Science Behind the Tool
Click on a quick link below to learn more about the science behind our tools:
Risk Zone Map
The research behind the Risk Zone Map is based on peer-reviewed science. That 2012 analysis used the best available national coverage elevation dataset at the time. Risk Zone Map now uses far more accurate laser-based (LiDAR) elevation data.
The research behind the Surging Seas Risk Finder is based on peer-reviewed science. One core study, published in 2012, projects local sea level rise and coastal flood risk; the other study (same year) maps and assesses exposure to sea level rise. Risk Finder improves on both studies by adding updated sea level projections and data.
Updated Mapping and Exposure Analysis
- Improved elevation data: Our 2012 analysis used the best available national coverage elevation dataset at the time. This analysis uses far more accurate laser-based (LiDAR) elevation data.
- Over 100 additional variables: Our 2012 research assessed land, population and housing vulnerable to sea level rise and coastal flooding. This research assesses over 100 additional variables, including socially vulnerable population, populations by racial and ethnic group, property value, roads, rail, airports, power plants, sewage plants, hazardous waste sites, schools, churches, and hospitals.
- Additional administrative areas: Our 2012 analysis tabulated exposure at state, county, and city levels. This analysis adds zip codes, planning areas, congressional districts, state legislative districts, and many county- and city-level districts.
Updated Sea Level Rise Projections
For sea level rise projections, this analysis uses updated scenarios for future emissions of carbon pollution, as developed by the global climate research community. We use updated models of the global warming expected from these emissions, and a selection of global sea level rise models, instead of just one. We then factor in local effects, such as sinking land, to develop local sea level rise projections, employing the same methods as in our original peer-reviewed research.
Updated Storm Surge Risk Methods / Capability
We also carry forward the same methods we previously used to characterize storm surge risk, and integrate it with projected sea levels, to develop projections of overall local flood risk by decade. However, we have updated analysis inputs to include the full available record of hourly water levels at each water level station through the end of 2012. This means 48-102 years of data (depending on the station) instead of 30 years (as in the original analysis), and that Sandy’s surge is factored in when developing risk statistics.
Mapping Choices is based on peer-reviewed scientific research led by Climate Central and published in the Proceedings of the National Academy of Sciences of the U.S.A.
Carbon pollution casts a long shadow. It is expected to persist in the atmosphere long enough to prolong temperature increases for hundreds and thousands of years, long after we stop burning fossil fuels or clearing forests. Our research first translates cumulative carbon emissions into locked-in long-term global temperature increases, and then translates these into locked-in sea level rise projections.
The sea level projections are based on four separate models for the expansion of ocean water as it warms; melting glaciers; and the decay of Greenland and Antarctic ice sheets. We develop local projections that can vary by several feet from the global average based mainly on changing gravity fields as the polar ice sheets lose mass. (Local projections shown do not factor in the continuation of current land subsidence or uplift. In most places, these might translate to inches per century, but some places, such as southeastern Louisiana, are sinking closer to one foot per century.)
Some research has suggested that the West Antarctic Ice Sheet has begun an unstoppable collapse, but the evidence is far from conclusive. The maps in Mapping Choices do not assume inevitable West Antarctic collapse. If collapse has in fact begun, all locked-in sea levels would be higher than shown. Carbon emissions levels would still influence all outcomes. These scenarios of inevitable collapse are detailed in the PNAS paper.