Introduction
You may have noticed that the weather is increasingly warm not only in Singapore but also in other parts of the world! Experts are pointing to global warming as the main culprit for this.
What exactly is global warming and how do human activities contribute to it?
To answer these questions, I will be analysing an examination question on the topic of Man’s Impact on the Environment from the 2015 Nanyang Primary School (NYPS) P6 SA2 Examination Paper.
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Let’s Take A Look At This Question
Source: Nanyang Primary School (NYPS) – 2015 P6 SA2 Examination Paper [Q11]
Thought Process
From 1950 to 2000, 50 years have passed. During these 50 years, what happened to the temperature of the surroundings based on the graph above?
The temperature has increased!
What do we call the phenomenon when there is an increase in the temperature of the Earth or the temperature of the surroundings?
When we talk about the rise in global temperature, we are referring to global warming. We want to find out whether activity A, B or C could lead to global warming.
Activity A: Increased Forest Fires
When there are more forest fires, more trees will be cleared. Therefore, there will be fewer trees left.
How can having fewer trees lead to global warming?
Trees are plants, and plants carry out photosynthesis to make food. During photosynthesis, trees take in carbon dioxide. When there are fewer trees left, less carbon dioxide will be taken in and it will start to accumulate in the atmosphere.
At this point, we still haven’t found the link between the concepts of carbon dioxide and global warming. To do this, you need to know that carbon dioxide is a very special type of gas! Carbon dioxide is what we know as ‘greenhouse gases’.
🌴 What Are Greenhouse Gases 🌴
‘Greenhouse gases’ can trap heat from the sun.
If the amount of carbon dioxide is increasing, this means the amount of greenhouse gases also increases. This will lead to more heat trapped by the sun over the years.
So if there is more heat trapped by the sun, what do you think would happen to the temperature of the Earth?
It will rise and will lead to global warming!
Could activity A cause an increase in the global temperature? Yes, it could!
This is only one possible way that forest fires could lead to global warming. Another possibility is that by burning the trees, the forest fire itself could also release pollutants and carbon dioxide!
A is definitely correct!
Activity B: More Recycling Activities
Let’s say you bought drinks in aluminium cans or plastic bottles. Once you have finished drinking from the can or the bottle, you can recycle these materials!
What happens is that the recycling factories will take all these existing materials and then recycle them or let them undergo a process where they use the same existing materials to create new things. For example, the existing materials can be used to make new bottles or even new drink cans!
What this does is that instead of using new resources to make more bottles, we can use whatever has already been existing on Earth to create what we want. By having more recycling activities, we’re using fewer resources to create new materials.
We mentioned resources so how do we actually create plastics? We need to burn fossil fuels to obtain energy to create new materials. If you have more recycling going on, you will use fewer resources and burn fewer fossil fuels too.
When we burn fossil fuels, they release carbon dioxide. If we burn less fossil fuels, what’s going to happen is that we’re going to release less carbon dioxide.
Carbon dioxide sounds familiar, doesn’t it? As we have mentioned earlier, it is a greenhouse gas. If you release less carbon dioxide, you have less greenhouse gases in the air. This means you will trap less heat from the sun and it will not lead to an increase in the Earth’s temperature.
So having more recycling activities does not cause an increase in the temperature of the Earth. Thus, we cannot choose B.
Activity C: Increased Road Vehicles
How do vehicles work? They need petrol to work!
Petrol is a fuel, or what we know as ‘fossil fuels’. As we mentioned earlier, when you burn fossil fuels, carbon dioxide is released.
More vehicles on the road would mean more fossil fuels will be burnt, leading to the release of more carbon dioxide.
Carbon dioxide, the greenhouse gas, will trap more heat which will lead to global warming!
So, could activity C have contributed to the change in temperature?
Yes, it could!
Suggested Answer
Since A and C are correct, and B is not, our final answer is option (2).
Conclusion
After reading this article, I hope that you have become more familiar with the 3 different activities A, B and C and how they either contribute or do not contribute to global warming. Do take note of these thought processes and explanations so that you will be able to obtain full marks if you encounter a similar Section B question.
Stay tuned for our upcoming articles on how to tackle other tricky Science questions!
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