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

Summary

This script delves into the profound impact of human activities on the environment, highlighting how lifestyle choices contribute to ecosystem degradation and species extinction. It emphasizes the indispensable role of ecosystems in providing essential services like water filtration, carbon regulation, and food production. The video outlines the four categories of ecosystem services, underscores the importance of biodiversity for resilience, and discusses the cascading effects of deforestation, desertification, and climate change. It also touches on the threats posed by invasive species and overharvesting, setting the stage for a deeper exploration of environmental issues.

Takeaways

• 🌏 Human activities have been studied for their environmental impact for over 50 years, with significant effects on ecosystems worldwide.
• 🚗 Lifestyle choices, including car usage, farming practices, and plastic consumption, contribute to environmental degradation and species extinction.
• 🌿 Ecosystems provide essential services such as water filtration, carbon dioxide absorption, and food production, which are vital for human survival.
• 🔢 Ecosystem services are estimated to be worth $46 trillion/year, highlighting their immense value to the global economy.
• 🔄 Healthy ecosystems offer support services like nutrient recycling and soil formation, which are foundational to life on Earth.
• 🐟 Provisioning services from ecosystems include food, water, fiber, and fuel, all of which are indispensable for human life.
• 🌳 Regulating services involve processes like decomposition, water filtration, flood control, and carbon absorption, which help maintain balance in Earth's systems.
• 🎨 Ecosystems also provide cultural services, offering aesthetic and recreational value, as well as opportunities for inspiration and learning.
• 🌱 Biodiversity is crucial for ecosystem resilience, allowing them to better withstand disturbances and maintain their functions.
• 🌴 Deforestation, such as the clear-cutting of the Amazon rainforest, leads to a cascade of environmental effects including flooding, erosion, and desertification.
• 🌊 The loss of forests and the increase in greenhouse gas emissions contribute to global warming, affecting habitats and leading to climate-related disturbances.
• 🐍 Introducing nonnative species can disrupt ecosystems by out-competing or preying on native species, altering the ecological balance.
• 🐟 Overharvesting of organisms, such as overfishing and predator extermination, reduces biodiversity and makes ecosystems more vulnerable to collapse.

Q & A

How long have humans been studying the impacts of their activities on the environment?

Humans have been studying the impacts of their activities on the environment for approximately 50 years.

What are some of the everyday human activities that contribute to environmental harm?

Everyday human activities such as driving cars, expanding farmland, and the use of plastic products contribute to environmental harm.

How many plant and animal species could human activity be responsible for the extinction of to date?

Human activity could be responsible for the extinction of nearly 1000 plant and animal species to date.

Why are the organisms that have gone extinct important to us, even if we don't particularly care about them individually?

These organisms are important because they are part of the ecosystems that provide us with essential services like filtering water, absorbing carbon dioxide, and producing food.

What are the four categories of ecosystem services mentioned in the script?

The four categories of ecosystem services are support services, provisioning services, regulating services, and cultural services.

What is the estimated monetary value of the services that ecosystems provide for humanity annually?

The estimated monetary value of the services that ecosystems provide for humanity annually is $46 trillion.

What is the significance of biodiversity in maintaining the health of ecosystems?

Biodiversity is significant in maintaining the health of ecosystems because it makes them more resilient to disturbances and changes, preventing ecosystem collapse when one species is removed.

How does deforestation contribute to desertification?

Deforestation contributes to desertification by removing trees that regulate water flow and prevent soil erosion. Additionally, overgrazing and over-irrigation can lead to soil salinization, making the land unproductive.

What is the term used to describe the chain reaction caused by deforestation, affecting not just the immediate ecosystem but also neighboring ones?

The term used to describe this chain reaction is a 'cascade effect'.

How does the removal of trees from the Amazon rainforest impact the local and global environment?

The removal of trees from the Amazon rainforest leads to a loss of biodiversity, increased flooding, changes in water quality, erosion, and contributes to global warming by reducing the capacity to absorb CO2.

What are some examples of human activities that can have immediate and direct impacts on biodiversity?

Examples of human activities that can have immediate and direct impacts on biodiversity include introducing nonnative species, overharvesting certain organisms like overfishing the oceans, and exterminating predators like wolves.

What is the term used to describe the negative effects stemming from humans putting the wrong amounts of certain substances in the wrong place at the wrong time?

The term used to describe these negative effects is 'pollution'.

