Amid the deluge of news headlines about wars across the world, political scandals, and celebrity feuds, a story relegated to the corner of the multiple news websites on an unusual double weather event was sufficiently alarming to briefly return the issue of climate change to public attention. On March 18th 2022, weather stations in the Arctic and Antarctic registered temperatures that were as high as 50 to 70 degrees above normal, shattering records in several locations.[1] The unexpected nature of this extreme outlier underscores the difficulty of anticipating unusual climate change driven weather events and their potential impacts. The U.S. Department of Defense acknowledges climate change as a critical national security issue and has developed a climate adaptation plan as well as a climate assessment tool.[2] But these measures are conservative in nature because they use emissions-based models for projections and do not have a mechanism to account for the potential impact of unexpected events and natural processes. As a result, the U.S. risks being blindsided if the actual effects of climate change exceed projections and outpace its efforts to adapt, impacting readiness by degrading facilities and infrastructure while raising costs by forcing adaptation measures to be extended or re-constructed to a higher standard.

Evaluating the Department of Defense’s response to climate changes requires examining the scenarios that are being used and how those scenarios are constructed.

The Department of Defense’s 2021 Climate Adaptation Plan’s climate-informed decision-making line of effort states that it will use the best available, validated, and most likely climate change outcomes.[3] The risks factored into this decision making include changes in precipitation patterns, loss of testing capabilities, rising sea levels, increasing energy use, more frequent wildfires, and reduced fresh water supply.[4] The issue here is with the selection of models, as the best available and most likely are ultimately subjective while validation takes time, and both availability and validity depend on our current level of understanding. The Climate Adaptation Plan also directs the use of the Department of Defense Climate Assessment Tool for vulnerability assessments, which include a low and high emissions scenario projected out to 2050 and 2085.[5] Evaluating the Department of Defense’s response to climate changes requires examining the scenarios that are being used and how those scenarios are constructed.

The Defense Climate Assessment Tool uses data from the fourth National Climate Assessment dating from 2017. This assessment uses data from the Intergovernmental Panel on Climate Change’s fifth report issued in 2014.[6] This Intergovernmental Panel is scheduled to issue their sixth report in segments in 2022. The result is that the scientific models used by the Department of Defense to assess climate risk are eight years out of date.

This is not necessarily a failure on the part of the tool’s designers, as the data available represented the most current information while they were developing the tool, and updating such a program is a resource intensive task that can take years. As a result, any risk estimation tool for a continually changing environment is necessarily out of sync with the latest available data. This can be a dramatic difference, as the fifth panel’s highest emissions estimate predicts a likely temperature rise of between 2.6 to 4.8 degrees Celsius while the sixth report’s highest estimate predicts a range between 3.3 to 5.7 degrees Celsius.[7] This newer estimate predicts greater disruption from climate change across all dimensions, increasing the risks the Department of Defense assesses from climate change.

Compounding this built-in delay is the problem of unpredicted events outside of emissions scenarios. The panel reports are focused on direct human emissions and do not necessarily include events that we understand are possible drivers of climate change but do not fully comprehend. These can be categorized as known unknowns, with two examples being uncertainty about feedback loops from greenhouse gases trapped in permafrost or under the ocean and the consequences of collapsing ice shelves allowing inland ice to reach the sea more quickly. The first example would increase the overall effects of climate change by increasing the rate at which temperatures rise worldwide, while the second would have a more direct impact by increasing sea level rise and threatening coastal infrastructure and base locations.

…the risks that the Department of Defense sees are not being assessed correctly and will likely be far more disruptive than the current impact analysis foresees.

A recent article in Nature pointed to the possibility of a methane feedback loop as rising temperatures increase microbial action, citing a sharp increase in atmospheric methane since 2007. In the article the authors also explain that this is significant because methane is a far more potent contributor to climate change than the carbon dioxide produced through fossil fuel emissions.[8] While this particular article focuses on wetlands and permafrost, another article published in March of 2021 indicates that a similar phenomenon may be occurring under the Arctic and releasing carbon and methane, with scientists unable to be sure precisely how much of either gas is present or how quickly it will be released.[9] Adding these factors to human-driven emissions used in the models that the Department of Defense relies on suggests the models underestimate both the rate at which and amount  temperatures will rise. As a result, the risks that the Department of Defense sees are not being assessed correctly and will likely be far more disruptive than the current impact analysis foresees.

