The Effects of Climate Change: Crash Course Biology #9

Summary

The video script highlights the profound impact of climate change on Earth's ecosystems, caused by centuries of fossil fuel use. It explains how rising temperatures disrupt habitats, leading to drastic changes in species populations and behaviors. Dr. Sammy, an entomologist, uses examples like pine trees and mountain pine beetles, American pikas, and kelp forests to illustrate the ripple effects of climate change. The script also discusses how increased CO2 affects plant growth and ocean chemistry, impacting food chains and human health. It emphasizes the urgency of reducing emissions and the importance of community resilience and adaptation.

Takeaways

• 🌍 **Climate Change Impact**: The release of carbon dioxide from fossil fuels is causing Earth's atmosphere to trap heat, leading to an alarming rate of global warming.
• 🔥 **Ecosystem Disruption**: Increased temperatures are causing more frequent droughts and wildfires, making forests more vulnerable to insect damage and disrupting animal habitats.
• 🌡️ **Thermal Stress**: Streams are heating up, affecting aquatic life like trout, and rising temperatures are pushing animals into unfamiliar territories.
• 🌿 **Interconnectedness**: Changes in one organism's environment can have a ripple effect on many others, including humans, due to the interconnectedness of life.
• 🐛 **Pine Beetles and Trees**: Heatwaves and droughts stress pine trees, reducing their ability to produce resin to defend against mountain pine beetles, leading to forest damage.
• 🐹 **American Pika**: As summers get hotter, the American pika, which has low heat tolerance, is forced to higher altitudes and risks running out of suitable habitat.
• 🌊 **Kelp Forests**: Warming oceans are causing bacterial growth which affects sea stars, leading to a decrease in their population and an increase in sea urchins, which can destroy kelp forests.
• 🌱 **Phenology Shifts**: Climate change is altering the timing of life cycles in plants and animals, which can disrupt symbiotic relationships and food chains.
• 🌳 **Plant Response to CO2**: While increased CO2 can stimulate plant growth, it doesn't necessarily benefit all plants and can lead to thicker leaves that are less efficient at absorbing CO2.
• 🌾 **Agricultural Challenges**: Climate change affects crop growth, with potential decreases in nutritional value and increased competition from weeds, impacting food security.
• ⚖️ **Social Inequality**: The effects of climate change are not evenly distributed, with low-income communities and those facing inequities being most vulnerable to its impacts.

Q & A

What is the primary cause of the alarming rate of global warming mentioned in the script?

The primary cause of the alarming rate of global warming is the centuries-long use of fossil fuels, which has released billions of tons of heat-trapping carbon dioxide into the atmosphere.

How does climate change affect forests and insect populations?

Climate change, through phenomena like droughts and wildfires, makes forests more vulnerable to damage from insects. As forests suffer, insect populations, such as mountain pine beetles, can increase dramatically due to the lack of defenses like resin production in stressed trees.

What impact does the heating of streams have on the trout that live there?

The heating of streams disrupts the habitat of the trout that live there. Warmer water can affect their metabolism, growth, and reproduction, potentially leading to population declines.

Why are thousands of walruses meeting up on Alaskan beaches?

Rising temperatures due to climate change are pushing animals into unfamiliar territories. In the case of walruses, they are gathering on Alaskan beaches because their usual habitats are being affected by the changing climate.

How does climate change affect the interconnectedness of life on Earth?

Climate change can cause a ripple effect in the interconnectedness of life on Earth. A change in one organism's environment can affect hundreds, if not thousands of others, as seen with the example of a rock dropped in a pond causing ripples.

What is the role of tiny cells in a pine tree and how does climate change affect them?

The tiny cells in a pine tree produce a sticky substance called resin, which helps protect the tree from pests like mountain pine beetles. However, when these trees are stressed by heatwaves and droughts, they lack the water needed to produce enough resin, making them more susceptible to infestations.

Why are American pikas struggling with the changing climate?

American pikas are struggling with the changing climate because they have low heat tolerance. As summers get hotter, they struggle to regulate their body temperatures and are forced to move higher up the mountain slopes, eventually running out of suitable habitat.