Outlines

00:00

🌏 Human Impact on Ecosystems and Biodiversity

The first paragraph discusses the undeniable impact humans have had on the environment over the past 50 years. It highlights how everyday human activities, including driving cars, expanding farmland, and using plastic, contribute to environmental damage. The script emphasizes that human actions could be responsible for nearly 1000 species extinctions, stressing the importance of maintaining ecosystems for their essential services such as water filtration, carbon dioxide absorption, and food production. The narrator introduces the topic of how human actions are affecting these vital ecosystems and outlines the five major ways humans are impacting the environment, starting with an overview of ecosystem services and their irreplaceable nature.

05:01

🌳 The Consequences of Deforestation and Biodiversity Loss

The second paragraph delves into the effects of deforestation, particularly in the Amazon rainforest, and how it leads to a cascade of environmental issues. It explains that the removal of trees not only reduces local biodiversity but also impacts neighboring ecosystems through altered water regulation, increased erosion, and runoff that can harm marine life. The paragraph also touches on desertification, which is exacerbated by overgrazing and over-irrigation, leading to soil salinization and the spread of unproductive landscapes. The connection between deforestation, reduced CO2 absorption, and global warming is made, with examples of its effects on polar ice levels and wildlife habitats. The paragraph concludes by discussing the impact of introducing nonnative species and overharvesting on ecosystems, emphasizing the vulnerability of less diverse ecosystems to disturbances.

10:03

📚 Wrap-Up and Invitation for Further Engagement

The final paragraph serves as a conclusion to the video, thanking viewers for watching and inviting them to engage further with the content. It provides a table of contents for review and encourages viewers to explore additional resources or leave their questions, comments, and suggestions on social media platforms or in the video's comment section. This paragraph also acknowledges the collaborative effort in creating the video content.

Keywords

💡Ecosystems

Ecosystems refer to the complex network of interactions between living organisms and their environment, including both biotic (living) and abiotic (non-living) components. In the video, ecosystems are highlighted as essential for providing a range of services that support human life, such as filtering water, producing oxygen, and offering food. The health and biodiversity of ecosystems are crucial for their ability to perform these services, which is why their degradation poses a significant threat to human well-being.

💡Biodiversity

Biodiversity is the variety of life in all its forms, including the variety within species, between species, and of ecosystems. The video emphasizes the importance of biodiversity for the resilience of ecosystems, explaining that high biodiversity allows ecosystems to better withstand disturbances without collapsing. The script provides the example of the Amazonian rainforest, which, despite its high resilience, is under threat from human activities that can reduce biodiversity and disrupt the ecosystem's balance.

💡Deforestation

Deforestation is the process of clearing forests by cutting down trees, often to make way for agriculture, grazing, or urban development. The script discusses deforestation as a major human impact on ecosystems, leading to a cascade of negative effects such as loss of habitat, increased flooding, erosion, and desertification. The example of clear-cutting in the Amazon to create land for cattle grazing is used to illustrate this impact.

💡Desertification

Desertification is the process by which fertile land becomes desert, typically as a result of drought, deforestation, or inappropriate agricultural practices. In the video, it is mentioned as a consequence of deforestation and overgrazing, which can lead to soil degradation and the spread of unproductive landscapes. The script cites the expansion of the Gobi Desert in China as a result of overgrazing and excessive water use as an example of desertification.

💡Climate Change

Climate change refers to long-term shifts in temperature, precipitation, and other atmospheric conditions on Earth. The video script explains that human activities, such as deforestation and the burning of fossil fuels, contribute to climate change by increasing the levels of carbon dioxide in the atmosphere, which acts as a greenhouse gas and traps heat. This leads to global warming, with examples including the melting of polar ice and shifts in species' habitats.

💡Invasive Species

Invasive species are non-native organisms that, when introduced to a new environment, can cause significant harm to the local ecosystem by out-competing or preying on native species. The video mentions the introduction of nonnative species as a direct way humans impact biodiversity, with examples like kudzu in North America and cane toads in Australia, which disrupt local ecosystems and lead to a loss of native species.

💡Overharvesting

Overharvesting is the practice of extracting a resource, such as fish or timber, from an ecosystem at a rate that exceeds its ability to regenerate. The script discusses overharvesting as a threat to biodiversity, particularly in the context of overfishing popular fish species like tuna and the extinction of predators like wolves to protect livestock. This practice can lead to the depletion of species and the destabilization of ecosystems.

💡Ecosystem Services

Ecosystem services are the benefits that humans obtain from ecosystems, such as food, water, climate regulation, and cultural values. The video script categorizes these services into four types: support services, provisioning services, regulating services, and cultural services. It emphasizes that these services are invaluable and irreplaceable, with an estimated monetary value that far exceeds the global economy's output.

