TY - JOUR

T1 - Sea-level rise in Denmark

T2 - paleo context, recent projections and policy implications

AU - Colgan, William

AU - Henriksen, Hans Jørgen

AU - Bennike, Ole

AU - Ribeiro, Sofia

AU - Keiding, Marie

AU - Seidenfaden, Ida Karlsson

AU - Graversgaard, Morten

AU - Busck, Anne Gravsholt

AU - Fruergaard, Mikkel

AU - Knudsen, Michael Helt

AU - Hopper, John

AU - Sonnenborg, Torben

AU - Skjerbæk, Maria Rebekka

AU - Bjørk, Anders Anker

AU - Steffen, Holger

AU - Tarasov, Lev

AU - Nerem, R. Steven

AU - Kjeldsen, Kristian K.

N1 - Publisher Copyright: © 2022, GEUS - Geological Survey of Denmark and Greenland. All rights reserved.

PY - 2022

Y1 - 2022

N2 - We present the most recent Intergovernmental Panel on Climate Change Sixth Assessment Report (AR6) sea-level projections for four Danish cities (Aarhus, Copenhagen, Esbjerg and Hirtshals) under the Shared Socioeconomic Pathway (SSP) family of climate scenarios. These sea-level changes projected over the next century are up to an order of magnitude larger than those observed over the previous century. At these cities, year 2150 sea-level changes of between 29 and 55 cm are projected under the very low emissions scenario (SSP1-1.9), whilst changes of between 99 and 123 cm are projected under the very high emissions scenario (SSP5-8.5). These differences highlight the potentially significant impact of remaining opportunities for climate change mitigation. Due to this increase in mean sea level, the mean recurrence time between historically extreme events is expected to decrease. Under the very high emissions scenario, the historical 100-year storm flood event will become a 1-to 5-year event at most Danish harbours by 2100. There is considerable uncertainty associated with these sea-level projections, primarily driven by uncertainty in the future evolution of the Antarctic ice sheet and future sterodynamic changes in ocean volume. The AR6 characterises collapse of the West Antarctic ice sheet as a low-probability but high-impact event that could cause several metres of sea-level rise around Denmark by 2150. In climate adaptation policy, the scientific landscape is shifting fast. There has been a tremendous proliferation of diverse sea-level projections in recent years, with the most relevant planning target for Denmark increas-ing c. 50 cm in the past two decades. Translating sea-level rise projections into planning targets requires value judgments about acceptable sea-level risk that depend on local geography, planning timeline and climate pathway. This highlights the need for an overarching national sea-level adaptation plan to ensure municipal plans conform to risk and action standards.

AB - We present the most recent Intergovernmental Panel on Climate Change Sixth Assessment Report (AR6) sea-level projections for four Danish cities (Aarhus, Copenhagen, Esbjerg and Hirtshals) under the Shared Socioeconomic Pathway (SSP) family of climate scenarios. These sea-level changes projected over the next century are up to an order of magnitude larger than those observed over the previous century. At these cities, year 2150 sea-level changes of between 29 and 55 cm are projected under the very low emissions scenario (SSP1-1.9), whilst changes of between 99 and 123 cm are projected under the very high emissions scenario (SSP5-8.5). These differences highlight the potentially significant impact of remaining opportunities for climate change mitigation. Due to this increase in mean sea level, the mean recurrence time between historically extreme events is expected to decrease. Under the very high emissions scenario, the historical 100-year storm flood event will become a 1-to 5-year event at most Danish harbours by 2100. There is considerable uncertainty associated with these sea-level projections, primarily driven by uncertainty in the future evolution of the Antarctic ice sheet and future sterodynamic changes in ocean volume. The AR6 characterises collapse of the West Antarctic ice sheet as a low-probability but high-impact event that could cause several metres of sea-level rise around Denmark by 2150. In climate adaptation policy, the scientific landscape is shifting fast. There has been a tremendous proliferation of diverse sea-level projections in recent years, with the most relevant planning target for Denmark increas-ing c. 50 cm in the past two decades. Translating sea-level rise projections into planning targets requires value judgments about acceptable sea-level risk that depend on local geography, planning timeline and climate pathway. This highlights the need for an overarching national sea-level adaptation plan to ensure municipal plans conform to risk and action standards.

KW - climate scenario

KW - coast

KW - Denmark

KW - projection

KW - sea level

U2 - 10.34194/geusb.v49.8315

DO - 10.34194/geusb.v49.8315

M3 - Journal article

AN - SCOPUS:85139470838

VL - 49

JO - GEUS Bulletin

JF - GEUS Bulletin

SN - 2597-2162

M1 - 8315

ER -