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Are you searching for a science lesson that brings climate change to life in your classroom? Positive feedback loops are not just fascinating—they’re a powerful way to help students grasp the dynamics behind our warming planet. By teaching about positive feedback loops, like the relationship between sea ice, albedo, and temperature, you’ll equip your students with a deeper understanding of one of the mechanisms fueling anthropogenic climate change. Let’s explore this complex topic so you can plan an impactful and accessible lesson for your learners!
Before we dive in: If you’re an educator planning to teach positive feedback loops in climate change, having great visuals to deepen understanding is key! I think you and your students will love my positive feedback loop diagram (plus you’ll support my blog with your purchase! ❤️)
What is a Positive Feedback Loop?
In science, a positive feedback loop is a cycle that keeps reinforcing or amplifying itself. A simple example is when laughter spreads. If your friend starts laughing, it might make you laugh too, which then makes your friend laugh even harder. This cycle continues, making everyone laugh more.
A positive feedback loop is called “positive”, because each part of the cycle strengthens the next, not because it is necessarily a good thing. For example, a forest fire can create a positive feedback loop. As more trees catch fire, the fire gets bigger and hotter, which makes it easier for the flames to spread to even more trees.
What is Albedo?
Have you ever noticed that a black T-shirt feels hotter than a white one on a sunny day? This is because of something called albedo. When sunlight hits a surface, some energy reflects off while the rest is absorbed, making the surface warmer. Albedo is a measure of how much sunlight a surface reflects. Light-colored or shiny surfaces have a high albedo, meaning they reflect more sunlight. Dark surfaces, like a black T-shirt, have a lower albedo, so they absorb more energy from the sun and feel warmer.
Side note: if you’re a teacher planning a lesson on albedo, read my blog post with a step-by-step guide to an albedo and sea ice experiment for the classroom!
Positive feedback loops play a role in climate change, and it begins with albedo. Sea ice in polar regions is light-colored and reflective, so it has a higher albedo than dark ocean water. When sea ice melts because of anthropogenic (human-caused) climate change and rising temperatures, the reflective ice is replaced by dark ocean water. The dark ocean absorbs more heat from the sun without the reflective ice to protect it. This causes the ocean to warm more and faster, which increases temperatures and speeds up climate change. As more sea ice melts, it creates a cycle that leads to even more melting.
A Positive Feedback Loop and Climate Change
Let’s break down a positive feedback loop step-by-step:
1. Temperatures Rise
Average global temperatures are rising. This is one of the main effects of climate change.
2. Sea Ice Melts
Ice melts at 32°F (0°C). When the average global temperatures rise, more sea ice melts.
3. Ocean’s Surface Becomes Exposed
As sea ice melts, the ocean surface is uncovered. Large areas that were once covered by light-colored ice are now dark ocean water.
4. Albedo Decreases
Light-colored sea ice reflects more sunlight than dark ocean water. When the ice melts, the ocean reflects less sunlight.
5. Ocean Water Warms
Without reflective sea ice, the ocean’s water absorbs energy from the sun. This causes the ocean to warm up. And the cycle begins again.
Why it Matters
Why should you care about ice melting in faraway places like the poles? Polar ice melting is a problem for several reasons. First, as ice melts, it raises sea levels around the world. This leads to flooding along coastlines, putting coastal and island communities at risk of disappearing underwater and displacing the people living there. Another issue is the loss of important habitats for animals in the Arctic and Antarctica.
Additionally, as polar regions warm, permafrost (frozen ground) also thaws, releasing greenhouse gases and contributing to further climate change. This is a second example of a positive feedback loop in climate change because more warming causes more gases released, which causes more warming.
Teach Positive Feedback Loops and Climate Change:
There’s no need to scramble to pull together materials for a positive feedback loop lesson – I’ve already created them for you! Support this blog when you purchase my Positive Feedback Loop Diagrams and my Albedo Lab Activity materials:
Upgrade Option: both of these sets are also found within my complete Antarctica Unit:
Explore lessons from Wild Earth Lab:
If you enjoyed this post, I know you will love trying my other science and nature units in your classroom too!
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