Constraining projections of summer Arctic sea ice

Massonnet, François; Fichefet, Thierry; Goosse, Hugues; Hezel, Paul; Bitz, Cecilia M.; Philippon, G.; Holland, Marika M.; Barriat, Pierre-Yves

doi:10.5194/tcd-6-2931-2012

Cited by 86 publications

(130 citation statements)

References 38 publications

(17 reference statements)

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“…Consistent with this interpretation, extratropical precipitation extremes are generally found to respond to climate change in a robust manner, unlike tropical precipitation extremes 12,39 . Inaccuracy in simulating Arctic sea-ice loss could affect the warming pattern and circulation, but this would not be expected to substantially alter the contrast between the responses of mean and extreme daily snowfall, and similar results are found here for the subset of models that have previously been identified 40 as performing well in simulating Arctic sea ice (not shown).…”

Section: Derivation Of Theory For Snowfall Extremessupporting

confidence: 80%

Contrasting responses of mean and extreme snowfall to climate change

O’Gorman

2014

Nature

177

138

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Snowfall is an important element of the climate system, and one that is expected to change in a warming climate [1][2][3][4] . Both mean snowfall and the intensity distribution of snowfall are important, with heavy snowfall events having particularly large economic and human impacts [5][6][7] .Simulations with climate models indicate that annual-mean snowfall declines with warming in most regions but increases in regions with very low surface temperatures 3,4 . The response of heavy snowfall events to a changing climate, however, is unclear. Here I show that in simulations with climate models under a high-emissions scenario, by the late twenty-first century there are smaller fractional changes in daily snowfall extremes than in mean snowfall over many Northern Hemisphere land regions. For example, for monthly climatological temperatures just below freezing and surface elevations below 1000m, the 99.99th percentile of daily snowfall decreases by 8% in the multimodel median as compared to a 65% reduction in mean snowfall. Both mean and extreme snowfall must decrease for a sufficiently large warming, but the climatological temperature above which snowfall extremes decrease with warming in the simulations is as high as -9 • C as compared to -14 • C for mean snowfall. These results are supported by a physically based theory that is consistent with the observed rain-snow transition. According to the theory, snowfall extremes occur near an optimal temperature that 1 is insensitive to climate warming, and this results in smaller fractional changes for higher percentiles of daily snowfall. The simulated changes in snowfall that I find would influence surface snow and its hazards; these changes also suggest that it may be difficult to detect a regional climate-change signal in snowfall extremes.Extremes of daily precipitation (including liquid and solid precipitation) are found to increase in intensity with climate warming in observations and simulations [8][9][10] , and this is physically consistent with greater saturation specific humidities in a warmer atmosphere [11][12][13] . However, little is known about the physical basis for changes in daily snowfall extremes, their past changes on a global or hemispheric scale, or how they change in global climate-model simulations. Regional observational studies show large interdecadal variations in measures of snowfall extremes 14 , but not necessarily significant long-term trends 15 . Extremes of seasonal-mean snowfall have been studied previously 16, 17 , but extremes on shorter timescales may respond differently 14 . Physically we expect heavy snowfall events to occur in a relatively narrow range of temperatures below the rain-snow transition; at much lower temperatures it is not "too cold to snow", but low saturation specific humidities make heavy snowfall unlikely. However, it is not clear what this means for the response to climate change, and previous studies have differed in their findings as to whether heavy snowfall events are predominantly associated with anomalou...

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Section: Derivation Of Theory For Snowfall Extremessupporting

confidence: 80%

Contrasting responses of mean and extreme snowfall to climate change

O’Gorman

2014

Nature

177

138

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“…In particular, the difficulty in current sea ice models to reproduce and forecast years with anomalously high or low SIE [63] is likely to be due to deficiencies in the physical representation of sea ice in these models. Moreover, the wide spread in the simulated mean state and trend of the main sea ice characteristics in our sensitivity study indicates that model physics uncertainty could dominate overall sea ice uncertainty in general circulation models [64].…”

Section: Discussionmentioning

confidence: 99%

Processes controlling surface, bottom and lateral melt of Arctic sea ice in a state of the art sea ice model

Feltham

Petty

Schröder

et al. 2015

Phil. Trans. R. Soc. A.

