US coastal communities underestimate the danger posed by rising seas
Local guidance in many coastal regions is inconsistent with the latest climate science, analysis shows.
More than half of US coastal communities are underestimating the rise in sea levels that global warming might cause in their regions, according to a study. In what they call a first-of-its-kind analysis, researchers reviewed dozens of documents — the current assessments of sea-level rise for more than 50 coastal locations — and found that many of the predictions had gaps, including not considering worst-case scenarios. They reported their findings on 23 January in Earth’s Future.
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Gaps in knowledge
“Planning for future sea-level rise is difficult,” says Andra Garner, a climate scientist at Rowan University in Glassboro, New Jersey, and a co-author of the study. Many variables must be considered to predict the extent to which water levels will increase. Some rise is inevitable, given that Earth’s temperature has already risen by around 1.1 ℃ compared with pre-industrial levels, thawing permafrost and melting ice sheets. Sea levels have responded by rising by about 20 centimetres in the past century. But some variables hinge on future greenhouse-gas emissions, which depend on the climate actions that governments take, and are therefore harder to predict.
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Risk tolerance
Assessing the full range of projections and timescales is beneficial because different projects have different risk tolerances, says Peter Ruggiero, principal investigator and co-director of the Cascadia Coastline and Peoples Hazards Research Hub, a network of scientists in Washington, Oregon and northern California funded by the US National Science Foundation. Garner explains that a power station near the coast, for example, would have a lower risk tolerance than a project such as a city park, because the power station would be likely to sustain greater damage from additional sea-level rise. Projects with a low risk tolerance therefore benefit from considering less probable — but more damaging — scenarios.
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