The Atmospheric Response to Projected Terrestrial Snow Changes in the Late Twenty-First Century

Alexander, Michael A.; Tomas, Robert A.; Deser, Clara; Lawrence, David M.

doi:10.1175/2010jcli3899.1

Cited by 29 publications

(26 citation statements)

References 20 publications

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“…4E) (8,35). ENSO influences the sea-ice dipole between the eastern Bering Sea and the Sea of Okhotsk (36,37), with increased sea-ice concentration in the Bering Sea during La Niña-like conditions (38). A diatom record from the Bering Sea confirms maximum sea-ice extent during the early Holocene and the persistence of greater-than-present ice cover through the middle Holocene (39), which are consistent with a response to a weakened Aleutian Low and prevailing northwesterly winds (39)(40)(41)(42).…”

Section: Resultsmentioning

confidence: 56%

Nonlinear response of summer temperature to Holocene insolation forcing in Alaska

Clegg

Kelly²,

Clarke³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Regional climate responses to large-scale forcings, such as precessional changes in solar irradiation and increases in anthropogenic greenhouse gases, may be nonlinear as a result of complex interactions among earth system components. Such nonlinear behaviors constitute a major source of climate "surprises" with important socioeconomic and ecological implications. Paleorecords are key for elucidating patterns and mechanisms of nonlinear responses to radiative forcing, but their utility has been greatly limited by the paucity of quantitative temperature reconstructions. Here we present Holocene July temperature reconstructions on the basis of midge analysis of sediment cores from three Alaskan lakes. Results show that summer temperatures during 10,000-5,500 calibrated years (cal) B.P. were generally lower than modern and that peak summer temperatures around 5,000 were followed by a decreasing trend toward the present. These patterns stand in stark contrast with the trend of precessional insolation, which decreased by ∼10% from 10,000 y ago to the present. Cool summers before 5,500 cal B.P. coincided with extensive summer ice cover in the western Arctic Ocean, persistence of a positive phase of the Arctic Oscillation, predominantly La Niña-like conditions, and variation in the position of the Alaskan treeline. These results illustrate nonlinear responses of summer temperatures to Holocene insolation radiative forcing in the Alaskan sub-Arctic, possibly because of state changes in the Arctic Oscillation and El Niño-Southern Oscillation and associated land-atmosphere-ocean feedbacks.Chironomidae | paleotemperature | climate change | high latitudes | land-ocean-atmosphere interaction A lthough radiative forcing by greenhouse gases is spatially uniform, temperature trajectories have displayed high variability both spatially and temporally during the 20th and 21st centuries. Understanding the patterns and causes of this variability is paramount to anticipating the impacts of climate change at local to regional scales. Among the major contributing factors is nonlinearity in regional temperature responses to large-scale climate forcings. Such nonlinearity may result from land-ocean feedbacks to atmospheric warming and atmosphere-ocean teleconnections associated with climate modes such as the Arctic Oscillation/North Atlantic Oscillation (AO/NAO) (1). For example, rising global mean temperatures are projected to increase prevalence of the AO/NAO positive phase by the end of this century. This change could accentuate the contrast of warming over Eurasia and interior Canada with cooling over northeastern Canada.Paleorecords can help elucidate mechanisms leading to nonlinear and spatially heterogeneous responses of temperature to radiative forcing. During the Holocene, high-latitude insolation varied markedly with the precessional cycle; for example, July short-wave radiation declined by ∼50 W m −2 at 65°N latitude throughout the Holocene (2). Paleoclimate data and model simulations have demonstrated the dominant effect of d...

