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Our knowledge about the Holocene evolution of the East Asian summer monsoon (EASM) and its relation to human activities remains incomplete. A detailed palynological investigation of two sediment sections from the Daiyun Mountain Nature Reserve (ca. 25°38′–25°44′N, 118°05′–118°21′E, Fujian Province) suggests EASM-controlled subtropical climate conditions that were wetter and warmer than present over the early and middle Holocene. After 5700 cal. yr BP, steadily increasing non-arboreal pollen and fern spore percentages imply an attenuation of the EASM. The general climate trend is interrupted by several century-scale changes in composition and concentration of arboreal pollen taxa around 8200, 7200, 6300, and 4400 cal. yr BP, coinciding with weaker precipitation (and lower temperature) as suggested by the EASM oxygen isotope record. Our results further support the hypothesis that the natural vegetation cover of southern China was not markedly affected by human activities until 3000 cal. yr BP. The pollen records suggest a quick decrease in the forest cover ca. 3000–2450 cal. yr BP followed by a generally open (agricultural) landscape and spread of secondary pine forests. This pattern is in line with a major population growth promoted by the southward expansion of rice-based agriculture across the region that postdates the widely accepted ‘Holocene climate optimum’ by several millennia. This highlights the multidimensional significance of this term, which is commonly used in palaeoenvironmental and archaeological studies and should be consequently applied with respect to the specific issue under consideration.

Assessing pollen distribution patterns in the sea is essential to understanding pollen provenance, upon which subsequent interpretation of Quaternary pollen data from marine sediments in the same study area should be soundly based. Here we present palynological data from seafloor sediments in Laizhou Bay and analogous samples from its inflowing rivers to elucidate the distribution patterns and provenance of modern palynomorphs. Our results demonstrate that the pollen assemblages of marine areas are dominated by arboreal pollen types, especially Pinus, and herbaceous pollen types are dominated by Chenopodiaceae and Artemisia. The higher pollen concentrations occur in the southwest area of Laizhou Bay, and the lower pollen concentrations are mainly distributed in the nearshore area of the Yellow River estuary. Such pollen distribution patterns are tightly correlated with the distribution features of grain size of the surface sediments. Specifically, the sediments with higher pollen concentrations are of very fine and fine silts, whereas those with lower pollen concentrations are of fine sands. The results of PCA analysis suggest that pollen grains in the nearshore areas are mainly transported by water flows, of which herbaceous pollen show relatively higher concentrations; while pollen grains in the offshore areas are largely carried by winds, especially those pollen types with sacs, such as Pinus. Dissimilarity analysis between marine and alluvial samples indicates that the pollen spectrum show close linkage with the regional vegetation in the surrounding watersheds. Pollen quantitative characteristics and pollen assemblage changes in different parts of the marine areas indicate various pollen provenance and changing landscape of terrestrial vegetation, particularly along the inflowing rivers. Our Assessments on pollen distribution patterns and provenance based on palynological investigation would strongly aid Quaternary palaeoecological and palaeoclimatological interpretation for our study area.

Paleoenvironmental records derived from pollen, fungal spores, and microscopic charcoal from Lake Baringo, Kenya, reveal a largely dry environment in the East African region since AD 1650. The dry environment is punctuated by a succession of centennial- to decadal-scale wet and dry episodes, disjointed by sharp transitions, including two intense dry episodes that led to drying of the lake at ca. AD 1650 and AD 1720 which coincide with the Little Ice Age (LIA) period in Europe. The Baringo record shows that land degradation in the area began prior to the colonial period in East Africa and has persisted to the present. Land degradation and increased soil erosion in the Lake Baringo drainage basin was severe enough to significantly 'age' the lake sediments due to influx of old carbon resulting in the dating inversion.

This study further investigates the reported “uniqueness” of MIS 3 climatic changes in northwestern China by focusing on the MIS 3 lacustrine-wetland sequences in the western part of the Chinese Loess Plateau. The lacustrine-wetland sequence at the Suancigou section documented four major environmental changes. Stratigraphic unit (i) was formed under lake-dominated environments (48,420–35,730 14 C yr BP), unit (ii) under wetland-dominated environments (35,730–20,480 14 C yr BP), and unit (iii) under eolian-dominated environments (20,480–13,090 14 C yr BP). Unit (iv) is a fluvially-reworked eolian (loess) unit (13,090–11,450 14 C yr BP). Pollen zone A (47,210–33,370 14 C yr BP), representing a coniferous forest, corresponds to stratigraphic unit (i). Zone B (33,370–28,280 14 C yr BP), representing a coniferous woodland landscape, and zone C (28,280–22,480 14 C yr BP), representing a landscape in which coniferous woodlands alternated with steppes; correspond to unit (ii). Zone D (22,480–11,450 14 C yr BP), representing a steppe landscape, corresponds to unit (iii) and unit (iv). We propose that the extremely wet MIS 3 was a combined result of mildly high summer insolation and constantly higher-than-normal winter insolation. That is, mildly high MIS 3 summer insolation was probably able to maintain the warmth of the ocean surface to the extent so that the Tibetan Plateau and northwestern China received an adequate supply of water-vapour. A constantly higher-than-normal MIS 3 winter insolation might have shortened the duration of the winter monsoon, so lengthening the rainy season. In addition, the soil-vegetation-air coupled feedback mechanisms under extensively well-vegetated wet conditions might have further enhanced the MIS 3 wet conditions.

