BaCCC/Module 1/Lesson 2/Part 3

What is global warming (or global heating)?

In Lesson 1, you learnt that some people use the terms “global warming” and “climate change” interchangeably. What is the difference between climate change and global warming? Watch this video to learn the difference:

Global Warming vs Climate Change

Global Warming vs Climate Change (4:57)

You can adjust the playback speed and/or turn on subtitles/captions.

If you have trouble accessing the video, a summary is available below.

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Global warming (or global heating) is attributed to the enhanced greenhouse effect. This is caused by the increased concentration of greenhouse gases in the atmosphere. Greenhouse gases, such as carbon dioxide, methane and nitrous oxides, act like a blanket (an electric blanket, and we keep turning up the heat) and trap heat inside the Earth’s atmosphere, thus causing global warming. In the video, you learnt that global warming has been taking place since 1880. The graph below shows the global temperature anomaly (the deviation from what had been normal) since 1880. Take note of when the temperature started rising up. Also, what might have caused the spike in temperature in the late 1930s and early 1940s?

Study the diagram below that illustrates the global temperature anomaly since 1880.

Graph showing global temperature anomaly since 1880

Feedback
Research shows that the 1930−40s spike can be attributed to the rise in greenhouse gases “as industrialized cities and nations continued burning coal to power factories and trains,” perhaps as the world was industrializing to pull itself out of the Great Depression (1929−1939) (Upton, 2016). "Scientists trace climate−heat link back to 1930s"

The graph below is a totally different way of visualising the temperature anomaly (increase) since 1880 from a seasonal perspective. Note that the temperature anomaly is greater (a wider spread in the bands of colour) in the winter months than in the summer months in the Northern Hemisphere. In other words, winters are warming even more than summers, which has an impact on snowfall, and hence freshwater availability.

Graph showing temperature anomaly since 1880

According to Australia’s National Science Agency, “there is no record of temperature having increased as rapidly as it has over the past century.”

The following sums up what you have learnt about global warming.

United Nations COP26 (2021) presentation slide (adapted)

Electricity from coal or diesel generators and industry or pollution from factories contribute the most. More greenhouse gases trap more heat in the atmosphere, leading to global warming. Since 1880, the global temperature has increased by almost 1°C. How much this rises depends on how much more greenhouse gas is released. The temperature could rise by almost 5°C by 2100 (Intergovernmental Panel on Climate Change [IPCC], Fifth Assessment Report). However, countries around the world agreed to keep this below 2°C. Humans have added so much greenhouse gas to the atmosphere that, even if all emissions stopped today, the planet would still continue to warm for decades to come. Global warming intensifies the water cycle. Higher temperatures increase the evaporation of water from oceans, lakes and rivers. Warmer air holds more water vapour, resulting in more intense rainstorms. This can lead to flooding. Floods, where water runs off into rivers and streams, do little to dampen the parched soil. This and increased temperatures can lead to drought. Weather patterns across the world are affected over time. This results in CLIMATE CHANGE.

Activity

Global warming is a process. Using the information in the text box, draw a flow diagram (using arrows) that shows the global warming process. You can then use this diagram to make a public presentation, describing the process of global warming. Make an audio or video recording of your presentation. .

The Process of Global Warming

Increased Greenhouse Gas Concentrations	Increased Temperatures	Human Activities: Burning Fossil Fuels, Deforestation, Synthetic Fertilisers, Industrialised Livestock
Enhanced Greenhouse Effect	Incoming Solar Radiation	Heat Absorbed by Land and Sea
	Atmosphere	Global Warming
Radiation Reflected Back into Space	Greenhouse Effect	Solar Energy

Now that you know the process of global warming, let us find out if there are any visible signs of global warming that you know of. Do the next activity based on the resources you have been learning from.

Activity

Respond to the following in your learning journal:

1. List any six signs of global warming.

2. Which of these signs have you experienced or are visible in your local area or country?

3. How do we relate global warming to ocean temperatures and sea levels?

4. Besides the increase in ocean temperatures and the rise of sea levels, what are other effects of global warming on oceans?

5. How does the warming up of the ocean affect the water cycle?

6. Carry out a mini-investigation on how sea level rise is a risk to some countries already and as the global average temperature rises. .

Feedback

1. Signs of global warming Glaciers are melting. Arctic permafrost is melting. Arctic sea ice extent is diminishing. The ocean surface temperature is increasing. Global sea level is rising. Humidity is increasing. The temperature of the lower atmosphere is increasing. Air temperature over land is increasing. Extreme natural events are increasing in frequency, intensity and duration. Tropical storms are becoming more frequent and severe. 2. In your local area, you may have observed or experienced extreme weather events, such as heavy and erratic rainfall, hailstorms and heatwaves. 3. Sea level rise is caused primarily by two factors related to global warming: the added water from melting land ice the thermal expansion of seawater as it warms 4. If global temperatures continue to increase, oceans will also be facing the ecological challenges of ocean acidification and deoxygenation. At the same time, fragile marine ecosystems, such as coral reefs, are also under threat. 5. Global warming speeds up (energises) the water cycle.