Lesson video

This lesson is called Global Climate Change and The Effects and is from the unit Atmosphere and Changing Climate.

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 describe some of the major effects of climate change and suggest some ways humans can help to limit these effects.

Now in our lesson today, we're going to come across a number of keywords and they're up here on the screen for you now, you may wish to pause the video and make a note of them, but I will introduce them to you as we come across them.

In our lesson today, we're going to firstly consider the effect of rising sea levels.

Then we're going to consider climate change more generally before looking at how we can reduce global warming.

So are you ready to go? I certainly am.

Let's get started.

Now, greenhouse gases are present within the atmosphere and include carbon dioxide, methane, and water vapour.

And what happens is that they absorb infrared radiation, which the surface of the earth has reflected from the sun and the gases.

The greenhouse gases in the atmosphere absorb this radiation and then emit that radiation back out again in all directions.

And this helps to warm the atmosphere of the earth.

Now this is really useful because it keeps the earth a nice warm 15 degrees on average, which is about 20 to 30 degrees warmer than it would be if the greenhouse gases weren't doing this role.

However, too many greenhouse gases leads to too much of this heat being absorbed and re-radiated around the atmosphere.

And this ultimately then leads to global warming, which is beyond what it should be and will lead ultimately to climate change.

Now, global warming will increase ocean temperatures, and this has perhaps unexpected consequence because what warming water does is cause it to expand.

Now, we are probably already aware that when solids heat up, they expand.

And this is why there's gaps between solid objects in places like road bridges and where they join the mainland or railway tracks or within a greenhouse, for instance, so that when all of these solid objects warm up in summertime, they have space to expand into without buckling.

But liquids expand as well when they heat up.

And water is no exception and warming oceans causing them to expand will cause the sea level to rise.

And about half the measured global sea level rise on earth is caused by the expansion of water in oceans.

So when we talk about sea levels rising due to climate change, what we are doing is actually talking about sea level rise due to the expansion of water in the oceans caused by climate change rather than there being more water in the oceans.

So what are the effects of rising ocean temperatures? A, an increased depth of water in oceans.

B, an increased mass of water in oceans or C, an increased volume of water in oceans.

I'll give you five seconds to consider.

Okay, so you should have said that the depth of the oceans will increase and that the volume of the water in the oceans will increase.

Well done if you spotted both of those.

Another factor of rising sea levels is found on glaciers.

Now glaciers are slow moving masses of ice that form on land and then gradually move downhill very, very, very slowly over tens of thousands of years towards the sea.

Now, global warming causes ice in these glaciers to melt more quickly and therefore for them to move faster and also for them to disappear quicker as well.

And in Greenland, it was found that the glaciers in Greenland are disappearing four times faster in 2018 than they were 15 years before in 2003, four times faster because of climate change.

Now this means that the water contained within the glaciers as it melts will flow down ultimately into the sea and further cause the sea levels to rise because this water is currently trapped on the surface of the earth, on the land, not in the sea.

And therefore if it's running off into the sea, it'll add water to the sea and therefore cause further sea level rise.

Sea ice is a different form of ice.

Sea ice forms on the surface of the oceans themselves if they get cold enough to freeze.

Now, global warming also causes sea ice to melt more quickly in the summer and for less of it to form in winter.

However, melting sea ice does not cause sea levels to rise because the water is already in the ocean.

And if you've ever made ice cubes at home, you'll know that water expands as it freezes.

The ice will always take up more space as ice than it did as water before you froze it.

And so when you melt ice, what you are doing is actually making it take up less space, not more, which is why sea ice does not contribute to rising sea levels.

However, melting glaciers, which is land-based ice, will contribute to rising sea levels and a warmer ocean will contribute to rising sea levels as the water expands, as it warms. However, losing sea ice has other implications.

Firstly, sea ice is a really important habitat for many different species, including polar bears and walruses.

They use it as a diving platform to feed, and they also use it as a nursery to rear their young.

And so, if they don't have sea ice because there is less sea ice, then they also have nowhere to live and to dive from in order to feed, which it will be hugely problematic for these species.

Also, the heating of the oceans, as we've already discussed, that is taking place.

