Maximum Glaciation Research Articles

Discovery of a large area of ice-wedge networks in Ordos: Implications for the southern boundary of permafrost in the north of China as well as for the environment in the latest 20 kaBP

The delineation of the southern boundary of the latitudinal permafrost in the north of China in the period of late Pleistocene, i.e. the last glaciation maximum (LGM), has been hampered for two reasons. Firstly, previous studies were limited to the eastern part of the north of China, and, secondly, the ages of the permafrost had not been determined systematically. In this paper, we suggest that the southern boundary of the high latitudinal permafrost in the north of China is bounded by approximately 38–40°N (eastern part) and 37–39°N (western part) lines of latitude based on our interpretation of periglacial phenomena and their implication to the environment during the late Pleistocene, and this southern boundary is plotted for the first time. Also, we reconstruct the migration of the southern latitudinal permafrost boundary and the environment after LGM. It is pro posed that two cold stages occurred in the LGM at 26 kaBP and 23–13 kaBP, when the annual mean temperature was 8 –12°C lower than at present.

Lithology, landscape dissection and glaciation controls on catchment erosion as determined by cosmogenic nuclides in river sediment (the Wutach Gorge, Black Forest)

AbstractCosmogenic nuclides, measured in quartz from recent river bedload, provide a novel tool to quantify catchment‐wide erosion rates at geologically meaningful time scales. Here we present an analysis of the geomorphological evolution of the 350 km2 Wutach catchment in the uplands of the south‐west German Black Forest. The robustness of the method is demonstrated by the fact that, although the area was affected by river capture at 18 kyr bp, the formed gorge is so narrow that spatially averaged erosion rates were not resolvably perturbed. However, because cosmogenic nuclides preserve an erosion memory of several thousand years, the only perturbation introduced was detected in the minor areas that have been subject to the last maximum glaciation. In unglaciated areas, an important relationship between lithology and erosion can by quantified: sandstone lithologies erode at 12–18 mm kyr−1, granite lithologies at 35–47 mm kyr−1 and limestone lithologies (as deduced from river load gauging) at 70–90 mm kyr−1.

Glacier variations in Breheimen, southern Norway: dating Little Ice Age moraine sequences at seven low‐altitude glaciers

AbstractMoraine sequences in front of seven relatively low‐altitude glaciers in the Breheimen region of central southern Norway are described and dated using a ‘multi‐proxy’ approach to moraine stratigraphy. Lichenometric dating, based on the Rhizocarpon subgenus, is used to construct a composite moraine chronology, which indicates eight phases of synchronous moraine formation: AD 1793–1799, 1807–1813, 1845–1852, 1859–1862, 1879–1885, 1897–1898, 1906–1908 and 1931–1933. Although the existence of a few cases of older moraines, possibly dating from earlier in the eighteenth or late in the seventeenth centuries cannot be ruled out by lichenometry, Schmidt hammer R‐values from boulders on outermost moraine ridges suggest an absence of Holocene moraines older than the Little Ice Age. Twenty‐three radiocarbon dates from buried soils and peat associated with outermost moraines at three glaciers—Tverreggibreen, Storegrovbreen and Greinbreen—also indicate that the ‘Little Ice Age’ glacier maximum was the Neoglacial maximum at most if not all glaciers. Several maximum age estimates for the Little Ice Age glacier maximum range between the fifteenth and seventeenth centuries, with the youngest from a buried soil being AD 1693. A pre‐Little Ice Age maximum cannot be ruled out at Greinbreen, however, where the age of buried peat suggests the outermost moraine dates from AD 981–1399 (at variance with the lichenometric evidence). Glaciofluvial stratigraphy at Tverreggibreen provides evidence for minor glacier advances about AD 655–963 and AD 1277–1396, respectively. Copyright © 2003 John Wiley & Sons, Ltd.

Timing of Late Pleistocene climate change in lowland Switzerland

A chronology of climate change in lowland Switzerland for the time between the Last Interglacial and the Last Glaciation Maximum (LGM) is provided by complementary radiocarbon, 230Th/U and luminescence dating of the Gossau key section. The Gossau-Interstadial-Complex is consistently dated to ∼50,000–30,000 yr BP and hence correlated with Marine Oxygen Isotope Stage (MIS) 3. Palaeotemperature readings reconstructed from coleoptera analyses and pollen assemblages evidence oscillating environmental conditions from tundra to open woodland and reflect changing climate during the Middle Würmian. Delta deposits from the lower part of the Gossau section indicate a cold period prior to the Interstadial-Complex. This severe climatic deterioration is correlated with MIS 5d based on luminescence dating. Sedimentological evidence implies the presence of glaciers at the northern margin of the Swiss Alps during this time.

