Climate Change poses a real and increasingly immediate threat to global stability. In 2014, the Department of Defense began incorporating climate change models into its defense planning cycles. The constantly evolving multi-domain approach of the defense establishment must account for the impact of climatological change. Although increasing temperatures and potentially intensifying weather patterns will impact conventional military operations, the broader impacts of climate change on global trends and the human domain pose a far larger dilemma for the American military. In the following interview, Over the Horizon Senior Editor Mark Nexon interviews Dr. April Melvin, exploring her scientific and policy-based perspective on climate change in order to provide multi-domain planners with an in-depth understanding of the specific risks posed by this threat.
April Melvin is a scientist who has spent most of her career studying the impacts of human activities on climate change and pollution. She is an Associate Program Officer at the National Academy of Sciences and was a Science Policy Fellow with the American Association for the Advancement of Science (AAAS). Dr. Melvin holds a PhD from Cornell University in Biogeochemistry. She was a contributing author to the Interagency Arctic Research Policy Committee – Research Plan FY2017 – 2021. Dr. Melvin has served as an AAAS Science and Technology Policy Fellow at the Environmental Protection Agency and was a Mirzayan Science and Technology Policy Fellow at the National Academy of Sciences. The following is an edited transcript of an interview conducted in March 2017, via telephone, during which she discussed the science of climate change and its impact on the human domain.
The views expressed herein are those solely of the interviewer and interviewee, and do not necessarily represent the official views of the National Academy of Sciences or the United States Air Force.
Over the Horizon (OTH): Thank you for taking time today to discuss climate change, your research experience, and to provide a scientist’s perspective on an issue that is currently under significant scrutiny in policy circles and is forecasted to have a disruptive effect on the world’s population.
April Melvin (AM): Thanks for having me. It is great to have an opportunity to discuss climate change with an audience that does not necessarily understand or discuss this issue to the same level of detail as the scientific community. Before we begin, I’d like to address a common misunderstanding of the differences between weather and climate. I often think of climate as my entire closet and weather as a particular item of clothing. Climate is the longer-term view of weather. If you live somewhere warm, you’ll likely have very few pieces of cold-weather clothing. Once in a long while you may wear a jacket, but the vast majority of the time you’re in shorts and a t-shirt. An unseasonable cold or warm spell means little in terms of global climate trends. Climate change is occurring now. We know that from changes in temperature, changes in CO2, and a number of other factors. Changes to our climate are observed as trends over time. Scientists generally look at windows of 30 years or more of data to attempt to account for the planet’s complexity and the natural variability in climate. Trends indicate that climate change is happening.
OTH: Beyond the obvious impacts of pollution, like air and water quality, do you mind detailing how the scientific community has concluded climate change is real and what climate change’s impacts are expected to look like around the world.
AM: We know that climate change is real and we know that it is human-caused. There are a lot of ways we can tell. The physics of greenhouse gases, also known as heat-trapping gases, is straight forward and very well understood. We know that human beings are pumping a lot of those gases into the atmosphere, mostly through the burning of fossil fuels. We can measure the increases in the concentration of greenhouse gases that begin during the industrial revolution. Also, the chemical composition of carbon dioxide in the atmosphere allows us to attribute increases in carbon dioxide (CO2) to particular sources. Using historical records, or through measurements of ice cores we can discern that the quantity of carbon dioxide in the atmosphere now exceeds that of any time in at least the last 800,000 years. Pollen records, based on plant pollen recovered from sediment samples, allow scientists to infer what previous climates were like. These records indicate human activity is the primary driver of the changes in earth’s climate and that today’s quantity of CO2 exceeds any inherent (statistically explainable) variability in how the earth’s climate functions.
OTH: But when did historical records, in terms of human observation, start being kept?
AM: Many of the types of measurements we make today began in the late 19th century. However, proxy records, like ice cores extracted from ice sheets contain air bubbles that provide looks tens of thousands of years into the past. Pollen records offer similar clues to climactic changes. As scientists, we are drawing upon as many lines of evidence as possible. Tree and sediment and sediment cores are other sources of records for related climate research.
OTH: Where are the air samples collected that research scientists analyze the chemical make-up of CO2?
