Draft Outline for Fourth U.S. National Climate Assessment Released

The Fourth National Climate Assessment (NCA4) is scheduled to be released in 2018, as mandated under the Global Change Research Act of 1990, which requires a quadrennial assessment report to the President and Congress. In anticipation of facilitating a national process to write the next NCA, the U.S. Global Change Research Program recently released a draft outline for the high-level report.

Emphasis on Regional Information

A Federal Register Notice published in late July presents an outline for NCA4 that is similar in structure to the Third National Climate Assessment (2014). The outline suggests NCA4 will place a stronger emphasis on how climate change is affecting each region of the U.S. and the potential impacts and adaptation for specific sectors within regions.

The regions themselves are essentially the same as in NCA3, with the exception of the Great Plains region, which is vast, and will be divided into the Northern Great Plains and Southern Great Plains.

Integrating Themes

To address gaps and needs identified in NCA3, several overarching themes are proposed for the Fourth National Climate Assessment. They include, for example:

  • Highlighting advancements and improvements in scientific understanding of human-induced climate change
  • Identifying populations of concern for the risks and potential impacts
  • Describing current and future risks with quantifiable metrics wherever possible
  • Consistently featuring timeframes of interest, including near-term (next few decades), long-term (end-of-century), and in some cases, legacy (well past 2100).

Topic Areas

The National Climate Assessment is mandated to address a specific set of topics of national interest: effects of global change on the natural environment; agriculture; energy production and use; land and water resources; human health and welfare; human social systems; and, biological diversity.

Further, the following additional topics are proposed for inclusion in NCA4: effects on tribal and indigenous communities; coastal effects; ocean acidification and marine resources; and, key international effects, particularly those with environmental, humanitarian, trade, or security implications for the United States. Cross-sectoral issues are also being proposed in NCA4; these may include: the water-energy-land nexus; the interactions among biodiversity, land use, and climate; and linkages between air quality and climate.”

Of these, ocean acidification and marine resources, and international effects are new topics proposed for the national-level chapter.

Full Outline

The full description of the proposed outline for NCA4 is available as Supplementary Information for the Federal Register Notice (FR Doc. 2016-15807 Filed 7-1-16; 8:45 am). That Supplementary Information, in its entirety is offered here:

USGCRP is mandated under the Global Change Research Act (GCRA) of 1990 to conduct a quadrennial NCA. Under its current decadal strategic plan (http://go.usa.gov/3qGU4), USGCRP is building sustained assessment capacity to support the Nation’s ability to understand, anticipate, and respond to risks and potential impacts brought about by global environmental change, namely the human-caused buildup of greenhouse gases in our atmosphere that is causing climate change. The last NCA from 2014 (NCA3: http://nca2014.globalchange.gov) and the process to develop it provide a foundation for subsequent activities and reports.

Recent special assessments by the U.S. Government will be utilized for NCA4, including: The Impacts of Climate Change on Human Health in the United States (https://health2016.globalchange.gov/); Climate Change, Global Food Security, and the U.S. Food System (http://www.usda.gov/oce/climate_change/FoodSecurity.htm); and Effects of Drought on Forests and Rangelands in the United States (http://www.fs.fed.us/science-technology/climate-change/drought-forests-and-rangelands). Other USGCRP special reports under development include the Second State of the Carbon Cycle Report (SOCCR-2, https://www.carboncyclescience.us/news/federal-register-notice-2nd-state-carbon-cycle-report-soccr-2) and the Climate Science Special Report (CSSR, https://www.federalregister.gov/articles/2016/03/31/2016-07208/united-states-global-change-research-program).

There will be a number of overarching themes and perspectives in NCA4 that are, in part, responsive to needs and gaps identified in NCA3. The following are likely to be such themes throughout NCA4:

  • NCA4 will attempt to highlight advancements or improvements, since NCA3, in understanding of the science of human-induced climate change and the resulting implications for the United States.
  • For risks and potential impacts, NCA4 will identify populations of concern, which was a theme highlighted in The Impacts of Climate Change on Human Health in the United States (2016).
  • Major research needs, key uncertainties, and information gaps will be identified.
  • Current and future risks associated with climate change will be characterized with quantifiable metrics wherever possible, and with the needs of multiple audiences in mind.
  • Consistent treatment of different timeframes of interest will be sought throughout NCA4, with emphasis on the near-term (e.,over the next few decades) trends and projections to inform adaptation needs, the long-term (i.e., latter half of this century) projections that are more scenario dependent, and in some cases timeframes well past 2100 to indicate legacy effects of the human influence on the climate and oceans.

Comments are sought on these proposed overarching themes. Additional suggestions will be reviewed as they relate to the proposed structure of the report.

What follows is a proposed high-level and draft annotated outline intended to guide the scope and content for NCA4. Public comments are sought on all aspects of this draft outline. The proposed outline is presented here in five parts: (1) Introduction and context for NCA4; (2) the foundational physical science; (3) human health and welfare, societal and environmental areas that are vulnerable to a changing climate; (4) regional analyses within the United States; and (5) identifying the information needed to support climate change adaptation, increased resiliency, and risk reduction.