How does the warming of oceans affect kelp forests and the species that depend on them?

Warming oceans can lead to an increase in certain bacteria populations, which in turn can make sea stars sick by taking up their oxygen supply. With fewer sea stars to control them, sea urchin populations can increase, leading to overgrazing of kelp forests and a collapse of the ecosystem that supports hundreds of species.

What is the significance of phenology in relation to climate change?

Phenology refers to the seasonal timing of life cycle events in organisms. Climate change can shift phenology, causing mismatches between species' life cycles and environmental conditions, such as plants sprouting too early for the herbivores that depend on them.

How does increased carbon dioxide in the atmosphere affect plant growth and ecosystems?

While plants use carbon dioxide for growth, increased levels do not necessarily improve their access to other necessary resources like nutrients and water. Thicker leaves formed at higher CO2 levels are less efficient at pulling CO2 out of the atmosphere, and high CO2 levels can also lead to the proliferation of weeds that outcompete crops.

What are some of the non-living systems affected by climate change and increased CO2 levels?

Non-living systems like oceans are affected by climate change and increased CO2 levels. The chemistry of the oceans changes, becoming more acidic, which makes it harder for organisms like coral and clams to build their shells and structures, and can even affect sharks' ability to hunt by scent.

How does climate change impact human communities, particularly the most vulnerable?

Climate change impacts human communities by affecting food supply, housing, and health. The most vulnerable, such as low-income communities and those facing inequities, are more affected as they have fewer resources and options to respond to events like floods, crop failures, or extreme temperatures.

What is the one surefire way to limit the effects of climate change mentioned in the script?

The one surefire way to limit the effects of climate change is by reducing emissions from carbon dioxide and other greenhouse gases.

Outlines

00:00

🌡️ Climate Change's Impact on Ecosystems

The script discusses the profound effects of climate change, which is accelerating at an alarming rate due to the excessive use of fossil fuels. This has led to an increase in global temperatures, causing more frequent droughts and wildfires. Forests are becoming more susceptible to insect damage, with insect populations thrown off balance. Aquatic life is also affected, with streams heating up and disrupting the habitats of trout. Warmer climates are pushing animals into unfamiliar territories, as evidenced by walruses gathering on Alaskan beaches and armadillos appearing on Indiana streets. The interconnectedness of life means that changes in one organism's environment can have far-reaching ripple effects. Dr. Sammy, an entomologist, introduces the topic and emphasizes that climate change is a significant disruptor of Earth's systems, akin to a large rock thrown into a pond, affecting not just individual species but entire ecosystems.

05:03

🌿 The Ripple Effects of Climate Change on Species and Ecosystems

This paragraph delves into specific examples of how climate change is impacting various species and ecosystems. It starts with the microscopic changes in pine trees, where heatwaves and droughts stress the trees, reducing their ability to produce resin to fend off mountain pine beetles. This leads to beetle infestations and forest damage. The American pika is highlighted as a species struggling with increased heat, being forced to higher altitudes and facing habitat limitations. The script then discusses the interconnected nature of ecosystems, using the kelp forest as an example. Warming oceans lead to bacterial growth, which in turn affects sea stars, causing a decline in their population. With fewer sea stars to control them, sea urchins overgraze on kelp, leading to the destruction of the kelp forest ecosystem. This has cascading effects on other species that rely on the kelp forest. The paragraph also touches on the broader implications of climate change on species' population dynamics, their migration patterns, and phenology, or the timing of life cycle events, which are crucial for survival and reproduction.

10:06

🌍 Addressing the Global Challenge of Climate Change

The final paragraph focuses on the broader implications of climate change and potential solutions. It emphasizes that the effects of climate change are not limited to specific species or ecosystems but extend to human communities as well. The increased levels of carbon dioxide in the atmosphere affect not only plant growth but also ocean chemistry, making it more acidic and impacting marine life such as coral and clams. The script points out that while carbon dioxide can stimulate plant growth, it doesn't necessarily benefit crops, as weeds can grow faster and compete for resources. Additionally, crops grown in high carbon dioxide conditions may be less nutritious, which could lead to widespread nutritional deficiencies. The paragraph underscores that climate change disproportionately affects vulnerable populations who have fewer resources to cope with its impacts. It concludes by stressing the importance of reducing emissions, supporting vulnerable communities, and conserving ecosystems to mitigate the effects of climate change. The script ends with a call to action, encouraging viewers to learn more about the issue and to work together to shape a better future.

