Using Plants to Fight Climate Change
Climate change has been a sensitive subject for many years, but it’s a topic we simply cannot ignore. Earth’s average temperature has been steadily rising for some time, and weather patterns are changing drastically. This phenomenon is a result of the expansion of a natural process known as the “greenhouse effect” caused by higher-than-normal levels of greenhouse gases in the atmosphere.
A greenhouse gas is a 3-atom molecule that absorbs infrared radiation and traps heat. This IR radiation is then reemitted in all directions, warming the earth’s surface and lower atmosphere. The primary greenhouse gases in our atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone.
Greenhouse gases are not inherently bad; they actually serve a very important purpose by contributing to the energy balance between our planet and the sun. However, industrialization has caused a significant increase in greenhouse gas levels, particularly carbon dioxide (CO2). This means that while our planet is still receiving the same amount of heat from the sun, more heat is being trapped as it is released from the earth’s surface back into the atmosphere. Rather than escaping into space like it normally would, the excess heat is reabsorbed and reemitted back towards Earth’s surface and the vicious cycle continues.
While other greenhouse gases certainly play a part in climate change, CO2 is by far the biggest offender. It is the most abundant (after water vapor) and it stays in the atmosphere longer than any other greenhouse gas molecule: after an emission of CO2 is released, 40% remains in the atmosphere after 100 years, 20% still after 1,000 years, and the final 10% will remain for 10,000 years. With that being said, it is pertinent to note that the average atmospheric CO2 concentration recently reached over 400 parts per million (ppm), the highest it’s been in the last 800,000 years.
Water vapor is the most abundant greenhouse gas, but it only stays in the atmosphere for an average of 10 days. Human activity does not have much direct effect on the amount of water vapor in the atmosphere; however, the warming of our planet’s surface due to the increase in other greenhouse gases (namely CO2) makes it easier for water to evaporate and remain in vapor form longer, thus warming the surface and lower atmosphere even further.
Time is of the essence in the fight against climate change, and innovative methods of removing CO2 from the atmosphere must be explored. We know that plants utilize carbon dioxide for cellular respiration and photosynthesis, so it stands to reason that they could be a key element in reducing the atmospheric concentration of CO2.
Living walls are compromised of a large surface area of mostly leaves, which makes them extremely efficient at absorbing CO2 from their surroundings. In fact, living walls have been shown to reduce the amount of CO2 in circulating air up to 56% (in a controlled indoor environment). If the majority of buildings in urban areas across the world had exterior living walls or green roofs using plants that could thrive in each area’s climate so as to prolong the life of the plants, we could be looking at a potentially drastic decrease in CO2 in the atmosphere.
Regular plants are great at removing CO2 from the air, but what if there were a “super plant” that could remove even more CO2 from the atmosphere than normal plants? Turns out, it there is: the Azolla fern.
The small but mighty Azolla Fern
Azolla is a genus of seven species of tiny aquatic ferns that can resemble moss or algae at first glance. This specialized plant grows on the surface of freshwater and forms a symbiotic relationship with a cyanobacteria that fixes atmospheric nitrogen, which gives the azolla easy access to this essential nutrient and allowing for rapid growth in ideal conditions. But one of the most impressive skills of the azolla fern is its ability to draw down as much as 6 tonnes per acre of carbon dioxide per acre per year, in addition to a tonne of nitrogen per acre per year. With these powers, the azolla fern could be a major player in slowing down or even reversing climate change.