1.  Introduction and Context for NCA4

The introductory and context-setting sections of the NCA4 will describe:

  • Context for the NCA4 as noted above, including the NCA’s relation to complementary domestic and international assessment efforts.
  • Advancements in science since NCA3 (2014), as well as any new approaches or differences in scope relative to NCA3. This information will include the special assessments completed or in-progress post-NCA3, in particular those under the auspices of USGCRP (some examples of these special assessments are provided throughout this notice).
  • Changing global and national conditions that influence (1) drivers of climate change, namely the activities that lead to emissions and thus the atmospheric buildup of greenhouse gas concentrations; and (2) resiliency and vulnerabilities, such as demographic change and economic development.
  • The geographic scope (see section 5) and the temporal scope (g.,recent historic to next 25 to 100 years) of NCA4. The lexicon used for the confidence and uncertainty levels associated with key statements and findings (and accompanying traceable accounts) may be similar to that used in the recent climate change and human health assessment (https://health2016.globalchange.gov/documenting-uncertainty).
2. The Foundational Physical Science (Based on the Climate Science Special Report)

The USGCRP is in the process of developing the Climate Science Special Report (CSSR). The CSSR will highlight advances in the physical science of climate change since NCA3 (2014), and will provide the primary scientific underpinnings and framing for the entire NCA4. The Federal Register Notice for the CSSR can be found at https://www.federalregister.gov/articles/2016/03/31/2016-07208/united-states-global-change-research-program. To briefly summarize here, it will generally cover:

  • Observations of changes in: Atmospheric composition, radiative forcing, temperature, precipitation, large-scale climate modes (g.,El Nino events), drought, floods and associated hydrologic events (streamflow, snowpack), sea level rise, ice sheet dynamics, biogeochemistry of land and marine systems, climate variability, ocean acidification, extreme storms such as hurricanes, atmospheric rivers, polar changes including permafrost and land-ice dynamics, and attribution of physical and biophysical processes to human activities.
  • Future projections of changes in the aforementioned climate system processes will be based on modeling results of the Coupled Modeled Intercomparison Project Phase 5 (CMIP5) driven by the emissions scenarios and Representative Concentration Pathways (RCPs) as used in the IPCC Fifth Assessment Report (g.,http://sedac.ipcc-data.org/ddc/ar5_scenario_process/RCPs.html). Future projections will include perspectives on mitigation pathways.
3.  Human Health and Welfare, Societal and Environmental Vulnerabilities to a Changing Climate

This section of NCA4 will provide national-level overviews of observed and projected future trends and potential effects in key areas of concern for people and the environment, including human health, social well being, and natural systems. These same areas will be addressed to varying degrees in each of the regional sections of the outline described under Part 4.

Within each of these areas, non-climatic trends (e.g., population changes) will be briefly discussed in order to set a broader context within which climate change effects can be understood. Observed and projected risks, impacts and potential benefits as a result of climate change will be identified in each of these areas, with quantifiable metrics wherever possible. The role of extreme events in each area will be addressed where possible. In addition, potential adaptive measures to minimize risks will be described for each area, to the extent these are identified in the published literature.

The GCRA of 1990 requires that the NCA analyze “the effects of global change on the natural environment, agriculture, energy production and use, land and water resources, transportation, human health and welfare, human social systems, and biological diversity.”

In addition to these mandated topics, the following additional specific areas are proposed for inclusion in NCA4: Effects on tribal and indigenous communities; coastal effects; ocean acidification and marine resources; and key international effects, particularly those that may raise environmental, humanitarian, trade, or security issues for the United States. Cross-sectoral issues where interactions can result in significant effects are also being proposed in this section of NCA4; these potentially include (but are not limited to): The water-energy-land nexus; the interactions among biodiversity, land use, and climate; and linkages between air quality and climate.

4.  Regional Analyses Within the United States

Under this proposed outline, the regional detail for each of the areas described in Part 3 above will be placed in this section of the report. In other words, Part 3 will provide more generalized information at a national level, whereas Part 4 will go into greater depth to provide information at sub-national and regional levels.

NCA3 included the following regions of the United States (see http://nca2014.globalchange.gov/report#section-1948): Northeast, Southeast and the Caribbean, Midwest, Great Plains, Southwest, Northwest, Alaska, Hawaii and Pacific Islands, Oceans and Coasts. The proposed regional breakout for NCA4 is the same with the exception of the Great Plains; because that was such a large region, stretching from the Gulf Coast to the Canadian border, it will be divided into two regions: Northern and Southern Plains.

In addition to the themes for each area described in Part 3, the regional sections in Part 4 will also include State-level information as appropriate and where available, as well as urban and rural case studies where possible to showcase, with local specificity, climate trends, potential risks, and resiliency planning.

5.  Identifying the Information Needed To Support Climate Change Adaptation, Increased Resiliency, and Risk Reduction

This part of NCA4 will focus on identifying near-term needs and opportunities for adaptive measures and resiliency planning in the face of observed and projected changes in climate, as well as the dependency of risk and potential impacts on greenhouse gas emissions scenarios over the longer term. NCA4 is not a policy document, and as such will not be evaluating policy measures, actions, instruments or mechanisms to deliver or incentivize either adaptation or mitigation responses at any level of government. Rather, the intention of this part of NCA4 is to inform the Nation, and different regions within the Nation, about near-term adaptation needs over the next few decades that are likely to persist regardless of emissions pathway, and, over the longer term, the reduced and/or avoided levels of risks and impacts in the United States, as a result of different levels of global greenhouse gas mitigation.

Adaptation needs and opportunities will be drawn from relevant information from Parts 2, 3 and 4 as outlined above.

In addition to physical metrics of changing risks and potential impacts over time under different greenhouse gas emissions scenarios, analysis of costs of adaptation options and potential impacts (or avoided impacts) will be included where possible, in part with input from recent EPA efforts, such as the report on Climate Change in the United States: Benefits of Global Action (https://www.epa.gov/cira).

Case studies and links to decision-support tools (e.g., the Climate Resilience Toolkit, http://toolkit.climate.gov) will also be included here.

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