, so that the total energy flow through the earth is 270 TW. That’s the power of the planet, in terms of the planetary metabolism. Now, let’s rescale that metabolism
in terms of the intensity of that metabolism. So we’re rescaling the
planet of metabolism based on the total amount
that’s being produced at a given time. And so you can see that
the tropical areas are kind of exaggerated, they’re
bloated out because that’s where a lot of terrestrial
photosynthesis then is occurring. And during the winter
time, the temperate zones, well it’s winter, there’s not a lot of photosynthesis occurring. But now what we can do,
is that we can animate this proportional aspect
of metabolism through time. This is the beating of
the heart of the world, the biosphere. It’s a living entity. So during the winter time,
the temperate zones perform a lot of photosynthesis
and they go dormant during the winter. So, ultimately, everything
that you do is fueled by this metabolism. The energy flow through
our metabolism describes our ability to change the world around us. Human metabolism is embedded
within this planetary metabolism, there’s no escaping it. So how does the metabolism
of humanity compare with metabolism of the
rest of the biosphere? So I’m gonna make a simple plot. I’m gonna show on the
x axis the energy used per individual versus the
energy used per unit area. And this is actually work
that’s done by a brilliant researcher here, Robbie Burger
at the University of Arizona. And so what Robbie did, was he
asked, “Well what if we look at all the mammals on the planet and ask where do they fall?” And that’s where all the mammals fall. So if you think about all the
different types of mammals then, on the planet, you can
see that there’s variability in the energy used per
individual, but also the energy used per unit area. Up above we have a
yellow dotted line here, that’s the average
metabolism of the biosphere per unit area, that’s the global average. So in general, mammals
across the planet, are using less energy per unit area,
right, which makes sense because there’s only so
much of food available, only so much energy available per unit area. And so they’re always lower
than that, because the world can’t supply increased
densities of mammals. Now we can also put people on here. Here’s our best estimate
of the metabolism of hunter gatherers, in terms of their,
not only biological metabolism the 120 watts per person,
but the extended metabolism. That is how much energy
then is required in order to support, then, these early societies. About 300 watts. We can now speed up time
to preindustrial humanity, we require more things,
we have technology, we require beasts of
burden, horses, cattle. Then in order to support,
then, our own societies, and if we then measure
that extended metabolism, then required to support
preindustrial humanity, we’re now up to about 2,000 watts. Again, in addition to the 120 watts of your biological metabolism. So our extended metabolism is now growing. What about today, what if
we measure your extended metabolism, what energy is
needed to, basically satisfy your daily lives? Here’s humanity today. Extended metabolism on
average, about 8,000 watts. We have now surpassed the global average net primary productivity. We’ve crossed a planetary boundary. If we graph going from present day all the way back, in total 16,000 years, and plot the social
metabolism watts per person, we see a gradual, gradual
increase, a little warp and wiggle because of
the black death, right? Pestilence, rise of modern society, science, modern medicine, an explosion
of social metabolism. So what’s fueling that rise? Ancient photosynthesis
is fueling that rise. So if we go back 200,
300 million years ago, the planet looked like this. All of that carbon stored
in these ancient tree trunks fell in these anoxic environments,
it was buried over time, got deposited, all that
ancient CO2 deposited, put away inside the earth, coal, oil, ancient photosynthesis. That is fueling the great acceleration. So here is an animation
showing the rise of industry across the planet, in terms
of the annual CO2 emissions, starting in the year 1751. Starting with the origin
then of the industrial, our modern industrial society in the UK. And we’re gonna animate this
forward, and what you’re gonna see is our industrial, our
extended metabolism light up. Fueling humanities growth. Notice there’s still large
parts of the planet that still haven’t lit up yet, but they will. Okay. So let’s go back to Kleiber’s Law. Can we help use this law to make sense of the change around us? Well we can take a few organisms
you may be familiar with, going from a dog to a rhino,
all the way to an elephant. Now let’s put these
different human societies, people from hunter gatherers
all the way up to modern society, and instead of
looking at their biological metabolism, let’s look at
their extended metabolism. So if we were a mammal
with the metabolic impact of our social metabolism,
how big would we be? The average industrial human
