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EPA no longer updates EPA's Global Warming Site, but is maintaining this archive for historical purposes. Please see EPA's Climate Change site for current information on climate change and global warming.
Forthcoming Products
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EPA is developing two types of map products, which will become available to the public over the next year.
Elevation MapsState Maps. An EPA Study recently published in the journal Climate Research provides maps at the scale of entire states, that depict the shoreline, 1.5-meter, and 3.5-meter contours, for the US Atlantic and Gulf Coasts. A key data source for this project was the USGS 1-degree digital elevation model. The underlying GIS files are online for an example site, so that you can see if this data is useful. The entire data set is available for anyone conducting an assessment where this relatively coarse resolution is sufficient (e.g., public information activities, regional assessments where results will be reported at the state level).
Local Maps. (1:24,000 scale). Assessing the impacts of sea level rise requires better vertical and horizontal resolution than the maps prepared by the 1-degree mapping project. Because sea level is only expected to rise about 50 cm in the next century, the 1.5- and 3.5-meter contours provide a rough approximation of the land vulnerable to sea level rise. Moreover, the state-scale maps provided only approximate locations of even those contours, because the USGS 1-degree maps generally have 5-meter contour intervals at a 1:250,000 scale.
EPA is developing digital elevation maps for the U.S. coastal zone. Those maps will use the best elevation information that is reasonably obtainable, which may often require a mosaic of several different sources, including USGS digital line graphs (DLGs), National Wetlands Inventory Data, Corps of Engineers spot elevation data, County elevation data, State wetlands and topographic data, DLG's created from printed USGS 7.5-minute quadrangles, and DLG's created by the local topographic maps that some communities submitted to FEMA in support of the Federal Flood Insurance Rate Maps. As a general rule, we rely on USGS DLG's or printed maps when they have 1-meter or 5-foot contour intervals, but we seek alternative elevation information for areas where the USGS maps have 10- and 20-foot contours.
The EPA elevation maps differ from most topographic maps in one key feature: we use wetlands maps as well as topographic maps. The maps will be provided in two separate formats, elevations relative to National Geodetic Vertical Datum (also used by topographic maps), and elevations relative to mean spring high water. Wetlands data provides us with the location of mean spring high water (MSHW), that is, the upper edge of tidal wetlands. For example, if MSHW has an elevation of 2 feet in a given area, we know that the land inundated by a 3-foot rise in sea level would be all the land between MSHW and the 5-foot contour. Without the wetlands data, we would have to interpolate between the shoreline and the 5-foot contour.
Although our objective is to provide elevation maps for all parts of the coastal zone, the difficulty of this task limits us to only a few states per year. We are focusing our initial efforts on areas where either very good data is available or a state or local government has requested our assistance. We will continue to be as responsive as possible to other coastal governments requesting technical assistance. In addition, we are interested in collaborating with other projects where combining our efforts will allow us to produce a more accurate product, map a larger area, and avoid duplicative efforts. Those interested in cooperative efforts should email the EPA sea level rise project manager.
Complete and Under Review: Delaware, Maryland, Virginia
In Progress: New Jersey, North Carolina
Planned for Next Year: South Carolina, Southwest Florida, Georgia, areas where cooperators seek assistance.
Sea Level Rise Planning MapsEPA is also developing maps that depict –at the county level– the land likely to be protected from rising sea level and the land likely to be inundated. EPA is developing these maps both to improve assessments of the impacts, and to help coastal decision makers plan for sea level rise.
Responses to sea level rise generally fall into three categories: elevate the land and beaches, hold back the sea with dikes and pumping systems, or allow the shore to retreat naturally. Although any one of these ptions may be appropriate for a given community, a coherent response is generally not feasible unless a community decides which of those three pathways it intends to follow. EPA is working with county planners in coastal states to make first-cut assessments of the areas likely to be protected under existing policies. Those maps may be a starting point that enables communities to consider whether or not they are satisfied with the expected long-term results of current policies; and the maps will be adjusted as necessary. Once complete, they can serve as a guide to ensure that infrastructure, homes, and erosion-control activities are generally consistent with the long-term response to sea level rise.
The maps will also allow for more realistic assessments of sea level rise. Published assessments and popular accounts tend to use maps depicting all the land that is low enough to be flooded–as if we would abandon our coastal cities. These maps will provide more realistic and less alarming graphics of the implications of global warming. Moreover, the environmental consequences of sea level rise are poorly understood in part because the adaptive responses, such as bulkheads and beach nourishment, may have a greater impact than the higher water level itself. Only when the likely response is fully mapped will it be possible for ecosystem modelers to assess the likely impact, or for environmental planners to determine whether current policies must be modified.
Complete and Under Review: Delaware, Rhode Island, North Carolina
In Progress: Maryland, Virginia, New Jersey, South Carolina, Georgia, Southwest Florida
Planned for Next Year: New York, Massachusetts, Texas, Alabama, Mississippi, South Florida
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