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John Daniel and Stephen Montzka
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John Daniel and Stephen Montzka

NOAA Scientists Contribute to 2014 Ozone Depletion Assessment

We talked with Dr. John Daniel, Research Physicist with NOAA Research’s Earth System Research Laboratory (ESRL) Chemical Sciences Division, and Steve Montzka, Atmospheric Scientist with ESRL’s Global Monitoring Division, about the World Meteorological Organization and the United Nations Environment Programme Scientific Assessment of Ozone Depletion: 2014 and what inspired them to pursue a career in science. Daniel and Montzka played vital roles in the development of the 2014 ozone depletion assessment, which is conducted every four years and provides the most recent information on the state of ozone depletion to policy makers, researchers, and the public worldwide.

What inspired you to pursue a career in physics and chemical and climate processes?

Stephen A. Montzka

Stephen A. Montzka

Montzka is an atmospheric scientist with NOAA Research's Earth System Research Laboratory Global Monitoring Division. Credit: NOAA

Daniel: Mathematics, specifically applied math, has always been one of my favorite subjects. I also have been very curious since childhood about how things work. As soon as I took my first physics course in college, I was hooked. Once I got out of graduate school, I was excited to be able to use a subject I enjoyed so much to solve scientific problems that were of such interest and value to the world.

 What inspired you to pursue a career in atmospheric science?

Montzka: I became interested in environmental science and chemistry in college, and was interested in bringing the two together in my graduate studies—that is why I attended the University of Colorado for my graduate studies.  The inspiration to pursue a career in the field came from wanting to be involved in the pressing environmental issues of the day during the 1980s—acid rain and ozone depletion.

John S. Daniel

John S. Daniel

Daniel is a research physicist with NOAA Research's Earth System Research Chemical Sciences Division. Credit: NOAA

How long have you been contributing to the WMO/UNEP Ozone Assessments?

Daniel: I was first involved in the 1994 Ozone Assessment. Since then I have participated in some capacity in each of the assessments (1998, 2002, 2006, 2010, and 2014).

Montzka: Since the 1998 report.  I was a contributor to the 1998 assessment, coordinating lead author of the 2003 and 2010 reports, co-author of the 2006 report, and review editor of the 2014 report.

How did you initially get involved with these reports, and what is your main role?

Daniel: I participated to the 1994 assessment as a contributing author.  I was also fortunate enough to be invited to the final meeting in Les Diablerets, Switzerland, where the executive summary was approved, word-for-word, by the 80 or so attendees. It was a great learning experience about how good leaders can build consensus among so many scientists, who might have somewhat different interpretations of the available data. You may end up being more conservative in some of the statements that are made, but when everyone walks away, there is no dispute regarding the accuracy of the final approved document. 

My role over the years has varied between this contributing role to being coordinating lead author on the policy chapter in two assessments. In the most recent report, I was in charge of running and analyzing all the future scenarios of the ozone-depleting substances. These scenarios are developed so the policymakers can see how additional controls would affect ozone depletion and climate change.

Montzka: I make measurements of trace gases that deplete ozone and their substitutes at sites across the globe.  My early contributions were providing unique data that helped policymakers and scientists understand how these gases were responding to controls on their use in the Montreal Protocol.  I consider the measurements we make data an “early-detection system” on providing feedback on the effectiveness of international policy measures such as the Montreal Protocol. Since then I have continued to provide that data, and similar data from my colleagues at NOAA.  Also, as a coordinating lead author, I play a role in distilling down the wide range of information available from the scientific community into a story that is understandable to scientists and non-scientist alike, and that addresses specific questions related to the Montreal Protocol that the Parties to the Protocol (nations) are interested in knowing about.

Why is the ozone assessment important to the public/society/policy makers?

Daniel: The Montreal Protocol has been referred to as the most successful international treaty ever put into force. I think a large part of that success is due to the interaction among the policymakers, industry, and the scientists. While the initial controls imposed by the Protocol slowed the growth of the ozone-destroying chemicals, it was the further understanding of these chemicals and their impacts on the ozone layer, assessed every four years in the ozone assessment, that gave the policymakers the confidence and knowledge to tighten the controls further in a way that was always consistent with the overall scientific understanding. While there were some individuals that continued to deny the link between chlorine- and bromine-containing compounds and ozone depletion, the scientific consensus that went into these documents provided simply too much evidence to be credibly disputed. In addition to having prevented catastrophic ozone depletion, the Montreal Protocol has also been shown to be several times more effective at reducing climate forcing than the Kyoto Protocol for climate would have been.

 Montzka: The assessment provides the most thoroughly vetted understanding of the science of stratospheric ozone depletion.  We write it with the intention that it is “news you can use”, reliable and robust information upon which policymakers can base decisions upon.  This type of communication tool is not provided by individual scientific papers, or other publications from the scientific community.  It represents a distillation of the plethora of individual scientific studies, potentially conflicting results, etc., to tell the reader not only “what we know”, but also, “what we don’t know”.  Both are important and useful to policymakers, and other communities, particularly the public and especially for scientists trying to focus their work on issues that remain unclear.

What has been some of the biggest changes you have seen in the reports over the years?

Daniel: In 1994 there were still rather significant ways that controls on ozone-depletion substances could accelerate the ozone layer recovery. The Montreal Protocol was still relatively young and we were substantially improving our understanding of ozone depletion every year. More recently, as the great success of the Protocol at avoiding ozone depletion is well understood, and as further regulatory action can accomplish less due to the tightening that has already occurred, there has become a greater interest in examining what this highly successful international protocol can do to mitigate future climate forcing.  As an example, people are currently very interested in knowing the extent to which hydrofluorocarbons (HFCs) might cause additional climate forcing in the future.  HFCs have been developed primarily as replacements for the ozone-depleting chemicals, and indeed they destroy no ozone, but they do lead to climate change. This fact gives the Parties to the Montreal Protocol some ownership of this emerging potential problem, so they are discussing possibly controlling these compounds.

Montzka: It has been interesting and rewarding to watch the results change from a situation that was worsening to one that is getting better.  The progress of the efforts of society to solve a global-scale problem are there to be seen in the reports.  Scientists identified a problem, worked with policymakers and industry to find a way to address the problem, and now we are seeing the fruits of that labor—that ozone depleting gases are on the decline, i.e., the threat to ozone posed by these gases is decreasing, and that the ozone layer itself is showing some initial signs of recovery.

What other research are you currently involved in, and what are the goals of your work?

Daniel: I believe one of the most important questions that needs to be addressed is the extent to which we expect the Earth to warm in the future. Many uncertainties remain in this understanding, and it would be helpful to reduce them so policymakers can have a firmer scientific foundation as they consider policy options. Two of the areas of research related to this that I am most interested in currently involve improving our ability to project future climate forcing of the HFCs and improving our understanding of shorter-term (i.e., decadal) climate response from forcing attributable to various chemical compounds and atmospheric processes.

Montzka: I measure trace gases that affect stratospheric ozone, climate, and air quality on a global scale, and I try to understand the human-influenced and natural processes controlling their abundance.  Most all of what I do is related to that. Some of my research goals include the following: understanding the concentration of trace gases before ongoing measurements were made by extracting old air from glaciers and measuring trace gas concentrations in that air, understanding how the climate-warming influence of long-lived trace gases is changing over time, understanding how constant and robust the natural processes are that remove pollutants from the atmosphere, and deriving from the atmosphere the rate of emissions of greenhouse gases and gases that deplete the ozone layer and affect air quality from measurements that we make in thousands of samples per year collected across the US.

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