In our final session before the cancellation of our program we discussed the question, "Does more carbon dioxide (CO2) in the atmosphere help plants grow?"
The scientific study we were discussing indicated that more carbon dioxide does make plants more efficient. This is because photosynthesis (the process essential for growth) relies on using the sun's energy to synthesise sugar out of CO2 and water. Plants use this sugar as an energy source and the basic building blocks for growth. When the concentration of carbon dioxide in the air around the plant goes up, it can be taken up faster, supercharging the rate of photosynthesis.
We humans are producing more carbon dioxide which is causing more plant growth, however this does not mean that producing more CO2 is a good thing. And it definitely does not mean that we should use the concept of carbon dioxide fertilisation to downplay the severity of climate change. While more carbon dioxide in the atmosphere does allow the landscape to absorb more CO2 (a little over a quarter), almost half of our emissions remain in the atmosphere.
The authors say their research highlighted the capacity of plants to absorb a proportion of human emissions, slowing the rate of climate change. They point out that this underscores the urgency to protect and restore ecosystems like forests, savannas and grassland and secure their carbon stock.
The authors also conducted research into how different aged forests around the world take up carbon. They found that young forests, often regrowing on abandoned agricultural land, draw down even more carbon dioxide than old-growth forests. In a mature forest, the death of old trees balances the amount of wood grown each year. A regrowing forest, on the other hand, is still accumulating wood, and that means it can act as a considerable sink for carbon until it reaches maturity.
Adding this age effect to the carbon dioxide fertilisation effect make young forests potentially very strong carbon sinks and so reforestation should be encouraged to enlarge the area of regrowing forests.
While our U3A sessions are shut down I will be providing class members some articles to read so that we all stay well informed. One interesting link I provided to them was to a climate change tracker, where after entering the year you were born, you can see how temperatures have changed over our lifetimes, and how we can mitigate future impacts if we all work to lower our emissions.