A team of MIT researchers has uncovered that growth in aviation is leading to poorer air quality. The team has quantified the air quality and climate impacts by looking closely at the aviation industry, breaking down its emission types, altitude, and location.
They've discovered that aviation causes twice as much damage to air quality as it does to the climate.
The study was published today in Environmental Research Letters.
Could this damage be curbed?
The MIT team looked into how this damage could be reduced, and have provided comparative assessments of aviation emission trade-offs.
Even when dealing with aviation emissions and climate change, the statistics are worrying.
The lead researcher on the study, Dr. Sebastian Eastham, from the Laboratory for Aviation and the Environment in MIT's Department of Aeronautics and Astronautics, said: "Aviation emissions are an increasingly significant contributor to anthropogenic climate change. They cause five percent of global climate forcing."
Eastham carried on to say, "When you consider the full flight, which includes emissions from takeoff, cruise, and landing, aircraft emissions are also responsible for around 16,000 premature deaths a year from impaired air quality. This is small compared to other sectors, being only around 0.4% of the total deaths attributed annually to global air quality degradation, but is often overlooked in policy analysis."
"The challenges for aviation sector decision makers wanting to reduce these impacts are the trade-offs between different emission types and their impacts in different locations."
Decreasing one emission can come at the cost of increasing another
The answer to this issue is not as clear cut as we may think. The study points out that simply reducing one type of emission doesn't always lead to a solution.
Eastham explained: "We could decrease NOx emissions by designing engines with lower combustor temperatures. However, the resulting loss in thermodynamic efficiency would mean we need to burn more fuel, meaning more CO2. These are the types of trade-offs that need to be quantified, and our study offers a fast way for decision makers to do this."
As we can see, there are many aspects to take into account. So the team looked at this further.
The team applied three different metrics to evaluate the effects of a global expansion in aviation.
They discovered that their results: "show three components are responsible for 97 percent of climate, and air quality damages per unit aviation fuel burn: air quality impacts of NOx at 58 percent; climate impacts of CO2 at 25 percent; and climate impacts of contrails at 14 percent," according to Eastham.
He continued, "These components—cruise NOx emissions, CO2 emissions, and contrails—are therefore primary targets for future strategies to reduce the atmospheric impacts of aviation emissions."
There's still room for improvement in the aviation industry to lower their emissions, especially thanks to studies like this one that help pinpoint the issues.