How Does Sea Level Rise Affect Us? Learning from New Jersey

Over the last century, sea levels in New Jersey have risen about 1.4 feet, due to both natural forces and groundwater pumping. The global average has been almost 8 inches. What does this mean for New Jersey residents? The effects of sea level rise will be felt in their daily lives, making coastal flooding more frequent even with fewer tides or storms. Data shows that the frequency of minor tidal flooding has increased since the mid-20th century in New Jersey. And due to sea levels rising, according to Rutgers University, about 40,000 people in New Jersey were exposed to Superstorm Sandy’s floodwaters, who otherwise would not have been affected.

Regulatory Measures for Sea-level Rise in New Jersey

The New Jersey Department of Environmental Protection (NJDEP) provides a set of guidelines to plan for and mitigate these impacts, recommending the use of the year 2100 as a planning horizon for decision-makers in general. NJDEP provides a range of scientific bases for sea level rise projections for planning purposes, a general framework outlining core principles and adaptive management strategies for moving forward. The underlying premise is that over the next 30 years, future reductions in greenhouse gas (GHG) emissions will not significantly alter the trajectory of sea level rise. However, in the longer term (over the next fifty to seventy years) there would be substantial benefits from reducing GHG emissions. By the end of the century, NJDEP predicts?a most likely range of sea level rise of the Jersey Shore to be 3-4 feet, with a full range of 2-7 feet. The latter, wider range, reflects the possibility that as temperature increases, there is a potential for sea level rise to reach higher levels, while lower emissions scenarios are more likely to result in the lower end of that range.

What do These Different Scenarios Mean from a Planning Perspective?

In technical terms, the NJDEP guidance recommends that planners analyze (1) 2 feet of sea level rise that is likely unavoidable, (2) 5.1 feet of sea level rise sufficient to plan for most activities in a community, and (3) a high-end estimate of 6.9 feet for those critical activities for which damages would have debilitating effects on public health and safety. These planning benchmarks are based on the relative risk tolerance of an activity, which is assessed by considering how the potential consequence of the activity being impacted by sea-level rise. Most residential and commercial properties fall under the category of ‘less risk tolerance’ and are advised to utilize the 5.1 feet sea level rise planning benchmark. This standard represents the upper end of the likely range in the moderate emissions scenario for 2100, reflecting a 17 percent chance of being met or exceeded.

Activities and Assets Associated with the SLR Planning Benchmarks

Once the types of activities and assets are evaluated using relevant sea-level rise projections, hazard mitigation plans need to be made accordingly, to address public safety and safeguard public investments. It should address concerns related to consistency and coordination, ensure a cohesive approach, and lead to appropriate adaptation pathways and management strategies. The planning process may require a multi-faceted comprehensive approach, incorporating land use planning, infrastructure improvements, and community engagement. For example, these may include approaches to enforce floodplain management regulations in flood-prone areas and preserve natural floodplains. Such efforts would involve establishing or updating zoning ordinances or building codes to minimize exposure to flood risk.

During the planning process, what’s worth noting is that the importance of aligning goals, policies, and strategies at the local, county, and regional levels is increasingly recognized, and active efforts are being made accordingly. For example, the New Jersey Office of Planning Advocacy (NJOPA) launched the “Plan Endorsement” process, a statewide program officially recognized by the New Jersey State Planning Commission, to ensure that local, county, regional, and state agency plans are consistent with the State Development and Redevelopment Plan (State Plan). The program benefits applying entities through state capital investments, technical assistance, priority for state grants and loans, and regulatory changes to implement the endorsed plan.

Different Implications for Urban vs. Coastal Areas

Beyond coastal flooding, urban areas are also prone to riverine floods and pluvial floods. As discussed above, coastal floods are the inundation of land areas caused by tides, waves, and storm surges, the risk of which stem from proximity to the ocean. In urban areas, communities are more prone to flash floods or riverine floods (situated along rivers or in low-lying areas). Pluvial floods (or flash floods), a type of inland flooding, occur during heavy rainfalls and form in flat, impervious surface areas where the terrain cannot absorb rainwater. The terrain profile and the intensity of rainfall usually determine the severity of pluvial floods. For example, urban areas will have more significant damage than rural areas having less soil to soak up the water.

Urban areas are also subject to the aforementioned planning standards and regulations–however, they may require slightly different strategies for mitigation due to differences in the built and natural environment. Urban areas usually have denser infrastructure networks, including buildings, roads, and utilities, and experience more concentrated economic activity with higher population density. One example of a strategy is nature-based solutions, which have recently gained attention as an effective approach to addressing flooding issues. Implementing green infrastructure practices, such as rain gardens, permeable pavement, green roofs, and urban forests, is an alternative to traditional grey infrastructure for managing stormwater in urban areas.

As such, many new approaches can be adopted to mitigate flooding impacts. This article is a broad overview of how sea level rise could impact communities and households, ways to mitigate these impacts from a policy and planning standpoint, and the varying implications for urban and coastal areas. Sea level rise will influence communities in various aspects, including infrastructure, land use, and property taxes, and understanding the risks associated with it will be an important first step in mitigating these impacts.