Name: 5 Human Impacts on the Environment: Crash Course Ecology #10
Uploaded: 2013-04-17T09:26:05.000Z
Duration: 10 min 38 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

At this point, people have been studying the impacts that

humans have had on the world around us for a solid 50 years.

Adverbs of manner

And while it's hard to get a handle on exactly how

the choices we make every day affect the environment,

and our love of all kinds of plastic stuff,

are putting the hurt on ecosystems all over the world.

Human activity all by itself, just people doing what they do,

could be responsible for the extinction of nearly a thousand

plant and animal species to date, most of them over the last century.

And even if you don't particularly care about the Barbary lion

or the Saint Helena olive, or the passenger pigeon,

or anything else we've driven into extinction, the thing is,

The ecosystems of the world are working very hard for us, every day:

filtering water, sucking carbon dioxide out of the air,

benefits that the natural world provides us for free.

So, having ecosystems and keeping them intact is important,

not only for the organisms who live in them, but also for us,

the animals who rely on them for thousands and thousands

of things that we could never do for ourselves.

we're going to look at these systems and how our actions are

affecting the ecosystems that we need for our survival.

Basically, we're messing up the environment 6 ways from Sunday.

But to make it easy on ourselves, let's start with the top 5.

We often hear about all the different ways

that our behavior is affecting the biosphere.

Extinctions, climate change, deforestation, acid rain,

But you're asking, "Well, why are all those things bad?

How is this stuff turning the earth into sausage?

Well I do understand, which is why I'm qualified to make this video.

The services that ecosystems provide for us, all the dirty work

they do, can be broken up into four different categories.

They're things that we could never, ever, ever duplicate or work around,

no matter what kind of smarty-pants technology we come up with:

First, healthy ecosystems provide support services that create

and replenish the foundation of the earth's biological systems.

These services include recycling all of the compounds that are

necessary for life, through the carbon, water,

They also include other processes we've talked about before,

like forming new soils and producing atmospheric oxygen.

Some ecosystems contribute more to these services than others, but

none of them can get these basic jobs done unless they are intact.

Two: Ecosystems also perform provisioning services,

giving us the raw materials we need to live.

Like, the ocean provides food in the form of fish sticks and stuff.

And rivers, aquifers and other freshwater sources give us water.

Plants and animals also yield all kinds of fiber

And all around us we find sources of fuel, whether it's biomass

in the form of grasses or wood, hydropower in the form of flowing

water, or the carbon locked in millions-of-years-old trees

that we're now re-releasing into the atmosphere.

Ecosystems also perform super-important regulating services,

moderating many of the earth's systems that

can get dangerous if they get out of whack.

Like as we learned in Biology: fungi and other organisms take on

the task of decomposing dead things and poop.

Meanwhile, plants help filter the water you drink

and the air you breathe, and provide flood control.

And they also absorb all that carbon you exhale and that your

car belches out, which in turn, helps regulate the climate.

And finally, number four, ecosystems are just kind of awesome.

It's nice to be surrounded by happy plants and critters,

Nice, robust ecosystems give us places to play,

scenes to inspire us, and things to just discover and learn about.

These are their less tangible, but still important cultural services.

An interesting thing about ecosystem services is that

economists actually can, and do, calculate the monetary value

If, for example, we had to do all of the things that ecosystems

do for us, it would cost us 46 trillion dollars per year.

Which is a lot, considering that the output of the global economy

So, yeah, we should be happy that we don't have to pay for all that.

But you'll notice that I keep saying that ecosystems

can only serve up all this awesome sauce if they are "intact."

By that I mean they specifically have to have

their biodiversity intact, because ecosystems are just

a bunch of living and nonliving things working together,

so unless their living parts are healthy,

they're basically just rocks and weather.

The main reason biodiversity is so important is that

it makes ecosystems more resilient to that never-ending change

Ecosystems with high biodiversity are way more resilient

to disturbances than those with low biodiversity.

In a high-biodiversity system, if you take one species out

of the mix, it's less likely that the ecosystem will collapse.

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5 Human Impacts on the Environment: Crash Course Ecology #10

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