Evidence of an LGM cooling in NW-Argentina (22°S) derived from a glacier climate model

A climate glacier model is used to interpret late Pleistocene maximum glaciations in the NW-Argentinan Andes (22°S). According to the model, massive cooling combined with a moderate precipitation increase is necessary to explain maximum glacier extension. Even given a factor of 2–4 precipitation increase, the model indicates that temperatures must have been lowered by 4.5–8°C, suggesting that maximum glaciation probably occurred during full glacial times of MIS 2 (25–18 ka). This conclusion is supported by dated proglacial lake sediments and evidence of past glacial geometry. The extremely long tongues and low accumulation area ratios indicate that ablation was reduced during cold periods in agreement with the model. A strong relationship exists between glacier geometry and prevailing climate. Contrary to the precipitation-controlled Late Glacial (12–10 ka) maximum glaciation of the arid Central Andes in southern Peru and northern Chile, the glaciations on the much more humid eastern Andean slope are mainly controlled by temperature and therefore reached their maximum extent during the MIS 2 cold conditions.

A new interpretation of the date of the ‘Little Ice Age’ glacier maximum at Svartisen and Okstindan, northern Norway

New results concerning the dating of ‘Little Ice Age’ glacier variations at Svartisen and Okstindan, northern Norway, are presented. Measurements of lichens of the Rhizocarpon subgenus on gravestones are used to construct several local sets of lichenometric dating curves. These are partly ‘adjusted’ in relation to well-established lichenometric dating curves from southern Norway. The ‘Little Ice Age’ maximum at Svartisen and Okstindan is thereby dated to the mid-eighteenth century (i.e., in agreement with southern Norway). Pre viously suggested earlier ‘Little Ice Age’ advances are demonstrated to have resulted from an underestimation of the growth rates of the Rhizocarpon subgenus. Synchroneity of ‘Little Ice Age’ maxima in southern Norway and at Svartisen and Okstindan suggest that a north–south migration of latitudinal depressional tracks can be excluded as the main forcing factor. As an alternative, an increased SE–NW trend of moist air‘ ow in winter parallel to the coast of Norway is suggested as the main forcing factor with recent glacier dynamics in response to recent climatic ‘ uctuations supporting this hypothesis.

Paléoenvironnements pléistocènes et peuplements paléolithiques dans le bassin de la Somme (nord de la France)

This paper represents a synthetic overview of the main results of the CNRS Programme " Palaeoenvironments and Hominids ". This project focused on the study of interactions between human occupation and environmental modification, between 500 and 10 kyrs BP, based on multidisciplinary and diachronic studies of key sites in the Somme Basin. The main analytic results concern ESR, TL-IRSL and 14C dates, which reinforce the chrono-stratigraphical interpretation of the various Palaeolithic sites. At the same time, bioclimatic analyses of fluvial sediments (palynology, malacology, analysis of Coleoptera), combined with the measurement of δ13C variations of organic carbon, and of the low-field magnetic susceptibility in loess and fossil soils, allowed the restitution of the various Pleistocene environments, and especially of the full Interglacials, to be refined. The main conclusions of the synthesis of archaeological, chronostratigraphical and environmental data are the following. 1) The earliest human occupations in the Somme Basin are no older than 500-450 kyrs BP and are straight away represented by well evolved Acheulean industries (beginning of MIS 12, according to the data from modern excavations). 2) During the last climatic cycle, human occupation of the Somme Basin was clearly discontinuous and strongly influenced by climatic and environmental modifications: maximum during the Early-Glacial, some occupations during the Lower and Middle Maximum Glaciations, rare occurrences around 23-24 kyrs (14C), total abandonment of the area between 23 and 13 kyrs, then reoccupation with the beginning of the Lateglacial climatic improvement. 3) Although the data are less numerous, the model of the last climatic cycle seems to apply during the Middle Pleistocene for the end of the Saalian (occupation at the end of MIS 7 or at the transition MIS7/MIS6, and desertion of the area during the cold maximum of MIS 6). 4) Finally, between 500/450 and 200 kyrs human settlements mainly occurred during periods of climatic transition (Early or Lateglacial). From a general point of view, the human occupation of the Somme Basin during the Middle Pleistocene was therefore discontinuous and strongly influenced by climatic and environmental factors.