AM: One of the longest used direct observation sites is the Mauna Loa Observatory in Hawaii, which is considered ideal since it is far-removed from significant sources of CO2 emissions and provides a more balanced measurement of global carbon dioxide levels. CO2 is also photosynthesized by plants and absorbed by water. Mauna Loa measurements reflect a relatively reduced level of carbon dioxide in the northern hemisphere during the summer months due to plants synthesizing CO2 and vice-versa in the winter months. This is commonly referred to as the earth “breathing.” Despite seeing this yearly change, the overall trend in the atmosphere’s CO2 concentration has sharply increased over time. Thus, it is a human-caused trend overlaid on a natural pattern. The northern hemisphere is the primary driver of this phenomenon since there is more plant matter in the northern hemisphere than the southern.
OTH: I’ve read that the earth has a sort of “fever.” Can you expand on that?
AM: The average global temperature has definitely increased. Since the start of the Industrial Revolution, the earth’s average temperature has increased 1.5 degrees F (temperature changes vary across the globe for a variety of reasons and this a global average). Although that might seem insignificant, the increase is dramatic given how quickly the rise has occurred. For instance, during the last ice age (or glaciation), the global average temperature was only 7 to 9 degrees Fahrenheit lower than it is today. Granted that change was in the opposite direction, but it provides a sense both of scale and how potentially unhealthy the current temperature changes are for the world’s population and ecosystems.
OTH: Pro Publica reported that Secretary of Defense Mattis, in unpublished written testimony to the Senate Armed Services Committee, considers climate change a national security challenge. Why does climate change matter to you and the scientific community?
AM: One of the things that makes climate change so challenging is that we are entering what are considered uncharted waters. The impacts of climate change will be diverse and far-reaching depending on where you live. My policy and research focus on climate change impact is largely with respect to the United States. Changing temperatures, heat stress and the associated crop yields are an example of a major concern to the US economy. Another is the changing rainfall patterns where greater rainfall occurs in shorter periods with increases in flash flooding. There may also be greater periods of drought in some areas and an increase in the number and size of wild fires. A significant portion of the world’s population is at risk to projected sea-level rises. Possible migration patterns and emerging socio-political instabilities driven by rising seas and higher temperatures are a major concern. Infrastructure in the developed world may be insufficient for the projected changes in some climates.
Aside from climate-specific impacts of CO2, ocean acidification (caused by the increased absorption of carbon dioxide) has the potential for far reaching, negative impacts on ocean life, particularly shellfish. Seafood, a primary protein source for millions of people and ocean acidification, could have serious food security implications for populations that rely on these food sources. A major concern about ocean acidification is that a tipping point may be crossed beyond which acidification could increase to levels less hospitable to life, where it will be extremely difficult to reverse. Cold water absorbs more CO2 than warm water and places like Alaska, where waters are already naturally more acidic, there are concerns about the negative impact of CO2 emissions on its fishing industry. The lower 48 receives significant amounts of its fish from Alaska waters, so this is a broader American problem in that sense.
Collectively, we have numerous lines of evidence that climate change is happening and people in different countries and regions will be significantly impacted in a variety of ways. In the US, a lot of the impacts, for instance rises in temperature, will negatively impact the economically disadvantaged. A lack of air conditioning and its increased cost will impact people’s health, as will increases in diseases in climates increasingly hospitable to a wider variety of pathogens. [Editor’s Note: For further information, The Joint Operating Environment: 2035, published in 2016, provides insight into the broad range of compounding political, social, and environmental issues that will help define the operating spaces of the future.]
OTH: In terms of the impact of agriculture, are methane emissions of any concern to climate scientists?
AM: Livestock are the largest reported sources of methane emissions in the US, followed by natural gas, landfills, manure management, and coal mining. Rice paddies are a large source, as well. Methane emissions are less (in terms of quantity) than CO2 emissions, but methane is a more powerful heat trapping gas than CO2. Methane remains in the atmosphere for less time than CO2. Methane’s lifespan in the atmosphere is approximately 10 years. Reducing methane emissions may have a larger short-term impact on climate change; however, the general policy mindset is that in order to limit long term climate change both CO2 and methane emissions need to be reduced. [Editor’s Note: For comparison, CO2 remains in the atmosphere for 20-200 years.]
OTH: Do changes in polar ice coverage and the related Arctic geopolitical considerations have any visibility in your policy discussions?
