Abrupt Climate Change

Arctic Ocean, ©Jupiterimages/ change has increased apprehension over possible large and rapid changes in Earth's physical climate system, which includes the atmosphere, land surfaces, and oceans. Some of these changes could occur within a few decades or even years, leaving little time for society and ecosystems to adapt.

Abrupt Impacts of Climate Change: Anticipating Surprises points out, however, that even steady, gradual changes in the physical climate system can have abrupt impacts elsewhere if critical thresholds are crossed. For example, relatively slow global sea-level rise could reach a "tipping point" and directly affect local infrastructure such as roads, airports, pipelines, or subway systems if a sea wall or levee is breached. The report says abrupt changes already underway are of immediate concern, including the disappearance of late-summer Arctic sea ice and increases in extinction rates of marine and terrestrial species.

Some changes such as a shutdown in the Atlantic Ocean circulation patterns or a rapid release of methane from high-latitude permafrost or undersea ice are now known to be unlikely in this century. But more research is needed to determine timelines for abrupt changes whose likelihood is unknown such as the collapse of the West Antarctic ice sheet.

The report calls for the development of an early warning system that could help society better anticipate sudden changes and emerging impacts. An effective system would need to be flexible and adaptive, including careful and vigilant monitoring, data collection and analysis, model testing and improvement, and model predictions that suggest future data needs.

The National Research Council study was funded by the National Oceanic and Atmospheric Administration, National Science Foundation, the U.S. intelligence community, and the National Academies.

Pesticides and Endangered Species

Whooping cranes at Aransas National Wildlife Refuge in Texas, photo by Steve Hillebrand/U.S. Fish and Wildlife ServiceBefore a pesticide can be sold or used in the United States, the U.S. Environmental Protection Agency must ensure that it will not cause unreasonable adverse effects on the environment, which includes species listed as threatened or endangered and their critical habitats. If EPA determines that a listed species or its habitat is likely to be adversely affected, it must consult with the U.S. Fish and Wildlife Service or National Marine Fisheries Service, which then conducts its own assessment and issues a biological opinion on the matter.

Each agency has developed its own methods for assessing those risks, and they have been unable to reach a consensus about which approaches to use. Together with the U.S. Department of Agriculture, the agencies asked the National Research Council to examine the scientific and technical issues.

Assessing Risks to Endangered and Threatened Species From Pesticides says that a common approach among the agencies is needed, and recommends following a risk-assessment paradigm grounded in two previous National Research Council reports: Risk Assessment in the Federal Government: Managing the Process (1983) and Science and Decisions: Advancing Risk Assessment (2009). After 30 years of use and refinement, the risk-assessment paradigm has become scientifically credible, transparent, and consistent, and it is already used elsewhere in the federal government.

If FWS and NMFS could build on EPA's initial analysis of whether a pesticide is likely to adversely affect a listed species rather than conduct a completely new analysis, the assessment would likely be more effective and scientifically credible, the report adds. Action is also needed to improve communication and coordination among the three agencies throughout the process. Coordination is necessary to ensure a complete and representative assessment of risk and that each agency's technical needs are met.

The study was funded by the National Oceanic and Atmospheric Administration, U.S. Department of Agriculture, U.S. Environmental Protection Agency, and U.S. Fish and Wildlife Service.

U.S. Tax Policy and Greenhouse Gas Emissions

©Nils Prause/iStock/ThinkstockTransportation fuel taxes, oil and gas depletion allowances, subsidies for ethanol, and tax credits for renewable energy are designed in part to achieve certain effects on energy production and consumption, which in turn could impact the level of greenhouse gas emissions. At the request of Congress, the National Research Council evaluated the most important tax provisions that affect carbon dioxide and other greenhouse gas emissions and estimated the magnitude of the effects.

Effects of U.S. Tax Policy on Greenhouse Gas Emissions says that although it is difficult to estimate the precise impact of energy-related tax provisions on emissions, they achieve very little greenhouse gas reductions at a substantial cost. The U.S. Department of the Treasury estimates that the combined federal revenue losses from energy-sector tax subsidies in 2011 and 2012 totaled $48 billion. While few of these provisions were created solely to reduce greenhouse gas emissions, they are a poor tool for doing so, the report says.

Several existing tax subsidies have unexpected effects, and others yield little reduction in greenhouse gas emissions per dollar of revenue loss, the report says. For example, provisions subsidizing renewable electricity reduce greenhouse gas emissions only slightly, while those for biofuels may have increased emissions by lowering the price of blended gasolines.

In addition to energy-related taxes, the report also examines broad-based provisions that may have indirect effects on emissions such as those for employer-provided health insurance or incentives for investment in machinery. The models indicate that these provisions affect emissions primarily through their effect on national economic output.

Tax policies that target emissions directly, such as carbon taxes or tradable emissions allowances, would be the most effective and efficient ways of reducing greenhouse gases.

The study was funded by the U.S. Department of the Treasury.

Rebuilding U.S. Fisheries

Black sea bass in Georgia waters, photo by Greg McFall, Gray's Reef National Marine Sanctuary, NOAAAbout 20 percent of the U.S. fisheries that have been assessed are overfished, according to a 2012 report by the National Oceanic and Atmospheric Administration. When fish stocks drop to an overfished level, the law requires that fishery managers implement plans to rebuild the stocks, in most cases within 10 years. These rebuilding plans usually require significant restrictions on fishing for the depleted species, limits that may also affect fishing for other species in the same waters.

