Lesson video

This lesson is called "Climate Change and Biodiversity: "Changes in the Distribution of Organisms" and is from the unit, Maintaining Biodiversity and Human Impacts.

Hi there, my name's Mrs. McCready, and I'm here to guide you through today's lesson.

So thank you very much for joining me today.

In our lesson today, we're going to evaluate evidence of the impacts of environmental changes on the distribution of organisms. Now we're gonna come across a number of keywords today, and they're listed up here on the screen for you now.

You may wish to pause a video to make a note of them, but I will introduce 'em to you as we come across them.

Now in our lesson today, we're going to first of all look at changing conditions before we consider how this affects the distribution of species.

So, are you ready to go? I certainly am.

Let's get started.

The Earth's atmosphere has remained relatively stable for many millions of years.

However, it is changing, and it is changing mainly because of human activity.

Now human activities are driving an increase in carbon dioxide levels within the atmosphere.

And if we look at the graph from Mauna Loa in Hawaii, we can see how the atmospheric carbon dioxide levels in parts per million has been on a steady but notable increase since 1962, more or less the present date.

There are seasonal fluctuations within that data, but the trend is very much and clearly upward.

So human activity is driving an increase in carbon dioxide levels within the atmosphere.

But why is this important? Well, we need to step back a little bit further in order to be able to appreciate that, because what we need to firstly understand is where energy is coming from.

Now the Earth is receiving infrared radiation, so infrared is felt in the form of heat from the sun.

So we're getting infrared radiation or heat from the sun.

We're getting energy from the sun in the form of heat and infrared radiation.

And some of this radiation is bounced straight back out into space.

It's reflected off the surface of the Earth, and off the atmosphere as well straight back into space.

But a lot of that energy, a lot of that infrared radiation is absorbed by the surface of the Earth as things warm up, and then reradiated back into the atmosphere.

Then what happens is the greenhouse gases present within the atmosphere, absorb that radiation, and then reradiate it back out, and essentially move it around the atmosphere.

And this heats the atmosphere up, causes the atmosphere to become warmer.

Now this is called the greenhouse effect, and this is facilitated by a number of greenhouse gases, which include carbon dioxide, methane, and water vapour.

So changes in the concentration of carbon dioxide in the atmosphere will change the ability, or change the strength of the greenhouse effect of the atmosphere.

So the greenhouse effect is useful up to a point.

It keeps the Earth warm enough for life to exist.

It keeps the Earth warm enough for life, for water to exist in its three states, solid, liquid and gas, as water ice, liquid water, and water vapour in the atmosphere.

And it enables life, therefore, to exist.

However, as the levels of greenhouse gases are increasing in the atmosphere due to human activity, what this is doing is increasing, enhancing the greenhouse effect.

And what this means is that the mean temperature, the average temperature on Earth is increasing as well.

It is increasing as a result of the increase in greenhouse gases within the atmosphere.

And an increase in the average temperature on Earth means that the Earth is, generally speaking, warmer.

And this is driving climate change.

Climate change is the long-term change in weather patterns.

And we are really beginning to see that happening quite clearly across the globe with various different excessive and unusual weather phenomena happening more and more frequently.

So this is being driven, these weather phenomena, this climate change is being driven by an increase in the number of greenhouse gases present within the atmosphere.

And they are trapping heat in the atmosphere, and therefore on the surface of the Earth, rather than allowing more of it to radiate out into space.

This is slowly warming the Earth up, and that is driving climate change.

So, which of the following are examples of greenhouse gases? Nitrogen, oxygen, methane, and carbon dioxide.

I'll give you five seconds to think about it.

Okay, did you choose methane and carbon dioxide? Well done if you did.

Now, even small increases in the Earth's surface temperature can have significant impacts.

So for example, if the Earth's surface temperature increases even by a small fraction of one degree, we will see an increase in the amount of polar ice that is melting, and an increase in the sea level as well.

We will also see exacerbated climate change.

Now climate change is when severe weather events become more common.

And severe weather events include phenomena such as intense storms and cyclones, droughts, and very heavy rainfall leading to floods.

So these types of phenomena are occurring more frequently as a result of climate change, which is as a result of an increase in greenhouse gases within the atmosphere due to human activity.

So as the Earth surface temperature increases, we are also seeing an increase in ocean temperature as well.

Now the ocean can absorb quite a lot of energy before any temperature change is noticeable.

But what an increase in ocean temperature means particularly is that there will be an increase, or there is an increase in evaporation of water into the atmosphere.