Turning to the other example of an unanticipated event, another recent study found that the ice shelf holding back the Thwaites Glacier is likely to collapse within the next five years. This will speed the melting of a structure that contains enough ice to raise global sea levels by more than two feet.[10] The Guardian reports that the Conger Ice Shelf, with an area of approximately 1,200 square kilometers, collapsed on March 15th in a region where such events are historically uncommon. According to the article, the glacier behind the Conger Ice Shelf is small, but the East Antarctic is made up of mutually supporting ice shelves, which means that larger collapses could release enough ice to seriously impact global sea levels.[11] Increasing the speed of sea level rise has the potential to flood coastal infrastructure and low-lying islands, including many strategically significant locations and military bases that are located near the shore. Failing to consider potential events like these when planning mitigation against rising sea levels could result in constructing inadequate protective measures, meaning that these projects would have to be expanded or possibly reconstructed further inland.

In both of the above examples the potential for an event is known, but the exact impact of the event or when it will happen is not. There is also a possibility that other climate-driven unexpected events could occur that the Department of Defense has not considered when assessing risk to its facilities and its continued ability to operate in certain parts of the world as rising temperatures and extreme weather events proliferate. These unknown unknowns could be identified by additional research by climate scientists and studied so they can be incorporated into the Department of Defense’s climate-based risk assessments and contingency plans. It is also possible that unanticipated events could lead to a natural mitigation of the effects of climate change. In either case, the key factor is having the clearest possible understanding of the risk that the Department of Defense faces when planning for the impacts of climate change.

In the meantime, there are some measures that the Department of Defense can take to improve its ability to mitigate the worst effects of climate change. The first of these is to move from a reactionary stance that does not keep pace with science and take a proactive approach that acknowledges it is better to be over-prepared in the face of a complex threat. This means taking the worst-case scenario in the most recent science and using that as a starting point, then adding a substantial safety margin to hedge against future uncertainty. This assessment may find that some locations are untenable for future use, meaning that the Department of Defense should begin considering alternatives now so that they are ready to be used when necessary. Secondly, the Department of Defense should establish procedures to collect information on currently anticipated events that may impact climate change and plan against those, including generating contingency plans in the event of major events like the collapse of a major glacier that leads to a rapid increase in sea levels. Climate change is a long-term threat, and it will require long-term thinking and an anticipatory mindset to ensure that an unwelcome surprise does not blindside the United States or its allies.

David Degenhardt is an officer in the U.S. Army and a resident student and Art of War Scholar at the Command and General Staff College. The views expressed in this article are the author’s alone and do not reflect those of the U.S. Army, the U.S. Department of Defense, or the U.S. Government.

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Header Image: Global Temperature Anomaly, 2015-2019, compared to a base period of 1951-1980. (Earth Observatory/NASA)

Notes:

[1] “Both of the planet’s poles experience extreme heat, and Antarctica breaks records,” NPR, March 19, 2022, https://www.npr.org/2022/03/19/1087752486/antarctica-record-heat-arctic.

[2] The Department of Defense Climate Adaptation Plan is available at https://www.sustainability.gov/pdfs/dod-2021-cap.pdf while the Department of Defense Climate Assessment Tool can be accessed at https://dodclimate.sec.usace.army.mil/dcat_conus_ak_hi.

[3] Department of Defense, Office of the Undersecretary of Defense (Acquisition and Sustainment), Department of Defense Climate Adaptation Plan (Washington D.C.: Department of Defense, September 1, 2021), 6.

[4] Climate Adaptation Plan, 13.

[5] Climate Adaptation Plan, 22.

[6]  U.S. Global Change Research Program, Climate Science Special Report: Fourth National Climate Assessment, Volume I (Washington D.C.: U.S. Global Change Research Program, 2017), doi: 10.7930/J0J964J6.

[7] Intergovernmental Panel on Climate Change (IPCC), Climate Change 2014: Synthesis Report (Geneva, Switzerland: IPCC, 2014),  https://www.ipcc.ch/site/assets/uploads/2018/02/SYR_AR5_FINAL_full.pdf, 10; IPCC, Climate Change 2021: the Physical Science (Genera, Switzerland: IPCC, 2021), https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM_final.pdf,

[8] Jeff Tollefson, “Scientists raise alarm over ‘dangerously fast’ growth in atmospheric methane,” Nature, February 22, 2022, https://www.nature.com/articles/d41586-022-00312-2.

[9] Matt Simon, “Underwater Permafrost Is a Big, Gassy Wild Card for the Climate,” Wired, March 21, 2022, https://www.wired.com/story/underwater-permafrost-is-a-big-gassy-wild-card-for-the-climate/.

[10] Carolyn Gramling, “Antarctica’s Thwaites Glacier ice shelf could collapse within five years,” Science News, December 13, 2021, https://www.sciencenews.org/article/antarctica-thwaites-glacier-ice-shelf-collapse-climate-5-years.

[11] Donna Lu, “Satellite data shows entire Conger ice shelf has collapsed in Antarctica,” The Guardian, March 24, 2022, https://www.theguardian.com/world/2022/mar/25/satellite-data-shows-entire-conger-ice-shelf-has-collapsed-in-antarctica.