Because of concerns about the economic and social impacts of these restrictions, Congress requested a National Research Council assessment of the rebuilding plans and their associated ecological and economic effects. Evaluating the Effectiveness of Fish Stock Rebuilding Plans in the United States says that these efforts have been successful at reducing fishing pressure on many overfished stocks, and numbers have generally increased. However, outcomes have been mixed across fisheries; fishing pressure is still too high for some fish stocks, others have not rebounded as quickly as projected, and many stocks have not been assessed.

Much of the variation reflects a mismatch between the current prescriptions for rebuilding within a limited time frame and the uncertainties inherent in assessing and managing fisheries given data limitations and complex ecosystem dynamics where fishing is only one of many influences on fish populations. Because climate change and other ecological factors can also drive changes in fish stocks, rebuilding fish populations within a certain time frame cannot be assured.

The report identifies strategies for accommodating these uncertainties that could lessen short-term economic and social impacts for the fishing industry and communities while still promoting rebuilding.

The study was funded by the National Oceanic and Atmospheric Administration.

A Different Approach to Damage Assessment

Shrimp boat captain sorts his catch after a delayed opening to the 2010 commercial shrimp season, U.S. Coast Guard photo by Petty Officer 3rd Class Nathan BradshawSince the 2011 Deepwater Horizon oil spill, federal, state, and local policymakers have been grappling with the difficult task of restoring the ocean and coastal ecosystems in the region to the condition they would have been before the spill. None of the agencies has ever been faced with a spill affecting such a wide area and broad range of ecosystems.

The extent and severity of these impacts and the value of the resulting losses cannot fully be measured without considering the goods and services provided by the Gulf, says An Ecosystem Services Approach to Assessing the Impacts of the Deepwater Horizon Oil Spill in the Gulf of Mexico. The National Research Council report offers an approach that could establish a more comprehensive understanding of the impacts and help inform options for restoration activities.

The impacts of environmental damage extend beyond individual resources such as number of fish killed or acres of wetland destroyed -- the kind of measures traditionally called for under current law, the report says. Rather, an ecosystemwide approach to damage assessment is needed, which requires an understanding of the environmental impacts from a disruption, the resulting decrease in ecosystem goods and services, and the value of those losses to individual communities and society at large.

The report illustrates how this approach might be applied to coastal wetlands, fisheries, marine mammals, and the deep sea -- each of which provide key services in the Gulf. Many may have enormous value despite being difficult to measure, and such services should be given adequate consideration in evaluating restoration options.

The study was funded by the National Oceanic and Atmospheric Administration.

Improved Flood Insurance Program

North Dakota flooding in 2011, photo by Andrea Booher/FEMAProperties located in floodplains but protected by an accredited levee system -- one built to withstand the kind of flood that has only a 1 percent chance of happening each year -- are exempt from the requirement to buy flood insurance. However, with the modernization of flood mapping, it has become apparent that some accredited levees no longer meet the standard of protecting against a "1 percent annual chance" flood.

In establishing flood insurance premium rates, the Federal Emergency Management Agency considers a non-accredited levee to be the same as no levee at all; this means that communities protected by levees that do not meet the standard would be considered "without levee" and required to buy flood insurance at the same rates as those with no levees. At the urging of Congress, FEMA was asked to replace its current "without levee" approach with one that would better reflect the flood risk in areas impacted by non-accredited levees. In response, FEMA is developing a new approach, the Levee Analysis and Mapping Procedure (LAMP).

Levees and the National Flood Insurance Program: Improving Policies and Practices, a report from the National Research Council, recommends a more modern approach to analyzing and managing flood risk behind levees -- one that would better inform public officials and give individual property owners a clearer idea of the risks they face. Although the LAMP approach is technically sound, it is a short-term response and is not based on modern risk-based analysis.

The report recommends flood risk analysis that would use 21st century computational and mapping techniques to produce state-of-the-art risk estimates for all areas that are vulnerable to flooding. It would assess how well levee systems are likely to perform, taking into account the probabilities that the many components of a system will function as designed. The report also proposes interim steps to deal with non-accredited levees.

The study was funded by the U.S. Federal Emergency Management Agency.

Management of Wild Horses and Burros

Wild horse roundup, photo courtesy Bureau of Land Management/Rocks Springs Field Office, WyomingIn 1971 Congress tasked the Bureau of Land Management with protecting and managing the wild horse and burro populations living on western public lands. BLM is also responsible for managing the lands for other uses -- such as recreation, forestry, mining, and wildlife habitat -- and maintaining a "thriving natural ecological balance."

To try to address these many responsibilities, BLM established Herd Management Areas and limits wild horses and burros to those areas. When crowding or habitat destruction becomes a concern, some horses and burros are removed and offered for adoption. Most are not adopted, however, and the expense of maintaining the relocated animals in long-term holding facilities consumes about half the Wild Horse and Burro program's budget.

The National Research Council report Using Science to Improve the BLM Wild Horse and Burro Program: A Way Forward concludes that continuing "business as usual" will be expensive and unproductive. Compelling evidence exists that there are more horses and burros on public rangelands than BLM has estimated, and that population growth rates are high -- 15 percent to 20 percent annually for most herds.

BLM could improve its estimates of population size by continuing its collaboration with the U.S. Geological Survey to conduct regular surveys of horse and burro populations using scientific methods. More accurate population estimates could be used with modeling to predict the results of management actions. BLM could also make greater use of fertility-control methods to lower population growth rates. Using these and other scientific management approaches consistently and communicating them transparently with the public could help increase public confidence in the program.

The study was funded by the Bureau of Land Management.