- [Instructor] What are some of the global threats

so biodiversity?

First, I want to emphasize that virtually everything

we do locally has global consequences.

When we talk about something like a greenhouse gas

or a pollutant, that's something we produce locally

from our car or from other things that make up

so many of our day to day human activities.

But in the grand scale of things,

even these local activities and impacts

can have global effects.

Greenhouse gases aren't just carbon dioxide,

they also include water vapor, methane,

ozone and nitrous oxide but for this tutorial,

we want to focus on the major effects

of carbon dioxide which chemists refer to as CO2.

Increases in the amount of carbon dioxide

in the atmosphere mostly come through

the burning of fossil fuels.

Fossil fuels contain huge amounts

of carbon and when they're burned,

they not only release heat energy

but they also release carbon dioxide

although it's the energy, the heat that we want,

carbon dioxide is a side product of the burning.

That's why atmospheric CO2 is increasing.

Why are so many people concerned about that

in terms of global change?

The answer means we need to say a few words

about the greenhouse effect and how that actually works.

Light rays from the sun arrive in our atmosphere

as shorter wavelength radiation.

This light energy hits the surface of the earth.

Some of it is reflected back in the form

of slightly longer wavelength radiation

and it's this longer wavelength radiation

that falls into what is known as the infrared area

of the spectrum.

Infrared is the same as heat, basically.

So when light hits the surface of the earth,

it's changed into heat energy.

That heat energy is, to a certain extent,

absorbed and some of it's reflected back up into space

but greenhouse gases actually have a kind

of snacking preference for longer wave radiation

like infrared energy.

This keeps the heat energy close to the earth's surface

instead of allowing it to go out into space.

The more greenhouse gas you have, the more

the heat builds up.

It's no coincidence that this is called

the greenhouse effect.

It works almost exactly like a gardener's greenhouse.

A greenhouse is made of panes of glass

and all that nice sunlight goes through the glass.

It strikes the plants, the soil, the stuff inside

the greenhouse but much of it becomes infrared light

or heat held within your greenhouse and bouncing around

through the air inside to make things nice and warm.

To a certain extent, like our little plants

in the greenhouse, earth's organisms benefit from

the greenhouse effect.

Life on earth would probably be quite different

or perhaps not exist at all if we didn't have

some greenhouse effect.

The problem is that now we've increased the rate

at which greenhouse gases are being introduced

to the atmosphere and therefore the rate

at which warming occurs.

Even gardeners have to regulate the flow of light

into a greenhouse to keep it from overheating

and cooking their veggies before they even get picked

off the plant.

So there's your problem.

Rate.

It's not so much that CO2 buildup is happening,

it's happened before in the history of the earth.

Scientists even see cycles to these things

but it's the current rate at which CO2 content

is changing that's the running theme behind all

of the problems that we're seeing today.

Life just can't keep up.

Here's a graph that demonstrates CO2 content

in our atmosphere over time.

What I like about this particular one is we go

from about 400 thousand years ago to the present.

We've got these hundred thousand year intervals

and a series of interesting drops and peaks

and drops and peaks and then coming to the present,

it kind of goes off the charts so much

that we've gotta magnify that part of the graph

to see it better.

In here, in the industrial age, we're experiencing

this greatly enhanced period of carbon dioxide production

through the activities of humans.

There are agencies out there that are very concerned

with this problem.

One of them is the Intergovernmental Panel

on Climate Change or IPCC.

According to the most conservative IPCC estimates,

the global temperature on earth,

and this is an average temperature

over the whole planet by the way,

is going to rise 1.1 to 2.9 degrees celsius

during this century.

That's two to 5.2 degrees fahrenheit.

Modeling or estimating what will happen is tricky

which is why we have these suggestive ranges

instead of precise single figures.

But what we can say is that in the worst case scenario

models, we're talking 2.4 to over six degrees celsius

and that's a whopping 4.3 to 11.5 degrees fahrenheit.

Imagine the repercussions.

If I think about going to my thermostat

and just suddenly overnight dialing it up 10 degrees,

not only are my electric and gas bills gonna go through

the roof but it gets beyond cozy

when it's over 80 degrees in my house.

It's not really my optimum temperature.

For one thing, the ice in my drink's gonna melt

a heck of a lot faster which is equally unfortunately

one of the major problems for the earth as well.

We're talking of course about global sea level rise.

It's really the continental ice masses

that should be giving us the greatest cause for concern.