And what this also does is melt sea ice faster.

And if sea ice is being melted faster, there is therefore less of it.

And the problem with reducing the amount of ice on the sea is that the sea ice is white and that reflects an enormous amount of the sun's radiation, infrared radiation back into the atmosphere and into space ultimately.

In fact, sea ice can reflect up to 90% of the sun's infrared radiation back away from the surface of the earth into the atmosphere ultimately to be lost out to space because it's so reflective.

I mean, if you've ever looked at snow in bright sunshine, it's dazzlingly bright because of the amount of sunlight that it is reflecting back to you.

So you can imagine that if we are losing large quantities of sea ice as it's melting, as the oceans are warming, then the amount of light and infrared heat that is being reflected by the ice is significantly reducing.

And this is simply compounding the problem because less heat is being reflected back into space.

More of it is being trapped on earth within the atmosphere and more of it can therefore heat up the earth, heat up the atmosphere, and heat up the oceans, and this will simply exacerbate the problem even further.

So which of the following cause a rise in sea levels? A, water for melting glacial ice.

B, more frequent flooding events, C, water for melting sea ice or D, increasing ocean temperatures.

I'll give you five seconds to consider.

Okay, so you should have said that water for melting glacial ice and increasing ocean temperatures are causing a rise in sea levels.

But water from melting sea ice is not causing a rise in sea levels.

Well done if you've got both of those.

Now, rising sea levels has further knock on implications.

Firstly, it increases flooding of coastal areas and there are some parts of the world which are very low lying, such as the Maldives, which is only a couple of metres above sea level at its highest point, which are threatened with being completely engulfed by the sea in a very short period of time.

Because of rising sea levels, rising sea levels also increases coastal erosion because there is more water and often greater storms, more stormier water causing coastal erosion and therefore any homes which are located close to the coastline risk being washed away, especially in high tides and high storms and rising sea levels also increase the amount of salt that is deposited in the land around the coastal environment.

And whilst many species are highly adapted to live in very salty conditions, in salt marshes, actually increasing the spread of these specific areas is not necessarily very helpful, especially where the land is already being used for something like farming.

So what are some of the impacts of rising sea levels? Is it A, fewer glaciers, B, increased flooding, C, more coastal erosion or D, an increase in the amount of fertile farmland? I'll give you five seconds to consider.

Okay, so you should have said that the impact of rising sea levels includes increased flooding and more coastal erosion.

Well done if you spotted both of those.

So what I'd like you to do now is to explain two ways in which global warming leads to rising sea levels.

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

Okay, so you should have said that higher temperatures cause the water in oceans to expand, which results in higher sea levels and higher temperatures cause glaciers to melt more quickly and water from melting glaciers flows into the sea and also increases sea levels.

You also should have said that global warming also reduces the amount of sea ice.

And melting sea ice does not add extra water to the oceans, but it does reflect infrared radiation.

And without doing that, the oceans will warm more quickly.

So as they warm the water they contain expands and the sea level rises as a result.

So well done if you've got all of those points, but do add two your notes if you've missed anything out and let's get ready to move on.

Okay, let's have a look at climate change now.

Global warming causes climate change and global warming is caused by an increase in the number of greenhouse gases in the atmosphere, which then trap and recirculate heat around the atmosphere, thus warming the atmosphere.

Now an increase in global temperatures, which is what global warming describes leads to more powerful convection currents in the atmosphere.

And this ultimately leads to an increase in the number and the severity of storms. So once in 100 or 400 year storms are now happening much more frequently than they ever have done before and bringing with it quite disastrous consequences.

Now, global warming also affects atmospheric airstreams and this causes both climate change and also changes in the weather patterns.

So this means that long established weather patterns throughout the year become less established and less predictable, much more unpredictable and therefore much harder to forecast and also to do anything about.

This means that some areas will experience an increase in rainfall and flooding will be more likely, and flooding has a negative impact on crop production because most plants can't cope with flooded land.

They'll die rather than grow.

Also, what will happen as rainfall patterns change and climate changes and weather patterns change is that other areas will become much drier and as areas become drier, there is an increase in the risk of drought.

