Interventions for a Warming World?

©Nastco/iStock/ThinkstockGlobal climate is changing faster than at any time in human history. Most research to date on countering the impacts of climate change has focused on reducing greenhouse gas emissions or on adapting human and natural systems to make them more resilient. However, if emissions cannot be slowed fast enough or if the effects of climate change manifest suddenly or prove intolerable, there may be demands for purposeful intervention in the climate system to counter climate change, also known as geoengineering.

There is no substitute for dramatic reductions in greenhouse gas emissions to mitigate the negative consequences of climate change or adaptive measures to better cope with the impacts, concluded an Academies committee in a two-volume evaluation of proposed climate-intervention techniques -- Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration and Climate Intervention: Reflecting Sunlight to Cool Earth. Strategies to remove carbon dioxide from the atmosphere are limited by cost and technological immaturity, but they could contribute to a broader portfolio of climate change responses with further research and development. Albedo-modification technologies, which aim to cool Earth by reflecting incoming sunlight back to space, pose considerable risks and should not be deployed at this time.

Carbon dioxide removal and albedo-modification techniques have been grouped up until now under the common term “geoengineering,” but they vary widely with respect to environmental risks, socio-economic impacts, cost, and research needs. Carbon dioxide removal addresses the root cause of climate change -- high concentrations of the greenhouse gas in the atmosphere -- and generally have well-understood benefits and risks, but current technologies would take decades to achieve moderate results and be cost-prohibitive at scales large enough to have a sizable impact. By contrast, albedo-modification techniques would only temporarily mask the warming effect caused by high CO2 concentrations and present serious known and possible unknown environmental, social, and political risks, including the possibility of being deployed unilaterally by one country.

These differences led the committee to evaluate the two types of approaches separately in companion reports, a distinction it hopes will carry over to future scientific and policy discussions. In addition, the committee believes that these approaches are more accurately described as “climate intervention” strategies -- purposeful actions intended to curb the negative impacts of climate change -- rather than engineering strategies that imply precise control over the climate with a predictable outcome.

If society ultimately decides to intervene in Earth’s climate, any actions should be informed by a far more substantive body of scientific research, including ethical and social dimensions, than is presently available, the report says. Decisions regarding deployment of carbon dioxide removal technologies will be largely based on cost and scalability, and research is needed to make current options more effective, more environmentally friendly, and less costly. Conversely, any future decision about albedo modification will be judged primarily on questions of risk. Although the albedo-modification techniques should not be deployed at this time, there are many opportunities to conduct research on albedo modification that furthers basic understanding of the climate system and its human dimensions that would better inform societal considerations. Earth observing systems need to be upgraded to monitor the effects of albedo-modification field experiments. In addition, a serious deliberative process should be initiated to examine the governance of albedo-modification research.

The Academies’ study was funded by the National Academy of Sciences, U.S. intelligence community, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, and U.S. Department of Energy.

Better Regulation for Diluted Bitumen

©Gunnar Pippel/Hemera/ThinkstockDiluted bitumen has been transported by pipeline in the U.S. for more than 40 years, but the amount has increased recently as a result of improved extraction technologies and production and exportation by Canada. Both new and existing pipelines are being proposed to accommodate this increased production. Congress and the U.S. Department of Transportation asked the Academies to examine the potential environmental impact of using U.S. pipelines to transport diluted bitumen.

A type of crude oil made up of bitumen extracted from tar sands, diluted bitumen has properties that warrant special preparations to limit environmental damage in the event of a spill, concludes Spills of Diluted Bitumen From Pipelines: A Comparative Study of Environmental Fate, Effects, and Response. DOT needs to modify its regulations and planning in order to strengthen preparedness for accidental spills of diluted bitumen from pipelines.

Although bitumen behaves similarly to other crude oils immediately following a spill, exposure to the environment induces rapid physical and chemical changes known as “weathering” that, in bitumen, causes changes of greater concern compared with commonly transported crude oils, the report says. Within days, diluted bitumen starts to turn into a heavy, viscous, sediment-laden residue that cannot easily be recovered using traditional response techniques. The residue has a strong tendency to adhere to surfaces, and it poses particular challenges if it is spilled into a body of water, because the residues can submerge or sink to the bottom.

