A Boulder scientist noted that in recent days an email has traveled through his circle that goes like this: “Everybody: You can’t shut down the whole world; Mother Nature: Hold my beer.”

Mother Nature has, effectively, done exactly what people said could not be done. In a manner no one would have ever asked for, with the approach of Wednesday’s 50th anniversary of the founding of Earth Day, humankind is living through a prolonged and unintended test case of what it might look like if homo sapiens’ footprint on the planet — and much of their attendant emissions of greenhouse gases and other pollutants — was dramatically reduced.

The jury is still out, but the early evidence is sufficient for some local scientists to at least talk about what it might mean — but also, what we can’t yet know.

“We’re all hoping that this may be a great experiment,” said Bruce Vaughn, a research associate and fellow at the University of Colorado Boulder’s Institute of Arctic and Alpine Research.

“I don’t think we could have designed an experiment like this, on our own, to be able to have such a widespread simultaneous and instantaneous reduction in fossil fuel emissions. That said, we’re all anxious to see what this perturbation in the atmosphere is going to look like in the upcoming weeks and months.”

The shutdown by many states is still less than a month old. But reduced industrial and ordinary day-to-day activities in China, where COVID-19 was first detected at the end of December, and Europe, where its devastation next made itself felt, has already manifest in data being examined closely by scientists.

When the virus was initially identified in Wuhan in the Hubei Province of China, factories were quickly shuttered, and people halted their daily routines. As the outbreak struck Lombardy in Italy, the same thing occurred.

The Tropospheric Monitoring Instrument known as TROPOMI, aboard the European Space Agency Copernicus Sentinel-5P satellite, a partnership among the European Space Agency, the Netherlands Space Office and the European Commission, has detected lowered air pollution over Italy and decreased nitrogen dioxide emissions over China.

And Thursday, it was reported that new data from the same satellite shows some cities experiencing a 45% drop in nitrogen dioxide levels since the pandemic’s outbreak..

“In terms of pollutants there may be other urban sites where measurements could, and probably already are, showing radical reductions, in terms of global greenhouse gases,” Vaughn said.

However, Vaughn added, “I would caution those who expect to see an instantaneous precipitous drop in the measurements of greenhouse gases, because the atmosphere is well-mixed. It’s a large buffer. There are a lot of other items in that equation for the atmospheric concentration of carbon dioxide. There are other sources and sinks that are major players, plants being one of them, and fossil fuels being a significant one,” meaning the net effect globally will take much longer to be detected.

Vaughn manages INSTAAR’s Stable Isotope Laboratory, which partners with the Global Monitoring Laboratory at Boulder’s National Oceanic and Atmospheric Administration in ongoing long-term research into greenhouse gases, carbon cycle feedback and more. A key part of the effort is the weekly collection of flasks of air samples from around the world that are shipped back to the Carbon Cycle Greenhouse Gas Group’s Boulder facility for analysis.

The lab’s data will ultimately be important to learning the shutdown’s true impact on the Earth’s atmosphere.

“NOAA and cooperating labs at the university who are considered essential employees because of this mission-critical research are doing their best to keep this flask collection project going,” Vaughn said. “Of the 55 (collection sites), 50 or more are still able to collect and ship samples.

“A few are not. For example, Mongolia has shut down their borders, so they can for now no longer ship their samples. And, a couple other sites as well. So there will be some gaps (in the data). But over 90% of the sites are still collecting.”

It is going to be some time before scientists know what samples being collected now will show.

“The most reliable indicator of fossil fuel CO2 is the abundance of CO2 with radiocarbon (14-Carbon), which we measure in partnership with INSTAAR,” Arlyn Andrews, chief of the Carbon Cycle Greenhouse Gases Group at NOAA’s Global Monitoring Laboratory, wrote in an email.

“Radiocarbon measurements are quite involved, and typically take several months to complete after the sample is collected. It will likely take six to 12 months before we can assemble all of the datasets and run the models to reliably estimate U.S. emissions.”

Andrews said her team also has tower and aircraft sites over the U.S. where they expect to see larger indications of reduced emissions, and they are conducting some increased sampling in their aircraft network to better track emissions from a large suite of gases, including carbon dioxide and methane.

An estimated 5% reduction

Kris Karnauskas said the unintended experiment through which we are all now living, and what it might prove — or even suggest — is something many have been asking in recent weeks.

