Lesson video

Hello, I'm Mrs. Adcock and welcome to today's lesson on human activity.

And we are going to be looking at climate change data to consider are humans responsible for climate change? Today's lesson outcome is I can evaluate the evidence for human activity causing climate change.

Some of the keywords that we will be using in today's lesson include correlation, uncertainties, isotopes, carbon emissions, and carbon footprint.

Here you can see each of those key words written in a sentence.

You might like to pause the video here, and read over those sentences and make some notes that you can refer back to later in the lesson when needed.

Today's lesson on human activity is split into three parts.

The first part is looking at the data and deciding are humans really responsible for climate change? Then we're going to look at some of the uncertainties in the data.

And finally we're going to move on to carbon footprint.

So let's get started on are humans responsible for climate change? Data shows that global temperatures are increasing, and we can see here we've got a chart of year against temperature anomaly, and that's measured in degrees Celsius.

Now, what is temperature anomaly? Temperature anomaly is the difference between current data on temperatures and an average of the previous 30 years.

So this is then represented as zero on the chart, and then anything above shows that the temperature is higher than the average of the previous 30 years.

So what we can see from this is for the last 45 years, the global temperatures have been increasing each year and the last 10 years have been the warmest years on record.

Data collected from more lower observatory in Hawaii shows that carbon dioxide levels have been increasing since records began in 1958, and we can see there on the graph we've got the year along the bottom and we've got the amount of carbon dioxide measured in parts per million in the atmosphere.

And we can see that over time the amount of carbon dioxide in the atmosphere has been increasing since 1958 to current day.

Is there a correlation between increasing carbon dioxide levels and increasing global temperatures? Correlation is a link between variables.

So as one variable changes, so does another, you can get a positive correlation, whereas one variable increases, then the other one also increases or a negative correlation, whereas one variable increases, another variable decreases.

So let's think about whether it's a positive or negative correlation between carbon dioxide levels and global temperatures.

There is a positive correlation between the carbon dioxide levels and global temperatures.

So as the carbon dioxide levels have increased, so have global temperatures.

However, a correlation does not mean that there is a causal link, and by that we mean where one thing causes or affects another.

So this correlation doesn't tell us that increase in carbon dioxide levels cause global temperatures to increase.

We are going to need to look at further data to be sure if increase in global temperatures is caused by increase in carbon dioxide levels.

Based on published peer reviewed evidence most scientists do believe that increasing carbon dioxide levels have caused an increase in global temperatures.

Are the increasing carbon dioxide levels a result of human activity? There is strong evidence also that human activity is responsible for increased carbon dioxide levels, which most scientists believe have led to climate change.

Carbon dioxide emissions have increased since the industrial revolution began in 1850, and we can see this on this graph that shows the year at the bottom and we can see carbon dioxide emissions in tonnes over the years.

Carbon dioxide emissions have increased rapidly since 1950 as developed and developing countries have combusted large amounts of fossil fuels.

When we combust fossil fuels, carbon dioxide is emitted into the atmosphere.

Time for a check for understanding scientific data shows that in recent years there have been, A, increasing levels of atmospheric carbon dioxide, which has the molecular formula, CO2.

Decreasing levels of atmospheric CO2, increasing levels of CO2 emissions or d, decreasing levels of CO2 emissions.

So choose any answers that you think are correct.

The correct answers are in recent years there have been increasing levels of atmospheric CO2 and increasing levels of CO2 emissions.

Further evidence that the rise in atmospheric CO2 levels are a result of combustion of fossil fuels can be found by studying the isotopes of carbon.

Now, isotope is one of our key words for today's lesson, and an isotope is an atom of an element with the same number of protons, but different mass number due to a different number of neutrons.

So we can study the isotopes of carbon and have a look to see whether any of those isotopes of carbon are found in higher levels in the atmosphere.

Now we've got three isotopes here at the bottom, we've got carbon 12, carbon 13, and carbon 14.

Each of those atoms of carbon contains six protons, so they all have the same number of protons.

However, they each have a different mass number due to a different number of neutrons.