DOT’s current regulations and practices do not take the unique properties of diluted bitumen into account, nor do they encourage effective planning for spills of diluted bitumen. The report calls for a more comprehensive and focused approach to improve preparedness and to spur more effective cleanup and mitigation measures when pipeline spills of diluted bitumen do occur.

The Academies’ study was funded by the U.S. Department of Transportation.

Water Storage in the Everglades

aerial view of Florida Everglades, ©Jupiterimages/Stockbyte/ThinkstockAquifer storage and recovery is a key component in the Central Everglades Restoration Plan (CERP), a joint state-federal effort to reverse the decline of the Everglades ecosystem. Over a century of canal drainage and inadequate water management has led to extensive losses of natural water storage, leaving a critical need for new storage. Originally CERP included a project to drill over 330 wells for aquifer storage and recovery that would pump underground up to 1.7 billion gallons of surface water per day during wet periods for later use during dry periods.

To address uncertainties about regional effects of implementing aquifer storage and recovery on a large scale, the U.S. Army Corps of Engineers and the South Florida Water Management District conducted an 11-year study to assess the regional effects and whether the recovered water poses ecological risks. The Aquifer Storage and Recovery (ASR) Regional Study concluded that the number of ASR wells in the region that can be operated without exceeding well pressure constraints is much lower -- about 131 wells -- than originally envisioned in the CERP.

Review of the Everglades Aquifer Storage and Recovery Regional Study says that although the ASR Regional Study significantly advances understanding of large-scale implementation in south Florida, many uncertainties remain and more research is needed before large-scale ASR is implemented. Instead, ASR could be phased in to answer several important scientific questions and provide some early restoration benefits.

Better understanding of the quality of recovered water and potential ecological risks should be obtained, the report says, including the effects of longer storage times and different operating conditions. Further assessment is also needed of the cost and performance of ASR compared with alternatives and the potential benefits ASR may provide by removing phosphorous from water over the long term.

The Academies’ study was funded by the U.S. Army Corps of Engineers Jacksonville District and the South Florida Water Management District.

Improving the National Flood Insurance Program

severe floods in Iowa, photo by Greg Henshall/FEMAThe National Flood Insurance Program (NFIP) within the Federal Emergency Management Agency faces dual challenges of maintaining affordable flood insurance premiums for property owners and ensuring that revenues from premiums and fees cover claims and program expenses over time. Recent reports from the Academies examine methods and measures that could make insurance more affordable for all policy holders.

Affordability of National Flood Insurance Program Premiums, Report 1 examines policy measures that could help NFIP address affordability issues and provides a framework for policymakers to use in in designing targeted assistance programs. Where Congress or FEMA determine insurance premiums to be unaffordable, households paying those premiums might be made eligible for assistance through the NFIP. It will be up to policymakers to select which households receive assistance, the form and amount that will be provided, and who will pay for and administer assistance.

Affordability of National Flood Insurance Program Premiums, Report 2 identifies an approach for FEMA to evaluate policy options for making premiums through NFIP more affordable for those who have limited ability to pay, while also moving the program to a firmer financial footing.

Microsimulation is a modeling approach that is well-suited to estimating premiums and future flood damage claims at the individual policy holder level, Report 2 says. This modeling approach would, for example, allow FEMA to compare the price of NFIP premiums that reflect true flood risk -- as called for in the Biggert-Waters Flood Insurance Reform Act of 2012 -- with measures of policy holders’ ability to pay. The agency then could evaluate how different premium and mitigation assistance programs might be designed to make premiums affordable for cost-burdened households. The report also suggests some near-term analyses FEMA might complete as it builds analytical capacity in the long term.

Report 2 also includes findings on changes called for in the Biggert-Waters Act and the subsequent Homeowner Flood Insurance Affordability Act (HFIAA) of 2014. Biggert-Waters eliminated grandfathering -- which had allowed policy holders to maintain their premium rates even if their property was subsequently mapped into a higher flood-risk zone -- but HFIAA reinstated it. The report describes how this reinstatement will limit the ability of the NFIP to employ risk-based pricing over time if climate change, land development, and more accurate mapping place more properties in higher flood risk zones.

The studies were funded by the Federal Emergency Management Agency.