Sea-level rise is seen as one of the most threatening impacts of climate change. But most analyses have focused only on the direct impact of a change in sea level, such as the number of people at risk from coastal floods, and there's been little study of other, more indirect, consequences.
Looking only at direct impacts may, however, give a biased view of the real consequences of sea-level rise. When coastal regions are affected by a disaster such as a hurricane it is more important to know whether and how the region can bounce back rather than simply assess the number of damaged houses, crucial though this is. In the same way, and over longer timescales, assessing the direct impact of sea-level rise is necessary but is clearly not sufficient. It appears more important to know how sea-level rise can impair development, especially in the poorest regions of the world. To do so, the direct impacts of sea-level rise should be understood as one additional burden on the shoulders of societies and economies that are undergoing constant evolution and that are subject to many other factors.
This is a highly complex problem, and it is difficult to compare studies based on different assumptions. To clarify the situation, we have proposed a framework for investigating the impact of sea-level rise on economic growth via five identified channels through which sea level can affect the growth potential of coastal regions. These are: loss of coastal land, loss of infrastructure and physical capital, loss of social capital, additional costs incurred from extreme events and coastal floods, and increased funds needed to protect coasts.
The study shows how little we know about these channels, and how important it is to know more. In particular, it highlights the need for more research on each channel to be able to answer questions that are really policy-relevant. Who cares how many houses are threatened by sea-level rise if we do not know whether this process represents a significant threat to alleviating poverty and economic development in coastal regions?
About the author
Stéphane Hallegatte is an economist and lead climate-change specialist with the World Bank and Méteo-France. His research deals with climate change and natural-disaster management, and with the public policies needed for green economic growth.