by Jana Dean
It was the day after Hurricane Sandy, and Eli and Krishna rushed into class with a question: “Ms. Dean, can it happen to us?” They’d seen images of buildings flooded up to the second story and cars that had floated to rest on top of each other. Our West Coast bayside town has early 20th-century buildings that look something like those flooded by Sandy in early 2013, and the students already knew that our streets flood when high tide, low air pressure, and heavy rainfall combine. The water backing up into storm drains in our streets has increased because of rising seas due to heat trapped by our carbon-laden atmosphere. Eli and Krishna gave me an exciting opening to connect their up-to-the-moment concern to the biology, geology, and physics of climate change. I knew I could squeeze a lot of relevant science out of just one hurricane.
I was in for a surprise, however. The first time I mentioned climate change, Trevor’s dad sent me an email insisting I “balance the science” and teach students that global warming may not be happening at all. Ultimately, this parent’s persistent scrutiny, as uncomfortable as it made me, had a silver lining. Instead of treating humanity’s effect on the atmospheric system generally and broadly, I decided to isolate the carbon cycle from climate change and help students explore the difference between the short and long carbon cycles. As a result, they became more informed about the science behind climate change than most of the adults in their lives.
Carbon cycles and, as it does, it changes form by bonding with other elements. It bonds with hydrogen to make the carbohydrates in plants and animals. It bonds with calcium to make the shells of sea creatures. It bonds with oxygen to make atmospheric carbon dioxide.
In the short term, carbon shifts from CO2 in the air—through both photosynthesis and digestion—to the starches and sugars that make up all living tissue. Then it shifts back to CO2 and methane through respiration and decomposition. Over millennia, carbon-holding plants and animals are compressed by layers of sediment into coal and oil, becoming hydrocarbons. When burned as fuel, coal and oil break down into CO2, which is suddenly released back into the atmosphere. What matters in climate science is not whether carbon enters the atmosphere, but how fast the carbon cycles from the atmosphere to living organisms, to rocks and oil, and back again.
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