Lesson video

Hello, Mrs. Harking here.

Today we're going to be exploring how forests have the power to change the world by changing climate.

Climate can also change the forests.

So we'll have a look at that today and break down how that works.

I'm really looking forward to learning with you.

Today's lesson is Climate Change and the Forests, taken from the Forest Biomes unit: Why are forests so important? Today we want to be able to explain how deforestation contributes to climate change and how climate change impacts forests.

Here we have some keywords that we'll be using in today's lesson.

If you would like to record these keywords and their definitions, please pause the video, that's absolutely fine.

You might, after listening to some, just find a few that you want to jot down, and that's absolutely okay.

First of all, we've got greenhouse gases.

These are gases in the Earth's atmosphere that trap heat.

Some examples are carbon dioxide, methane.

You may have heard of those before.

Solar radiation is our next keyword.

So solar radiation is energy radiated from the sun via electromagnetic waves.

So energy from the sun.

Carbon dioxide is one of our greenhouse gases in the Earth's atmosphere that traps in heat, as we mentioned.

Deforestation is the complete removal of trees from an area.

Decompose means to break down a substance into smaller parts.

Today's lesson outline looks like this.

There'll be two parts to our lesson.

First of all: How do forests affect climate change? And then: How does climate change affect forests? So to start us off, we are looking at how do forests affect climate change? Climate change describes any change to global climate over time, such as the planet getting cooler or warmer.

So climate change is not the same thing as global warming.

Just have another read of that.

Climate change describes any change to global climate over time, such as the planet getting cooler or warmer.

Okay? Recently, global temperatures have been increasing because of climate change.

Global warming refers to the increase in Earth's temperatures.

This occurs when greenhouse gases are released into the atmosphere, trapping heat, and warming our planet.

So global warming is a type of climate change, which is why you might have heard those two words used interchangeably in the past.

But when the planet is heating, we can call it global warming and we can call it climate change.

If the planet is cooling, then we cannot call it global warming, obviously, but we can still call it climate change.

Which correctly defines climate change? Is it A: Any change to global climate? For example, the planet getting cooler or warmer.

Is it B: The warming of global temperatures as humans are emitting more greenhouse gases, which insulates our planets? That means trapping heat.

Is it C: The cooling of global temperatures as humans are emitting more greenhouse gases which insulates our planet? What do you think? Well done.

Excellent.

Yes, it's A: Any change to global climate, for example, the planet getting cooler or warmer.

So climate change could be either and the planet has become cooler in the past and occasionally does get a bit cooler for a variety of reasons.

So we're going to look at the natural greenhouse effects.

This is what would be happening in our atmosphere if humans were not interfering.

First of all, we've got solar radiation from the sun hitting the Earth's surface.

Some of that solar radiation is reflected back into space.

The greenhouse gases that surround our planets trap some heat.

This means that the Earth is warm enough for us to survive.

So this is a good thing.

The natural greenhouse effect allows humans and other species on earth to be able to survive.

It keeps our planet warm enough but not too warm.

True or false? The natural greenhouse effect is bad for the planet.

What do you think? See if you can have a think about why as well.

Well done.

So that is false.

I'm sure you've come up with some reasons why.

If you'd like to pause the video to listen to those, that's great.

And my reason why would be that we need the greenhouse effect in order for our planet to be warm enough for us to survive.

Did you get that? Excellent.

Well done.

So that was the natural greenhouse effect.

Now we're going to look at the enhanced greenhouse effect.

This is what's happening because humans are on the planet and interfering with the natural systems. So first of all, the same amount of solar radiation from the sun hits the Earth's surface.

Nothing on the sun has changed.

There's not more or less heat coming from it.

Everything is exactly the same.

Okay? The second thing has changed.

We do have more greenhouse gases because they are emitted by humans.

So more of the gases in the atmosphere that trap in that heat.

You can see there's a thicker layer now around the Earth compared to our previous diagram.

Thirdly, more heat is trapped in than previously.

So this means that the Earth is warming up and we call that global warming.

So let's just take a look at the arrows where we've added them for number three.

We can see that actually the arrow that is leaving the atmosphere, where the solar radiation is leaving the atmosphere, it's a lot thinner, so there's less heat being radiated back out into space, and more heat is being trapped within the atmosphere because we've got more greenhouse gases.

So this is the enhanced greenhouse effect.

This is the one created by human actions.

True or false? In the enhanced greenhouse effect, more solar radiation is emitted by the sun.

Are you able to answer and explain? Is it true or false and could you have a think about why? Well done.

Again, this one's false as well.

So this is something that lots of students do write in exam answers, and it is not correct.

It is false.

The amount of solar radiation is the same, the same amount of solar radiation is admitted, emitted, sorry, from the sun.