So Carbon 12 has got six neutrons, carbon 13 has got seven neutrons and carbon 14 has got eight neutrons.

So we would describe carbon 12, carbon 13 and carbon 14 atoms as isotopes of carbon.

Most carbon is carbon 12, so it's more likely to be used by plants during photosynthesis than carbon 13 and carbon 14.

Carbon 13 does exist in our atmosphere and it's often released in volcanic emissions.

Carbon 12 is found in the atmosphere to and is used by plants when they photosynthesize.

So carbon 12 is the isotope found in even higher proportions in fossil fuels form from dead plants and animals.

So the plants taking carbon dioxide from the atmosphere that contains this carbon 12 isotope.

This 12 isotope due to the process of photosynthesis is now stored within the plant.

So when animals eat plants, the carbon 12 is transferred to the animals.

And when these plants and animals die, the carbon 12 over millions of years can be in fossil fuels.

And these fossil fuels contain the Carbon 12 isotope.

Why don't these fossil fuels contain carbon 14? Well, due to the radioactive decay of Carbon 14, it's not found in fossil fuels.

The levels of carbon 12 in the atmosphere have increased as increasing amounts of carbon dioxide is produced from burning fossil fuels.

So when we combust these fuels, these fossil fuels that contain Carbon 12 and it reacts with oxygen in the atmosphere, we produce carbon dioxide that contains carbon 12 isotope.

We know that lots of that carbon dioxide has come from the combustion of fossil fuels because it contains the Carbon 12 isotope and the other product of combustion is water.

This all provides further evidence that the carbon dioxide levels in the atmosphere have been increasing and these have increased due to human activity, the combustion of fossil fuels that's released this Carbon 12 isotope into the atmosphere.

Based on lots of scientific evidence most scientists also believe that the carbon dioxide levels increasing leads to global warming.

Time for a check in understanding data shows a correlation between carbon dioxide levels and global temperatures.

As carbon dioxide levels increase, the global temperatures increase, global temperatures stay the same or global temperatures decrease.

Well done if you chose option A, data shows a correlation between carbon dioxide levels and global temperatures, and as the carbon dioxide levels increase, the global temperatures also increase.

Another question for you to have a go at here.

Which isotope of carbon is found in the higher concentrations in fossil fuels? Do we find carbon 12, carbon 13 or carbon 14 in higher concentrations in fossils? Well done If you chose option A.

Carbon 12 is the isotope of carbon found in the highest concentrations in fossil fuels.

Time for our first practise task of today's lesson, you need to firstly describe what the graph shows, and this is a graph on the annual carbon dioxide emissions.

Pause the video now and have a go at answering this question.

And remember, when we describe what graphs show, we should be talking about increases or decreases or whether things stay the same.

The second part of this task, you need to think about what evidence is there that the increasing levels of carbon dioxide in the atmosphere are from the combustion of fossil fuels.

If you pause the video now, answer this question, then when you come back, we'll go over the answer to both questions.

Question one, describe what the graph shows.

The graph shows that the amount of carbon dioxide emitted into the atmosphere has increased since the industrial revolution, which was about 1850.

And the carbon dioxide emissions have rapidly increased since 1950 to present day.

So well done if you talked about there being an increase in carbon dioxide emissions and if you were able to talk about how that increase has become more rapid since the 1950s.

Question two, what evidence is there that the increasing levels of carbon dioxide in the atmosphere are from the combustion of fossil fuels? Question two, what evidence is there that the increasing levels of carbon dioxide in the atmosphere are from the combustion of fossil fuels? Your answer may include different wording, but where you've talked about the isotopes of carbon.

So scientists can study the isotopic composition of carbon atoms present in the carbon dioxide in the atmosphere.

There are increasing levels of carbon 12 in the atmosphere which is found in fossil fuels and the combustion of fossil fuels containing carbon 12 atoms increases the levels of carbon 12 in the atmosphere, and there is a correlation between fossil fuel consumption and atmospheric carbon dioxide levels.

Well done if you answered that question correctly.