💡Resilience

Resilience in an ecological context refers to the ability of an ecosystem to withstand or recover from disturbances. The video explains that ecosystems with high biodiversity are more resilient, meaning they can better adapt to changes and maintain their function even if some species are lost. The contrast between the high biodiversity of the Amazonian rainforest and the low biodiversity of the Sonoran Desert illustrates this concept.

💡Pollution

Pollution is the introduction of harmful substances or energy into the environment, causing disorder or harm. The video script mentions pollution as a separate set of impacts that humans have on the biosphere, which can include air, water, and soil pollution. It suggests that pollution can result from placing the wrong substances in the wrong place at the wrong time, leading to detrimental effects on ecosystems and biodiversity.

💡Carbon Dioxide

Carbon dioxide (CO2) is a greenhouse gas that plays a significant role in climate change by trapping heat in the Earth's atmosphere. The video script discusses how human activities, such as deforestation and the burning of fossil fuels, increase CO2 levels, contributing to global warming. The script also explains that plants absorb CO2, making the reduction of forests a double blow to climate regulation.

Highlights

Human activity has been studied for its impact on the environment for over 50 years.

Daily choices affect the environment, contributing to the extinction of nearly 1000 plant and animal species.

Ecosystems provide essential services like filtering water and producing food, which are crucial for human survival.

Ecosystem services are categorized into four main types: support, provisioning, regulating, and cultural services.

Ecosystems' monetary value to humanity is estimated to be $46 trillion/year.

Biodiversity is vital for ecosystem resilience and maintaining their services.

High biodiversity ecosystems are more resilient to disturbances than those with low biodiversity.

Deforestation leads to a cascade of environmental impacts, including erosion, flooding, and desertification.

Desertification is driven by factors such as overgrazing and over-irrigation, leading to landscapes that are dry and unproductive.

Overharvesting and introducing nonnative species are direct ways humans impact biodiversity.

Invasive species can out-compete or eat native species, disrupting entire ecosystems.

Overfishing and exterminating predators like wolves for livestock protection reduce ecosystem diversity and resilience.

Pollution, resulting from placing the wrong amounts of substances in the wrong places at the wrong times, is another significant human impact on ecosystems.

Climate change, driven by deforestation and greenhouse gas emissions, is causing rapid environmental shifts with severe consequences.

The rapid pace of environmental change is challenging organisms' ability to adapt, moving faster than historical rates.

Transcripts

At this point people have been studying the impacts that humans have had on the world around us for a solid 50 years.

And while it's hard to get a handle on exactly how the choices we make every day affect the environment,

there's no question that our lifestyles, our cars, our need for more farmland,

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 1000 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 St. Helena olive, or the passenger pigeon,

or anything else we've driven into extinction, the thing is: we need these other organisms.

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

filtering water, sucking carbon dioxide out of the air, producing all the food we eat...

All very important ecosystem services, 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.

Over the next two episodes 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 six ways from Sunday,

but to make it easy on ourselves, let's start with the top five.

[Theme Music]

We often hear about all the different ways that our behavior is affecting the biosphere:

extinctions, climate change, deforestation, acid rain, desertification, pollution and more!

But you're asking, "Why are all those things bad? What is going on?

How is this stuff turning the Earth into sausage? I don't understand."

Well, I do understand which is why I'm qualified to make this video, so let me lay it on you.

The services that ecosystems provide for us, all the dirty work they do, can be broken up into 4 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, nitrogen and phosphorous cycles.

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 and aquifers and other freshwater sources give us water.

Plants and animals also yield all kinds of fiber that we use for clothing and shelter.

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.

But I'm getting ahead of myself.

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, doing their business.

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 they provide for humanity.

If, for example, we had to do all of the things that ecosystems do for us, it would cost us

$46 trillion/year.

Which is a lot, considering that the output of the global economy is $66 trillion/year.

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 we talked about a few weeks ago.

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.

Take a hectare of Amazonian rainforest:

in that little patch of land, there are more different species of plants and animals than there are in all of Europe.

So if a species of insect goes extinct, there's less risk that the whole house of cards will fall than, say,

in the Sonoran Desert, where there are very few organisms,

so the disappearance of one species could affect the entire ecosystem.

So the best way to understand our impacts on the environment is through how we affect biodiversity.

Unfortunately, it turns out that we've been doing a really bang-up job of

endangering some of the highest biodiversity ecosystems on the planet.

In some cases, we're having impacts on the organisms themselves directly.

In other cases, we're affecting biodiversity indirectly, by creating one or two changes

in that ecosystem that cascade into all kinds of problems for living things.

