Lesson video

Hello, my name is Ms. Gilyeat and I'm your geography teacher for today.

Today's lesson is called "Evidence of the Anthropocene." Our lesson outcome for today is that you can describe and evaluate key evidence that shows how humans have altered Earth's systems. We've got five keywords for today's lesson.

So the first one is CO2 concentration, which is the amount of carbon dioxide in the atmosphere at a given time, measured in parts per million or PPM.

An ice core are long cylinders of ice drilled from glaciers or ice sheets.

Biodiversity is the variety of living things in an ecosystem or area.

A geological marker is something found in layers of Earth like rock, ice, or mud that shows a big change in the planet's history.

Land cover is the physical material at the surface of the Earth.

Okay, we have got two learning cycles.

So to start off with, we're gonna look at evidence of human impact in the atmosphere, and then we're going to look at evidence of human impact on Earth.

Now, humans are changing Earth in ways that can be seen in the soil, in rocks, ice, and even from space.

This is evidence that we might be in a new time period called the Anthropocene.

The Anthropocene is a term used to describe a new geological age shaped by humans.

Now, since the Industrial Revolution, which started in 1750, people began using machines powered by burning fossil fuels, including coal, oil, and gas.

So we can see on the slide here, we've got a picture of what a city would've looked like during this period of time.

Now, burning fossil fuels releases greenhouse gases including carbon dioxide into the atmosphere.

An increase in greenhouse gases in the atmosphere is leading to climate change.

So basically our planet is getting hotter and we are seeing more extreme weather.

So if we have a look here, we have got a graph.

So we've got CO2 concentration in PPM on the y-axis and we've got years from 1750 to over 2000 on the x-axis.

Now, before 1750, the CO2 concentration in the atmosphere was about 280 parts per million.

However, in 2025, the CO2 concentration reached over 430 parts per million.

So that's a very, very steep increase.

And we can see there that the real steep increase started in 1950.

So there's lots of things which have kind of led towards that steep increase.

A big one is population increase, because the more people that there are on the planet, the more energy is used, which means more of those fossil fuels have been burned.

But CO2 concentration wasn't measured in the atmosphere hundreds of years ago.

So I want you to have a think or a quick chat with your partner.

How do you think we know what CO2 concentration was hundreds of years ago, even if they weren't recording it? Any thoughts? Now, ice cores are long cylinders of ice drilled from glaciers or ice sheets.

Each layer in the ice holds tiny air bubbles from the past.

Those air bubbles contain ancient air, including gases like CO2 and methane.

Scientists can measure how much of each gas there was in the atmosphere thousands of years ago using this ancient air.

The oldest ice core ever recorded, recovered, sorry, was drilled in Antarctica and dates back 800,000 years ago.

So if you imagine if you drill the ice core and you get a really deep one, that bit of ice was laid down up to 800,000 years ago.

So they look at the gases that were in the ice at that time, and that gives an indication to how much CO2 and methane there was in the atmosphere at that time.

Okay, let's have a look what the ice core data shows them.

So we can see there a graph again that shows that carbon dioxide in the atmosphere has changed over the last 800,000 years.

So up until fairly recently, it never really got above 300 parts per million, okay, but it did fluctuate, okay, so it went up and down during that period of time.

Yup, so it steadily fluctuated between about 200 to 300 parts per million for the last 800,000 years.

After 1750, CO2 and other greenhouse gases rose sharply.

This matches the start of human industrial activity.

Okay, so if you look at the graph there at the zero point, and we are very, you know, very recent in Earth's history really, okay, we can see that the carbon dioxide has gone up very, very steeply.

Ice cores provide strong evidence that humans are changing its atmosphere, which is proof of the Anthropocene.

Okay, let's check our understanding.

True or false? CO2 concentration in the atmosphere has been fairly stable over the past few hundred years.

That is false.

And can you tell me why? So before 1750, CO2 concentration was about 280 parts per million.

In 2025, the CO2 concentration reached over 430 parts per million.

Well done if you got that right.

Okay, let's check our understanding again.

What is shown in the picture? Have a quick chat with your partner.

Okay, let's see what Lucas says.

"This picture shows a scientist holding an ice core.

We can use these ice cores to find out how much CO2 there was in the atmosphere thousands of years ago." Well done, Lucas.

Okay, we're onto our first task for this lesson.

So what I would like you to do is have a look at the graph that I've got on the slide here, and I would like you to describe what the graph shows and explain it.

So describe and explain what the graph shows.

Okay, and for your second task, I'd like you to, using the photograph, explain how scientists know that CO2 concentration in the atmosphere has changed.

Okay, let's have a look at some answers then.

So for this one, the graph shows that carbon dioxide in the air has increased a lot since 1750.

It stayed around 280 parts per million for a long time, but started rising after people began using coal, oil, and gas during industrialization.

After 1950, it went up even faster.

Okay, so you didn't have to write exactly what I've put there, but something along those lines.

And it'd be really good if you've got some data from the graph in your answer as well.

So it might be worth pausing the video and seeing if you can improve your answer there.

Okay, so let's have a look at this.

The picture shows a scientist holding an ice core.

Ice cores trap tiny bubbles of ancient air, including gases like CO2 and methane.

By measuring how deep the ice is, scientists can figure out how old it is.

Then they test the air bubbles to see how much CO2 was in the atmosphere at that time.

Okay, let's get onto our second learning cycle now, which is looking at evidence of human impact on Earth.