But there are more greenhouse gases to trap the radiation in the Earth's atmosphere.

So the only thing that has changed is the amount of greenhouse gases.

The amount of solar radiation has not changed.

The sun has not been influenced by this.

Carbon dioxide is one of the greenhouse gases that are causing climate change.

Laura's asking "What human activities emit carbon dioxide?" Do you know any? You can pause the video now.

Well done.

There are lots of different examples that we could come up with.

One would be burning fossil fuels is one source of carbon dioxide.

Examples of this include burning petrol in cars, or diesel, burning coal in power stations to make electricity.

And we've also got burning gas in a household boiler.

It might be worth thinking about.

Do you have a boiler in your home that looks like that? Can you relate to this? Can you give me one example of a human activity that emits carbon dioxide by burning fossil fuels? Have a think now.

Well done.

We've got coal in power stations, gas in a boiler or petrol in cars.

Which one did you get? Did you get that right? Excellent.

Well done.

Next we're going to relate this back to forests.

So plants actually take in carbon dioxide from the Earth's atmosphere during a process called photosynthesis.

The plant absorbs the carbon and releases oxygen.

Look at the diagram, we can see that carbon dioxide gas is entering the leaf and then oxygen is being released.

The forests are called carbon sinks as they store carbon, they trap it.

Trees store carbon in the trunks, leaves and roots as well as their branches.

So that carbon is locked in.

It's part of the building blocks that actually make up the tree.

So it's really important for climate change, for us to be storing some carbon, one of our greenhouse gases.

Trees take in this carbon dioxide during photosynthesis.

The amount of carbon dioxide in the atmosphere reduces because it's locked in the tree, and then less carbon dioxide in the atmosphere reduces the rate of global warming.

Trees are very powerful.

However, deforestation is thought to contribute 10 to 15% of global carbon dioxide emissions.

So deforestation removes the trees that are absorbing that carbon dioxide.

So we've got less trees to absorb the carbon dioxide to start with, but it can get even worse than that.

What happens to the tree after it has been cut down is really important.

So trees that are burnt, maybe it's firewood, maybe any other reason, or if they decompose, if they break down, that carbon stored inside them will be released.

So there'll be more carbon dioxide in the atmosphere and that will increase the rate of global warming.

So the best case scenario with trees is if we have really fast-growing trees that are locking away all of that carbon fast.

They're absorbing as much as they can, they're growing and they're locking loads of carbon away.

On the other hand, trees can slow their growth and some trees are very slow growing from the start, but they're still really important because they are storing that carbon.

If they're chopped down, these trees are then useful still as a carbon store, as long as the wood, the timber that is used from that tree, is used for something with a long lifespan.

So something like furniture or construction, something that the item won't be burned or won't decompose anytime soon.

If we are using it for a single life product, maybe paper for example, this might mean that the carbon dioxide enters the atmosphere a little faster and that is not ideal.

So ideally, we want loads of new trees growing nice and fast, and the forest being managed really well.

Going for a check for understanding.

Deforestation leads to a reduction in carbon.

Is it A: sources, B: transfers, or is it C: sinks? Well done.

It's sinks.

Right, another quick check, just to make sure we fully understand this.

Why does deforestation increase global warming? I'd like you to select two answers.

Is it A: the loss of carbon sinks, B: the increase in carbon sinks, C: the release of greenhouse gases through burning or decomposition? Well done.

Yes, it's A and C.

So deforestation increases global warming because there's a loss of carbon sinks and also greenhouse gases are released through the burning of the trees and also the decomposition if that happens.

Right, time for our first task of the lesson.

We are going to rewrite Laura's statement using the correct geographical terminology.

Let's have a look at her statement to start with.

"Trees are important as they take in and store lots of gases that cause the Earth to heat up.

By having lots of trees, it can reduce the amount the Earth heats up." I mean everything she said is correct.

However, there's not a lot of key terminology in there, is there? So I would like you to add some in.

You might want to swap out a few words, you might want to add in a little sentence or add in some words.

However you want to do it is fine, but there's quite a few changes we'll have to make there to make that a really good answer.

I'll give you some time now.

Feel free to pause the video.

The second part to our task today is to complete the flow chart to explain why deforestation can lead to more global warming.

Include the words: burned, carbon dioxide and decompose in your answer.

Let's have a look at the diagram.

Deforestation removes trees.

What did that lead to? There were two different aspects, wasn't there? Then more carbon dioxide in the atmosphere increases the rate of global warming.

So what's the step in between? There were two separate ways in which that can increase.

Please pause the video now.

Well done, everyone.

Right, let's have a look at your answers compared to mine.

See if we can tweak any to make them even better.

