 |
| Titel |
Coupled Northern Hemisphere permafrost–ice-sheet evolution over the last glacial cycle |
| VerfasserIn |
M. Willeit, A. Ganopolski |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1814-9324
|
| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 9 ; Nr. 11, no. 9 (2015-09-18), S.1165-1180 |
| Datensatznummer |
250117403
|
| Publikation (Nr.) |
 copernicus.org/cp-11-1165-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
Permafrost influences a number of processes which are relevant for
local and global climate. For example, it is well known that
permafrost plays an important role in global carbon and methane
cycles. Less is known about the interaction between permafrost and
ice sheets. In this study a permafrost module is included in the
Earth system model CLIMBER-2, and the coupled Northern Hemisphere
(NH) permafrost–ice-sheet evolution over the last glacial cycle is
explored.
The model performs generally well at reproducing present-day
permafrost extent and thickness. Modeled permafrost thickness is
sensitive to the values of ground porosity, thermal conductivity and
geothermal heat flux. Permafrost extent at the Last Glacial Maximum
(LGM) agrees well with reconstructions and previous modeling
estimates.
Present-day permafrost thickness is far from equilibrium over deep
permafrost regions. Over central Siberia and the Arctic Archipelago
permafrost is presently up to 200–500 m thicker than it
would be at equilibrium. In these areas, present-day permafrost
depth strongly depends on the past climate history and simulations
indicate that deep permafrost has a memory of surface temperature
variations going back to at least 800 ka.
Over the last glacial cycle permafrost has a relatively modest
impact on simulated NH ice sheet volume except at LGM, when
including permafrost increases ice volume by about 15 m sea
level equivalent in our model. This is explained by a delayed melting
of the ice base from below by the geothermal heat flux when the ice
sheet sits on a porous sediment layer and permafrost has to be melted
first. Permafrost affects ice sheet dynamics only when ice extends
over areas covered by thick sediments, which is the case at LGM. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|