has the resource consumption of a 15 metric ton primate. In North America even
bigger, 30 metric tons. For those of you trying to
do some quick visualizations of what that would look like, it’s this. (audience laughing) Each of you King Kongs,
sitting in your seat, roaming around the world. Okay. So let’s switch gears, how
will species and ecosystems respond in to climate change? Now this is a big important
complicated question and issue, and we’re doing
our best to address this, but we’ve learned a few things. So what is gonna be the impact
of this great acceleration on the planet? Could be a traumatic train wreck, right? A big calamity. Here’s my favorite train wreck, 22 of October 1895, the driver was late
getting into the station. Decided to kind of put, you
know, the pedal to the metal, increase the speed, entered
the train station going way too fast, put on
the brake way too late, hit a series of barriers,
the barriers did not stop the train, it kept going all
the way through the station and out to the street below. Okay. Planetary boundaries. The train is rapidly
coming into the station. If we look at humanities
influence on planetary processes, going back over 10 million
years, we see this gradual increase in terms of the
impact of humans on the planet. And we can measure, then,
that in various different ways and we can mark it with
differences, and technology, and so on. Now, what’s going to be the future impact? And this is where choices come in, we have several different choices, the different futures
that we want to live in, and this is not a far off future. You sitting here will
actually start to experience some of these futures, your
children will experience these futures, and their
children’s children are definitely gonna
experience these futures. And it’s up to us to decide
which future biosphere we want to live in. So are we entering a safe
Anthropocene, or are we going to totally rupture and
surpass all of the limits? Okay, so here are our choices. It’s actually this easy, we
have two different worlds to choose from. Temperatures are gonna change,
that’s gonna be baked in, but we can decide which rate
of change we’re gonna enter in. We call this either the
best case scenario or the worst case scenario. These are the future global temperatures in approximately 100 years. This is now, I put this in
Fahrenheit because often times people have a hard time, here
in this country with celsius, a world where we’re seeing
increases, I don’t know, maybe three, five degrees
Fahrenheit change, best case scenario. Or a world where we’re talking
about changes, 9, 15 degrees Fahrenheit changes. And then that’s just the
mean, this isn’t showing the extreme temperature changes. Choose your temperature. So we’re now entering in what
is know as the Anthropocene. It means different things
to different people. It could mean an Earth system
where humanity is bouncing against and rupturing
planetary boundaries. It could also be a distant
event in Earth, a distinct event in Earth’s history
recording in the rock record, the stratigraphic record. It’s a modern world where
human influence is pervasive. It’s a world “After
Nature”, where the “natural” no longer exists. All of Earth history
touched by human activity. So given then the Anthropocene,
given the acceleration of these changes, can
we predict the future of the biosphere? We know what’s gonna happen
to the atmosphere, we know what’s gonna happen to
the oceans, but what about the living aspect of the planet? So it could be that
Huxley, instead of writing the “Brave New World”, should have written “Brave New Biosphere”. So how do we envision
these potential scenarios of the future of the biosphere? Well on the left hand
side we have one part of the hour glass, on the right
hand side we have a future part of the hour glass. The left hand side is the
world that humanity grew up in, the biosphere that humanity,
basically evolved in. That’s in the past. There’s gonna be a bottleneck,
a bottleneck constricted by resources available
to other living things, area available to preserve living things, and all of the biosphere’s
gonna go through this bottleneck and what comes out on the other
side is gonna be influenced by our decisions. We can influence the size
of this bottleneck, in terms of what passes from the
past into the future by noting what the pressures
are, constricting what makes it into the future, but
also our responses, the way we manage the world, our
decisions then that we make will influence what
progresses from the past into the future. So here at the University
of Arizona, there are an impressive number of
researchers working on this question right now,
in terms of not only what our current status of the
biosphere is, but also what the future of the
biosphere is going to be. So we have groups known as
the Bridging Biodiversity in Conservation Science,
this is an interdisciplinary cross college initiative,
kind of a rapid response team to bring together people
