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It is not easy to discern the significant from the merely interesting in science journals, but papers often appear which are, to all intents and purposes, lost in the ether; they don’t see the light of day beyond the relatively narrow confines of their academic environment. Here are a few examples from recent journals. Links are to abstracts. Some of the journals, for example the ones published under the EGU/Copernicus system, are open access. Others may require a subscription or a chase through Google Scholar to find the authors and a copy of the main text.

The criteria for being offered here is that each may contain something which is illuminating to the ongoing discussions in climate science or policy. Their presence here is not to be read as support or endorsement, or as assumption of truth or accuracy. In all cases, attempts have been made to respect the copyright privileges of the publishers and authors.

The following examples all come from ‘Climates of the Past’.

  Clim. Past, 3, 77-87, 2007
© Author(s) 2007. This work is licensed
under a Creative Commons License.

Linking glacial and future climates through an ensemble of GCM simulations

J. C. Hargreaves1, A. Abe-Ouchi1,2, and J. D. Annan1
1FRCGC/JAMSTEC, Yokohama, Japan
2CCSR, Tokyo, Japan

The MIROC3.2 model shows an asymmetry in climate sensitivity calculated by decreasing rather than increasing the greenhouse gases, with 80% of the ensemble having a weaker cooling than warming. This asymmetry, if confirmed by other studies would mean that direct estimates of climate sensitivity from the LGM are likely to be underestimated by the order of half a degree. Our suspicion is, however, that this result may be highly model dependent. Analysis of the parameters varied in the model suggest the asymmetrical response may be linked to the ice in the clouds, which is therefore indicated as an important area for future research.

Summer temperature trend over the past two millennia using air content in Himalayan ice

S. Hou1,2,3, J. Chappellaz1, J. Jouzel2, P. C. Chu4, V. Masson-Delmotte2, D. Qin3, D. Raynaud1, P. A. Mayewski5, V. Y. Lipenkov6, and S. Kang3

Abstract. Two Himalayan ice cores display a factor-two decreasing trend of air content over the past two millennia, in contrast to the relatively stable values in Greenland and Antarctica ice cores over the same period. Because the air content can be related with the relative frequency and intensity of melt phenomena, its variations along the Himalayan ice cores provide an indication of summer temperature trend. Our reconstruction point toward an unprecedented warming trend in the 20th century but does not depict the usual trends associated with “Medieval Warm Period” (MWP), or “Little Ice Age” (LIA).
  The DO-climate events are probably noise induced: statistical investigation of the claimed 1470 years cycle

P. D. Ditlevsen, K. K. Andersen, and A. Svensson
The Niels Bohr Institute, Department of Geophysics, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen O, Denmark

Abstract. The significance of the apparent 1470 years cycle in the recurrence of the Dansgaard-Oeschger (DO) events, observed in the Greenland ice cores, is debated. Here we present statistical significance tests of this periodicity. The detection of a periodicity relies strongly on the accuracy of the dating of the DO events. Here we use both the new NGRIP GICC05 time scale based on multi-parameter annual layer counting and the GISP2 time scale where the periodicity is most pronounced. For the NGRIP dating the recurrence times are indistinguishable from a random occurrence. This is also the case for the GISP2 dating, except in the case where the DO9 event is omitted from the record.

  Quasi-100 ky glacial-interglacial cycles triggered by subglacial burial carbon release

N. Zeng
1Department of Atmospheric and Oceanic Science, University of Maryland, College Park, MD 20742-2425, USA
2The Department of Geology and the Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742-2425, USA

Abstract. A mechanism is proposed in which climate, carbon cycle and icesheets interact with each other to produce a feedback that can lead to quasi-100 ky glacial-interglacial cycles. A central process is the burial and preservation of organic carbon by icesheets which contributes to the observed glacial-interglacial CO2 change (the glacial burial hypothesis, Zeng, 2003). Allowing carbon cycle to interact with physical climate, here I further hypothesize that deglaciation can be triggered by the ejection of glacial burial carbon when a major icesheet grows to sufficiently large size after a prolonged glaciation so that subglacial transport becomes significant. Glacial inception may be initiated by CO2 drawdown due to a relaxation from a high but transient interglacial CO2 value as the land-originated CO2 invades into deep ocean via thermohaline circulation and CaCO3 compensation. Also important for glacial inception may be the CO2 uptake by vegetation and soil regrowth in the previously ice-covered regions. When tested in a fully coupled Earth system model with comprehensive carbon cycle components and semi-empirical physical climate components, it produced under certain parameter regimes self-sustaining glacial-interglacial cycles with durations of 93 ky, CO2 changes of 90 ppmv, temperature changes of 6°C. Since the 100 ky cycles can not be easily explained by the Milankovitch astronomical forcing alone, this carbon-climate-icesheet mechanism provides a strong feedback that could interact with external forcings to produce the major observed Quaternary climatic variations. It is speculated that some glacial terminations may be triggered by this internal feedback while others by orbital forcing. Some observable consequences are highlighted that may support or falsify the theory.


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