Keywords

💡Fossil fuels

Fossil fuels are natural resources such as coal, oil, and natural gas that are formed from the remains of ancient plants and animals. They are a major contributor to climate change due to the release of carbon dioxide when burned. In the script, the 'centuries-long love affair with fossil fuels' is highlighted as the primary reason for the billions of tons of heat-trapping carbon dioxide being released into the atmosphere, leading to global warming and its associated effects on ecosystems.

💡Carbon dioxide

Carbon dioxide (CO2) is a greenhouse gas that traps heat in the Earth's atmosphere, contributing to the greenhouse effect and global warming. The script mentions that the release of carbon dioxide from burning fossil fuels has led to an alarming rate of planetary heating, causing disruptions in natural systems and affecting the living organisms on Earth.

💡Droughts and wildfires

Droughts are periods of unusually low precipitation, leading to water scarcity, while wildfires are uncontrolled fires in wildlands. The script indicates that as the Earth heats up, droughts and wildfires become more frequent, which in turn makes forests more vulnerable to damage from insects and disrupts the habitats and behaviors of various species.

💡Insects

Insects are a class of invertebrates with exoskeletons, a three-part body, and six legs. The script points out that climate change has thrown insect populations 'all out of whack,' making forests more susceptible to damage from insects like the mountain pine beetle, which can devastate pine forests when trees are stressed and unable to produce enough resin to protect themselves.

💡Trout

Trout are freshwater fish known for their beauty and sport in fishing. The script discusses how streams are heating up due to climate change, which disrupts the habitats of trout and can lead to changes in their behavior and distribution.

💡Walruses

Walruses are large marine mammals with tusks that live in the Arctic. The script uses the example of thousands of walruses meeting up on Alaskan beaches as an illustration of how rising temperatures are pushing animals into unfamiliar territories, indicating the far-reaching effects of climate change on wildlife.

💡Armadillos

Armadillos are small to medium-sized mammals with distinctive armor-like exoskeletons. The script humorously mentions armadillos strolling the Indiana streets to illustrate how climate change can lead to unexpected encounters between wildlife and human environments as animals adapt to new conditions.

💡Interconnectedness

Interconnectedness refers to the complex web of relationships and dependencies among different organisms and ecosystems. The script emphasizes that a change in one organism's environment can cause a ripple effect that impacts hundreds, if not thousands of others, including humans, highlighting the importance of understanding and protecting these connections in the face of climate change.

💡Resin

Resin is a sticky substance produced by plants, often used for defense against herbivores and pathogens. The script explains that pine trees produce resin to trap and kill mountain pine beetles, but under heatwave and drought conditions, the trees are stressed and unable to produce enough resin, leading to a population explosion of the beetles and defoliation of the forests.

💡American pika

The American pika is a small mammal that lives in high-altitude habitats and is sensitive to heat. The script describes how the pika struggles to regulate its body temperature as summers get hotter, being forced to move higher up the mountain slopes, which can eventually lead to a loss of habitat and population decline.

💡Kelp forests

Kelp forests are underwater ecosystems characterized by large brown algae known as kelp. The script uses kelp forests as an example of how climate change can disrupt an entire ecosystem. As oceans warm, certain bacteria thrive, leading to a decrease in sea stars due to disease and oxygen depletion. This, in turn, allows sea urchin populations to increase, which overgraze on kelp, leading to the collapse of the kelp forest ecosystem and affecting numerous species that rely on it.

Highlights

Human activities, particularly the use of fossil fuels, have released large amounts of carbon dioxide into the atmosphere, leading to an alarming rate of global warming.

Increased frequency of droughts and wildfires makes forests more vulnerable to damage from insect populations that are now disrupted.

Rising temperatures are causing animals to migrate into unfamiliar territories, such as walruses gathering on Alaskan beaches and armadillos appearing in Indiana.