from medicine, from ecology, from the school of natural
resources, to all focus on some of these pressing problems. There’s a lot of expertise
here at the University of Arizona, increasingly
focused on Big Data, we have a lot of information
now coming from satellites, coming from natural history
collections, about biodiversity and how our world is changing
in terms of the biosphere. But we also have a lot of
theoretical work going on, in terms of, kind of, trying
to figure out and predict what’s going to happen in
the future, both in terms of developing mathematical
models, but also computer simulation models to figure
out our best understanding in terms of predicting and
forecasting what the future of the biosphere is going to be. So I wanna highlight a
little bit of this work, to give you a sense of the
work that’s currently going on. And I wanna start with,
maybe a simple example, but maybe something that is more familiar. So I wanna focus, actually
on one species of tree, Subalpine Fir. So if you go to some of
the highest mountain tops here in Arizona or if you
go into Colorado throughout the west, you’ll see this
tree, beautiful tree. And it is distributed, and
here’s the geographic range map of where you’ll find Subalpine
Fir throughout the west, and here is its current distribution. Now what we can do, is
that we can take a lot of the information about
changes in climate, changes in temperature, and the pace
at which that’s changing, and we can take information
about the physiology then of this tree. And we also can have
information about where it tends to occur to make some good
educated guess, in terms of where it likely will be
in the future or could be in the future. So we can design then these
animations that are going through a 10 year time
steps, 10 year time steps. And so what I’m showing you is
the change in the suitability of the climate for Subalpine
Fir, just one species. Now unfortunately Subalpine
Fir just can’t get up and walk and move. And what you’ll see, and this
is the same for many species that we looked at, a changing
distribution, quite rapid changing distribution, for
Subalpine Fir the future does not look good,
especially in the west. But what we can do, is I can
give you how Subalpine Fir that’s distribution will
change in the blue line according to the best case
scenario of our emissions, or the red line, the worst case scenario. I can tell you approximately
how much forest area you may or may not loose,
according to these different choices that we may make. We can do the same for
another species, in general if you like trees, we like
Aspen trees, beautiful. And what a better place
to study what’ll happen to Aspen than in the
town of Aspen, Colorado. Named for the wonderful Aspen trees. So I’m gonna show you a map
here, there’s another different way of visualizing how
the change in the climates suitability of the Aspen,
is going to change on very short ecological time scales. And so what we can see
here is a map, you can see the mountains with snow on
it, but you see this dark green, these dark green areas
right here, that’s where we expect the climate for Aspen currently to be best. And in general it works
pretty well, you go to those areas you tend to see Aspen trees. But we can do is that we
can also kind of animate, and I can go back and
forth, how the distribution and the climate distribution
of Aspen may change under the best case climate scenario. But I can also show you
what the town of Aspen will look like under
the worst case scenario, we’re not expecting Aspen trees to survive in Aspen Colorado. Now we can do this for
many different species, it gives us a back of the
envelope way of approximating, not only the rate of change,
but the types of different change we may see under the
blue line the best case scenario and the red line the worst case scenario. So we can give you this
choice, do you want to loose approximately 40% of your
forested area of Colorado or 10%, it’s up to you? So biodiversity. So how do we protect threatened
species and ecosystems? This is a daunting challenge,
a rapidly more increasingly dire challenge. So, how we used to do conservation biology has totally changed. We used to design conservation
areas and our protected areas as if species
were kind of, you know, always gonna be in the landscape. And the only changes were
land clearing and humans, but now species are on the
move, it’s not a static world, it’s a dynamically changing world. And I’m gonna show you
an animation that starts in the year 1700, and
this is for South America, and there’s gonna be three
different colors here. The red areas are developing areas, okay, so if we go back to the 1700s
and if we map out where people tended to be, where their
agriculture was, but then the dark, the blacker areas
more urbanized environments, high densities then of people. But then there’s gonna be
another color that comes up, and that’s the yellow areas. The yellow areas are the protected areas, things like National
Parks or areas set aside for biodiversity management