This study focuses on an eolian section (Shaamar section) in the Northern Mongolian Plateau and compares the eolian sequences in the Northern Mongolian Plateau with those along the southern boundary of the Gobi Deserts to better understand the dynamics of the Gobi deserts during the past ∼ 35,000 14C yr BP. Only a weak Entisol-like paleosol was formed around 29,000 14C yr BP in the exposed MIS 3 portion at the Shaamar section, whereas an eolian–colluvium–paleosol sequence at nearby Bureghkanga section exhibits three paleosols formed around 29,000 14C yr BP, 31,000 14C yr BP, 34,000 14C yr BP. Loess–paleosol sequences in the western Siberian Lowland exhibit four paleosols formed from > 40,000 to 25,000 14C yr BP (i.e., MIS 3). During MIS 2 two Mollisol-like paleosols were formed from ∼ 25,000 to ∼ 21,000 14C yr BP and from ∼ 16,000 to ∼ 13,000 14C yr BP and one Entisol-like paleosol was formed around 9500 14C yr BP at the Shaamar section. The MIS 2 was characterized primarily by silt deposition, except for the interval between ∼ 21,000 and ∼ 16,000 14C yr BP that was dominated by sand deposition. The Holocene began with the Mollisol-like paleosol formation (from ∼ 8600 to ∼ 7000 14C yr BP). The mid-Holocene (∼ 7000 to ∼ 3000 14C yr BP) was marked by a relatively poor vegetation cover and the late Holocene (since ∼ 3000 14C yr BP) by the densest vegetation cover of the entire Holocene. In summary, the maximal extent of hyperarid and arid areas (Gobi deserts and Gobi-like) occurred twice: (1) from ∼ 21,000 to ∼ 16,000 14C yr BP and from ∼ 13,000 to ∼ 8600 14C yr BP when the dominant eolian deposition conditions extended from 56° N to 33° N or even larger. The extent of hyperarid and arid areas retreated to the area between 38° N and 48° N or even much smaller several times during MIS 3 and during the early Holocene. Considering the uncertainties of dates, it seems that the Holocene bioclimatic conditions might have changed more or less synchronously between the north and the south and that the bioclimatic conditions varied more frequently in the north than in the south during MIS 3. Two Mollisol-like paleosols (IIc: ∼ 13,000 to ∼ 16,000 14C yr BP; and IIIa: ∼ 21,000 to ∼ 25,000 14C yr BP) were well developed during MIS 2 in the north, but no corresponding major paleosols were discovered in the south, suggesting that the climate did not change synchronously during MIS 2. The climates during the stadial–interstadial MIS 3–2 transition (∼ 25,000 to ∼ 21,000 14C yr BP) and during the last glacial maximum-deglacial transition (∼ 16,000 to ∼ 13,000 14C yr BP) were much more humid in the north than in the south.

The western part of the Chinese Loess Plateau has experienced a series of environmental changes during the Holocene. A desert-steppe of late glacial was succeeded by a forest-steppe from 8850 to 7540 14 C years BP, and a Pinus -dominated forest occupied the landscape from 7540 to 6560 14 C years BP. A deciduous forest of high density and diversity existed from 6560 to 5790 14 C years BP. Afterwards the vegetation changed to a Pinus -dominated forest-steppe (5790–4950 14 C years BP) and then to an Ulmus -dominated forest-steppe (4950 to ∼ 4000 14 C years BP). The vegetation subsequently changed to a steppe from ∼ 4000 to 3120 14 C years BP and further to a desert-steppe from 3120 to 2900 14 C years BP. After a period of vegetation improvement (steppe) from 2900 to 2460 14 C years BP, a desert-steppe resumed (2460–2020 14 C years BP). Steppe vegetation was re-established around 2020 14 C years BP and seems to have then deteriorated again around 1000 14 C years BP. The general trend of aforementioned climatic changes is proposed here to have been modulated by the insolation changes. Specifically, the insolation started to increase around 15,000 years BP and peaked around 9000 years BP when the obliquity-driven seasonality reached a maximum with the summer insolation being about 8% more than the present. As a result, tropical Holocene SST increased steadily from ∼ 10,000 to ∼ 6,000 years BP, thus effectively strengthening the East Asian summer monsoon. In addition, the documented high temperatures from 10,000 to 4000 years BP in high northern latitudes might have weakened the strength of the winter monsoon and thus enhanced the strength of the summer monsoon probably via lengthening of the rainy season, directly contributing to the “megahumid” climate between 10,000 and 4000 years BP in the western part of the Chinese Loess Plateau.