Estimates made of lowland precipitation and evaporation in Britain during the last (Devensian) glaciation suggest that during the cold periods of the Devensian precipitation was probably low, between 260 and 370 mm/thermal maximum of the Upton Warren Interstadial lowland precipitation was probably in the range 450 to 650 mm/year. Two summer precipitation regimes are identified during the cold periods, one with high values and the other with low. The high summer precipitation variant leads to moist conditions with July and August precipitation values similar to those at the present day, and global circulation models suggest that the moist regime may have existed at the time of the maximum advance of the ice sheets. On the other hand, the low summer precipitation variant leads to a dry summer with wind action creating aeolian deposits, and this variant probably existed at earlier times in the glacial period. About 6500 yr B.P., in the Atlantic period, forest conditions probably caused increased evaporation which more than compensated for the increased precipitation of the time, causing low runoff conditions. The clearance of British forests by man since 6500 yr B.P. has probably led to an absolute increase in runoff values even though precipitation values have fallen.

Dated macrofossil evidence documents the widespread occurrence of woodland in what are now desert lowlands of southwestern North America from the last pleniglacial (ca. 20,000 yr B.P.) to late glacial/Holocene transition (12,000–8000 yr B.P.). The composition of the Pleistocene woodlands indicates that they had already differentiated geographically in modern form, though immensely more extensive than today. The pinyon-juniper woodland (Pinus monophylla, Juniperus osteosperma) of the Mohave Desert province had not yet penetrated the central Great Basin, but extended from southern Nevada south through the vast lowlands of the Mohave and westernmost Sonoran Deserts to southeastern California and Baja California. The strongly xerophytic Mohavean woodland was characterized by a very well-marked altitudinal and latitudinal zonation with juniper-Joshua tree (Yucca brevifolia) sorting out below pinyon-juniper woodland, and with live oaks restricted to the upper level along the lower Colorado River drainage. Southeastward, the Sonoran Desert province was similarly zoned, but with the more slender-leaved Pinus edulis var. fallax as pinyon and with more live oaks in the upper zone. However, the pleniglacial woodland of the Chihuahuan Desert province was almost unzoned, inasmuch as the less xerophytic species of pinyon and live oaks prevailed over the entire span of available elevation; the pinyon was the very slender-leaved P. cembroides var. remota.

The overall paleozonation indicates a strong northwest-to-southeast gradient of increasing summer rain with decreasing distance from the monsoonal source area over the Gulf of Mexico, as at present, but augmented pluvially along the same gradient. A key piece of evidence is the counterintuitive latitudinal-zonational anomaly between about 30 and 40° N in southwestern North America; the lower limits of modern vegetational zones are depressed with decreasing latitude (e.g., ca. 500 m lower at 34° than at 36° N). The axis of the gradient actually extends from northwest to southeast, paralleling the monsoonal gradient of increasing summer rain, which no doubt causes the apparent anomaly. During the Wisconsinan glacial, the latitudinal anomaly was greatly steepened, a fact requiring a pluvial increase in precipitation over the Southwest. The monsoonalpluvial pattern is supported by the Neotoma record of a northwest-to-southeast gradient of increasing diversity of evergreen oaks requiring summer rain, and by a parallel segregation of pinyon species. Equability of seasons during the last glacial is also suggested by the Neotoma macrofossil data.

Measurements of saturation isothermal remanent magnetization (SIRM) for recent ombrotrophic peats show that the rate of deposition of magnetic particulates from the atmosphere varies strongly in response to the persistent, small-scale, spatial changes in vegetation and microtopography characteristic of many raised bogs. Hummock environments may trap over an order of magnitude more magnetic particulates than do Sphagnum lawns and pools. These results, thought to reflect the interception of subhorizontally moving particles by the hummock forming plants, have potentially important implications for studies of pollen deposition (“influx”) rates in peat.