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We present a modelling study of processes controlling the summer melt of the Arctic sea ice cover. We perform a sensitivity study and focus our interest on the thermodynamics at the ice-atmosphere and iceocean interfaces. We use the Los Alamos community sea ice model CICE, and additionally implement and test three new parametrization schemes: (i) a prognostic mixed layer; (ii) a three equation boundary condition for the salt and heat flux at the ice-ocean interface; and (iii) a new lateral melt parametrization. Recent additions to the CICE model are also tested, including explicit melt ponds, a form drag parametrization and a halodynamic brine drainage scheme. The various sea ice parametrizations tested in this sensitivity study introduce a wide spread in the simulated sea ice characteristics. For each simulation, the total melt is decomposed into its surface, bottom and lateral melt components to assess the processes driving melt and how this varies regionally and temporally. Because this study quantifies the relative importance of several processes in driving the summer melt of sea ice, this work can serve as a guide for future research priorities.

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“…The Arctic sea ice pack has lost about 30% of its summer coverage over the last thirty years [e.g., Comiso, 2010] with a spectacular culmination in 2012. This could lead to a summer ice-free Arctic Ocean by the middle of this century [e.g., Massonnet et al, 2012]. The Antarctic sea ice extent has slightly increased over the last thirty years (~1% per decade).…”

Section: Introductionmentioning

confidence: 99%

Role of sea ice in global biogeochemical cycles: emerging views and challenges

Vancoppenolle

Meiners

Michel

et al. 2013

Quaternary Science Reviews

212

213

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International audienceObservations from the last decade suggest an important role of sea ice in the global biogeochemical cycles, promoted by (i) active biological and chemical processes within the sea ice; (ii) fluid and gas exchanges at the sea ice interface through an often permeable sea ice cover; and (iii) tight physical, biological and chemical interactions between the sea ice, the ocean and the atmosphere. Photosynthetic micro-organisms in sea ice thrive in liquid brine inclusions encased in a pure ice matrix, where they find suitable light and nutrient levels. They extend the production season, provide a winter and early spring food source, and contribute to organic carbon export to depth. Under-ice and ice edge phytoplankton blooms occur when ice retreats, favoured by increasing light, stratification, and by the release of material into the water column. In particular, the release of iron - highly concentrated in sea ice - could have large effects in the iron-limited Southern Ocean. The export of inorganic carbon transport by brine sinking below the mixed layer, calcium carbonate precipitation in sea ice, as well as active ice-atmosphere carbon dioxide (CO₂) fluxes, could play a central role in the marine carbon cycle. Sea ice processes could also significantly contribute to the sulphur cycle through the large production by ice algae of dimethylsulfoniopropionate (DMSP), the precursor of sulphate aerosols, which as cloud condensation nuclei have a potential cooling effect on the planet. Finally, the sea ice zone supports significant ocean-atmosphere methane (CH₄) fluxes, while saline ice surfaces activate springtime atmospheric bromine chemistry, setting ground for tropospheric ozone depletion events observed near both poles. All these mechanisms are generally known, but neither precisely understood nor quantified at large scales. As polar regions are rapidly changing, understanding the large-scale polar marine biogeochemical processes and their future evolution is of high priority. Earth system models should in this context prove essential, but they currently represent sea ice as biologically and chemically inert. Palaeoclimatic proxies are also relevant, in particular the sea ice proxies, inferring past sea ice conditions from glacial and marine sediment core records and providing analogues for future changes. Being highly constrained by marine biogeochemistry, sea ice proxies would not only contribute to but also benefit from a better understanding of polar marine biogeochemical cycles

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Constraining projections of summer Arctic sea ice

Cited by 86 publications

References 38 publications

Contrasting responses of mean and extreme snowfall to climate change

Contrasting responses of mean and extreme snowfall to climate change

Processes controlling surface, bottom and lateral melt of Arctic sea ice in a state of the art sea ice model

Role of sea ice in global biogeochemical cycles: emerging views and challenges

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