The interconnectedness of life means that a change in one organism's environment can have a ripple effect on many others, including humans.

Climate change disrupts the entire chain of life, from microscopic cells to whole ecosystems, with even small changes potentially having a huge impact.

Pine trees stressed by heatwaves and droughts cannot produce enough resin to protect themselves from mountain pine beetles, leading to forest damage.

The American pika, sensitive to heat, struggles to regulate body temperature as summers get hotter, forcing them to move higher up mountain slopes.

Kelp forests, vital ecosystems, are threatened by warming oceans that promote bacterial growth, leading to sea star die-offs and overpopulation of sea urchins.

The decline of sea stars due to bacterial overgrowth allows sea urchin populations to increase, which in turn destroys kelp forests and disrupts the entire ecosystem.

Climate change can cause populations to vary wildly, with some species thriving in hotter climates while others, like the pika, struggle and decline.

Species are moving to new locations as the climate changes, which can lead to the breakup or reorganization of entire communities.

Phenology, the seasonal timing of life cycles, is being disrupted by climate change, causing mismatches in species' reproductive and feeding cycles.

Increased carbon dioxide levels can lead to thicker leaves in plants, which are less efficient at pulling carbon dioxide from the atmosphere, exacerbating climate change.

High levels of carbon dioxide in the atmosphere are causing oceans to become more acidic, affecting the ability of organisms like coral and clams to build their shells.

Carbon dioxide enrichment can lead to faster growth of weeds, outcompeting crops and contributing to less nutritious food with lower vitamins, minerals, and proteins.

The effects of climate change are not evenly distributed, with low-income communities and those facing inequities being most affected by events like floods, droughts, and heatwaves.

Adapting to climate change requires reducing poverty, investing in infrastructure, and conserving ecosystems to protect vulnerable communities.

The only surefire way to limit the effects of climate change is by reducing emissions of carbon dioxide and other greenhouse gases.

Climate change is a global issue that connects all living things, emphasizing the need for collective action to shape a sustainable future.

Transcripts

Thanks to a centuries-long love affair with fossil fuels,

we’ve released billions of tons of heat-trapping carbon dioxide into our atmosphere.

And that’s shaking up all of Earth’s systems – including the living ones.

Our planet is heating up at a truly alarming rate.

And as droughts and wildfires become more frequent,

forests become extra vulnerable to damage from insects

whose populations are  now all out of whack.

Streams are heating up— disrupting the trout that live there.

And rising temperatures push animals into unfamiliar territory—

like thousands of walruses meeting up on Alaskan beaches,

or armadillos strolling the Indiana streets.

Because so much of life is interconnected,

a change in one organism's environment,

like a rock dropped in a pond,

can cause a ripple effect that reaches hundreds, if not thousands of others – including us.

And trust me, climate change is the biggest rock you have ever seen.

Hi! I'm Dr. Sammy, your friendly neighborhood entomologist,

and this is Crash Course Biology.

Now, climate change may be the biggest  metaphorical rock you’ve ever seen

but this is literally the rockin-est theme music you will hear all day.

[THEME MUSIC]

Ever since we started burning fossil fuels  to power our homes, cars, and smart toilets,

we’ve been altering Earth’s natural climate.

And a changing climate disrupts the entire chain of life,

from tiny cells to whole ecosystems.

Some changes may seem very small,

but even microscopic changes can have a huge impact.

Like, there are these tiny cells in a pine tree

that make a sticky ooze called resin

which traps and kills mountain pine beetles that want to eat the tree.

But, when the tree is stressed by heatwaves and droughts,

its cells don’t have the water that they  need to make enough of that precious resin.

That means entire forests transform into  all-you-can-eat buffets for these beetles.

Or, consider the American pika—

a little puffball that you might mistake for a living Pokemon.

They’re high in cuteness, but not so much in heat tolerance.

As the summers get hotter,

pika struggle to regulate their body temperatures.

They are forced to move higher and higher up the mountain slopes where they live,

and eventually run out of room at the top.

Now, I know what you’re thinking,

[Cartoonishly Evil Sammy] “I dare say, Dr. Sammy,

if climate change’s effects end there,

with the pika and the pine tree,

maybe that’s manageable.