that could have people or not, these are areas then dedicated to the preservation of nature. So let’s watch this movie. So you’ll see the slow progression
of areas then dominated by humans, and the rapid proliferation,
relatively recently, of protected areas. And I think what you
understand is now the world is effectively full. This is a complicated graph,
but it’s actually very easy if I walk you through it. On the x axis is time and
years going back from 1900 to present day, but also
out to the year 2100, and there’s two curves,
there’s a curve on the top that’s angled down, and there’s a curve on the bottom going up. And there’s kind of different
flavors of the curves, based on different ways we estimate. The curve on the bottom
is the rise in areas under conservation in some
sort of way, protected areas. The curve on the top is
the area of land then, that is potentially
available for conservation that’s not being impacted
then by people, in terms of our agriculture or urban environments. And I think what you’ll notice
is that those two curves are going to intersect,
and when they intersect that means all of the land
on earth is accounted for. And we estimate that, that
crossing of those two curves is gonna occur sometime around 2050. We call this the last
call for protected areas. We have a closing window
of opportunity in order to protect nature, and to anticipate the areas important for nature. Some of you may know of the
biologist Edward Wilson, he has a recent book
known as “Half-Earth”. He’s argued that to maintain
the integrity of biodiversity and the functioning of
the biosphere, we need 50% of Earth preserved for nature. Well, we crossed that line,
depending on how you estimate it, either shortly after
1950 or sometime around 2000. 50% of Earth is now passed. We’re now trying to get to 30%. So how we do conservation
now has totally changed. So why is this important? Species are and will be on the
move, we need to anticipate and prioritize key areas where
they’re going to be moving, so that by the time we
get to 2050, 2070, maybe at the latest, this is our last call. So rapid changes in biodiversity is gonna have cascading impacts. So in our planetary history,
Earth history, we’ve had several mass extinctions, usually precipitated by a large asteroid or something cataclysmic. A big debate now is if we’re actually in the sixth mass extinction. We know if we look across
different groups of animals and plants, currently there’s a significant fraction of species that are currently
endangered or threatened with extinction, if we look across birds, mammals, amphibians. Now how we impact the
probability of a species going extinct is complicated,
due to many different factors. Changes in land use and
agriculture, differences in kind of the rise of new technologies,
differences in hunting pressures, complex
interconnections with our global economic markets and different
demands, you know from society, but also changes in regional and planetary boundaries. So one of the best
predictors of extinction that we know of, is
actually something simple, how many individuals there are. So something is endangered
or at risk of extinction if the numbers of individuals
get really really small. That’s an easy way to
identify if something is going to go extinct, well there’s
not too many of them. This is one of my favorite botanists, this is Steve Perlman, he’s kind of the Indiana Jones of botany. So here he is repelling
off these steep cliffs in Hawaii, looking for
these rare and threatened, endangered plants that have
somehow managed to survive a lot of the changes going on
Hawaii, by kind of clinging to these cliffs off the side. And so here is collecting
one of the few seeds from one of the few
remaining species of orchids, this is very important
work, it’s very tough work, but how can we speed this
effort to identify what is potentially risk of extinction. How can we rapidly identify
all of the Earth’s species in risk of extinction? Can we maybe identify,
maybe some shortcuts, maybe first find where
are areas of the planet that are hot spots of extinction? So here at the University
of Arizona, we’ve been compiling all the world’s
biodiversity data, everything that we know
about the locations of all different species on the planet. And so we wanted to focus
on an important group, plants, photosynthesis remember? And so here for this data
set that we assembled, we’re over 200 million
observations of plants across the globe. And with this we actually
identified the total number of plants on the planet,
in terms of species. We estimate about 435,000 plant
species across the planet. Now when we look at the
aspects of biodiversity, the flavor of biodiversity
in terms of rarity and commonness, and if we plot
the number of observations per species and look at the
frequency of observations per species, you’ll
get this inverse curve. And what that is saying
is that very few species have been observed a lot of
times, these are the really common things, but there