We have looked at the data, which leads us to think that humans are responsible for climate change.

We've seen how carbon dioxide levels have increased, how there's a correlation between this and global temperatures increasing, and how we have isotopic evidence that the carbon 12 levels are increasing in the atmosphere as we burn more fossil fuels.

We're now going to move on to the second part of our lesson where we look at some of the uncertainties in the data.

Computer models are used to model climate change.

These models are often simplifications as there are many factors that affect the climate.

Climate models, however, are based on data.

And global temperature data is collected and analysed from research centres all over the world, such as NASA, the Met Office, NOAA, which is the National Oceanic and Atmospheric Administration and the Japanese Meteorological Agency.

And here we've got an image of some apparatus that is used to record temperature data.

The research centres gather worldwide temperature data from multiple sources.

So they each gather their own data from multiple sources around the world.

So they use land weather stations, weather balloons, ships, buoys and satellites.

And we can see there a picture of a weather buoy, despite the fact that they gather so much information, there are some uncertainties in their data.

And this is due to the difficulty in collecting data across the great expanse of the oceans, which affects the average global temperatures.

Here we can see global temperature data collected over the years and it's measured in annual temperature anomaly in degrees Celsius.

This shows us the global temperatures compared to an average of the past 30 years.

If the data is above zero, then the global temperatures are higher than the average for the last 30 years.

We can see in recent years that the global temperatures are higher than the annual temperature anomaly, which shows us that the global temperatures are increasing and we know that they've been increasing for the last 45 years.

And certainties in the data also arise for other reasons such as the location of the weather stations.

So we've seen how it's difficult to gather data in the vast expanse of the oceans, but also the location of the weather stations can impact the temperature readings that are taken.

Higher altitudes tend to be cooler than lower altitudes, and urban areas tend to be warmer than more rural areas.

Depending on the exact location of the weather station, the research centres may get slightly different temperature readings.

Time for a question to check we've understood why may there be uncertainties in temperature data collected in different research centres globally? Is it A, the temperatures may be recorded at different altitudes.

B, weather stations may vary in whether they are positioned in a rural or urban setting or C, the temperature measurements were recorded in different units.

Now choose any options that you think are correct.

The correct answers are A and B.

So the temperatures may be recorded at different altitudes and they may be positioned in different settings, so they may be rural or urban, and both of these will impact the temperature data that was collected.

There are uncertainties in other data, not just the temperature data.

There is a lack of historical data on carbon dioxide levels and scientists study air samples trapped inside ancient ice to measure historical CO2 levels.

So there aren't records from thousands or millions of years ago.

So therefore scientists have to take ice samples and study the carbon dioxide levels from air trapped inside ice.

We can see here on the graph we've got the years before today and zero was 1950 and we can see the amount of carbon dioxide in parts per million in the atmosphere.

And there are large variations in the carbon dioxide levels historically.

So as you can see, that yellow line is going up and down quite a lot.

However, recent data does show a clear increase in carbon dioxide levels, and you can see at the end of the chart the carbon dioxide levels current levels compared to 1950.

And there's been a sharp increase in the atmospheric carbon dioxide levels.

The uncertainties with the data lead to some scientists not believing that increasing greenhouse gases are responsible for global warming.

There is also much speculation and a wide range of opinions presented in the media on climate change.

And some of these views may be biassed, including industries reliant on fossil fuels who are going to support in the media that the combustion of fossil fuels and the production of carbon dioxide is not responsible for climate change because this does not benefit these industries.

And also there may be bias from industries promoting renewable energy sources.

We've looked at this data and seen that there may be some uncertainties in the data due to the difficulty in taking temperatures across the oceans and also due to the location of the weather stations.

However, the global temperature data from the research centres does have very few uncertainties.

So we can see on that chart we've got the data from NASA, from the MET Office, from the NOAA and also from the Japanese Meteorological Agency.

And they are all following a very similar pattern with very little differences between the data.

We can tell that there are very few uncertainties in the data as the different sources of data show the same trend.

And this trend is that global temperatures are increasing.