“Is there a fingerprint of COVID-19 in all this sort of curbing of life as we know it, on the atmosphere? I think the answer is yes,” said Karnauskus, a fellow at CU Boulder’s Cooperative Institute for Research in Environmental Sciences and associate professor in Atmospheric and Oceanic Sciences. The previous day, he’d been asked the same thing by the “Today” show’s Al Roker.

“Is it generally a healthy fingerprint for the environment? Sure, for measured aerosols, or even, like you say, carbon dioxide, and for global warming. We’re at this interesting intersection between climate change and coronavirus, and we’re wondering, is this really what it’s going to feel like, if we get serious about making progress on the climate crisis?”

Karnauskas offered some tempering words for those who think the impact of a couple months’ shutdown could be transformative for the condition of the bruised planet we inhabit.

“If you look at the emissions for this year, depending on how long this lasts and how quickly the global economy can recover, I think the biggest reduction in emissions we can reasonably expect is probably around 5%,” he said. “And we’re talking about a reduction of 5% of a very, very large number.

“For context, humans are currently pumping 37 gigatons of carbon into the atmosphere each year. That’s last year’s annual amount of carbon that humanity pumped into the atmosphere. A 5% reduction that means we’re only going to add 35 gigatons, which is still way more than zero.”

That, he said, is not going to facilitate meeting the goal of the 2015 Paris Agreement — from which President Donald Trump has served notice the U.S. will withdraw — to limit global warming to 1.5 degrees Celsius above preIndustrial levels.

“A 5% reduction for one year is not even close to what’s going to prevent global warming from reaching 1.5,” Karnauskus said. “It’s going to take something more like 8% a year, every year, not just one year and then we clap our hands. It’s going to have to be about an 8% reduction, year upon year, in order to avoid 1.5 degrees. That’s a tall order.”

Meanwhile, the Colorado Department of Public Health and Environment in recent days released early data that offer a sense of what is happening on the Front Range.

Based on data from five air monitoring sites in the Denver area, when comparing data from March 2019 to March 1-25 of this year, significant declines were seen in levels of nitric oxide, nitrogen dioxide, carbon monoxide, sulfur dioxide and particulate matter. Particulate matter with a diameter of less than 2.5 micrometers, for example, known as PM2.5, was down between 36% and 49%, while PM10 concentrations were down 29 to 41%.

State health officials, however, are not making grand statements based on those early numbers.

“Attempting to predict or formally model the long-term air quality impacts of this crisis is difficult, premature, and not a current priority,” Garry Kaufman, director of CDPHE’s Air Pollution Control Division said in a statement.

“Limiting the spread of this disease and ensuring that our health care system is equipped to care for all Coloradans is our priority. We have never faced a pandemic like this, and that means there is tremendous uncertainty in trying to predict second- or third-order outcomes from the crisis.”

Reductions in emissions playing ‘large role’

Additional localized results will be coming eventually from testing being done from the CU Boulder campus under the direction of Joost de Gouw, a professor in the Chemistry Department who also is at CIRES.

“My research group measures organic pollutants in the air, and just before we were shut down (by the campus closure due to the COVID-19 pandemic), we started to make measurements of the Boulder air from campus in an effort to get our own data set during the lockdown,” he said. “So we have been doing so for the past month, and we intend to keep doing this until we’re allowed back in.

“It’s clear that we’ve seen some very clean days, but now the hard work really starts, to decide if this was because of the lockdown, or just because of the weather conditions. We’ve had days with snow, all kinds of days, of course, as is common in Colorado in the spring. And that plays a very significant role as well. But I think the reductions in emissions have played a large role.”

Asked if the pandemic presented an unexpected opportunity for climate scientists, even while claiming more than 156,000 lives globally and in excess of 37,000 in this country, he rejected that language.

“I would not use the word ‘opportunity,’” de Gouw said. “Obviously, this is something we wanted to avoid at all costs. But now it is here, there are things we can learn. And I think we owe it to ourselves to try and get that data and learn those lessons, learn everything there is to be learned.”

In “Walden,” Henry David Thoreau wrote almost 170 years ago, “Live in each season as it passes; breathe the air, drink the drink, taste the fruit, and resign yourself to the influence of the Earth.”

On the eve of the 50th Earth Day, people are now having the chance — even if forced, for most — to slow down and focus on their immediate environment, the hectic daily flow of life around them suddenly stilled in a profoundly unique way.

As the pandemic continues to unwind, Karnauskas said, “I get a little hope that people see our emissions are going down, and maybe the carbon dioxide level will be lower than it would have been.

“And that means that we’re in control, and it’s a diet that works. And you just want it to be done the right way.”