It's fairly simple, melting of ice on places

like Greenland and high mountains, for example,

will result in more water going into the ocean.

The frozen elephant in the room is Antarctica

because almost all of the ice there is on the continent

which means that when it melts, it will add enormously

to the amount of water in the ocean.

Even partial melting of Greenland and Antarctica together

could result in four to six meters or about 13 to 20 feet

more water in the ocean worldwide.

But it could take several hundred years for that.

People are looking at this very, very carefully

because if you think about 20 feet, that's enough

that entire countries like the Maldives which exist largely

as low lying atolls in the Indian Ocean

would disappear underwater.

Almost any low lying area, the Netherlands, aka Holland,

for example, or New Orleans, would face

serious additional flooding threats

and then you add to that things like hurricane

and typhoon storm surges and it's an enormous problem.

What does this mean for biodiversity though?

Well, in the first place, you're gonna lose

these low lying places and therefore their habitats

and the species living in them.

Some of these habitats are home to rare

and endangered species.

Apart from the actual change in sea level,

what really is a major problem for biodiversity

is the warming itself.

Again, remember that every species has its own

optimal habitat and tolerance ranges

and that includes all the things that go along

with living in the right temperature regime.

The IPCC estimates that a four degree celsius increase,

just over seven degrees fahrenheit is gonna result

in major extinction due to the inability

of organisms to adapt to the changes.

It's this rate thing again.

Organisms can't move to cooler areas fast enough

or adapt fast enough.

Sure, some migratory animals can change their patterns

of migration a bit but what about the organisms

that can't change, what about the ones that can't move?

Entire forests come to mind, think of mountain ranges.

Forests will move further up the mountainsides

completely altering or displacing entire ecosystems

as they go and we've got really interesting examples

from some of our own investigators here at the academy,

please like Dave Kavanaugh who studies endemic beetles

specialized to live in the icy areas high on mountains.

These colder places are disappearing.

The beetles are moving to higher and higher elevations

but pretty soon, they're going to run out of mountain.

Even marine ecosystems are not immune.

A two degree celsius increase in the ocean,

about 3 1/2 degrees fahrenheit doesn't sound like that much

but it's a lot because we're talking about a huge amount

of extra heat over the entire huge size of the ocean

and we've been talking about an average number.

Some places are going to be warmer than that.

Some are going to be cooler but an overall two degree

celsius increase is enough to result

in major coral reef die offs.

Reefs just can't respond to these rapid temperature changes

fast enough nor move to other places.

Even assuming that other suitable habitat was available.

Those are some of the effects of global warming

but we also need to talk about the chemistry of adding CO2

to the world's ecosystem.

There's some early evidence that shows all the regions

of the world are gonna be affected one way or another

just by the simple addition of CO2 even if you don't talk

about the global warming consequences.

Studies indicate that plant life tends to react

to an increase in CO2 by building more of themselves

through that amazing process of photosynthesis.

The amount of carbon dioxide that plants use

and turn into organic molecules for their own use

is what we're talking about in fancy terminology

like sequestration and carbon fixation.

It's just plants saying, "Oh, hey, there's more carbon

"dioxide, I can make more of myself."

That sounds on the face of it like a good thing.

How bad could more plants actually be?

In fact, sequestration and fixation are likely reasons

that we haven't already had truly runaway global warming.

But there's a limit.

There's an upper level to how much plants can collect,

use or sequester carbon and thereby reduce

surrounding carbon dioxide levels.

That's because CO2 is not usually the chemical

that runs out first as plants build more of themselves.

It's kind of like saying well you know I could put lots

and lots of oil in my car and it seems to be running fine.

Without remembering to add some gas every now and then,

you're gonna run out of gas and your car eventually stops

even though you have lots of oil.

Biodiversity in that sense could actually decrease

as the carbon dioxide levels increase

because you've got unequal abilities among plant species

to sequester or absorb all this new carbon dioxide.

As that happens, biodiversity or species' richness

can drop because plants more sensitive to the limitations

of other necessary chemicals will die.

Forests, marine fighter plankton

and their surrounding ecosystems become less functional

as species die off and therefore less effective

in sequestering carbon dioxide

causing a kind of feedback loop

in which global climate change actually

gets worse and worse as the unused CO2 builds up.

Think of that next time you hear a car go by.

Even something that local can go global in a way

that has huge effects really worth thinking about.

(gentle music)