Time for a question.

How do scientists study historical carbon dioxide levels in the atmosphere? Is it A, studying air samples trapped inside ice.

B, looking at records from billions of years ago, or C sampling carbon levels in ancient trees? The correct answer is studying air samples trapped inside ice.

This is how scientists gather evidence on historical carbon dioxide levels.

So well done if you chose option A.

Time for our second practise task of today's lesson.

There's two questions here.

The first one, why may there be some uncertainties in the data collected on global temperatures? And secondly, why does the media present differing views on climate change? Pause the video now.

Have a go at answering those two questions and come back when you're ready to go over the answers.

Question one, why may there be some uncertainties in the data collected on global temperatures? Your answer may include it's difficult to collect average global temperatures due to the expanse of the oceans.

And also global data may differ slightly between different research centres due to the location where the data was collected.

And you might have gone into further detail and said altitude affects temperature as well as whether it was recorded in an urban or rural setting.

Question two, why does the media present differing views on climate change? Most scientists worldwide have studied peer-reviewed, published data and agree that increased levels of carbon dioxide in the atmosphere lead to global warming.

However, some scientists disagree with this due to discrepancies in the data.

The media publish opinions which may be biassed, such as people favouring fossil fuel use or those who promote renewable energy sources.

Well done if you answered question one and question two correctly.

So we have now looked at the data and looked at whether humans are responsible for climate change.

We've looked at some uncertainties in the data.

Now we're going to move on to have a look at carbon footprint.

We can measure the impact a person, product, organisation, or event has on global carbon emissions.

And this measurement of the total carbon emissions is known as a carbon footprint.

We could measure our own carbon footprints by considering activities we do in our lives which result in the production of greenhouse gases such as carbon dioxide.

What name is given to the total amount of carbon dioxide emitted during the lifecycle of a product? Is it global warming, carbon footprint, greenhouse effect or greenhouse gas? And this is the total amount of carbon dioxide emitted during the lifecycle of a product.

We call this the carbon footprint so well done if you chose B carbon footprint.

A, global warming is an increase in earth's global temperatures.

C, the greenhouse effect refers to how greenhouse gases can trap infrared radiation and greenhouse gases answer D, we have examples such as carbon dioxide and methane.

And these are the gases responsible for the greenhouse effect that trap infrared radiation emitted from the earth's surface.

Some ways we could, our carbon footprint include, turning off lights and electrical appliances when not in use.

If we use less electricity, then less fossil fuels will need to be burnt to generate that electricity.

And therefore, as individuals, we will be responsible for less carbon dioxide being emitted into the atmosphere.

We could use low energy LED light emitting diode light bulbs.

We could insulate our homes.

If we insulate our homes, then we won't need to put the heating on as often, and therefore we won't need to combust fossil fuels and we will reduce our carbon dioxide emissions.

And if we wash clothes at lower temperatures, how could the carbon footprint of products be reduced? So if we think of items like a washing machine, microwave, a hair dryer, how can we reduce the carbon footprint of these products? There are lots of ways we could reduce the carbon footprint of products.

Now, when we consider the carbon footprint of a product, we need to think over its whole life cycle.

So the carbon dioxide that was emitted during its manufacture, during its use, and also during the disposal and the following, are some ways that would help to reduce the carbon footprint of many products and organisations.

The first one is carbon capture and storage.

And this involves rather than releasing carbon dioxide into the atmosphere at power stations, for example, we capture that carbon dioxide and we pump it underground to old oil reserves and coal mines.

And we store the carbon dioxide deep underground.

Another way we could reduce carbon footprint of a product is carbon offsetting.

And this means when a product involves the production of carbon dioxide.

To offset that, the company invests in renewable energy projects, which will remove carbon dioxide from the atmosphere.

So carbon offsetting, such as investing in renewable energy projects or planting more trees.

So thinking of ways that carbon dioxide can be removed from the atmosphere when you are making a product that's releasing carbon dioxide into the atmosphere may be during the manufacture, the use or the disposal of the product, and also invest in carbon neutral fuels.

