BaCCC/Module 1/Lesson 3/Part 4

Global climate change commitments and irreversibility

Because the full effect of greenhouse gases is not felt as soon as the gases are emitted (due to the inertia – resistance to change – of the oceans, the carbon cycle and the climate system), the IPCC has established that there is a very high chance the Earth’s climate will continue to warm in the coming decades. In other words, the global climate is committed to carrying on heating up until long after we have stopped emitting greenhouse gases.

Why is this important? Intuitively some (and perhaps most) people think that as soon as we substantially decrease our CO₂ emissions (which we have not done so far), the problem will be solved. It will not, not by a very long shot. Even if we reduce CO₂ emissions to zero over a realistic timeframe, the CO₂ concentration in the atmosphere – and thus also the global average temperature – will still remain elevated for thousands of years. But the longer we postpone reducing our emissions, the more severe those emissions reductions will need to be in order to have the same mitigating effect on long-term warming. — Adapted from Bart Verheggen (2016)

Another problem we are facing is that some irreversible changes to the Earth’s climate system are already underway, such as the melting of glaciers and ice caps, the rise in sea level and changes in weather patterns.

Activity

First, read this short report from the Australian Academy of Science:

"How do we expect climate change to evolve?"

Next, respond in your learning journal to this quotation from it:

These characteristics of the climate system mean that the only way to stop human-induced climate change (without resorting to “geoengineering” – the deliberate, large-scale modification of climate) is to reduce net greenhouse gas emissions to near-zero levels. The longer this takes to achieve, and the more greenhouse gases that are emitted in the meantime, the larger the scale of future climate change.

With whom would you want to share this report or quotation? With whom would you not want to share this report or quote?

Answer the following questions in your learning journal.

1. What are the historic indicators of climate change?

2. How do scientists collect evidence about climate change?

3. How has the global average temperature changed since the Industrial Revolution?

4. What do most climate scientists unanimously agree on regarding

• global warming
• CO₂ emissions and
• climate change?

.

Assignment

Imagine that you are hired as a temporary teacher for a Grade 6 class. You are asked to teach and set a test for the class on the topic “What is climate change?” Do the following tasks in your learning journal:

1. What class activities would you come up with for teaching this topic?

2. Set a test for this class on this topic and provide the answers. .

Lesson Summary

In this lesson, you

• looked for and found credible information on the climate system and climate system change;
• used graphs from various sources, including NOAA and NASA, to describe the current state of planet Earth;
• used different forms of media to communicate climate change awareness messages; and
• explored your national sources of information on climate change.

Module Assessment

Now complete the Module 1 assessment