Paleosols as the basis of environmental reconstruction in Altai mountainous areas

Detailed study of the Late Pleistocene–Holocene paleosols and sediments revealed the geographic pattern of climatic fluctuations in different Altai regions. The study is based on application of the pedohumic method, which distinguishes paleosols at any degree of conservation. Existing geographic pattern of mountain slopes, bordering intermountain depressions and river valleys, was taken into consideration. Thus, a combination of pedohumic method with soil geographic research made it possible to reconstruct the environmental evolution of the whole mountainous territory, based on the regularities of modern landscapes. A schematic map of the reconstructed mountainous landscapes of the Central and Northwestern regions of Altai is presented not only for main stages of the Late Pleistocene–Holocene, but also for certain intervals within each. Periods of maximum glaciations were characterised by the simplest scheme of altitude sequence. At interglacial and interstadial periods the number of landscape zones was maximal and the structure of soil cover was more complex.

Asynchroneity of maximum glacier advances in the central Spanish Pyrenees

AbstractThe deglaciation history of the Escarra and Lana Mayor glaciers (Upper Gállego valley, central Spanish Pyrenees) had been reconstructed on the basis of detailed geomorphological studies of glacier deposits, sedimentological and palynological analyses of glacial lake sediments and an accelerator mass spectrometry (AMS) 14C chronology based on minimum ages from glacial lake deposits. The maximum extent of the Pyrenean glaciers during the last glaciation was before 30 000 yr BP and pre‐dated the maximum advances of the Scandinavian Ice Sheet and some Alpine glaciers. A later advance occurred during the coldest period (around 20 000 yr BP), synchronous with the maximum global ice extent, but in the Pyrenees it was less extensive than the previous one. Later, there were minor advances followed by a stage of debris‐covered glaciers and a phase of moraine formation near cirque backwalls. The deglaciation chronology of the Upper Gállego valley provides more examples of the general asynchroneity between mountain and continental glaciers. The asynchroneity of maximum advances may be explained by different regional responses to climatic forcing and by the southern latitude of the Pyrenees. Copyright © 2002 John Wiley & Sons, Ltd.

One-way and quasi-periodic climate changes: Geologic evidence

During the last three billion years, the Earth has been experiencing a slow global cooling, expressed in the progressively increasing frequency and scale of glacial events. Based on these indications, geologic history can be divided into three climatic stages: (a) non- glacial (Early and Middle Archean), (b) with episodic glaciations (Late Archean to Middle Riphean), and (c) with frequent periodic glaciations (Late Riphean-present). The cooling has apparently been caused by changes in the density and composition of the atmosphere, by the waning of heat flow from the Earth's interior, and by an increase in the planet's albedo in response to continental growth. The irreversible climate trend was modulated and obscured by numerous superposed temperature oscillations of varying periodicity and amplitude. A broad spectrum of such oscillations, from ultralong-term (a few hundreds of million years) to decadal-scale, have been established. The Phanerozoic exhibits a hierarchy of coordinated periods of climatic oscillations of 10-12 ranks. Climatic oscillations of the first two or three ranks are to be detected in Proterozoic glacial sequences. In light of the above, the Earth's climate history appears to be naturally determined, the slow irreversible cooling of the Earth's surface being superposed by a rather regular pattern of periodic oscillations. The inference suggests itself that the Earth's highly complex and open climate system has been rather close to a stationary state, and that among the multitude of nonlinear processes bearing on climate there were a small number of those most influential, governing processes with periodic attractors. Glaciation maxima preceded principal tectonic phases, and they are clearly correlative to suprasubduction volcanic maxima, whereas the periods of degradation or cessation of glaciation coincide with tectonic, granitization, metamorphic, and, occasionally, mantle-plume volcanic maxima. This suggests that onsets of glaciation were triggered by explosive volcanism and by the ensuing volcanic winters. Deglaciations must have been due to increases in atmospheric transparency, to carbon oxidation and partial decarbonatization in sedimentary sequences of orogens, and to pulses of mantle plume volcanism. A similar explanation applies to long-term climatic oscillations that lasted 30 m.y. on average. Short-term climatic oscillations are explicable by variations in the astronomical parameters of our planet, and ultrashort-term ones, apparently, by solar activity variations.

