Comparing Coastal Planner Expectations of Change to Climate Science Projections

Coastal planners' expectations of climate change play an important role in their assessment of potential risks, vulnerabilities, and adaptation strategies. This paper assesses coastal planners' expectations of climate change and compares their estimates to widely referenced climate science projections. It focuses on assessing expectations of the magnitude and uncertainty of global temperature and sea-level change by 2030 and the likelihood of four climate change impacts by the mid-to-late twenty-first century. A web-based questionnaire (n=137) was used to elicit coastal planner expectations of climate change in three coastal states (Alaska, Florida, and Maryland) across three levels of management (local, state, and non-government organizations). Findings indicate that over half of the planners were unsure of the magnitude of global temperature and sea-level rise (SLR). Among those who responded, planner estimates of the magnitude and uncertainty of global temperature and SLR are higher than climate science projections reviewed in this research. Roughly 80% of all participants believed that each of the four climate impacts were at least more likely than not' to occur. We discuss the consequences of these expectations for how climate risk, vulnerability, and adaptation are managed and suggest pathways for aligning expectations and facilitating adaptation.