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Section: Resultsmentioning

confidence: 56%

Nonlinear response of summer temperature to Holocene insolation forcing in Alaska

Clegg

Kelly²,

Clarke³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…2, bottom), is greatly enhanced across the majority of the winter season in the EUR experiment, whereas it is more focused in the midwinter for the NA scenario. This increase in low clouds over greater snow extent conditions was noted by Alexander et al (2010) also, but exact causes of this cloud pattern are unclear.…”

Section: A Surface and Low Cloud Responsementioning

confidence: 72%

“…Each of the 40 years was considered independent, where the snow forcing was constant from year to year but varies monthly from September through May and reverts to a model climatology during summer months. This experiment design is of similar structure to previous modeling studies using NCAR's model (Alexander et al 2010;Lawrence and Slater 2009).…”

Section: B Anomalous Snow Grid Productionmentioning

confidence: 99%

Circulation Response to Eurasian versus North American Anomalous Snow Scenarios in the Northern Hemisphere with an AGCM Coupled to a Slab Ocean Model

2013

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The difference between snow-covered and snow-free conditions is the most climatically significant natural seasonal change the land surface can experience. Most GCM studies investigating snow-atmosphere interactions have focused on impacts of Eurasian snow anomalies caused by the magnitude of snow mass, while North American snow has been shown to have a weaker relationship with downstream climate. Experiment design of recent snow-atmosphere interactions studies has been limited to atmosphere-only models, with sea surface temperature (SST) and sea ice extent represented as boundary conditions. The authors explore the circulation response to anomalous snow scenarios, for both North America and Eurasia, using a slab ocean model. Surface response include significant SST cooling directly downstream of each individual forcing region in addition to upstream centers of remote cooling under maximum snow conditions. Atmospheric response to anomalous snow conditions is consistent through multiple levels in the lower troposphere under maximum snow conditions throughout much of the midlatitudes in both experiments during early winter. Areas of strengthened midtropospheric eddy kinetic energy correlate well with steep geopotential height gradient differences and increased zonal wind at 250 hPa over the western Pacific. Both experiments show similar atmospheric response pathways; however, circulation response to maximum Eurasian snow is focused downstream in early winter, whereas upstream response is particularly evident from the North American experiment. This paper focuses on differences as a result of Eurasian versus North American snow forcing in atmospheric circulation response using an AGCM with a slab ocean model.

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“…Walsh and Ross, 1988;Vavrus, 2007) studies suggest a strong direct influence of snow cover on the overlying lower troposphere, but also on the upper atmosphere (e.g. Alexander et al, 2010). This gives rise to the well-known snow-albedo feedback which (i) is thought to be one important reason for the polar amplification of ongoing and projected climate change (e.g.…”

Section: Introductionmentioning

confidence: 99%

An analysis of present and future seasonal Northern Hemisphere land snow cover simulated by CMIP5 coupled climate models

2013

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Abstract. The 20th century seasonal Northern Hemisphere (NH) land snow cover as simulated by available CMIP5 model output is compared to observations. On average, the models reproduce the observed snow cover extent very well, but the significant trend towards a reduced spring snow cover extent over the 1979-2005 period is underestimated (observed: (−3.4 ± 1.1) % per decade; simulated: (−1.0 ± 0.3) % per decade). We show that this is linked to the simulated Northern Hemisphere extratropical spring land warming trend over the same period, which is also underestimated, although the models, on average, correctly capture the observed global warming trend. There is a good linear correlation between the extent of hemispheric seasonal spring snow cover and boreal large-scale spring surface air temperature in the models, supported by available observations. This relationship also persists in the future and is independent of the particular anthropogenic climate forcing scenario. Similarly, the simulated linear relationship between the hemispheric seasonal spring snow cover extent and global mean annual mean surface air temperature is stable in time. However, the slope of this relationship is underestimated at present (observed: (−11.8 ± 2.7) % • C −1 ; simulated: (−5.1 ± 3.0) % • C −1 ) because the trend towards lower snow cover extent is underestimated, while the recent global warming trend is correctly represented.

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The Atmospheric Response to Projected Terrestrial Snow Changes in the Late Twenty-First Century

Cited by 29 publications

References 20 publications

Nonlinear response of summer temperature to Holocene insolation forcing in Alaska

Nonlinear response of summer temperature to Holocene insolation forcing in Alaska

Circulation Response to Eurasian versus North American Anomalous Snow Scenarios in the Northern Hemisphere with an AGCM Coupled to a Slab Ocean Model

An analysis of present and future seasonal Northern Hemisphere land snow cover simulated by CMIP5 coupled climate models

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