Atlantic Sea-Level Rise: Adaptation to Imaginable Worst Case Climate Change (ATLANTIS)
by
Robert J. Nicholls
Flood Hazard Research Centre, Middlesex University, UK

The climate change impact literature is largely restricted to the projected modest global warming of the 21st century, and suggests that impacts on Europe will be significant but not dramatic. However, more severe climate change and post-2100 time frames strongly raise the chances of destabilization of (parts of) the climate system, such as a shut-down of the thermohaline circulation, a large-scale release of methane from clathrates, and a collapse of the West Antarctic Ice Sheet. Although the probabilities of these events are not zero, and people have expressed widespread concern about such possibilities, almost nothing is known about the consequences for society of these low-probability, high-consequence events.

ATLANTIS will investigate the implications of a 5-6 metre sea-level rise following the collapse of the West Antarctic Ice Sheet via case studies of the Rhone Delta, France, the Netherlands, and the Thames Estuary, UK. We restrict ourselves to sea-level rise because the impact on the natural system is relatively straightforward. We restrict ourselves to Western Europe because that is the area of expertise of the project team. However, the French, Dutch and English societies are sufficiently different to allow some generalisation of the findings of the case studies.

Because of the large uncertainties about future sea level, and the even greater uncertainties in the social structure and land use in the distant future, ATLANTIS will use only rough estimates of the changes in the natural system based largely on espert judgement. Hence, we will develop dense scenarios (storylines, or future histories) that are largely qualitative in nature, but do reflect, in an internally consistent manner, the complex implications of, say, having to abandon Marseille, Amsterdam or London. The proposed project thus focuses on what a 5-6 metre sea-level rise would "mean" to people rather than on the "facts".

The methodology will draw upon notions of social risk assessment derived from studies of earthquake prediction and nuclear winter. Common elements of such studies are: plausible scenarios that are of great social concern but cannot be readily quantified within a range of useful probabilities, effects across multiple sectors and regions analyses using multi-disciplinary research teams, and multi-stakeholder perspectives regarding responses to hazard, perceptions of risks and decision making.

While useful as a starting point, existing methodologies for low probability-high consequence risk assessment will need to be extended to apply to climate change. The major requirement is to examine the intersection between slowly evolving changes in the hazard (such as rising sea levels due to thermal expansion of the water), changes in underlying vulnerability (the coastal infrastructure and state of sea defences, for example), responses to disasters (the realisation of an extreme event such as a coastal storm and storm surge), and information about long-run risks. Stakeholders are not passive agents in accepting risks-and this becomes increasingly important for impacts timed for decades into the future.

Date received: August 15, 2002

Copyright © 2002 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caji-55.