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Climate Change

SURFO Special: Has COVID-19 Affected Plane Emissions?

 

Each summer, the University of Rhode Island Graduate School of Oceanography (GSO) hosts undergraduate students from all over the country to participate in oceanographic research. These Summer Undergraduate Research Fellows (SURFOs) have not only been working with GSO scientists, but they also have spent part of their time learning how to communicate this science to the public. Although their research experience was virtual this summer, they still did a fantastic job. Read on to find out what they have been up to, and why they everyone should be as excited as they are about their work.

This post was written by Bella Luikart. Bella is a a senior majoring in environmental chemistry at SUNY ESF. She had the pleasure of working with Dr. Jaime Palter this summer as a SURFO summer intern.


Since the US lockdown began in March of 2020, passenger plane travel has been highly restricted within the United States. As a result, there has been a decrease in the contrails left by planes. Contrails, or condensation trails, form when water vapor condenses around soot particles released from the plane’s exhaust. They form high flying clouds (cirrus clouds), which can last anywhere from minutes to hours depending on wind conditions, and plane contrails will often join larger cloud banks.

Figure 1: Fish and coral communities like this one are part of the EBUS ecosystem and are richly diverse and important to the health of the ocean! (image credit: Adam Obaza, NOAA Fisheries
)

Clouds in the atmosphere are responsible for reflecting and scattering energy from the sun, as well as storing energy within themselves. The energy the Earth gets from the sun is called shortwave radiation (not related to nuclear radiation), which describes all wavelengths of energy that are in the visible light region, the UV region, and the near infrared region. The amount of shortwave radiation scattered by clouds is an important factor in weather patterns and other systems on Earth because it determines the temperature in the lower parts of the atmosphere. Different types of clouds have different effects on temperature—high-flying cirrus clouds like the ones that contrails form have a warming effect because they absorb more radiation than they reflect, while low-lying clouds have a net cooling effect because they are denser and more reflective. Temperature—and especially temperature differences with altitude—are main drivers of the winds, and in turn the winds drive ocean currents. The impacts of clouds are far reaching and affect all the systems on the planet. This is why it is important to understand the possible impact of anthropogenic activity such as plane travel on clouds.

COVID-19 presents a unique opportunity to examine whether contrails have a meaningful effect on weather patterns and ocean currents. Usually, there are so many factors at play in the atmosphere that it is difficult or impossible to isolate just one and determine its impact. A study was conducted in the three days following 9/11 when all US planes were grounded. However, three days is not enough time to gather meaningful data because weather anomalies (any weather events that are outside of normal conditions) are always possible. The effects of the pandemic have lasted much longer and allow scientists to gather and average data over several months, which will account for any possible weather anomalies.

Figure 2: Even without understanding the units of this graph, you can see a few large spikes where the red line is much higher than the black line. The black line is the average of a normal year, and the red line is the data just from 2020, and this graph illustrates the difference.

At the URI Graduate School of Oceanography, the Palter Lab is comparing this year’s data with an average taken over the previous nineteen years (from 2001 through 2019), and looking specifically at the region known as the California Current, which includes part of the coast of California (near San Francisco and Los Angeles) and extends into the Pacific Ocean. The California Current was chosen because it is known as an EBUS region, which stands for Eastern Boundary Upwelling System. EBUS regions are extremely productive fisheries due to the nutrients that are brought up to the surface in these areas, so it is important that we monitor their health.

While the study is still underway, preliminary findings suggest that there is a significant difference in the data from this year compared to previous years. Overall, this year has a lower rate of radiation scattering than normal years, which would make sense given the hypothesis that airplane contrails cause the atmosphere to scatter more radiation.

Most people are aware that the carbon emissions from planes pose a large problem for climate change, but few may be aware of the similar issue posed by contrails. Should the results of this study prove conclusive, it would give us important insight into other ways that humanity impacts the climate that we may not even be aware of yet. Hopefully, this will open a conversation about developing more environmentally friendly modes of transport.

I’m a PhD student at the University of Rhode Island’s Graduate School of Oceanography. I use a small-scale computer model to study how physical features like surface waves at the air-sea interface produce friction for the wind that can limit momentum, energy, gas, and heat exchange between the ocean and atmosphere. In the future, I hope to learn more about the role waves play in different parts of the world as weather and climate patterns evolve. Also, I love to write.

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