ESRL Quarterly Newsletter - Fall 2009

Profile: Stephen A. Montzka

The ESRL scientist’s work tracking ozone-depleting substances has helped underpin scientific discoveries, international policy

When Steve Montzka was considering a position at NOAA nearly 19 years ago, the job description was daunting. It involved continually analyzing air samples from around the world for chemicals that were eating away at Earth’s protective ozone layer. “The work was to do this, day in and day out, for…well, forever,” Montzka said.

He took the job. Ozone depletion had become a hot topic in atmospheric science, and many of the key players—from NOAA’s Susan Solomon to Harvard University’s James Anderson - were returning from Antarctica, giving fascinating talks in Boulder, and planning new experiments.

Steve Montzka in the laboratory.

Steve Montzka in the laboratory.

“It was exciting to be involved in this community of scientists at the forefront of the issue,” Montzka said. “And frankly, it was a way to stay in Boulder, which my wife was going to do with or without me,” he said, smiling.

Since then, Montzka has combined his expertise— in chemistry, atmospheric science, and data analysis—to go well beyond filling a database with 18 years of ozone-depleting gas data. With his colleagues he tracks about 40 different gases now, his papers are very highly cited in the field, and Montzka has worked closely with colleagues across ESRL and NOAA to contribute to national and international scientific assessments read by policy makers around the globe.

Steve Montzka at the South Pole.

Steve Montzka at the South Pole.

“Our bread and butter is still to analyze air samples from remote locations day after day,” Montzka said, “but on top of that, there have been all sorts of interesting twists and turns in the science we’ve been able to do.”

From 1989 to 1991, Montzka worked as a postdoctorate researcher with Fred Fehsenfeld and Paul Goldan, studying how plant-produced volatile organic compounds were involved in the generation of rural haze and tropospheric ozone (ozone is a pollutant at low altitudes, but up in the stratosphere, a layer of ozone protects the Earth from damaging radiation).

Soon after starting at NOAA, Montzka participated with Jim Butler (today, Director of ESRL’s Global Monitoring Division) in a cruise from Seattle to San Francisco, to study natural oceanic sources and cycling of methyl bromide, a significant ozone-depleter. The chemical has manmade sources, too, as a fumigant pesticide, and the relative importance of each source wasn’t clear at the time. “Our data really helped refine the methyl bromide budget,” Montzka said. And the cruise itself, on the NOAA ship Discoverer, was terrifically exciting. “I felt like I was in a National Geographic special,” he admitted.

A few years later, in 1996, Montzka and his NOAA colleagues hit another scientific high: Documenting a drawdown in the global atmospheric concentration of ozone-depleting substances—a direct consequence of a 1987 international treaty, the Montreal Protocol on Substances that Deplete the Ozone Layer, and its amendments.

“Seeing that turnaround in our data and being able to tell others about the Protocol’s initial success, well, it was nice to be a part of that,” Montzka said.

Since then, the researcher has been involved in groundbreaking measurements of 100-year-old air trapped in Antarctica’s snow— which revealed an atmosphere remarkably free of industrial ozonedepleting substances. He helps with aircraft missions that soar into the stratosphere to measure ozone-depleters directly in the environment in which they wreak havoc. And Montzka and his colleagues have been able to take advantage of policy decisions— the mandated end of most methyl chloroform production, for example—to gain insight into fundamental atmospheric processes.

“It was similar to studying the decay of radiocarbon after the nuclear tests of the 1950s,” Montzka said. “We were there, equipped to study the atmospheric changes with the appropriate tools, and we were able to draw some powerful conclusions about the chemistry of the atmosphere and how it rids itself of pollutants.”

Two years ago, Montzka shared the U.S. Environmental Protection Agency’s Ozone Protection Award of 2007 with other ESRL scientists. He has also shared two Department of Commerce Silver Medals, was named NOAA Research Employee of the year in 2000, and co-authored nine papers that won Outstanding Scientific Paper awards (some of those and other papers that bear Montzka’s name have been cited more than 100 times—a very high rate).

Today, he continues to track trace atmospheric chemicals along with his colleagues in the halocarbons research group, especially chemicals that are substitutes for ozone-depleting substances. Some of those chemicals are milder ozonedepleters, and others are potent greenhouse gases— so Montzka is collaborating increasingly with ESRL’s carbon cycle and greenhouse gas experts.

He’s also a bit busier than usual now, because he’s one of two coordinating lead authors of Chapter 1 of the 2010 Scientific Assessment of Ozone Depletion Report, conducted by the World Meteorological Organization and the UN Environment Programme. The assessments, published every four years, update scientists, policy makers, and the public on the status of ozone depletion.

The extra work is worth it, Montzka said. “We at NOAA get to take the pulse of the global atmosphere weekly—those samples are a tremendous resource. Using them to address science issues is great fun, and being able to address policy issues as well makes it very rewarding.”