Burial of Different Types of Organic Carbon in Core 17962 from South China Sea since the Last Glacial Period

Total organic carbon (TOC), black carbon (BC), and land-derived organic carbon (LOC) extracted from marine sediment core 17962 from the southern South China Sea and analyzed by pyrolysis gas chromatography, elemental analyzers, and mass spectroscopy can be interpreted in terms of regional land biomass burning, climatic conditions, vegetation cover, and ocean paleoproductivity. Carbon from terrestrial sources, including BC and LOC, appears to be a significant component of TOC (3.1–39.3% range, 16.5% average for BC; 4.4–56.6% range, 14.6% average for LOC). The production of BC and LOC was only slightly higher during the Last Maximum Glaciation (LGM) than during the Holocene. Therefore, dramatic changes in climate and vegetation cover do not seem to have occurred at the Pleistocene–Holocene boundary. Paleoproductivity data calculated from marine organic carbon, proved to be more accurate than those calculated from TOC and exhibit the same pattern of temporal variation. However, the glacial–interglacial contrast in the refined palaeoproductivity is less evident than that calculated from TOC.

Numerical simulation of mud-rich subaqueous debris flows on the glacially active margins of the Svalbard–Barents Sea

Seismic images and sediment core data from the Bear Island and Isfjorden fans localized along the Svalbard–Barents Sea continental margin, reveal an interesting depositional system consisting of stacked debris flow lobes. The frequent release of debris flows was associated with large volumes of sediment rapidly delivered to the shelf break during periods of maximum glaciation. The compositions of the lobes for both fans are similar, consisting of mainly clay and silt. The data show, however, a dramatic difference in runout distances for the two areas. Isfjorden debris lobes are 10–30 km in length whereas Bear Island lobes are 100–200 km in length. Even more intriguing is the fact that the large runout distances on the Bear Island fan occurred on slopes less than 1° whereas the Isfjorden fan flows occurred on slopes greater than 4°. Depth-averaged non-linear one-dimensional equations for balance of mass and linear momentum are applied to simulate the subaqueous debris flow. The equations are solved by the numerical model BING, describing the flow as a visco-plastic Bingham fluid. The model is employed to study the effect yield strength, viscosity and bathymetry have on debris flow runout. The study shows that the large runout distances can be achieved on the Bear Island fan by visco-plastic flows with sufficiently low yield strength. High yield strength sediments require an additional mechanism, such as hydroplaning, to reach measured runout distances. Most importantly, this study shows the necessity of good rheological measurements for accurate numerical modeling of subaqueous debris flows.

Distribution patterns of cavernicolous Collembola in AustriaProceedings of the Xth international Colloquium on Apterygota, České Budějovice 2000: Apterygota at the Beginning of the Third Millennium

Summary The recent distribution of cave Collembola in Austria is discussed in the light of Quaternary climate oscillations. Four principal patterns are described: (1) widely scattered alpine cave-dwellers which have survived the last glaciation on nunataks; (2) endemic troglobionts within the borders of maximum WIrm glaciation which have endured in their original subterranean habitats; (3) relicts in periglacial refugia at the eastern margin of the Alps; (4) Holocene remigrants from periglacial refugia.

Modeling Modern and Late Pleistocene Glacio-Climatological Conditions in the North Chilean Andes (29–30 °)

An empirical-statistical climate-glacier model is used to reconstruct Late Pleistocene climate conditions in the south-central Andes of northern Chile (29–30° S). The model was tested using modern climate data and the results compare favorably with key glaciological features presentlyobserved in this area. Using several glaciers at 29° S as casestudies, the results suggest an increase in annual precipitation(Δ P = 580 ± 150 mm, today 400 mm), and a reduction inannual mean temperature (Δ T = −5.7 ± 0.7 ° C).These data suggest full glacial LGM (Last Glacial Maximum) conditionsfor the maximum glacier advances at 29° S, a scenario that is asynchronous with the timing of maximum advances north of the Arid Diagonal (18–24° S) where late-glacial climate was moderately cold but very humid.The reconstructed case study glaciers at 29° S do not allow conclusions to be drawn about the seasonality of precipitation. However, comparison with regional paleodata suggests intensified westerly winter precipitation and a stable position for the northern boundary of the westerlies at ∼ 27° S. However, the meridional precipitation gradients were much steeper than today while the core area of the Arid Diagonal remained fixed between 25–27° S.