Sad…—one moment,  I must blot my tears—

sad but manageable, I say.”

[record scratch]

[Dr. Sammy] I hear you, cartoonishly evil alternate universe me,

but the problem is, they don’t end there.

As one population changes, so does another, and another.

And even though the ripples may start with one species,

climate change’s effects  can turn them into waves

that disrupt an entire ecosystem.

Let’s head over to the Thought Bubble…

A kelp forest is much more than a bunch of seaweed.

It’s also a carbon storage container,

an ocean oxygen-booster,

and a defender against coastal erosion.

And for a bustling community of hundreds of species,

it’s a place to call home.

Basically, kelp forests  are the hot neighborhood.

But as the oceans warm, that becomes true…in a more literal way.

See, many bacteria love the heat provided by a warming climate,

so a lot of them are doing great.

But as their population grows,

they make sea stars sick,

taking up their oxygen supply.

With less oxygen, their muscles waste away, and eventually, they die.

Sea stars are a natural predator of the sea urchin—

the spiky purple stress balls of the kelp forest.

So a decrease in sea stars means an increase in sea urchins.

As kelp falls to the ocean floor,

sea urchins gobble it up.

Which is an important job—

but without enough  sea stars to rein them in,

urchins overdo it.

They chomp the kelp forest to smithereens.

And that affects the whole neighborhood—

the whales who use the kelp forest like a daycare,

the fish that sleep there,

the birds that treat its canopy like a charcuterie board.

These creatures have few choices:

pack it up and move on —or simply die out.

And long after everything else is gone,

the urchins remain—

lying in wait, devouring new kelp sprouts before they even have the chance to grow.

So by affecting just one population,

climate change can have a profound effect on a whole community

—and even turn it into a zombie town.

So much for “a beautiful day in the neighborhood.”

Thanks, Thought Bubble!

There’s no single story that captures how Earth’s organisms

and ecosystems will respond as the climate changes.

Plants and animals alike will face shifts in water availability,

temperatures, extreme weather,  exposure to disease, and more.

Depending on how well a species tolerates those changes,

their story might be a tale of resilience—or tragedy.

Three big climate-caused stories are already playing out in many ecosystems.

First, climate can cause populations to vary wildly depending on the species.

Some species do better in a hotter, drier climate –

and they multiply, like the mountain pine beetles we met earlier,

living large on stressed-out trees.

But other populations, like the pika, struggle in a warmer climate and are dwindling.

Second, many species pack up and move as the climate changes.

That can mean whole communities  splitting up or reorganizing.

For example, herring, one of the puffin’s favorite fish,

are moving north as oceans get warmer.

Puffin parents are substituting a larger  species of fish as dinner for their chicks,

but they're often too big for the chicks to eat.

Third, climate change is shifting many species’ phenology,

the seasonal timing of their life cycle.

For a lot of organisms, their reproduction, hibernation, or feeding

is dictated by the seasons.

Which is way more complicated than the ferocious hankering for sweet potato pie that I get every fall.

When summers lengthen, the whole dance changes.

Species that depend on each other end up with different rhythms—or they miss their dance partners entirely.

Like, an early spring cues Arctic plants to sprout sooner.

But the caribou who count on those plants are still migrating by the old rhythms.

So when they arrive, expecting their favorite food,

dinner is already over.

And there aren’t enough leftovers to go around.

Dr. Tanisha Williams, a plant ecologist and botanist,

found a similar thing was happening with a plant called Pelargonium—

which you might know as the common geranium in your Grandma’s flower pot.

Over the past century, South Africa’s temperature has increased by almost 3 degrees Celsius

—more than twice the global average.

By comparing today’s plants to historical records,

Williams found that South African Pelargoni are now blooming prematurely

compared to their early 1900s counterparts

—by almost 2 weeks.

That might not sound like a lot.

But if the bees can’t sync up their pollination schedules with the flowers,

that could threaten both species.

And it’s not just climate change  itself that is making waves

—but also the billions of tons of carbon dioxide in our atmosphere.

Plants use carbon dioxide to fuel growth.

So you might imagine that  they’re filthy-rich with the stuff.