And prolonged periods of drought will affect crop production because many crops cannot withstand long periods of drought and still survive and produce crop.

They might be able to get away with a couple of dry days, but not periods of weeks or even months worth of drought.

And also drier periods increase the risk of wildfires and all too frequently wildfires make headline news around the world because they are happening in places where they don't often happen or haven't previously happen and are often encroaching so very close or into areas where humans are living as well.

And so are not just destroying forests, but are also destroying human habitats as well.

So what can global warming cause to happen? A, an increased number of severe storms. B, an increased number of droughts in some regions.

C, an increased number of floods in some places, and D, an increased risk of forest fires everywhere.

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

Okay, so you should have said that global warming will cause an increased number of severe storms and increased number of droughts in some regions and an increased risk of flooding in some places.

But whilst the number of wildfires will increase, it does not increase the number of forest fires everywhere.

Well done if you spotted all three of those, there are lots of impacts of climate change and one of those is that climate change puts living organisms under immense pressure and organisms respond to this pressure in a variety of different ways.

So some plants may flower earlier due to the changing conditions.

So daffodils, for instance, may start flowering at the same time as snow drops in January or early February instead of slightly later than they would normally do.

Climate change forces animals to move into new areas or change their migration patterns or their hibernation patterns in order to respond to the changing conditions.

And whilst some animals appear to be able to cope with these changes quite easily actually these changes are incredibly stressful and not very easy to cope with at all because sometimes the climate is changing too fast for these sorts of adaptations to really take effect.

And ultimately what it may well lead to instead is extinction for some organisms instead of them surviving elsewhere.

So how are some animals changing their behaviour in response to more rapid climate change? Are they A, migrating at different times? B, moving into new habitats, C, changing times of flowering or D, changing hibernation habits? I'll give you five seconds to consider.

Okay, so you should have said that animals are changing their behaviour by migrating at different times, moving into new habitats and changing hibernation habits.

But C is not an animal behaviour.

So well done if you didn't include that one.

So what I'd like you to do now is just to summarise that part of the lesson by firstly describing changes to the climate caused by increasing temperatures on earth, and then to describe how climate change affects plants and animals.

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

Okay, let's see what you've written.

So firstly, I asked you to describe changes to the climate caused by increasing temperatures on earth.

And you should have included that increasing temperatures on earth can affect convection currents, which increases the number and severity of storms, and also that global warming can alter weather patterns, which increases the levels of rainfall in some areas resulting in flooding or reduction of rainfall in other areas leading to droughts and an increase risk of wildfires.

Well done if you've got both of those.

Then I asked you to describe how climate change affects plants and animals, and you might have included that climate change can alter migration patterns and hibernation periods.

It can also destroy habitats, cause flowers to flower earlier and birds to lay eggs earlier.

And all of these will impact food webs and the survival of the organisms within those food webs.

So well done if you've got most of those, but do add to your responses if you need to.

Okay, let's move on to look at how we might reduce global warming because this has been quite a doom and gloom lesson so far.

But there are plenty of things that we can do to make the situation much better.

And ultimately, all of these things will involve changing human behaviour because what we need to do is to reduce the amount of greenhouse gases such as carbon dioxide and methane that we are putting into the atmosphere.

And if we do this, then we are likely to see a reduction in the global temperature rise and that will improve the climate situation.

So one change that we could all make is to walk or cycle more often and where possible rather than drive in our cars, this will reduce the emissions which are being put into the atmosphere.

And it will also improve our health because walking is not only physically good for us, but it's also good for our mental wellbeing as well, as well as it reducing local air pollution and greenhouse gas emissions leading to climate change.

So walking more or cycling more is certainly two easy things that we can do.

We can also reduce carbon dioxide emissions by generating electricity through renewable energy rather than by burning fossil fuels.

Renewables include wind, solar, tidal, hydroelectric, those sorts of things.

While we're not burning fossil fuels in order to generate electricity, we could also reduce the carbon dioxide emissions by reducing the amount of forests that we chop down.

So reducing deforestation will reduce the amount of carbon dioxide that gets released into the atmosphere when those trees are burnt, which is often what happens to them.

