http://www.highstand.org/erohling/Rohling-papers/2004-Mayewski%20et%20al%20Holocene%20climate%20variability%20QR62.pdf

Holocene climate variability

Although a sizable body of knowledge is prerequisite to expert skill, that knowledge must be indexed by large numbers of patterns that, on recognition, guide the expert in a fraction of a second to relevant parts of the knowledge store. The knowledge forms complex schemata that can guide a problem's interpretation and solution and that constitute a large part of what we call physical intuition.

Expert and novice performance in solving physics problems

Changes in solar radiation arising from changes in the orientation of the earth's axis had pronounced effects on tropical monsoons and mid-latitude climates as well as on ice-sheet configuration du...

https://science.sciencemag.org/content/sci/241/4869/1043.full.pdf

Climatic changes of the last 18,000 years: observations and model simulations

https://www.ldeo.columbia.edu/~peter/site/Papers_files/deMenocal.etal.2000.pdf

Abrupt onset and termination of the African Humid Period:rapid climate responses to gradual insolation forcing

Chapter 2 emphasises change against a background of variability. The certainty of conclusions that can be drawn about climate from observations depends critically on the availability of accurate, complete and consistent series of observations. For many variables important in documenting, detecting, and attributing climate change, data are still not good enough for really firm conclusions to be reached. This especially applies to global trends in variables that have large regional variations, such as pre-

/pdf/observed-climate-variability-and-change-165j4c1upm.pdf

Observed climate variability and change

A major problem in the study of Holocene palaeoenvironments of the arid and wind-deflated Sahara is the low preservation potential of sediments from which a record of past climatic change can be established. Several indirect and imprecisely dated pieces of evidence have suggested humid episodes in the Holocene that may have supported more productive ecosystems and denser human populations than today. Searches for reliable proxy data on past climates, however, have failed to yield satisfactory results. We report here the discovery of buried lake muds in north-west Sudan, in the hyperarid core of the Eastern Sahara, which yield sedimentological and palynological data clearly interpretable as recording an early to mid-Holocene humid episode that supported a relatively-deep stratified lake surrounded by tropical savanna woodland vegetation.

Sediment and pollen evidence for an early to mid-Holocene humid period in the eastern Sahara

According to the Milankovitch theory of global climatic change, maximum summer solar radiation at high latitudes of the Northern Hemisphere occurred at 10,000 yr BP (refs 1, 2). In particular, it predicts summer solstice radiation greater by 9–10%. Preliminary climate simulation experiments with these increased values of radiation confirm that high-latitude land surfaces received maximal insolation at ∼10,000 yr (refs 3, 4). Paradoxically, however, the large volume of fossil pollen and other evidence from North America indicates a maximum of Holocene warmth at 7,000–6,000 yr (ref. 5), and a recent review of the evidence from New England suggests that the warming began at 9,000 and ended at 5,000 yr, but also stresses the difficulties of interpretation in terms of climate change6. We summarize here data from sites in the north-west corner of mainland Canada (Fig. 1) that directly support the Milankovitch hypothesis.

Evidence from north-west Canada for an early Holocene Milankovitch thermal maximum

Recent discoveries of fossil-bearing Holocene lake sediments from the eastern Sahara have brought further confirmation and detail to earlier indirect evidence that a major pluvial episode occurred between 9,500 and 4,500 yr BP1–3. The botanical results, mainly palynological, show that savanna and desert grassland occupied regions that today are plantless hyperarid deserts. We present here the first evidence from the entire Saharan region of a latitudinal zonation of Holocene vegetation, extending across a 500-km wide belt in north-west Sudan. We have completed detailed pollen analyses of three of the several sites discovered so far, and the salient features from two, the northernmost and the southernmost, are presented here to demonstrate a steep gradient of past vegetative cover.

Holocene vegetation zonation in the eastern Sahara

Holocene palaeoecology of the eastern Sahara; Selima Oasis

The first reliable, securely dated full- and late-glacial pollen stratigraphy from Eastern Beringia forces the rejection of the widely held hypothesis of a steppetundra or grassland associated with extinct vertebrates and early humans. The arctic-alpine fossil flora and low pollen influx suggest a sparse tundra similar to modern herb fell-field vegetation.

https://science.sciencemag.org/content/sci/208/4450/1375.full.pdf

J. C. Ritchie

Papers

Sediment and pollen evidence for an early to mid-Holocene humid period in the eastern Sahara

Evidence from north-west Canada for an early Holocene Milankovitch thermal maximum

Holocene vegetation zonation in the eastern Sahara

Holocene palaeoecology of the eastern Sahara; Selima Oasis

Arctic steppe-tundra: a yukon perspective.