Glacial Variability Research Articles

On the Role of Equilibrium Atmospheric Climate Models in the Theory of Long-Period Glacial Variations

Lorenz (1970) avait discute un super-modele qui permettrait d'obtenir les variations du climat incluant les grandes periodes glaciaires. Ici, on fait remarquer la grande difficulte pratique a obtenir les solutions d'un tel super-modele. Plus simplement, on propose une approche inductive (ou inverse) de la theorie, sous la forme d'un systeme dynamique-stochastique d'equations regissant des variables moyennes sur un ensemble, mobiles sur plusieurs annees et independantes des coordonnees de l'espace (exemples: modes selectionnes de Fourier, integrales globales). Un tel systeme peut etre resolu en un systeme diagnostique d'equations qui constituent un modele de l'equilibre climatique reliant les variables, a reponse rapide, entre elles et les variables a reponse lente, et en un systeme prognostique d'equations qui expriment la physique qualitative, regissant les variables a reponse lente comme la masse glaciaire. C'est la partie diagnostique qui dependra du developpement d'un super-modele. Il est note que les deux parties diagnostique et prognostique, peuvent etre combinees en un seul systeme couple mais sans gain de rigueur par rapport a un modele d'ordre inferieur

Modeling the Late-Quaternary Glacial Variations with Multi-Component Climatic Systems (Abstract)

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Modeling the Late-Quaternary Glacial Variations with Multi-Component Climatic Systems (Abstract)

Modeling the Late-Quaternary Glacial Variations with Multi-Component Climatic Systems (Abstract)

A Comment on John A. Matthews's Article Regarding 14C Dates of Glacial Variations

An article by Matthews in a previous number of Geografiska Annaler is discussed. The improbability of the statement that 1750 marks the time of the maximum advance of Norwegian glaciers is emphasized. Also the marked difference in the size of lichens on end moraines in Norway and on moraines in northern Sweden is pointed out. '4C dates from four moraines are presented, and as the rising radiometric age is accompanied by increasing lichen diameter, it is concluded that the ages of these moraines are distinctly different. It is also concluded that dates previously presented are of the correct order of magnitude.

A Comment on John A. Matthews's Article regarding 14 C Dates of Glacial Variations

A Comment on John A. Matthews's Article regarding 14 C Dates of Glacial Variations

Pleistocene Climate: Deterministic or Stochastic?

Application of a simple linear model to the earth's ice volume record of the past 730,000 years indicates that although forcing by variations in the earth's orbital parameters of tilt and precession is real, it is small (less than 25 percent of the variance in the record). No relationship with the eccentricity is observed. This indicates that the Pleistocene glacial variations are largely stochastic in nature.

New Zealand climate: The temperature record, historical data and some agricultural implications

Evidence is presented that suggests that annual and seasonal temperatures are in phase throughout the New Zealand region for climatic variation. Annual and seasonal temperature curves dating back to 1853 based on the longest instrumental records show a warming of over 1 °C between the early 1860's and the present day, with a 0.5 °C discontinuity since the mid 1940's. Although the warming is regional, the magnitude and timing of the fluctuations vary because of the country's high relief, and wide latitude range. These factors give differing exposure to the atmosphere and oceanic circulations, the resultant interaction of which allows the country to be divided into six temperature response areas which are homogeneous for fluctuations. The information of the last fifty years in these areas is compared. The story from the longer record is supported by phenomena documented from historical sources such as glacial variations, iceberg sightings, and severe snowstorm occurrences. The length and intensity of the growing season is examined in two climatically different areas of New Zealand to ascertain the agricultural significance of the described climate record.

Holocene glacial variations in Sarek National Park, northern Sweden

Detailed mapping of well‐preserved moraine systems fronting 17 small alpine glaciers in Sarek National Park in Swedish Lapland reveals two Holocene intervals of prolonged glacier expansion, each involving a complex of minor fluctuations. The younger interval, which corresponds to the Little Ice Age, experienced advances that culminated about A.D. 1916–1920, 1880–1890, 1850–1860, 1800–1810, 1780, 1700–1720, 1680, 1650, and 1590–1620. The older expansion interval, which probably centered around 2500 14C yr B.P., experienced several minor fluctuations spread through about 600 years.Lichen data collected on moraine systems in Sarek are internally consistent from glacier to glacier. Lichen measurements on surfaces of known age in Sarek and nearby Kebnekaise match closely, allowing moraine correlations between these areas. Several older expansion intervals are recorded in the Kebnekaise Mountains. Taken together, the two sequences suggest that a series of prolonged expansion intervals, each similar to the Little Ice Age, has characterized the Holocene in Lapland. Fluctuations of the Scandinavian Ice Sheet in Sweden suggest that this series of Little‐Ice‐Age events extends back into the late Weichsel in the form of the Younger Dryas and Oldest Dryas stadials.

Les variations récentes des glaciers dans les Alpes françaises (1900-1970). Possibilités de prévision

Abstract. — Since the beginning of the Century over twenty alpine glaciers have constantly been researched by French glaciologists. Every second or third year a thorough investigation of their extensive variations as well as their thicknesses have been constantly checked. In the meantime French glaciers have been affected by important recessions, though four phases of extension have taken place by the end of the XIX Century, between the year 1915-25, in 1940, and since 1955 [the number of glaciers in extension has increased from 10 to 18 %). The problem of forecasting glacial variation is being studied and discussed from local data collected from the Mer de Glace.

VICISSITUDES OF THE AFRICAN BIOMES IN THE LATE PLEISTOCENE

During the last glaciation, for at least 50,000 years prior to 18,000 years ago, the temperature of Africa must have been lower than the present, probably by some 5° C at the glacial maxima. The corresponding reduction in evaporation would have increased the effectiveness of the rainfall.Owing to the surface relief of the continent the reduction in temperature would have enormously extended the area of the montane biomes of tropical Africa at the expense of the lowland, except west of the Cameroons. Continuous communication for montane species, which are at present reduced to isolated and small areas, would have been open from the Cameroon highlands to Abyssinia and South Africa.Changes of similar magnitude would be expected with each glaciation.Apart from these general effects there is geological evidence for sub‐regional fluctuations on a large scale; the dating and the relationship of some of them to the glacial variations remain to be established. The most important are the southward movement of Palaearctic communities at least 400 miles into the Sahara, the northward movements of the Sudanese climatic belts, bringing the Sahelian biome at least 300 miles north, on the last occasion around only 7,000 years ago, the extension of Lake Chad to about four times the size of Lake Victoria, which implies a northward movement of the equatorial rain‐belt over the southern edge of its basin, the southward movement of the Sudanese climatic belts, with fragmentation of the Upper Guinea forests, the fragmentation of the main Congo (Lower Guinea) forest prior to about 60,000 years ago and the desiccation of an area covering eastern Angola, the middle Zambesi and probably the south of the Congo basin as recently as 12,000 years ago.

Glacial variations in West Greenland in historical time. Part I. Southwest Greenland

The present work is an exposition of a study made of the situation of the ice front in the glaciers of West Greenland, based on the information in the literature, diaries and in picture material. It is also a comparative study of that material for the purpose of forming a picture, fragmentary though it may be, of the ice shrinkage along the margin of the inland ice and at certain isolated glaciers in the various regions investigated.