The timing of the Last Glacial Maximum in Australia

Late Pleistocene glaciation of Australia was restricted to the Snowy Mountains and the Tasmanian highlands. Glaciers were most extensive in Tasmania where ice caps formed on the Central Plateau and West Coast Ranges, and systems of valley and cirque glaciers formed on surrounding mountains. To investigate the timing of maximum glacier advance during the Last Glacial Maximum (LGM), we dated boulders on 18 moraines in 8 glaciated areas using cosmogenic 36Cl and 10Be. We sampled moraines deposited by cirque and valley glaciers, in a range of climate types and lithologies over a 7° latitudinal and a 1430 m altitudinal transect. Exposure ages for LGM moraine boulders group tightly in the range 17–20 ka. Boulders from the Hamilton moraine, often treated as the LGM type moraine, range in age from ∼190–350 ka, indicating that it was deposited well before the last glaciation. Collectively, the exposure ages show that southeastern Australia was glaciated briefly during and after the LGM, and deglaciated well before the Holocene. Ice retreated from the terminal moraines after the period of coldest sea-surface temperatures in the southwest Pacific Ocean. No evidence was found for readvance of glaciers during the Antarctic Cold Reversal or the Younger Dryas period.

A new lichenometric dating curve for southeast iceland.

This paper presents a new lichenometric dating curve for southeast Iceland. The temporal framework for the curve is based on reliably dated surfaces covering the last 270 years, making it the best constrained study of this nature conducted in Iceland. The growth of lichen species within Rhizocarpon Section Rhizocarpon is non‐linear over time, with larger (older) thalli apparently growing more slowly. The linear ‘growth’ curves derived previously by former authors working in Iceland represent only part of a curve which has an overall exponential form. Reasons for the non‐linearity of the new dating curve are probably physiological, although climatic change over the last three centuries cannot be ruled out. Use of linear ‘growth’ curves in Iceland is problematic over time‐spans of more than c. 80 years. Pre‐20th century moraines dated using a constant, linear relationship between lichen size and age are probably older than previously believed. Those moraines lichenometrically ‘dated’ to the second half of the 19th century in Iceland may actually pre‐date this time by several decades (30–100 years), thus throwing doubt on the exact timing of maximum glaciation during the ‘Little Ice Age’.

Late Quaternary history around Nioghalvfjerdsfjorden and Jøkelbugten, North‐East Greenland

Nioghalvfjerdsfjorden in North‐East Greenland is at present covered by a floating glacier. Raised marine deposits in the surrounding area contain shells of marine molluscs, bones of marine mammals and pieces of driftwood. A fairly systematic sampling of such material has been conducted, followed by extensive radiocarbon dating. We suggest that the Greenland ice sheet extended onto the shelf offshore North‐East Greenland during isotope stage 2, perhaps even reaching the shelf break. During the subsequent recession of the ice sheet, the entrance of Nioghalvfjerdsfjorden had become ice‐free by 9.7 cal. ka BP. The recession culminated between 7.7 and 4.5 cal. ka BP, during which time the fjord was glacier‐free along its entire 80 km length. No dates younger than 4.5 cal. ka BP are available on marine material from the fjord, and it seems probable that the fjord has been continuously covered by the floating glacier since this time. The maximum glaciation was attained around AD 1900, after which thinning and recession took place. The marine limit increases fromc.40 m above sea level near the present margin of the Inland Ice toc.65 m above sea level at the outer coast. These figures fit into the regional pattern of the marine limit for areas both to the south and north. The marine fauna comprise two bivalves,Macoma calcareaandSerripes groenlandicus, that may represent a southern element present during the Holocene temperature optimum. Remains of three taxa of southern extralimital terrestrial and limnic plants were dated to 5.1 cal. ka BP, and remains of another extralimital plant were dated to 8.8 and 8.5 cal. ka BP. The known Holocene time ranges of the willowSalix arcticaand the lemmingDicrostonyx torquatushave been extended back to 8.8 and 6.4 cal. ka BP, respectively, providing minimum dates for their immigration to Greenland.

