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  • - [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)

(gentle music)

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