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| Titel |
Temperature trends during the Present and Last interglacial periods - A multi-model-data comparison |
| VerfasserIn |
Pepijn Bakker, Valérie Masson-Delmotte, Belen Martrat, Sylvie Charbit, Hans RENSSEN |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082035
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| Zusammenfassung |
| We present the first multi-model-data comparison of transient millennial-scale temperature
changes through the Present and Last interglacial periods (PIG and LIG respectively).
Though primarily driven by insolation changes associated with well-known variations in
Earth’s orbital parameters, the response of the climate system includes a diversity of
feedbacks involving the atmosphere, ocean, sea ice, vegetation and land ice. A thorough
multi-model-data comparison is essential to assess the ability of climate models to resolve
interglacial climate trends and to help in understanding the recorded climatic signal and the
underlying climate dynamics.
During the last decade, substantial progress has been made by documenting past climate
variability from new archives with improved chronologies for the PIG and LIG periods. In
parallel, the increased computing capacities as well as the development of computationally
efficient climate models have enabled transient multi-millennial climate simulations. This
allows us to compare PIG and LIG multi-millennial temperature trends derived from transient
climate experiments (9 different climate models) with alkenone-based temperature
reconstructions (117 locations globally distributed; about 45% of them with the LIG interval)
and ice-core-based temperature profiles from Greenland and Antarctica (12 sites; 6 include
the LIG).
Our analysis shows that in Greenland and Antarctica the multi-model-mean temperature
trends for the warmest months compare well with ice-core based temperature reconstructions.
Regarding reconstructed annual mean temperatures based on alkenone-data, models
and data are in reasonable agreement with some exceptions at high-latitude areas.
The next step in the analysis is to assess whether the simulated warmest month
temperature trends of the PIG and LIG periods are linearly scaled to the orbital forcing. In
the Northern Hemisphere the models consistently show a linear response to the
trends in the insolation forcing for both interglacial periods. The exceptions are the
Arctic region, where the simulated trend are relatively small compared to that of
the insolation signal and the Sahel and Indian regions where a negative relation
is observed. For the Southern Hemisphere climate models are consistent in the
simulated warmest month temperature trends but the relation with the insolation
trends is more complex. We find a positive relation over South America and Africa,
and a positive though strongly dampened response over the low and mid-latitude
oceans of the Southern Hemisphere. However, despite the positive trend in the
warmest month insolation forcing, which is especially large in the LIG period,
the simulations lack any substantial temperature changes for the Southern Ocean
and the Antarctic region. This suggests that, regardless of the large differences
in model-complexity, the climate models consistently show that the increase in
summer insolation is balanced out by a considerable growth of the Southern Ocean
sea-ice cover resulting from obliquity-related changes in the seasonal distribution of
insolation. |
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