But if we replant after deforestation or leave the trees there, instead of chopping them down in the first place, the trees will be able to absorb carbon dioxide outta the atmosphere and that will reduce climate change as well.

However, we'd have to do this to an enormous amount of forest land to really see a significant impact.

So we have to do lots of other things as well.

Another thing that we need to do is to reduce the amount of methane or CH4 emissions that are put up into the atmosphere.

Now we can do that by reducing the amount of waste that we send to landfill because especially food waste, organic waste, this gets broken down by microorganisms and in the process of doing so, methane is released and so putting less food into a landfill will certainly help to reduce methane emissions.

Also reducing the amount of meat that we eat.

In particular, the meat from cows will reduce the amount of methane emissions.

Cows are particularly problematic as far as methane is concerned because the digestive processes that they have in order to break down grass and turn it into their own body is driven by bacteria and produces a lot of methane.

And so, cows belch or burp a lot of methane out as part of their digestion.

And so, if we reduce the number of cows that we are farming, we will reduce the amount of methane that is going into the atmosphere.

We could also reduce the amount of methane that is produced by certain crops such as rice.

There are some varieties of rice which produce less methane than others.

And so growing those varieties in preference to those which produce high quantities of methane will also help to reduce methane emissions.

And the problem with methane is it is a much more potent greenhouse gas than carbon dioxide.

It has a significant impact on the way heat is radiated around the atmosphere, but methane also has a shorter half-life in the atmosphere.

In other words, it gets broken down into other compounds much faster than carbon dioxide in just over a decade rather than in 50 or 60 years as is the case with carbon dioxide.

So if we can reduce methane emissions, then we will reduce global warming much more rapidly because of the impact that methane has on global warming and also how quickly it has turned over in the atmosphere compared to carbon dioxide.

So how could humans alter their behaviour to reduce methane CH4 emissions? Could they A, plant more trees? B, reduce waste centre landfill, C, use renewable energy resources or D, eat less meat from cattle? I'll give you five seconds to consider.

Okay, so to reduce methane emissions, we could reduce the waste which we send to landfill and we could eat less meat from cattle.

Well done if you spotted both of those.

So we've talked about lots of changes that humans can make to the behaviours that we have which contribute to climate change, but there are plenty of technological responses that are being worked on at the moment as well.

And climate engineers are working to find other ways that could either reduce or slow down global warming and there's a number of different avenues that they're pursuing, including developing technologies to reduce greenhouse gas emissions into the atmosphere in the first place, to remove some of those greenhouse gases from the atmosphere and also to lower global temperatures to counteract the effects of greenhouse gases.

Now, some of these technologies are already being developed and implemented and others are still ideas that are being researched.

However, all of them will require significant investment and support from governments around the world.

So they aren't quick or cheap responses, but hopefully they will be quite a high impacting.

One of those responses is about capturing carbon and storing it.

So this is an example of climate engineering and what it does is prevent large quantities of carbon dioxide from reaching the atmosphere in the first place.

So what happens is the carbon dioxide that is being emitted from factories or power stations, for instance, is captured and then the carbon dioxide is separated from other emissions and then it's compressed.

It's compressed down into a liquid, so turned from a gas back into a liquid under high pressure and then it's stored somewhere.

And often it can be stored in old oil and coal fields where essentially large holes underground exist where carbon used to be stored in the form of coal, oil or gas and has now been vacated because we've removed that store of carbon.

And if we can pump that carbon dioxide back into those spaces and store them, then we are removing that carbon dioxide from the atmosphere and storing it underground instead.

So which of these is not part of the carbon capture and storage process? A, separating CO2 from other emissions, B, piping CO2 deep underground, C dissolving CO2 in the oceans, or D injecting CO2 into old oil and gas reserves.

I'll give you five seconds to consider.

Okay, so the item that is not part of the carbon capture and storage process is C, dissolving carbon dioxide in the oceans.

Well done if you spotted that.

So carbon capture and storage is one example of climate engineering.

Another example is solar geo-engineering.

And what this is hoping to do is to reflect more sun radiation back into the atmosphere and ultimately into space, thus reducing the amount of heating that is going on in the earth's atmosphere.