So the liquid water in the ocean is turning into water vapour in the atmosphere.

And water vapour is one of greenhouse gases.

And this will, this is encouraging an increase in temperature.

Now, an increase in temperature in the oceans reduces the quantity of carbon dioxide that the oceans can store by dissolving.

So carbon dioxide dissolves in the oceans, and as the water temperature increases, less carbon dioxide can be stored.

So what an increase in temperature in the oceans also means is an increase of in the release of carbon dioxide from the oceans into the atmosphere.

So an increase in temperature on the surface of the Earth has a double whammy for the oceans, because not only does more water vapour enter the atmosphere, also more carbon dioxide enters the atmosphere, and the ocean is able to store less carbon dioxide as well.

So these factors are compounding each other and building up to make the situation even worse.

Now, changes to the environment, and climate change can affect the distribution of species.

This is where species are located.

Now this is driven by environmental factors, and a number of these affect the distribution of organisms, including the temperature, the availability of water, whether it's too much or too little, and also the amount of atmospheric gases that are present within aquatic environments, so the amount of gas which is stored within water, for instance, both within the oceans and within lakes and rivers.

So, which of the following is not an abiotic factor that is closely linked to the distribution of species in an ecosystem? Is it, A, an increased mean temperature, B, a change in the availability of water, C, a change in the dissolved gases in aquatic environments, or D, the number of predators? So which is not an abiotic factor? I'll give you five seconds to think about it.

Okay, did you decide that the number of predators is not an abiotic factor, remembering that abiotic means without life, so something which is not living, and therefore the thing which is not not living is the number of predators.

Well done if you got that correct.

Now climate change can have a significant impact on ecosystems. We've seen how climate change is significantly impacting weather and weather patterns.

Well, this is going to have a significant impact on ecosystems, because changes in weather patterns can change the environmental conditions of the ecosystem by introducing more water or less water, higher or lower winds, for instance, higher or lower temperatures.

Now if conditions change, especially if they change very quickly, organisms that live within that environment, within that ecosystem may find it very, very difficult to adapt quickly enough to be able to survive.

And they may find that their extremely suitable adaptations now suddenly become extremely unsuitable.

So if we consider the case of the golden toad, for instance, the golden toad was last seen in 1989, and it was declared extinct in 2004.

Now the golden toad lived within a high altitude cloud forest in Costa Rica, which was about 1500 metres above sea level.

And the ecosystem conditions were extremely specific.

There was high humidity with a constant mist situated within a canopy, a foliage of leaves.

Now, these toads, the golden toads were only found within a four square metre range, and they were therefore very highly adapted, which made them highly sensitive and extremely vulnerable to environmental change.

Now, one theory for the extinction of the golden toad is that there was a sudden change in climate conditions, because even just a couple of years' worth of abnormal rainfall, abnormal weather patterns such as severe drought or a lack of rainfall, which have made quite a significant difference to the climate conditions of that ecosystem.

And by doing so, the adaptations of the golden toad would've become much less of a good fit for the conditions that then were present within that environment.

And it is very likely that this is what drove the extinction of the golden toad.

So you can see how climate change can have a significant and extremely detrimental effect on the organisms that it affects.

Now species in polar regions are also significantly impacted by changing climate as well.

So let's have a look at the musk ox as an example of this.

Now, musk ox are highly adapted to live in extremely cold and barren environments.

They have very thick fur coats which are extremely warm, excellent insulators and keep the animals warm through very, very cold conditions.

Now, the musk ox population was significantly reduced by humans, which hunted them for their meat and fur.

But now, changing climate conditions are affecting the musk ox population too.

Now, the musk ox, with their thick fur coats are highly adapted to live in cold snowy conditions.

And what they do is they use their nose and their legs to bury through, to dig through the snow, to find lichens and mosses which are buried underneath the snow layer that they can eat.

That's their food.

But with climate change conditions and an increase in temperature, what's happening now is instead of snow falling, rain is falling instead.

And this has two significant impacts on the musk ox.

Firstly, the rain falls onto the snow, and then freezes, and this forms a really thick layer of ice on top of the snow.

And it is so thick and hard that the musk ox cannot bury through it, cannot dig through it to unearth, to dig up the lichens and moss that they need to eat.

So they have reduced access to the food that they need to eat.

Also, what rainfall means, instead of what snow means to the ox, is that the rain can get into their coat.