So these are when we burn our fossil fuels at the moment, we release carbon dioxide into the atmosphere, but could we use fuels that during the production of these fuels, carbon dioxide was removed from the atmosphere? And example would be using plants to produce our fuels because these will remove carbon dioxide when they photosynthesize.

But when the fuel's burned, carbon dioxide will be released back into the atmosphere, which is why they're described as carbon neutral.

Because overall, there's no increase in carbon dioxide into the atmosphere.

So carbon capture and storage, carbon offsetting and carbon neutral fuels of all ways that the carbon footprint of products and organisations could be reduced.

More steel needs to be done to reduce carbon dioxide emissions and international efforts are needed to reduce these carbon emissions.

The Paris Agreement is a legally binding international treaty where 196 nations pledge to limit the increase in global temperatures.

Internationally, there has been a drive to finding zero carbon solutions, which are already being seen in the power and transport sectors.

And this is good news at the bottom because in the UK, carbon emissions have fallen by 50% between 1990 and 2022 according to UK official statistics.

Time for a question, how could the carbon footprint be reduced when manufacturing a plastic bag? A, use carbon capture and storage.

B, use carbon offsetting.

C, use carbon neutral fuels.

D, use carbon containing fossil fuels.

Choose any answers that you think are correct.

Ways that the carbon footprint could be reduced include, using carbon capture and storage using carbon offsetting and using carbon neutral fuels.

So well done if you chose all three of those options.

We don't want to use D 'cause we don't want to use carbon containing fossil fuels because when we combust these, they release carbon dioxide into the atmosphere, which is not going to reduce a carbon footprint.

Which of the following are actions humans could take to reduce their carbon footprint? So how can we reduce the amount of carbon dioxide that we are releasing into the atmosphere? A, walk or cycle where possible.

B, wash clothes at higher temperatures.

C, improve insulation in our homes.

D, turn electrical devices off when not in use.

Again, choose any answers that you think are correct.

The correct answers are walk or cycle where possible, improve insulation in our homes or turn off electrical devices when not in use.

So well done if you got those three correct, it wasn't answer B.

We want to wash clothes at lower temperatures.

So less energy is used in this process and therefore reducing our carbon emissions.

For the final practise task of today's lesson, you need to evaluate the carbon footprint of the washing machines using the information from the table.

Below we've got three washing machines, washing machine A, B, and C.

And you can see how much carbon dioxide is released when they are manufactured.

The massive carbon dioxide produced for one wash cycle, the total massive carbon dioxide produced from 2000 wash cycles and the total mass of carbon dioxide produced in kilogrammes from manufacture and the 2000 wash cycles.

So overall, for each washing machine, you need to use this information to evaluate the carbon footprint of the washing machines.

So make comparisons between the washing machines using the data and consider the carbon footprint of the washing machines.

Pause the video now, have a go at answering this question, then come back when you're ready to go over the answer.

Evaluate the carbon footprint of the washing machines.

So your answer may include washing machine C produces the most carbon dioxide during manufacture, but the least mass of carbon dioxide during one wash cycle.

Washing machine C has the lowest carbon footprint over the lifecycle of the product as it produces the least total amount of carbon dioxide when taking into account the carbon dioxide emissions from both manufacture and the 2000 wash cycles.

You may have answered this question slightly differently where you focused and made comparisons between other points, but well done having a go at this question.

And for evaluating the carbon footprint of the washing machines, we've reached the end of today's lesson on human activity.

Let's just summarise some of the key points that we've covered before we go.

There is a correlation between changing carbon dioxide concentration and consumption of fuels and global temperature changes.

There are uncertainties in data caused by locations where the measurements are taken.

Historical accuracy of measurements should be evaluated.

Fossil fuels derived carbon dioxide has a different isotopic composition than carbon dioxide from other sources.

And carbon footprints are a way of measuring a person's or a products or organization's impact on global carbon emissions.

Well done, you've worked really hard during today's lesson.

I've really enjoyed it.

I hope you have too, and I hope you're able to join me in another lesson soon.