are very few species that are very common. Most of the species
are actually very rare, and it turns out, about
36% of all plant species have only been observed in
our data sets five times. That’s amazing. We know very little about a
large majority of species. So most species are very
rare, which means a large fraction of species are in
potential danger of extinction. Now, we can ask where
are these rare species? Well what we identify in
these maps here, where they’re highlighted in kind
of increasingly more orange and brown color, these are what
we call hot spots of rarity. These are locations on the
planet, like the Andes, they find most in South
America, Madagascar, South East China, New
Guinea, these are areas that have a disproportionate
number of rare species, areas that maybe we can
quickly target in terms of our conservation effort. But we also asked, “Well,
why are there a lot of rare species here to begin with? Why do we find them in these areas?” And it turns out, and
this is really interesting and quite important, is
that these are the areas of the planet that have
been climatically stable over the last 20,000 years. These are the areas of
the planet that have had the most stable climate through that time. So you can think of these
areas as kind of being able to protect these rare things. Now when we look into the future and ask, “What about the stability of
the climate in these places that harbor the rarest species?” What we find is very sobering. So what I’m showing you is
a heat map, we’ll call it a heat map, the redder
the color the more worse it is unfortunately. We are forecasting the change
in climate then associated then with rarity, and what
we find is that in areas that house the most plant
species, those areas are going to be experiencing,
they’re forecast to experience the fastest rate of change. So, we can use this
information now to identify, where should we place protected
areas for climate change? So here at the University
of Arizona we’re involved in this project with
Conservation International and the GEF out of the UN,
something known as SPARC, Spatial Planning for
Protected Areas in Response to Climate Change. How could we rapidly go
out and identify areas of the planet that are
changing very quickly, that likely have the
highest number of species at risk of extinction? Can we foresee and
target things in advance before they happen? So I’ll show you just one example. Here we’re going out, we’re
forecasting the climate suitability of a given species. And as you can see the
climate suitability of a given species, this one species
through time, is kind of moving then up the mountain. The green areas, those
are protected areas, and you’ll see that here,
the climate suitability is moving kind of in and then
out of the protected area. We can do this for many
different species, but then we can also overlay on top
of that what we call these tracks or these chains. This is the, effectively the
potential suitable climate movement of different
species, and we can do this one at a time, and then
with massive computation we can do this hopefully for
all species on the planet. To look to see and identify,
where then are these tracks then, that species may
need or suitable areas for the most number of species. And we’ve done that in
many different locations. And so here what I’m
showing are within one of the biodiversity hotspots,
rarity hotspots, the Andes of South America, I’m showing
you a density of these total number of chains or tracks
of different species. And so the red areas are
likely areas that are going to be, kind of potentially
climatically favorable to a lot of species
moving into the future. These would be potential priority areas. Okay. So that’s what we’re doing at the U of A. And another aspect of
research occurring here, is trying to assess, well let’s step back and now let’s assess the biosphere. And so this is the last point
that I want to make today. In particular, what happens
on the planet if we loose Earth’s largest species. We call these species the
megabiota, the largest plants and animals on the planet. And I have to say that,
I think that this by far is going to be the most
single important change, and long lasting change that
we’re doing to the biosphere. Because we disproportionately
impact the largest things in the planet. So human activities across the
globe has disproportionately hunted and exploited the
largest animals and plants. We’ve lost a lot of giants. A tremendous number of giants
that are no longer with us, but were with us in our
evolutionary history. So to give you a sense,
here’s kind of a temporal aspect of this loss. So we’re going back years
ago, over a 100,000 years ago to today, and we’re looking
across each of the major kind of continents across the globe. And we’re looking at the
mean body mass of the animals that used to live in those
different environments, and if you notice starting
around 10,000 years we see this precipitous drop. So that happened in the