A pollen analytical investigation of the sediments of Berry Pond, Berkshire County, Massachusetts, has demonstrated a sequence of pollen assemblage zones similar to those detected elsewhere in New England. From about 13,000 to 12,000 yr B.P. the vegetation of the region was treeless, probably tundra. By 11,500 yr tundra had been replaced by open boreal forest. Closed boreal forest became dominant by 10,500 yr. Boreal forests were replaced by mixed coniferous and deciduous forests with much white pine about 9600 yr ago. A “northern hardwoods” complex with much hemlock, beech, and sugar maple succeeded the mixed forests 8600 yr ago. Hemlock declined very rapidly approximately 4800 yr ago and was replaced by birch, oak, beech, ash, and red maple. This decline may have been biologically rather than climatically induced. There is a slight maximum of pine (much of it pitch pine) from 4100 to 2600 yr ago, perhaps indicative of warmer and/or drier conditions. There were slight changes in the forests about 1600 yr ago as chestnut immigrated and spruce and larch increased slightly. European land clearance and subsequent land abandonment are detectable in the uppermost levels.

Pollen and plant macrofossils preserved in lake sediment from Lake West Okoboji, Dickinson County, Iowa, indicate how the vegetation of that area changed during the late glacial and postglacial. A closed coniferous forest, dominated by spruce and larch trees, produced the Picea-Larix pollen assemblage zone. Fir trees were a minor constituent of this forest; pine trees were probably absent. Black ash trees increased in abundance at Lake West Okoboji and by 13,500 yr ago were an important constituent of the forest. The sediment accumulation rate and the pollen influx were low throughout this time. Birch and alder pollen peaked in abundance approximately 11,800 yr ago. Pollen influx increased rapidly as birch and alder replaced coniferous trees on the uplands. A deciduous forest, containing abundant oak and elm trees, replaced the birch-alder-coniferous forest. This forest inhabited northwestern Iowa from approximately 11,000 to 9000 yr B.P. Nonarboreal species became prevalent between approximately 9000 and 7700 yr B.P. as prairie began to replace deciduous forest on the uplands. Charred remains of Amorpha canescens and other upland species attest to the presence of prairie fires as an aid in establishing prairie and destroying the forest. The pollen influx declined. The warmest, driest part of the postglacial occurred in northwestern Iowa from approximately 7700 to 3200 yr ago. Lake level fell 9 to 10 m, and prairie extended to the edge of the lake. Wet-ground weeds inhabited areas near lake level which were alternately flooded, then dry. Pollen influx was approximately 100 grains/cm2/yr during the driest time in this dry interval.

Deciduous trees, particularly oaks, returned after approximately 3200 yr B.P. Prairie continued to occupy the uplands but trees were more common in the lowlying wet areas. Settlement by Europeans in northwestern Iowa about 1865 is marked by an increase in weed pollen. Macrofossil deposition changed in 1910 in response to the stabilization of lake level.

A quantitative analysis of radiolarian species in 57 deep-sea surface sediment samples from the South Atlantic Ocean produced four geographically distinct assemblages (tropical, polar, gyre margin, and subtropical). The distributions of these assemblages or factors coincide with present-day patterns of sea-surface temperatures or water masses.

These four assemblages were used to construct a transfer function relating radiolarian distribution in the surface sediments to present-day winter and summer temperatures using standard regression techniques. As a test of the quality of this transfer function, temperatures were estimated on surface sediment samples from the eastern South Pacific. The temperatures produced by the transfer function compared favorably with the observed (present-day) winter and summer sea-surface temperatures at these sites.

Temperature estimates produced by a radiolarian-based transfer function, factor distributions of radiolarian assemblages, and variations in calcium carbonate were used to reconstruct the oceanographic conditions in the South Atlantic during the last glacial maximum (18,000 yr B.P.). This study suggests that while the position of the Subtropical Convergence at 18,000 yr B.P. was very similar to its present position, the Antarctic Polar Front shifted northward 1° to 3° of latitude in the eastern South Atlantic and 3° to 5° of latitude in the western South Atlantic. The largest temperature changes occurred in the subantarctic region and along the eastern portion of the Subtropical Gyre.