Evaluation of emission reduction and other societal and environmental outcomes: Structured decision making for the Louisiana climate action plan

Climate action planning continues to accelerate rapidly across the globe as communities seek to prepare to thrive in an uncertain future. Climate action planning is a particularly contentious and complex topic in the southern United States, however, because of significant economic reliance on industries that contribute substantially to greenhouse gas emissions, and due to a complicated relationship between industry and persistent racial and economic inequities that contribute to distrust between communities, businesses, and state governments. Within the last decade, research efforts have begun to evaluate approaches used to develop city, state, and national-level climate action plans, finding that planning efforts are often as diverse as the localities they represent. Climate action planning processes that evaluate the potential implications of climate action on greenhouse gas emissions and societal values are often driven by either qualitative stakeholder engagement or by the results of numerical models. While both approaches are valuable, they also have limitations that can result in climate action plans that are unrealistic or unimplementable. Limited research is available that assesses planning efforts that integrate multiple evaluation methodologies. In this study, we evaluate the strengths and limitations of integrating qualitative and quantitative climate action evaluation methodologies in a planning process grounded in structured decision making using Louisiana as a case study. This mixed method planning approach applied both quantitative numerical models and qualitative expert elicitation to evaluate potential implications of climate action for Louisiana. We found that integration of approaches through a transparent, structured, and objectives-orientated process allowed for robust analysis of potential climate actions while engendering process buy-in across diverse stakeholder interests. This process ultimately resulted in the unanimous adoption of Louisiana's climate action plan, characterized by a wholistic and implementable set of climate actions balanced against the values of Louisianians. The process outlined in this study represents a replicable approach for other climate action planning efforts.

Climate change mitigation potential of Louisiana's coastal area: Current estimates and future projections

Coastal habitats can play an important role in climate change mitigation. As Louisiana implements its climate action plan and the restoration and risk-reduction projects outlined in its 2017 Louisiana Coastal Master Plan, it is critical to consider potential greenhouse gas (GHG) fluxes in coastal habitats. This study estimated the potential climate mitigation role of existing, converted, and restored coastal habitats for years 2005, 2020, 2025, 2030, and 2050, which align with the Governor of Louisiana's GHG reduction targets. An analytical framework was developed that considered (1) available scientific data on net ecosystem carbon balance fluxes per habitat and (2) habitat areas projected from modeling efforts used for the 2017 Louisiana Coastal Master Plan to estimate the net GHG flux of coastal area. The coastal area was estimated as net GHG sinks of -38.4 ± 10.6 and -43.2 ± 12.0 Tg CO₂ equivalents (CO₂ e) in 2005 and 2020, respectively. The coastal area was projected to remain a net GHG sink in 2025 and 2030, both with and without the implementation of Coastal Master Plan projects (means ranged from -25.3 to -34.2 Tg CO₂ e). By 2050, with model-projected wetland loss and conversion of coastal habitats to open water due to coastal erosion and relative sea level rise, Louisiana's coastal area was projected to become a net source of GHG emissions both with and without the Coastal Master Plan projects. However, in the year 2050, the Louisiana Coastal Master Plan project implementation was projected to avoid the release of +8.8 ± 1.3 Tg CO₂ e compared with an alternative with no action. Reduction in current and future stressors to coastal habitats, including impacts from sea level rise, as well as the implementation of restoration projects could help to ensure coastal areas remain a natural climate solution.

Voluntary Restoration: Mitigation's Silent Partner in the Quest to Reverse Coastal Wetland Loss in the USA

Coastal ecosystems are under pressure from a vast array of anthropogenic stressors, including development and climate change, resulting in significant habitat losses globally Conservation policies are often implemented with the intent of reducing habitat loss. However, losses already incurred will require restoration if ecosystem functions and services are to be recovered. The United States has a long history of wetland loss and recognizes that averting loss requires a multi-pronged approach including mitigation for regulated activities and non-mitigation (voluntary herein) restoration. The 1989 "No Net Loss" (NNL) policy stated the Federal government's intent that losses of wetlands would be offset by at least as many gains of wetlands. However, coastal wetlands losses result from both regulated and non-regulated activities. We examined the effectiveness of Federally funded, voluntary restoration efforts in helping avert losses of coastal wetlands by assessing: (1) What are the current and past trends in coastal wetland change in the U.S.?; and (2) How much and where are voluntary restoration efforts occurring? First, we calculated palustrine and estuarine wetland change in U.S. coastal shoreline counties using data from NOAA's Coastal Change Analysis Program, which integrates both types of potential losses and gains. We then synthesized available data on Federally funded, voluntary restoration of coastal wetlands. We found that from 1996 to 2010, the U.S. lost 139,552 acres (~565 km²) of estuarine wetlands (2.5% of 1996 area) and 336,922 acres (~1,363 km²) of palustrine wetlands (1.4%). From 2006 to 2015, restoration of 145,442 acres (~589 km²) of estuarine wetlands and 154,772 acres (~626 km²) of palustrine wetlands occurred. Further, wetland losses and restoration were not always geographically aligned, resulting in local and regional "winners" and "losers." While these restoration efforts have been considerable, restoration and mitigation collectively have not been able to keep pace with wetland losses; thus, reversing this trend will likely require greater investment in coastal habitat conservation and restoration efforts. We further conclude that "area restored," the most prevalent metric used to assess progress, is inadequate, as it does not necessarily equate to restoration of functions. Assessing the effectiveness of wetland restoration not just in the U.S., but globally, will require allocation of sufficient funding for long-term monitoring of restored wetland functions, as well as implementation of standardized methods for monitoring data collection, synthesis, interpretation, and application.