past and it’s continuing to happen now. If we just focus on the
most charismatic animals that you know of, elephants,
gorillas, cheetahs, leopards, lions, giraffes, polar bears,
all of their populations in general are decreasing. They continue to decrease. We haven’t lost them yet,
but they’re nowhere near as abundant as they used to be. So we can estimate to
the best of our ability, how much animal biomass there
was about 10,000 years ago. In terms of millions of metric tons. And here it is today. But we can also put on this
graph the biomass of humanity and our commensals, cattle,
sheep, horses, and so on. And between 1970 and 2010 we’ve lost 52% of all individuals
of animals on the planet. So the population sizes
of animals on the planet have been getting smaller
and smaller and smaller. Now we haven’t lost a
lot of them, especially the charismatic ones, but
there’s a lot fewer of them. And what’s amazing, is that
we’re still discovering new things in the world. So for example, just this
past year they discovered in the Amazon, thanks to
new satellite technology, the tallest tree in the Amazon coming in at almost 90 meters. The story of trees isn’t a good one. But now with new technology we
can estimate the distribution then of forests across the planet, and we can map the tree
density at global scales, and we can estimate that
currently there’s about three trillion trees on the
planet, that’s a great number. Did you know there are three
trillion trees on the planet? All right. But it’s nowhere near what it used to be. Each year over 15 billion
trees are cut down, every year, and since the start of human
civilization we have lost about 46% of all trees on the planet. But it’s not just any
tree, it’s the largest and the oldest ones. Big and old trees are
currently declining anywhere on the planet that you
look, and we’ve tried, we’ve scoured the literature. Everywhere we’re seeing
decreases disproportionately in the biggest plants. So why are these big things important? Well small things are
important too, but big things have a disproportionate
impact on the biosphere. So these big things have
all these interactions, ecological interactions, all right. We have beetles, we have
parasites, we have scavengers, we have birds, ectoparasites,
we have herbivores and carnivores, and
they’re all linked together in an ecological web. And so if you pull out these
big organisms from this web, it has dramatic cascading changes. And it’s the type of change
that you don’t notice, you don’t necessarily see,
because hey, there’s still life out of there, right? But if we actually go in
and measure the ecological impact in terms of metabolism,
it’s a very dramatic effect. So how do these large
plants and animals influence the functioning of
ecosystems in the biosphere? So in 2009 we had an analogous experiment. The great recession, mainly caused by the
trouble and failure of some of our largest banks and corporations. So what happens to the economy
if we take out the biggest bank or pull out the biggest corporation? The largest cities and
corporations disproportionately impact the global economy. And the same is true for
the economy in nature. So we can update Kleiber’s
Law, and we can now put all these different
organisms on Kleiber’s Law, and we can now estimate as
we change the body sizes of species on the planet, what
does that mean for not only the individual metabolic demand, but the total biosphere metabolic rate? So why are they important, big things? So here’s a great group of
elephants, elephants travel over long distances. And they have a big impact,
because they may eat in one location, and they’re
herbivores they eat a lot of grass, a lot of leaves
even wood, all that nutrients all of that food stuff,
ultimately has to come out the other end. So elephants, large
animals, even large trees, they are fertilizers of the planet. They take nutrients in
one location and move them and spread them out, and
imagine a planet filled with big things, spreading their
fertilizer over everywhere. So big things provide a lot
of benefits, we can talk about benefits for
ecological systems and also socio-economic systems. So our own economy, our human wellbeing. And so we can measure all
of these various different benefits, and it turns out that they provide disproportionate benefits, not only on biodiversity,
but also on human wellbeing. So how do we begin to
tackle how the loss, then of these largest things
in the world is actually impacting the biosphere? Well, we can simulate it. Our computational power now
has increased to the fact that we can simulate the
entire biosphere with these equations of energy, but
also the rules of how species interact with each other
and how they compete, fend for themselves and so on. So this is known as the Madingley model, it was actually originally
put together by Microsoft, and it’s now kind of spun
off into it’s own thing. And so here what we’re doing
in each of these grid cells, we’re actually simulating
the ecology, we’re simulating the growth of plants and