Their coat is much less well adapted for keeping rain off than it is for snow, 'cause snow is dry, but rain is not.

Rain is very, very wet, and it penetrates their coat.

And especially for young musk ox, it causes them to freeze to death.

So it makes them cold and wet, not at all insulated, and they die of cold.

So musk ox are being doubly affected by changing climate because not only is it restricting their access to their food supply by forming this layer of ice across the top of the surface of the snow, which stops 'em from being able to dig their food up, it is also penetrating their fur with wet rain and causing them to freeze to death as well.

And as a result, the musk ox population is significantly decreasing due to climate change.

So let's consider this then.

The population size of a species can be used to monitor changes in temperature of the environment.

So what is the advantage of using a population rather than measuring the temperature with the thermometer? Is it, A, thermometers can only record temperatures within a specific range, is it, B, thermometers do not record temperatures accurately, or is it, C, the population size will show long term changes to the species? I'll give you five seconds to think about it.

Okay, so did you decide that C, the population size will show long-term changes as the correct answer? Well done if you did.

Okay, what I'd like you to do now is to consider this example.

So the adelie penguins spend most of their time living on ice in Antarctica at the South Pole.

And the population of adelie penguins has reduced by more than half in the last 60 years, which is an alarming and rapid decrease in their population numbers.

Now the ice around Antarctica, as you can see from the maps there, has reduced in this same 60 year period.

You can see that the ice, which was beyond the land of Antarctica on the sea, has significantly reduced over the course of that 60 year period.

So what I'd like you to do is to use this information and explain why the population of adelie penguins has declined in the last 60 years.

So pause the video, and come back to me when you are ready.

Okay, let's review your work and see what you put.

So I asked you to use the information about ice coverage, and the change in ice coverage over the last 60 years, and the penguin population reduction in the last 60 years to explain why the population of adelie penguins has declined over the last 60 years.

So you might have included in your answer that penguins spend most of their time on the ice, and there has been a reduction in the area of ice since 1960.

You might also have included that the reduction in the area of ice may be a result of increased sea temperatures caused by climate change.

And this means that there is a less habitat for the penguins to live in, therefore there are fewer places for the penguins to nest in.

And this means that they are perhaps less well adapted to the changing habitat as a result of climate change.

So just review your answer and see whether you've got all those key points.

And well done.

Okay, let's have a look now at how climate change can affect the distribution of species.

So we've seen how climate change is having a significant impact on many ecosystems and the communities of organisms that are living within them.

Now, environmental changes include an increase in temperature, the availability of water and changes to that, and the concentration of dissolved atmospheric gases in aqua environments, as we've seen in the last section of this lesson.

And we can assume therefore that lack of water will force animals to migrate in hunt of a better source of water.

And all of these environmental changes can result, therefore, in the distribution of species.

That is, where organisms are located.

And it can also affect their abundance, how many of those individuals there are.

So environmental changes are affecting distribution and abundance of species.

So let's look at a bit more detail.

Now organisms are highly adapted to live within the conditions that they are present in.

So the adaptations of an organism allow them to live within a certain range of conditions.

And climate change causes those conditions to change.

And this includes an increase in the average temperature.

And this is driving the changes in the distribution and abundance of species.

For instance, some mountain plants are now growing 10 to 50 metres further up the mountain due to rising temperatures.

It is now warmer, higher up the mountain, and therefore perfectly okay for these organisms for these plants to live higher up the mountain than they ever have before.

And so you can see how climate change is directly affecting distribution and also abundance, and this is affecting biodiversity, the range of organisms present within an ecosystem.

Now we can see climate change happening here in the UK, and you may well have noticed this as you've moved around the country, going on walks, being in countryside, for instance.

Now there's a value that is measured called the spring index in the UK every year.

And this is the day upon which spring events occur, particular spring events occur, including the flowering of specific spring plants, such as Hawthorne.

And the day of spring, the spring index has been recorded every year in England between 1891 and 1947, and then again between 1998 and 2023, so to current years.

And you can see that data plotted on the graph there.

So there's a blank space in the middle of that graph where no data was collected, but there's data sitting before that up to 1947, and then from 1998 onwards to the present day.

And the graph shows an average, if we were to draw a line through the average point of those two sets of data, we would see that the average day of spring is now about nine days earlier now than it was back in 1947.

And this is because there are warmer temperatures in March and April, causing spring events to happen earlier.

So spring is now about nine days earlier, about a week and a half earlier than it was about 80 or so years ago.