Holocene and latest Pleistocene fluctuations of Stutfield Glacier, Canadian Rockies

The Holocene and late glacial history of fluctuations of Stutfield Glacier are reconstructed using moraine stratigraphy, tephrochronology, and dendroglaciology. Stratigraphic sections in the lateral moraines contain tills from at least three glacier advances separated by volcanic tephras and paleosols. The oldest, pre-Mazama till is correlated with the Crowfoot Advance (dated elsewhere to be Younger Dryas equivalent). A Neoglacial till is found between the Mazama tephra and a paleosol developed on the Bridge River tephra. A log dating 2400 BP from the upper part of this till indicates that this glacier advance, correlated with the Peyto Advance, culminated shortly before deposition of the Bridge River tephra. Radiocarbon and tree-ring dates from overridden trees exposed in moraine sections indicate that the initial Cavell (Little Ice Age (LIA)) Advance overrode this paleosol and trees after A.D. 1271. Three subsequent phases of the Cavell Advance were dated by dendrochronology. The maximum glacier extent occurred in the mid-18th century, predating 1743 on the southern lateral, although ice still occupied and tilted a tree on the north lateral in 1758. Subsequent glacier advances occurred ca. 1800–1816 and in the late 19th century. The relative extent of the LIA advances at Stutfield differs from that of other major eastward flowing outlets of the Columbia Icefield, which have maxima in the mid–late 19th century. This is the first study from the Canadian Rockies to demonstrate that the large, morphologically simple, lateral moraines defining the LIA glacier limits are actually composite features, built up progressively (but discontinuously) over the Holocene and contain evidence of multiple Holocene- and Crowfoot-age glacier advances.

Can Lichenometry be Used to Date the “Little Ice Age” Glacial Maximum in Iceland?

In Iceland, there are numerous examples of glacier advances dated to the latter half of the last century. However, in marked contrast to the Alps and northern Europe, the record of historical-age moraines before ca. 1850 is rather sparse. This paper examines to what extent this pattern reflects the actual history of glacier fluctuations, and to what extent it could be a function of preservation and dating of the geomorphological record. Measurements of Rhizocarpon geographicum sp. lichen thalli on ice-marginal moraines and sandur form the basis for the late “Little Ice Age” glacial chronology in south Iceland. Recent studies have converged on the view of a maximum glacier extent in the late nineteenth century, and not during earlier and possibly colder parts of the “Little Ice Age”. Here, results of independent dating of moraine ridges and a jokulhlaup deposit demonstrate that conventional lichenometric techniques tend to cluster dates of these landforms to the 1860s–1880s, underestimating tephrochronological dates on the same landforms by > 100 yr in some cases. A mid-eighteenth century glacial maximum may be better represented in the landform record than hitherto thought, with implications for reconstruction of North Atlantic circulation patterns.

Permafrost and climatic change in China

The permafrost area in China is about 2.15×10 6 km 2, and is generally characterized by altitudinal permafrost. Permafrost in China can be divided into latitudinal and altitudinal types, the latter can be further divided into plateau and alpine permafrost. Altitudinal permafrost also can be divided into five thermal stability types. The permafrost environment has changed significantly since the Late Pleistocene. In northeastern China, the southern limit of permafrost extended to 41–42°N during the last glaciation maximum; in the Holocene megathermal, it retreated northward. The ice wedges and permafrost formed during the Late Pleistocene are still present in the northern part of the Da-Xing'anling Mountains. The inactive ice wedges at Yitulihe indicate a cooling and subsequent permafrost expansion during the Late Pleistocene. The lower limit of altitudinal permafrost in western China has elevated from 800 to 1500 m since the last glaciation maximum. Compared with that in northern Europe and North America, latitudinal permafrost in northeastern China is less sensitive to climatic warming, but altitudinal permafrost, especially permafrost on the Qinghai–Tibet Plateau (QTP), is sensitive to climatic warming. Since the early 20th century, significant permafrost degradation has occurred and is occurring in most permafrost regions in China. Due to the combined influence of climatic warming and increasing anthropogenic activities, substantial retreat of permafrost is expected on the QTP and in northeastern China during the 21st century. Permafrost degradation has and will cast great influence on engineering construction, water resources and environments in the cold regions of China. The wetlands in the cold regions of China emit significant amounts of CH 4 and N 2O to the atmosphere and uptake atmospheric CO 2 at a considerable rate, which might contribute to the global atmospheric carbon budget and feedback to climatic systems. However, uncertainties about permafrost changes, rates of changes and their environmental impacts are still large and call for intensive studying.