how plants interact with the environment, but also
how animals then eat plants and then other animals eat
other animals, and we put in all of these energetic
and metabolic rules to produce a simulation of the biosphere. And in this case we can keep
track of the bookkeeping, and we can then do experiments
where we reduce the size ranges of animals and plants
within the simulation model, and we can ask, all right,
what does a biosphere look like in a Pleistocene world, in both temperate and tropical environments. If we move to the modern
world now we’ve lost some of the biggest things, and
we can also then expect and forecast a future world, more devoid of animals and plants. And we can ask then what
happens to the total biosphere biomass, in terms of the
heterotrophic, the animal biomass, but also the total
heterotrophic metabolism, but also the global
nutrient fertility, that is the regeneration of nutrients
and the spread of nutrients across the biosphere, the
fertility of the planet. And what we see for all of
these different measures, is a reduction. And so we estimate that
with the continued loss of the largest animals and
plants, we’re gonna see a 44% reduction in heterotrophic
biomass, a 17% reduction in the total biosphere
metabolism, but a almost 90% reduction in the fertility of the planet, just by losing the big things. So, I’ve emphasized four aspects
of the great acceleration, in terms of their impact
and on the biosphere. And these changes are
driven, ultimately by this great acceleration,
in particular our metabolic demand for resources is
accelerating and the impacts of those demands are also accelerating. So we have some choices to
make, in terms of the future of the biosphere. We’re going to be increasingly
entering into a bottleneck. Now, we get to choose what
makes it to the other side. We can choose the future
of our biosphere, in terms of understanding and trying to
mitigate differing pressures, differences in climate and
the rate of climate change, but also how we manage then
the world and how we anticipate then these changes. So remember, the math when
you step back at the scale, is kind of simple. It’s the number of people
and our metabolic demand, and our metabolic demand is huge. So what we’ve been doing
is shrinking the metabolism of the planet, the natural
metabolism of the planet. And that has come at
the expense of the rise of our own metabolism, so
it shouldn’t be a surprise. So to conclude. There’s a lot of bad news
here, I’m sorry about that. No getting around that, okay. Yeah, these drivers of
change in the Anthropocene are rapid, and the scary
thing about this change is it’s gonna be accelerating. It’s scary. Now, the aspect of this, is
the time to act is now to potentially avoid catastrophic changes, because increasingly it’s
gonna be very hard to reverse. But I also wanna leave you
with this, there’s a lot of good news. There really is a lot of
good news, because we now can start to foresee what
the biosphere will be like, and we can provide quantitative
predictions for what the world is gonna look like. We can also communicate and
now visualize these changes in a way that’s
understandable, on time scales that are understandable
for us in our normal day-to-day lives. And despite the enormous
complexities, we can start to simplify the problem
and start to get a good approximations for what
we think the magnitude of these potential changes would be. But also with conservation
efforts, again because the way we’re doing conservation
is now rapidly changing, we can now streamline a
lot of conservation efforts by focusing on things
like hot spots, the rarity hot spots of extinction, of
current and future diversity, but also we can do simple
things like try to promote the largest animals and
the largest trees because they have such a disproportionate impact. And all of this gives us
less guess work, more focus, and the efficient use of funding. So, I wanna send out a
get well soon to Rachel. Unfortunately couldn’t be here. But also to thank a
tremendous number of people, even though it’s been me
standing up here yammering, a lot of brilliant people
I’ve had the pleasure to work with, who are actually behind
the majority of this work. As well as the support
from many institutions. So thank you. (audience clapping)

2 thoughts on “Our Rapidly Changing Biosphere

  1. i was really looking for solutions to the cascading array of indications that are making themselves apparent. When i see people like Dr. Patrick Moore telling me things are great and that C02 is Plant Food and that im stupid, … well, … i would like to thank the brave people that stand up and confirm that i am NOT alone.

  2. i was looking for solutions to the cascading array of indications that are making themselves apparent. But when i have people like Dr. Patrick Moore telling me that things are great and that C02 is Plant Food and that im stupid, … well, .. it is good to know that i am NOT alone.

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