Now, what does that mean? Well, if plants flower at the wrong time of year, it can disrupt other organism life cycles, especially when there is a relationship between plants and animals, where plants depend on animals to help pollinate plants, and when animals depend on plants as a food source.

So let's look at this in a bit more detail.

Some spring plants are now flowering before it is warm enough for insects to be active, beetles, for instance.

Now, beetles are a pollinator, just like bees are, and they're an insect, just like bees are.

Now they are cold-blooded animals.

They need to be warmed up by the external environment in order for them to be able to move around effectively.

And if it's not warm enough for them, but it's warm enough for the plants to flower, then those two organisms, the plants and the beetles won't be able to work together.

So if the plants are flowering before the insects are available to pollinate them, then the flowers will produce less seed, because their pollen hasn't been distributed amongst the flowers within their species.

This means that the following year, there will be fewer flowering plants, because there were fewer seeds produced in order to make those flowering plants the following year.

And what this means is that because there's fewer flowers the following year, that means there will be less food for pollinators, and that means that fewer animals will survive as well.

And if there are fewer pollinators, then there will be fewer distributors of pollen.

And the problem will compound itself, and lead to a continued decrease in both flowers, well, plants which are producing flowers, and insects, which are pollinating those flowers as well.

So a reduction in the abundance of pollinators affects other animals as well, other animals within that food chain.

And that is the predators of those pollinators, the animals which are eating the pollinators, for instance, spiders.

So spiders eat insect pollinators, and therefore changes in the pollinator population numbers will also affect spider population numbers, their abundance.

So a decrease in pollinator abundance will cause a decrease in the abundance of predators to those pollinators as well, such as spiders.

Now, climate change not only is affecting the population numbers, the abundance of organisms, but it's also causing organisms to move as a result of changes in temperature.

So let's look at the wasps spider as a more specific example of this.

Originally, the wasp spider was only found in Europe, and on the very sheltered sections of the south coast, as you can see on the map there.

However, over the past 20 years, the spider population has spread as far north as Derbyshire.

And you can see how far north that is.

That is not near the south coast at all.

But over the course of the last 20 years, the spider population has spread northwards due to changing climate.

The winter temperatures are now warmer in the larger part of the south of the UK, up to Derbyshire, warm enough for the wasps spider to survive.

And so climate change is not only affecting the abundance of organisms, but it is also affecting the distribution of organisms, where those organisms are living.

Climate change and the availability of food causes other changes as well in other organisms, including those which migrate.

So let's look at that in a bit more detail.

Let's consider the cuckoo, for instance.

Many birds migrate to take advantage of the seasonal changes in resources, where they move to where there's plentiful food at one time of year, but less at another time of year.

And then when that food supply starts to decrease and run low, they migrate to a different location on the planet, where there is plentiful food for them to survive the winter.

And then they return back to their original place in the summertime.

And they switch between the two, and this is called migration.

Now the cuckoo arrives in the spring in the UK, and it leaves in summer, and it overwinters in Africa.

So it's here in the UK in the summer where there's plentiful food for it to eat, and the temperatures are nice but not too hot.

And then when the temperatures start to decrease and the food supply runs out, the cuckoos migrate down to Africa where it is warmer over winter, and there's also a plentiful food supply.

However, climate change is reducing the availability of food.

And this means that the cuckoos are struggling to build up enough energy to make those long distances of migration.

You know, several thousand kilometres of distance that they're travelling when they're migrating.

If they don't have adequate food supply, then they won't be able to build up enough reserves within their body in order to be able to cope with that long journey, and therefore, they're unlikely to survive.

And those organisms which do survive or have fewer chicks because they just can't raise sufficient numbers of chicks based on the food supply.

And so the population is decreasing, the cuckoo population is decreasing because there is less food, and less food means fewer chicks, and it also means reduced chance of survival because of lack of food due to climate change.

So let's just stop and review that.

As average temperatures increase due to climate change, species distribution may change because of what reason? A, they are able to adapt to the changing conditions quickly, B, the organisms that they rely on for food may be impacted by the change in temperature, or C, the habitat in which the species lives may be significantly changed or destroyed.

What do you think? I'll give you five seconds to consider.

Okay, so did you decide that both answers B and C are reasons that distribution of species changes? Well done if you did.

So we've seen how changes in temperature affect both species distribution and their abundance.

But now let's have a look at changes in freshwater availability, because this is also another important factor which affects the distribution and the abundance of species.

