Tom Sharkey, a University Distinguished Professor at Michigan State University, recently posed a seemingly radical question: “Should we cut down all the oak trees?” While it may sound drastic, this question stems from Sharkey’s latest research, published in the Proceedings of the National Academy of Sciences. The study delves into the consequences of a warming planet on plant emissions and their role in air quality, focusing on compounds like isoprene.
Isoprene, the second-highest emitted hydrocarbon on Earth, is released by plants, making it a crucial but often overlooked component of our environment. While it plays a role in clean air quality and enhances plant resilience to stressors like insects and high temperatures, isoprene can also exacerbate poor air quality by contributing to particulate matter and low-atmosphere ozone, a significant environmental concern.
The challenge, as Sharkey explains, lies in finding the right balance: “Do we want plants to make more isoprene so they’re more resilient, or do we want them making less so it’s not making air pollution worse? What’s the right balance?” These fundamental questions underpin Sharkey’s research, aiming to better understand the effects of climate change on isoprene production.
Isoprene has an intricate relationship with nitrogen oxide compounds found in air pollution, created by sources such as coal-fired power plants and vehicle emissions. These interactions lead to the formation of ozone and aerosols, posing health risks to both humans and plants. Sharkey elaborates on the issue, “There’s this interesting phenomenon where you have air moving across a city landscape, picking up nitrogen oxides, then moving over a forest to give you this toxic brew. The air quality downwind of a city is often worse than the air quality in the city itself.”
The research team’s work is centered on unraveling the biomolecular processes plants use to produce isoprene and how the environment, particularly climate change, affects these processes. They discovered that rising carbon dioxide levels suppress isoprene production, while increasing temperatures have the opposite effect, resulting in a competition between these influences. Notably, the study identifies a specific reaction inhibited by carbon dioxide, clarifying that the temperature effect prevails. As temperatures rise, isoprene emissions increase significantly.
In their experiments using poplar plants, the team observed that a 10°C increase in leaf temperature led to a more than tenfold rise in isoprene emissions. The findings offer valuable insights into predicting future isoprene emissions and preparing for their implications. The research team hopes that this knowledge can guide informed choices made by individuals and communities.
One potential implication could involve planting fewer oak trees to limit isoprene emissions, particularly in locations like MSU, home to over 20,000 trees. Sharkey suggests an alternative solution that doesn’t involve cutting down existing trees: “My suggestion is that we should do a better job controlling nitrogen oxide pollution.”
This research offers a deeper understanding of the complex relationship between plants, climate change, and air quality, shedding light on potential solutions to mitigate the adverse effects on the environment and human health.