Arithmetic of ice ages

Calder, Nigel

doi:10.1038/252216a0

Cited by 58 publications

(28 citation statements)

References 10 publications

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“…Several models now exist, from simple (Calder, 1974) to sophisticated ones (Mason, 1978), which allow the spread of ice till 50~ and which generate variations of zonal mean temperatures in reasonable agreement with the patterns of major climatic changes of the recent geological past, if summer, or better, monthly insolation falls by a percentage well within the range of astronomical variations. Moreover, Kukla (1978) demonstrated that the Earth's surface temperature is most affected by seasonal change of irradiation and Berger (1979) showed that insolation signatures of Quaternary climatic changes can be found in monthly values which can depart from their longterm mean values by as much as 10%.…”

Section: Astronomical Theory Of Paleoclimates: the Milankovitch Efmentioning

confidence: 80%

Spectrum of climatic variations and their causal mechanisms

Berger

1979

Geophysical Surveys

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Abstract. This paper surveys the history of the Earth's climate and deals with facts, techniques, and causes. A review of climatic history since the origin of the Earth demonstrates the changes and variability of our climate along different scales. These variations can probably be fully understood only when taking into account both external forcing and non-linear interactions between the components of the climatic system: atmosphere, oceans, cryosphere, lithosphere, and biosphere. At least, as far as boundary conditions and forcing are concerned for the 108 to 109 yr time scale, atmospheric composition, solar evolution, and tectonism have to be considered, while variations of the Earth's orbital elements, and subsequently of the insolation, best explain the glacial-interglacial occurrences during the Quaternary Period. For shorter time scales, volcanic dust, solar activity, sea surface temperatures, and atmosphere-ocean autovariations have to be taken into account. Furthermore, the man-made effects have now to be considered: atmospheric loading of dust and air pollution particles, changes in surface albedo, and mainly the increasing rise of atmospheric CO 2 and other trace gases adding to a greenhouse effect.This man-made warming effect of future CO2 increase will probably emerge as a clearly recognizable trend against the background of natural climatic fluctuations by the end of this century. This carbon dioxide induced super-interglacial will be superimposed on the expected natural long-term cooling trend of the ice age chronology.

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Section: Astronomical Theory Of Paleoclimates: the Milankovitch Efmentioning

confidence: 80%

Spectrum of climatic variations and their causal mechanisms

Berger

1979

Geophysical Surveys

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“…During the former period, the Antarctic Ice Sheet was more variable in size, while the latter period is characterised by glaciations and deglaciations of the Northern Hemisphere. A marine benthic δ 18 Oisotope model will be incorporated in order to allow for an independent comparison with palaeo-proxy-records (Lisiecki and Raymo, 2005;Zachos et al, 2008;Cramer et al, 2009). …”

Section: Discussionmentioning

confidence: 99%

“…Hays et al, 1976;Shackleton, 2000) and ice cores (Jouzel et al, 1989). The influence of solar insolation changes on the waxing and waning of ice sheets was discussed in many studies of varying complexity (Calder, 1974;Imbrie and Imbrie, 1980;Paillard, 1998) as well as in studies with ice-dynamical models (Pollard, 1978;Oerlemans, 1980Oerlemans, , 1982. However, simulating ice ages solely with solar variability remains difficult because of the lack of spectral power in the eccentricity (100 kyr) band (Imbrie et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

Interaction of ice sheets and climate during the past 800 000 years

et al. 2014

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Abstract. During the Cenozoic, land ice and climate interacted on many different timescales. On long timescales, the effect of land ice on global climate and sea level is mainly set by large ice sheets in North America, Eurasia, Greenland and Antarctica. The climatic forcing of these ice sheets is largely determined by the meridional temperature profile resulting from radiation and greenhouse gas (GHG) forcing. As a response, the ice sheets cause an increase in albedo and surface elevation, which operates as a feedback in the climate system. To quantify the importance of these climate-land ice processes, a zonally averaged energy balance climate model is coupled to five one-dimensional ice sheet models, representing the major ice sheets.In this study, we focus on the transient simulation of the past 800 000 years, where a high-confidence CO 2 record from ice core samples is used as input in combination with Milankovitch radiation changes. We obtain simulations of atmospheric temperature, ice volume and sea level that are in good agreement with recent proxy-data reconstructions. We examine long-term climate-ice-sheet interactions by a comparison of simulations with uncoupled and coupled ice sheets. We show that these interactions amplify global temperature anomalies by up to a factor of 2.6, and that they increase polar amplification by 94 %. We demonstrate that, on these long timescales, the ice-albedo feedback has a larger and more global influence on the meridional atmospheric temperature profile than the surface-height-temperature feedback. Furthermore, we assess the influence of CO 2 and insolation by performing runs with one or both of these variables held constant. We find that atmospheric temperature is controlled by a complex interaction of CO 2 and insolation, and both variables serve as thresholds for northern hemispheric glaciation.

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“…However, spectral analyses of model results and marine oxygen isotope records have revealed shortcomings. Models 2 and 4 (Calder, 1974;Imbrie and Imbrie, 1980), for example, exaggerate the amount of power at the precessional periodicities of 23 000 and 19 000 yr compared with that at 41 000 yr, the obliquity periodicity. Neither of these two models nor Model 6 produce sufficient power at the 105 yr eccentricity period (Imbrie and Imbrie, 1980;Kukla et al, 1981).…”

Section: (I) the Milankovitch Theorymentioning

confidence: 99%

A first approach to assessing future climate states in the UK over very long timescales: Input to studies of the integrity of radioactive waste repositories

1990

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Projected timescales for the transport of radionuclides from an undisturbed undergound nuclear waste repository to the surface are in the range of tens of thousands to millions of years. Over these timescales major natural and potentially major anthropogenic changes in climate can be expected. As part of the UK disposal safety assessment programme, time-dependent models of the repository environment are being developed. The Climatic Research Unit has undertaken a study of relevant climatic change and climatic effects. This has required assessment of the probable range, succession and duration of major climate states likely to be experienced in the UK over very long timescales, up to 106 yr. Two methodologies have been employed. The first uses the Milankovitch theory, which is considered to be the major cause of the Pleistocene glacial/interglacial cycles. The second involves empirical analysis of the long-term reconstructed climate record: no assumptions about the specific causes or mechanisms are made. A period of 'sub-tropical" climate is included in the sequence to represent a period of anthropogenically-induced greenhouse warming. The climate sequence established using these methods will form the basis for studying related processes, such as erosion and groundwater movement and transfer by vegetation, and their implications for radioactive waste disposal. This has involved the construction of instrumental climate analogues.

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Arithmetic of ice ages

Cited by 58 publications

References 10 publications

Spectrum of climatic variations and their causal mechanisms

Spectrum of climatic variations and their causal mechanisms

Interaction of ice sheets and climate during the past 800 000 years

A first approach to assessing future climate states in the UK over very long timescales: Input to studies of the integrity of radioactive waste repositories

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