After all, all organisms require water in order to survive.

And waterholes are very important resources for many animals.

And changes in weather patterns as a result of climate change can alter the level of precipitation.

This can lead to very reduced rainfall, which causes droughts, or extremely high rainfall leading to flooding.

So let's consider an organism which is dependent on relatively high rainfall, the wildebeest.

Now wildebeest follow the seasonal rains.

They are animals which live in Africa, in particular within Kenya and Tanzania.

And they follow seasonal rains throughout the course of the year, and the lush growth that follows it.

So you can see on the map how they move around in this extended oval pattern around Kenya and Tanzania throughout the course of the year following the seasonal rains.

And throughout the course of the year, they travel about 1,000 kilometres around this route following the seasonal rains.

Now, they follow the rains because after rainfall comes significant growth of plants, in particular, grass.

And so the grass is really lush and rich after the rainfall, and that is what the wildebeest are following.

They are following the rains so that they can eat this delicious lush grass afterwards.

Now this lush grass is really important because it provides them with the energy that they need in order to make this very long continuous journey.

Now we know that climate is changing, so let's look at this graph and see how it is changing and how it is impacting the population of wildebeest.

So we can see the trend of wildebeest population on the graph itself, and then those shaded areas of red indicating periods of high rainfall, and green indicating periods of drought.

So just consider the graph now, what does it show? Well, it shows that periods of drought are increasing in frequency.

You can see that in 1980 to 1990, there was just one period of drought.

There were three within the decade of 1990 to 2000, and there's been another three in the following decade as well.

So these periods of drought are becoming more frequent, and they're also lasting for longer.

There is also a reduction in the population of wildebeest, a relatively steady decline in population, albeit with some fluctuations.

And there has been only one period of high rainfall in the whole of that 30 year period.

So an increase in the annual rainfall in the areas where the wildebeest are migrating will impact the size of the population.

But why? Why might the population of wildebeest decline during periods of drought? Would it be because, A, there are more predators of wildebeest, B, there is less fresh grass for wildebeest to eat, or C, there is more water for wildebeest to drink? I'll give you five seconds to think about it.

Okay, did you decide that the population of wildebeest would decline during periods of drought because there is less fresh grass for them to eat? Well done if you did.

So what I'd like you to do now is to consider another example.

And this time we are looking at Cetti's Warbler.

Now the Cetti's Warbler is a small bird.

It was first seen in the UK in Hampshire in 1961.

And it was first recorded as breeding in the UK in Kent in 1972, about 11 years later.

Now these birds eat small insects.

And if we look at these two diagrams of where the Cetti's Warbler was found in 1975 compared to where it is found now in 2020, we can see that the population has changed.

So what I would like you to do, please, is to describe the change in distribution of the Cetti's Warbler as shown in the maps from 1975 to 2020.

And I would like you to suggest why the distribution has changed.

So pause the video and come back to me when you are ready.

Okay, let's review your work then.

So what I asked you to do was to describe the change in the distribution of the Cetti's Warbler as shown from the distribution maps, and suggest why this distribution has changed.

So you may have included in your answer that the birds distribution has moved both northwards and westwards since 1975.

And this may be because as the average temperatures have increased due to climate change, the birds have been able to survive over winter, and have successfully reproduced.

And what this has led to is a distribution change.

And this has allowed the species distribution to increase, they are found in more locations.

The distribution of small insects that the birds are feeding on may also have changed.

So you might have included that as another reason why the Cetti's Warbler has spread further across the UK over the 45 year period.

So did you get all of that work? Well done if you did.

Just add anything that you need to to fulfil your answer.

And well done.

Okay, we've come to the end of our lesson now.

So what we've seen in our lesson today is that greenhouse gases, including carbon dioxide, methane, and water vapour help to keep the Earth warm enough for life to exist.

However, an increase in those levels of greenhouse gases in the atmosphere is causing climate change.

And these levels are increasing because of human activity.

And we've seen how that even very small changes in an ecosystem, such as a slight increase in temperature of water availability can have a significant impact on the distribution and the abundance of organisms. And this affects the biodiversity of ecosystems, usually causing them to reduce, because organisms are not able to adapt quickly enough to the changing conditions, or are able to move to better locations that are more suited to their adaptations.

And these organisms therefore become extinct, or at least risk extinction as a result.

So I hope you found our lesson interesting today.

We've certainly looked at lots of very interesting organism examples.

Thank you very much for joining me today, and I hope to see you again soon.

Bye.