Now, evidence of the impact of humans can be seen in the geosphere, so that's rocks and soil, and the biosphere, so the plants and animals.

So we can see plastic pollution on Earth, fast biodiversity loss, land cover change, and radioactive layers in the soil.

Okay, so there's quite a lot of evidence for biodiversity loss.

Species are going extinct much faster than normal, up to 100 times faster.

More than one million species are at risk of disappearing within the coming decades.

And the main causes of this are deforestation, pollution and climate change, overhunting and overfishing, and invasive species taking over.

Now, some of the main, or some examples of species at risk include, so the bees are dying from pesticides and habitat loss, and that can have a major, major impact on ecosystems because bees are pollinators.

Amphibians disappearing due to disease and warming, and orangutans are losing their homes to palm oil farming.

Okay, let's check our understanding.

How many species are at risk of extinction in the coming decades? Over one million.

Now, a geological marker is something found in layers of Earth like rock, ice, or mud that shows a big change in the planet's history that can be used as evidence for the Anthropocene.

Now, geological markers tend to be widespread, so they're found all over the world, permanent, stay in the Earth for thousands of years, and are sudden or unusual, show that something big happened fast.

We are also seeing evidence of plastic pollution.

Over 400 million tonnes of plastic are made every year.

Most of it is thrown away and doesn't break down for hundreds of years.

It ends up in lands, rivers, oceans, and even animals.

Now, where can we find it? We find it in ocean garbage patches, which are areas in the water of the ocean where plastic accumulates due to ocean currents.

They are found inside fish, seabirds, whales, plankton, and humans, and also in soil, snow, rain, and in rock.

Now, plastic are now being found in sediment layers like fossils.

Future geologists could dig up a layer full of plastics and say, "This was the human age." So if we have a look on the slide here, you can see a rock layer.

So this is when sediment has been layered down over time, and it creates these lovely layer features.

Now, geologists are finding that some of these layers are having plastic in them, and that shows that humans have had an impact on Earth.

Okay, let's check our understanding.

Where can plastic be found? Can you name three places? A, B, and C? So we've got here fish, rock, and the ocean.

Okay, so also there is evidence of radioactive elements, which is proof of human impact on Earth.

Now, between the 1940s and 1960s, countries tested nuclear bombs above the ground.

These explosions sent radioactive dust high into the atmosphere.

This does not occur naturally and is therefore proof of human activity.

The dust spread all around the world and settled into the soil.

So where are these radioactive elements being found? So radioactive elements like plutonium-239 and cesium-127 are found in soil layers, lake and ocean sediments, and ice cores and tree rings.

Okay, so we are finding these radioactive pieces from the '40, '60s, all around the world.

Evidence of land cover changes seen from satellite images and maps are also other evidence of it.

So satellites can show changes on Earth's surface.

So forests being cut down, cities growing, and deserts expanding.

And old maps help us see how the land has changed by comparing maps to satellite images.

So we can look at maps from 50, even over hundreds of years ago and see how the land has changed from looking at those maps to seeing what we have there today.

So for example, we've got a satellite image here of an area which has been deforested.

So there's the satellite image in 2000, and there it is in 2006.

So you can see that in six years, there has been a drastic change and a lot of the trees have been cut down.

So over one million kilometre square of forest has been lost in the last 30 years, and that's about the size of Egypt.

So very, very sad.

Okay, so we've got a GIF on the slide here.

Now we can see here that as the screen goes across, it shows how Sheffield has changed.

Okay, so we've got an old map of Sheffield compared to a satellite image today.

So I want you to look at that and see what can you see has changed in Sheffield in that time.

Okay, so you might have seen that there's some new roads there, there's quite a lot new houses as well, and there's also some very big residential buildings.

Okay, let's check our understanding.

So what evidence can you see that humans have altered this landscape? Let's have a look.

It says many more buildings and roads have been built.

Well done if you spotted that.

Okay, we're on to our main task or last task for this lesson.

So what I'd like you to do is imagine you are a geologist in the year 2125.

So quite a few years into the future.

While studying a layer of rock, you discover clear evidence of human impact on Earth.

What I'd like you to do is write a short paragraph explaining what you found in the rock, so for example, did you find plastic, radioactive dust, or extinct species, or a fossil of an extinct species, how it shows that we may be living in a new period called the Anthropocene? I'd like you in your answer to use clear scientific language, but make it something a younger student could understand too.

So the pause the video and have a go.

Okay, let's have a look at my example answer here.

While studying rock layers from the early 2000s, I discovered thin fragments of plastic buried in the soil.

These materials do not occur naturally and were created by humans.

Their presence in Earth's layers marks a clear signal of human activity.

Because these plastics are found all over the world and last for hundreds of years, they can help define a new geological time period, the Anthropocene, when humans began to leave a permanent mark on the planet.

Now, obviously you do not have to write exactly that, but hopefully you wrote something along those lines.

Okay, we've got a summary for today's lesson.

So atmospheric CO2 levels have risen steeply since the Industrial Revolution.

Ice core data shows a sharp increase in greenhouse gases linked to human activity, and biodiversity loss is happening faster than natural extinction rates.

Plastics and radioactive elements form geological markers of human impact.

And land cover change is visible from satellites and historical maps.

Now that's it for today's lesson.

You've done a fantastic job there, and that's it from me, so I'll see you next time.

Bye.