AM: Definitely. The US, for the past few years, has chaired the Arctic Council. The 8-nation Arctic Council is designed to increase coordination and collaboration with respect to research and safety in the Arctic. There is a lot of interest in the scientific community (and the defense community) with the linkages between defense and energy resources, as well as how they tie into climate change and the indigenous populations living in the Arctic.
OTH: What do the scientists who argue climate change either isn’t real or isn’t human-caused base their views on?
AM: There is not an alternative reality that can be pointed to. However, there are cherry-picked pieces of evidence that skeptics point to. One line of argument is that plants benefit from higher levels of CO2. Technically, that isn’t incorrect. There is something known as the CO2 fertilization effect. However, that argument fails to appreciate the entire complex system. Certainly, plants will grow better with more CO2 and an appropriate amount of water and fertilizer. Unfortunately, increases in CO2 are resulting in droughts or excessive rain or heat that stress plant growth, not improve it. This narrow perspective oversimplifies the reality of CO2’s contribution to climate change. Another theory attributes heat increases to an increase in occurrences of solar flares. Recent satellite observations of solar flares suggest a relatively minor impact on the earth’s temperature compared to human causes. The last example I’ll share is a growth of Antarctic sea ice over past decades. Honestly, a lot is still unknown about the causes of Antarctic sea ice growth in recent times because it is a complex system and a hard place to take measurements given its remote location and harsh conditions. In the past couple of years large portions of the Antarctic sheet have calved, which is concerning for sea levels. This year Antarctic sea ice has shrunk.
OTH: What role does the National Academy of Science play in the interagency process? Does the NAS advocate for specific policies or investment in climate mitigation technologies?
AM: The NAS does not have an advocacy role in the interagency process. The organization is designed to be an unbiased, non-partisan, objective advisor to the federal government. Our job is to provide information on the state of science, medicine, or engineering for specific topics – often tasked by the government. The Academies bring together leading scientific experts who provide this information in ways that are intended to be useful to policymakers. There may be some prioritization or recommendations in that space, but it will be specific to the questions asked.
In terms of climate change mitigation, my office did some work in climate intervention technologies, including solar radiation management or albedo modification. The concept is to mimic a volcanic eruption by releasing metallic particles into the atmosphere to reflect light and reduce temperatures. There are a lot of unknowns associated with doing something like that. There are studies that are also exploring CO2 removal from the atmosphere. The conclusions of the climate intervention reports thus far are that we need to better understand the long-term impact of these technologies, as well as conduct smaller scale studies prior to any global-scale implementation. Also, at least in the case of solar radiation management, it wouldn’t address other issues like ocean acidification. Unfortunately, there are not a lot of good options in terms of reversing the effects of climate change. [Editor’s Note: The Atlantic’s April 2017 Issue includes an article, Pleistocene Park, by Ross Andersen, that examines the possible reintroduction of genetically engineered, lab-nurtured woolly mammoths to the Siberian tundra in an effort to reduce the thawing of permafrost and slow global warming.]
OTH: As a scientist who has dedicated her career to studying pollution and the human contributions to climate change, what keeps you up at night?
AM: The inability of the scientific community, in the face of so much scientific evidence of climate change, to sway elected policymakers to address the risks climate change poses to the human race. Unfortunately, most discussions today seem oriented on misconceptions regarding climate change and its causes. There are important conversations to be had and actions that need to be taken regarding the substantial, growing risks that are already confronting society.
OTH: Given that many of us in the defense establishment probably only have time for a book or two on this topic, what do you recommend?
AM: The Royal Society and the National Academy of Sciences publishes a short booklet, Climate Change: Evidence and Causes, which is very accessible. The US National Climate Assessment is also a great resource with information concerning climate change’s impact on various parts of the US. A movie, “Age of Consequences,” was recently released which may be of interest to the defense community. Two other resources include EPA Climate Change Indicators and Mauna Loa Observatory CO2 data set.
OTH: Thank you for your time, Dr. Melvin.
AM: It was my pleasure, Mark. Take care.
The interview was conducted by Mark Nexon, Senior Editor, in March 2017. Pritchard Keely and Katrina Schweiker, Senior Editors, also contributed significantly in the editorial process.
Disclaimer: The views expressed are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government.