Report 2004-6

Future Climate Scenarios for Olkiluoto with Emphasis on Permafrost

Cedercreutz, J.

English

72

951-652-132-0

This study is part of Posiva’s Safety Case for the long-term safety assessment of the nuclear waste repository to be constructed at Olkiluoto. The natural threats to the integrity of a nuclear waste repository are likely to be greatest during ingrowths and retreats of future ice sheets and the development of permafrost.The aim of the study was to search the literature for the newest research results concerning future climate scenarios in order to obtain relevant climate evolution for Olkiluoto as far as possible into the future. In practice this means up to 125-225 ka AP. Emphasis was put on examining permafrost occurrence and shoreline displacement during a glacial cycle.The Earth’s climate system is extremely complex. Many processes, feedback mechanisms and interdependencies are not fully understood. Predictions of future climate include uncertainties.Five future climate scenarios for Olkiluoto were established. Two scenarios were based on information on past ice ages and on simple models not including CO2. The other three scenarios were based on more intricate models that included CO2 concentrations of pre-industrial level, low fossil fuel contribution and high fossil fuel contribution, respectively.The scenarios showed that the current interglacial will last for at least a further 50 ka but that future climate development depends much on atmospheric CO2 concentration. Permafrost will occur at Olkiluoto before glaciations but will not reach repository depths.

Climate scenario, permafrost, ice age, nuclear waste repository, Olkiluoto

Future Climate Scenarios for Olkiluoto with Emphasis on Permafrost (pdf) (1.9 MB)