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| Titel |
What caused mid-Piacenzian warming? Energy balance results from PlioMIP Experiment 2 |
| VerfasserIn |
Daniel Hill, Alan Haywood, PlioMIP Participants |
| 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 |
250081037
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| Zusammenfassung |
| The Pliocene model intercomparison project (PlioMIP) was initiated to assess the ability of
climate models to reproduce a warmer, higher CO2 climate of the recent geological past. The
model boundary conditions were specified, so each of the eight models in the coupled
ocean-atmosphere Experiment 2 were running equivalent experiments. Here we
present a new analysis of the energy balance of each of the PlioMIP Experiment 2
simulations, elucidating the causes and important features of the warm mid-Piacenzian
climate.
Energy balance results from each of the different models show broadly similar patterns.
Greenhouse gas warming and changes in cloud albedo drive mid-Piacenzian warming of 1 - 2
°C at tropical and Southern Hemisphere temperate latitudes. At the poles the warming is
dominated by a reduction in the cloud free albedo, which originates from ice sheet and Arctic
sea ice retreat and snow albedo feedbacks. The other components in the analysis all
show smaller but significant impact on the warming of the polar regions, but the
negative impact from cloud albedo and meridional heat transport approximately
balance the enhancement from greenhouse gas warming and cloud emissivity. The
response of the Northern Hemisphere temperate latitudes to the prescribed forcing
in each of the models seems to be different. Although greenhouse gas increases
produce a similar warming, the models disagree on both the magnitude and sign
of change for each of the other components. As well as increasing the spread of
PlioMIP surface air temperatures, this model disparity is particularly prevalent in
sea surface temperatures in the North Atlantic and Nordic Seas, where previous
data-model comparison have identified significant differences between the data and
models.
Moves towards timeslices within the mid-Piacenzian warm period may reduce
uncertainty in the data and provide a target sea surface temperature reconstruction for a
coherent single time period. Despite the North Atlantic being the most well studied
region of the Pliocene ocean, it seems that it is here and in the Nordic Seas where
further data could provide better understanding of the mid-Piacenzian climate and
greater possibilities for evaluating climate models. Combining new data with model
sensitivity simulations may also increase our understanding of the importance of Arctic
and North Atlantic palaeogeographic differences on temperature changes in these
regions. |
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