The Natural Experiment

Summer is normally cruise ship season in Southeast Alaska. Starting in late April ships filled with tourists sail up the inside passage, stopping at little coastal port towns. One of the popular destinations along this route is Glacier Bay. It’s this spectacular bay filled with icebergs, sea otters, and lots and lots of humpback whales. The National Park Service regulates how many cruise ships can come in and out of the bay, but still, the humpbacks that are there in the summer have to live alongside the roaring of boat engines. Michelle Fournet is an acoustic ecologist at Cornell, and she says that these sea animals change their behavior when the waters get noisy.

Every summer Fournet travels to Glacier Bay to drop a hydrophone in the water and listen in on what the whales are saying, and how it’s affected by ship noise. This year she was preparing for her annual trip to Southeast Alaska when the COVID-19 shutdowns were announced. Although it meant that her research trip was canceled, she realized it was an incredible opportunity. For the first time in decades, the ocean would be quiet for an entire summer, “What that means for somebody like me as a researcher, is that we have the opportunity to listen to undisturbed behavior for the first time,” explains Fournet.

Usually, Fournet relies on quiet periods in an individual day to try and understand how ship noise changes whale behavior. If she’s lucky she’ll get 6-7 hours of silence, but now the ocean was about to experience months of quiet. Fournet is all set to record an entire summer of whale sounds in strangely quiet seas, “This is the first time in human history that we’ve been able to listen to truly quiet behavior,” she says. “We will finally get a baseline for what the ocean sounds like in the absence of human activity.”

In general, the coronavirus shutdowns have been terrible for academic research. Trips have been canceled, labs have shut down, and long-running experiments have been interrupted. But there are some researchers, like Fournet, for whom the shutdowns have provided a unique opportunity—a whole new data set, a chance to gather new information, or to look at information in a new way. In science, the term natural experiment refers to an experiment that happens outside of the lab, where a variable out in the world changes in ways that allows you to do research that hadn’t seemed possible in controlled settings. And so, this week, we’re bringing you stories from very different academic fields, about researchers who are using this bizarre, tragic moment to learn something new about the world. 

Air Pollution

Jalandhar is a city in Northern India, in the state of Punjab. Like all Indian cities Jalandhar has been in lockdown with everybody inside their homes, but a couple of weeks ago, there was this bright sunny day and the residents of the city went outside onto their roofs, and what they saw was this amazing view of snow-capped mountains—the Himalayas. This view was celebrated all over social media. There are tons of pictures of these mountains on Instagram and TikTok videos of people zooming in on these crisp snow-capped peaks.

This was a big deal because many people were seeing these mountains for the first time. Raghu Karnad wrote about this phenomenon for The New Yorker and he says that because of air pollution, the mountains have been completely obscured for decades. Karnad says that locals think the last time these mountains had been visible had been around 30 years ago.

Jalandhar is a dramatic example, but in cities all across India people are experiencing exceptionally clean air. Air pollution is normally a huge problem in India, and not just an aesthetic one. “WHO had an estimate that 100,000 Indian children had died that year from a particular type of particulate found in air pollution,” explains Karnad, “Indians are dying and being made sick in huge numbers, numbers that are almost too large to process.”

Raghu Karnad says that there’s this sense in India that the problem is almost so big that it can’t be solved. But seeing the vast improvement in air quality because of COVID-19 has made people rethink that, “And that’s what makes this moment so extraordinary, is that we fixed this problem without intending to,” says Karnad.

The shutdowns have also been incredible to researchers who study air pollution, researchers like Sarath Guttikunda. Guttikunda says that in their work they are always looking to understand the baseline air quality, like what a clean air scenario looks like. Usually, they use rainy days to do this, but the problem with rain is that it doesn’t last. “When it rains, it’s clean for one day and then the build-up starts again. But what we are seeing here is a sustained period of low numbers.” And so this shutdown feels like the entire country is running an experiment for him… a forced experiment that shows what happens if you turn many of the major sources of pollution down basically to zero.

Having this extended period of clean air is also allowing them to do more fine-tuned research experiments. Some of those experiments are chemistry experiments looking at particular pollutants like ozone. But they’re also trying to do a forensic accounting of where all this pollution is coming from because there’s actually a lot of confusion about that. And a big question people have is: is the pollution being generated inside the city, by things like cars, trash burning, and dirty cookstoves? Or is it floating in from outside sources, things like power plants and heavy industry outside the city, or farmers in the countryside who burn their fields before they replant?  All of those sources are contributing to the problem but the uncertainty has allowed cities to throw up their hands and say this isn’t a problem we can solve. It allows people in power to pass the buck of responsibility.

One of the goals of Guttikunda’s research is to use this period to show how much of the pollution is coming from those outside sources, and how much of it is generated locally, from things like traffic. He has found that at least 50-70% of the pollution in a city like Delhi was coming from sources inside the city, meaning that the cities could do a lot more to clean up the air.

It is possible for big cities to change. If you look at Beijing before the 2008 Olympics, air quality was one of the most toxic in the world. The city implemented restrictions to try to clean up the air quality before the games and it worked. And after the games ended, citizens of Beijing didn’t want to go back to poor air quality, so they pushed the government to control pollution.

One revealing aspect of COVID-19 is that it shows that in dire circumstances, we are able to change our habits in order to address a crisis. The challenge is determining which crises in which to implement extreme measures. A pandemic is clearly a public health problem, but air quality is also a matter of life and death. The World Health Organization says that as many as 4.6 million people die a year due to air pollution. The reason we under-react to threats like air pollution probably has to do with the fact that many of them have disproportionate impacts on poor people. If you have money and you live in a city like Delhi you can take an Uber from your air-conditioned apartment to your air-conditioned office job. But there are millions of people who walk or ride their bikes to get around and shop in open-air markets. For those people, returning to “normal” levels of air pollution would be deadly. Raghu Karnad hopes that now that Indians have experienced weeks of blue skies, they will be moved to demand cleaner air all year long. “We have to hope that everyone can be brought around to realizing the necessity of collective action, just the way everyone has been brought around to realizing that with coronavirus.”