Greenland during the last interglacial: the relative importance of insolation and oceanic changes
Insolation changes during the Eemian (the last interglacial period, 129 000–116 000 years before present) resulted in warmer than present conditions in the Arctic region. The NEEM ice core record suggests warming of 8 ± 4 K in northwestern Greenland based on stable water isotopes. Here we...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-09-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/12/1907/2016/cp-12-1907-2016.pdf |
| Summary: | Insolation changes during the Eemian (the last interglacial period,
129 000–116 000 years before present) resulted in warmer than present
conditions in the Arctic region. The NEEM ice core record suggests
warming of 8 ± 4 K in northwestern Greenland based on stable water
isotopes. Here we use general circulation model experiments to investigate
the causes of the Eemian warming in Greenland. Simulations of the atmospheric
response to combinations of Eemian insolation and preindustrial oceanic
conditions and vice versa are used to disentangle the impacts of the
insolation change and the related changes in sea surface temperatures and sea
ice conditions. The changed oceanic conditions cause warming throughout the
year, prolonging the impact of the summertime insolation increase.
Consequently, the oceanic conditions cause an annual mean warming of 2 K at
the NEEM site, whereas the insolation alone causes an insignificant change.
Taking the precipitation changes into account, however, the insolation and
oceanic changes cause more comparable increases in the precipitation-weighted
temperature, implying that both contributions are important for the ice core
record at the NEEM site. The simulated Eemian precipitation-weighted warming
of 2.4 K at the NEEM site is low compared to the ice core reconstruction,
partially due to missing feedbacks related to ice sheet changes and an
extensive sea ice cover. Surface mass balance calculations with an energy
balance model further indicate that the combination of temperature and
precipitation anomalies leads to potential mass loss in the north and
southwestern parts of the ice sheet. The oceanic conditions favor increased
accumulation in the southeast, while the insolation appears to be the
dominant cause of the expected ice sheet reduction. Consequently, the Eemian
is not a suitable analogue for future ice sheet changes. |
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| ISSN: | 1814-9324 1814-9332 |