But that doesn’t easily translate into riches for plants.

Plants are complicated systems.

So turning up the carbon dioxide dial

doesn’t necessarily improve access to any of the other stuff they need,

like nutrients and water.

Many plants also thicken their leaves at higher carbon dioxide levels

—as if the atmosphere is muscle milk and every day is leaf day.

But thicker leaves are actually less efficient at pulling carbon dioxide out of the atmosphere

—so more of it stays trapped there,

where it contributes to global climate change.

Nonliving systems like oceans get messed up, too.

High carbon dioxide levels change its  chemistry, causing it to be more acidic.

That acidity makes it harder for organisms like coral and clams

to build their calcium-rich shells and structures.

It even messes with the sharks’ ability to hunt by scent.

And while carbon dioxide can sometimes increase plant growth,

it won’t necessarily be the plants we want.

Weeds will grow even faster,

competing with the crops people depend on for food.

Those crops will also be facing other stresses,

like less water and drier soil, as temperatures rise.

And many crops grown at high carbon dioxide  levels are actually less nutritious,

losing crucial vitamins, minerals, and  proteins that make them good eating.

So these ripples will affect any creatures that eat plants —including us.

And this nutrient loss could cause millions of people

to face protein, iron, and zinc deficiencies by 2050.

So, when we talk about the effects of increased CO2 and climate change on living things

—and even non-living things—

we’re not just talking about communities of urchins and kelp.

We’re talking about communities of people—like you and me.

But also, like, your Grandma,

and all your Grandma’s bingo buddies,

and the cashier at the store who asks you about your day.

These aren’t far off, hypothetical situations—

the impacts are being felt right now.

Even when you don’t see the original stone drop,

by tipping the balance of Earth’s living and nonliving systems,

climate change sends out waves that affect all of those people—

risking their food supply, their housing, and their health.

And while climate change does involve everybody,

its worst effects aren’t shared by everyone evenly.

When heatwaves, droughts, wildfires, or floods strike,

people with the fewest resources also have fewer options for how to respond.

Low-income communities and people who consistently face inequities

will be most affected by climate change.

They’re more vulnerable when their homes flood,

their crops fail, or temperatures soar.

A lot of these people are concentrated in communities

where the effects of climate change are especially intense.

Each community has different needs,

so there’s no one-size-fits-all approach for the challenges ahead.

But reducing poverty and investing in infrastructure

can help the most vulnerable communities adapt.

That includes supporting and  conserving ecosystems—

like coastal mangroves that defend against floods—

to protect those communities and pull carbon out of the atmosphere.

But really, there’s only one surefire way to limit climate change’s effects:

reducing emissions from carbon dioxide and other greenhouse gases.

There are some cool ways that people are working to do just that,

you can learn more about them in  Crash Course's Climate & Energy series.

But it’s not just a matter of gases way up there;

it’s also about justice down here.

The effects experienced in any community won’t happen in isolation.

That’s true for all living things—

whether they’re a person, a puffin, or a pine tree, or, yes, a platypus.

Sometimes it can be hard to see the connections we all share—

you, me, and our billions of neighbors, on this little blue-and-green rock.

But climate change makes those connections impossible to ignore.

In the span of a few human lifetimes,

we and our fossil fuels have altered Earth’s climate at a rate that has never happened before.

What began as a ripple is now a tidal wave,

rushing outward to affect virtually every species and every ecosystem on Earth,

including us.

There is a lot happening,

and no simple, single story that can capture it all.

But, by working together, we can shape what happens next.

We’ll see more of that in our next episode,

as we learn about how life’s dazzling diversity is under threat,

and what we can do to change course.

This series was produced in collaboration with HHMI BioInteractive.

If you’re an educator, visit BioInteractive.org/CrashCourse

for classroom resources and professional development related to the topics covered in this course.

[Cartoonishly Evil Sammy] Thanks for watching this episode of Crash Course Biology,

which was filmed at our  studio in Indianapolis, Indiana,

and was made with the help of all these dapper people.

If you want to help keep Crash Course free for everyone everywhere

you can give us your money on the Patreon.

Yes yes, good show old bean, good show.