First, let's look at that hectare of Amazonian rainforest again,

because even though it's one of those super-resilient ecosystems, we're having serious impacts on it.

How? Well, first by removing a lot of what makes a forest a forest: trees.

According to some estimates, we're clear-cutting around 8,000 hectares of trees a day

to provide land to graze cattle on, and to harvest wood to make coffee tables or whatever.

When you cut down a hectare of rainforest, suddenly

a place where a few thousand species used to live turns into a place where just a handful of species live:

some grass, some weeds, maybe some rats or mice, some insects and, you know, some cows.

Because man, we love cows.

And when you take out so many of the living things on that hectare of land, a bunch of things happen.

For starters, you're not just affecting that ecosystem, but neighboring ecosystems as well.

For instance, all those trees that were cut down provided the service of regulating the

flow of all that rain that rainforests get,

not only by absorbing some of it but also by slowing down runoff, letting the water seep into the soil,

before slowly making its way into streams and rivers and ultimately the ocean.

But when those trees are gone, the water hits the land and shoots off in the nearest stream,

causing erosion and washing minerals and chemicals all the way to the sea, where it affects marine ecosystems.

And when I say "affect," I don't mean in a good way.

This, my friends, is what's called a cascade effect, in this case caused by deforestation,

one of the most obvious, observable human impacts.

In addition to causing more flooding and changes in water quality,

deforestation on a large scale can lead to another impact:

desertification, or the spread of dry, unproductive landscapes.

But cutting down trees doesn't automatically turn a forest into a desert,

desertification is driven along by additional factors, like overgrazing by cattle, and over-irrigation.

So how can over-watering something make it turn into a desert?

Well, when we use groundwater to irrigate crops, the natural salts in the groundwater build up in the soil,

eventually making it so salty that nothing wants to live there.

Over time, fertile land near desert ecosystems becomes overtaxed, and the desert spreads.

And this is exactly what has happened in China over the past century,

where overgrazing and the cities' unquenchable thirst for water have caused

the Gobi Desert to grow by 3,600 square kilometers every year.

Now, these two impacts by themselves clearly limit the biodiversity of otherwise lush ecosystems.

But because they also result in fewer trees that provide the all-important services of

releasing oxygen and absorbing CO2, you know what domino's gonna fall next: the climate.

Carbon dioxide: the principle greenhouse gas. It insulates the Earth.

So it stands to reason that the more CO2 there is in the atmosphere, the warmer the earth will be.

And the thing is, we're reducing the size of forests at the same time as

we're unleashing all kinds of greenhouse gases by burning fossil fuels.

This double-whammy is much of what's driving global warming.

As a result, we're seeing decreases in the levels of polar sea ice,

which means less habitat for polar bears, seals and sea birds.

More temperate animals are moving closer to the poles,

and hotter, drier conditions are causing more grass fires and forest fires.

And while the climate has changed many times in the past,

those changes usually took place over centuries or even millennia, giving organisms time to adapt or move.

These changes are taking place within our lifetimes and it's kind of a huge deal, and it's complicated.

It'd take me at least, like, 10 minutes and 52 seconds to explain it all in detail.

Which is why I did that in another video.

By now hopefully you can see how one human impact can lead to another,

and how, even indirectly, they can end up reducing biodiversity.

But it's hard to overlook the more immediate impacts we can have on ecosystems.

One of the more in-your-face ways we affect biodiversity is by introducing nonnative species,

either intentionally or unintentionally.

Again, there are so many examples of this that you can learn more about it in another video I did.

But suffice it to say: whether it's kudzu in North America, or cane toads in Australia,

invasive species have a knack for out-competing or outright eating native species

to the point that it rocks the world of an entire ecosystem.

And finally, probably the most direct impact we have on biodiversity is simply overharvesting certain organisms.

We're overfishing the oceans to meet growing demand for popular fish species, like tuna,

while on land we're exterminating important predators, like wolves, to protect livestock...those cows again.

And the less diverse those ecosystems are, the more vulnerable they become to disturbances,

including those other four impacts I just mentioned.

And the fact is, there's a bunch more where those came from

because there's a whole separate set of effects that humanity has on the biosphere

that stems simply from us putting the wrong amounts of certain stuff in the wrong place at the wrong time.

That's what we call pollution, so tune in next time when we'll explore what it really is,

where exactly it's coming from, and what we can do about it.

Thank you for watching another kind of depressing episode of Crash Course Ecology

and thanks to everyone who helped us put it together.

There's a table of contents over there if you want to click to review anything.

Or the links are down below in the description.

And if you have any questions or comments or ideas for us,

please leave them on Facebook or Twitter or of course, down in the comments below.