So your answer could look like this.

Trees are important as they absorb and store lots of greenhouse gases, so not just gases, but greenhouse gases, like carbon dioxide.

This makes them a major carbon sink.

That word carbon sink's a really good one to use.

By having lots of trees, it can reduce the amount of global warming.

We're not just saying the world's heating up, we're just actually being very specific and using the correct terminology.

And that's something we like to see in geography, and let's be honest, in most subjects.

For the second part of our task, your answer should look like this: Deforestation removes trees, which means that we have less trees to absorb carbon dioxide leading to more carbon dioxide in the atmosphere, increasing the rate of global warming.

And way that can be more carbon dioxide in the atmosphere is if those trees aren't used for timber, for construction or furniture or anything with a long life and instead are burned or decompose, then they will release the stored carbon that they do have.

Did you get that right? Well done.

You can pause the slide now if you'd like to tweak anything.

Now we're onto the second part of our lesson: How does climate change affect forests? So we've looked at how forests can change the world, how they can affect climate.

Now we're flipping that.

We're looking at actually how does climate change impact the trees, the habitats, the ecosystem in general in our forests? So impacts of climate change on forests include: species changes, more and worse wildfires, and pests and diseases.

Species will change because animals and plants that can't adapt to warmer temperatures and changes in the climate, they may become extinct.

In forests, as some species of trees struggle, others may take over, affecting the ecosystem.

So we might have a change in the species of trees that are there, or we might have some that just disappear.

Animal habitats are also affected.

Caribou numbers are reducing in Canada due to the habitat loss, human interference and climate change.

You can see this located on the map with the black arrow.

That is where this is happening.

Now you see the picture of the caribou at the top? Right, quick check here.

Caribou numbers are increasing in Canada due to the warming temperatures.

Is this true or false? And can you tell me why? Well done it is false, and this is because caribou numbers are reducing in Canada due to habitat loss, human interference and climate change.

Pests and diseases now.

As temperatures warm, pests and diseases can spread to, and thrive in, areas which were previously too cold for them to survive.

One example is the bark beetle, which has spread north in North America.

Large populations can destroy healthy trees and they can carry diseases that harm trees.

We've also got the effects of more and worse wildfires.

So warm and drier conditions can increase the number of wildfires and they can be more extreme.

An example of this, the Siberian wildfires of 2022 in Russia.

So climate change can cause these by increasing the drought conditions or drier conditions than normal.

Meaning that the leaf litter, the leaves that have fallen from trees, is drier and acts as perfect fuel to allow the fire to burn.

Check for understanding now.

Warmer and drier conditions can.

Is it A: decrease the number of wildfires but increase the size of them, B: increase the number of wildfires and they can be more extreme as well, or is it C: increase the number of small wildfires? Well done.

Yes, that is B.

So increase the number of wildfires and they can be more extreme as well.

So the fires can be worse.

They can be bigger.

Right, onto our practise task now.

I would like you to create a spider diagram naming and outlining three impacts of climate change on forests.

I've put the middle of the spider diagram here for you.

So impacts of climate change on forests, and there's probably three aspects you'd want to cover that we've talked about today.

Pause the video now to make sure you've got time to do this task properly.

Well done, everyone.

Let's compare your answers to mine and see if there's anything else we can add.

So your answer may include: species changes, so animals and plants that can't migrate or adapt to warmer temperatures and changes in the climate may become extinct.

So we might have animals reducing in number or becoming extinct.

And then, as some species of trees struggle, others may take over, affecting the ecosystem.

So you might have a change in the species that are there as well.

Then at the bottom here, we've got pests and diseases.

So as temperatures warm, pests and diseases can spread to areas which were previously too cold for them to survive.

And lastly, we've got more and worse wildfires.

Warmer and drier conditions can increase the number of wildfires and they can be more extreme.

So one thing you do to add to this spider diagram further would be to add examples.

You weren't asked to add examples here, I just said for you to name and outline, but you could add examples to take this a little bit further.

So, in our species changes, we could talk about the caribou in Canada.

For the pests and diseases, we could talk about the bark beetle.

And more and worse wildfires, we could talk about those 2022 Siberian wildfires.

So that's something that you could add if you hadn't already.

Let's take a look at our summary.

Global temperatures are increasing because of climate change.

Forests remove carbon dioxide from the Earth's atmosphere and replace it with oxygen.

Deforestation is a major contributor to climate change.

Climate change can cause changes to the species in a forest; the spread of pests and diseases and more and worse wildfires.

I hope you've enjoyed learning about this today and how powerful forests are when it comes to climate change and the impacts on them.

I've really enjoyed learning with you.

Hopefully I'll see you next time.

Thank you.