Climate change between the mid and late Holocene in northern high latitudes – Part 2: Model-data comparisons 1Bert Bolin Centre for Climate Research, Stockholm University, 10691 Stockholm, Sweden
2Department of Meteorology, Stockholm University, 10691 Stockholm, Sweden
3Department of Physical Geography and Quaternary Geology, Stockholm University, 10691 Stockholm, Sweden
Received: 11 Jun 2009 – Published in Clim. Past Discuss.: 25 Jun 2009 Abstract. The climate response over northern high latitudes to the mid-Holocene orbital
forcing has been investigated in three types of PMIP (Paleoclimate Modelling
Intercomparison Project) simulations with different complexity of the
modelled climate system. By first undertaking model-data comparison, an
objective selection method has been applied to evaluate the capability of the
climate models to reproduce the spatial response pattern seen in proxy data.
The possible feedback mechanisms behind the climate response have been
explored based on the selected model simulations. Subsequent model-model
comparisons indicate the importance of including the different physical
feedbacks in the climate models. The comparisons between the proxy-based
reconstructions and the best fit selected simulations show that over the
northern high latitudes, summer temperature change follows closely the
insolation change and shows a common feature with strong warming over land
and relatively weak warming over ocean at 6 ka compared to 0 ka.
Furthermore, the sea-ice-albedo positive feedback enhances this response. The
reconstructions of temperature show a stronger response to enhanced
insolation in the annual mean temperature than winter and summer temperature.
This is verified in the model simulations and the behaviour is attributed to
the larger contribution from the large response in autumn. Despite a smaller
insolation during winter at 6 ka, a pronounced warming centre is found over
Barents Sea in winter in the simulations, which is also supported by the
nearby northern Eurasian continental and Fennoscandian reconstructions. This
indicates that in the Arctic region, the response of the ocean and the sea
ice to the enhanced summer insolation is more important for the winter
temperature than the synchronous decrease of the insolation.
Revised: 27 Aug 2010 – Accepted: 06 Sep 2010 – Published: 17 Sep 2010
Citation: Zhang, Q., Sundqvist, H. S., Moberg, A., Körnich, H., Nilsson, J., and Holmgren, K.: Climate change between the mid and late Holocene in northern high latitudes – Part 2: Model-data comparisons, Clim. Past, 6, 609-626, doi:10.5194/cp-6-609-2010, 2010.