So there are lots of different ways of improving reflectivity, reflecting more infrared radiation back into space.

And one of the ways which is being pursued is to see whether the reflective qualities of leaves in crops can be improved so that they reflect more light back into space.

So carbon capture and storage and solar geo engineering are two technologies that climate engineers are currently working on, but there are other processes and projects that climate engineers are also working on to improve climate change outcomes and reduce the effect of global warming.

These include making more efficient renewable energy technologies such as wind turbines, making industrial processes more energy efficient, using fertilisers in the oceans to increase phytoplankton levels.

And phytoplankton uses photosynthesis to harvest light energy and carbon dioxide from the atmosphere that has been dissolved in the ocean to grow their bodies and to create more phytoplankton.

So increasing the number of phytoplankton in the ocean should remove carbon dioxide by storing it inside their biomass.

Climate engineers are also considering designing a chemical catalyst to mimic photosynthesis, and they're also researching how we could turn carbon dioxide into an edible protein, essentially bypassing the processes of plants that do this already and manufacturing it instead in perhaps a more efficient process.

However, all of these technologies have costs associated with them and they also have pros and cons associated with them.

There are benefits to all of these processes, but there are also disadvantages and weighing up the benefits and the risks of these projects and deciding whether the benefits do outweigh the risks is something that climate engineers are grappling with as part of their research.

So which of these is not a technique investigated by climate engineers to reduce global warming? Is it A, artificial photosynthesis? B, carbon capture and storage, C deforestation or D reflecting radiation? I'll give you five seconds to decide.

Okay, so you should have chosen deforestation as a technique not being investigated by climate engineers.

Well done.

Okay, what I'd like you to do in our last task for today's lesson is to firstly give two ways that individuals can reduce carbon dioxide emissions.

Then I'd like you to give two ways that individuals can reduce methane emissions before describing how carbon capture and storage can slow down the increase in atmospheric carbon dioxide levels.

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

Okay, let's see what you wrote.

So firstly, I asked you to give two ways that individuals can reduce carbon dioxide emissions and you might have included walking, cycling, using public transport rather than driving a car or turning off devices when they are not in use such as lights and the TV or improving home insulation or repairing items rather than replacing them.

Or maybe you've included other things that can reduce carbon dioxide emissions.

Just make sure that that is what they can do.

Then I asked you to give two ways that individuals can reduce methane emissions.

And you might have said that we could eat less meat from cattle or we can recycle or reuse items to reduce the waste that is sent to landfill.

And again, well done if you've included those, but you might have included other ideas as well.

Then finally, I asked you to describe how carbon capture and storage can slow down the increase in atmospheric carbon dioxide levels.

So you might have said that firstly, carbon capture and storage captures emissions before they enter the atmosphere and they separate out carbon dioxide from the other emissions and compress that carbon dioxide into liquid form.

Then that compressed carbon dioxide can be injected into rock formations, which are deep underground and be stored there permanently, essentially replacing oil and gas that we have already extracted from the earth.

So just check your answer over.

Did you include all of those points? Well done if you did.

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

So thank you very much for joining me.

In our lesson today, we've seen how global warming increases average global temperatures and rising temperatures have multiple implications including the increase in water temperature in the oceans.

And what this does is cause the oceans to expand and for land glaciers to melt more quickly.

And both of these lead to an increase in sea levels.

Now, rising temperatures also increase the frequency and intensity of extreme weather events such as storms. They can alter regional climates, they can make flooding more common in some areas and drought more common in other areas.

So have significant knock on implications.

But changing our behaviour can help to slow down climate change.

And there are plenty of things that we can do on an individual basis which really aren't significant changes whatsoever, but if we all did them, we'd mount up to quite a significant impact indeed.

And then there are other things that are being considered by climate engineers.

They are busy developing a variety of different technologies that can reduce greenhouse gas emissions in the first place, or remove carbon dioxide and other greenhouse gases from the atmosphere to reduce the global warming effect, or can reduce global temperatures through other ways such as increasing the reflectivity of the surface of the earth.

So I hope you found this lesson interesting.

There's certainly plenty of things to be hopeful for in the future.

So thank you for joining me and I hope to see you again soon.

Bye.