The framework of a national land use and land cover classification system is presented for use with remote sensor data. The classification system has been developed to meet the needs of Federal and State agencies for an up-to-date overview of land use and land cover throughout the country on a basis that is uniform in categorization at the more generalized first and second levels and that will be receptive to data from satellite and aircraft remote sensors. The pro-posed system uses the features of existing widely used classification systems that are amenable to data derived from re-mote sensing sources. It is intentionally left open-ended so that Federal, regional, State, and local agencies can have flexibility in developing more detailed land use classifications at the third and fourth levels in order to meet their particular needs and at the same time remain compatible with each other and the national system. Revision of the land use classification system as presented in US Geological Survey Circular 671 was undertaken in order to incorporate the results of extensive testing and review of the categorization and definitions.

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A land use and land cover classification system for use with remote sensor data

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-

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Observed climate variability and change

Anomalous-fading rates were measured in K-feldspars separated from 49 sediment samples, mainly from North America. The intensity of the optically stimulated luminescence was found to decrease linea...

Ubiquity of anomalous fading in K-feldspars and the measurement and correction for it in optical dating

The permafrost monitoring network in the polar regions of the Northern Hemisphere was enhanced during the International Polar Year (IPY), and new information on permafrost thermal state was collected for regions where there was little available. This augmented monitoring network is an important legacy of the IPY, as is the updated baseline of current permafrost conditions against which future changes may be measured. Within the Northern Hemisphere polar region, ground temperatures are currently being measured in about 575 boreholes in North America, the Nordic region and Russia. These show that in the discontinuous permafrost zone, permafrost temperatures fall within a narrow range, with the mean annual ground temperature (MAGT) at most sites being higher than −2°C. A greater range in MAGT is present within the continuous permafrost zone, from above −1°C at some locations to as low as −15°C. The latest results indicate that the permafrost warming which started two to three decades ago has generally continued into the IPY period. Warming rates are much smaller for permafrost already at temperatures close to 0°C compared with colder permafrost, especially for ice-rich permafrost where latent heat effects dominate the ground thermal regime. Colder permafrost sites are warming more rapidly. This improved knowledge about the permafrost thermal state and its dynamics is important for multidisciplinary polar research, but also for many of the 4 million people living in the Arctic. In particular, this knowledge is required for designing effective adaptation strategies for the local communities under warmer climatic conditions. Copyright © 2010 John Wiley & Sons, Ltd.

Permafrost thermal state in the polar Northern Hemisphere during the international polar year 2007–2009: a synthesis

Stocks of soil organic carbon represent a large component of the carbon cycle that may participate in climate change feedbacks, particularly on decadal and centennial timescales. For Earth system models (ESMs), the ability to accurately represent the global distribution of existing soil carbon stocks is a prerequisite for accurately predicting future carbon–climate feedbacks. We compared soil carbon simulations from 11 model centers to empirical data from the Harmonized World Soil Database (HWSD) and the Northern Circumpolar Soil Carbon Database (NCSCD). Model estimates of global soil carbon stocks ranged from 510 to 3040 Pg C, compared to an estimate of 1260 Pg C (with a 95% confidence interval of 890–1660 Pg C) from the HWSD. Model simulations for the high northern latitudes fell between 60 and 820 Pg C, compared to 500 Pg C (with a 95% confidence interval of 380–620 Pg C) for the NCSCD and 290 Pg C for the HWSD. Global soil carbon varied 5.9 fold across models in response to a 2.6-fold variation in global net primary productivity (NPP) and a 3.6-fold variation in global soil carbon turnover times. Model–data agreement was moderate at the biome level (R2 values ranged from 0.38 to 0.97 with a mean of 0.75); however, the spatial distribution of soil carbon simulated by the ESMs at the 1° scale was not well correlated with the HWSD (Pearson correlation coefficients less than 0.4 and root mean square errors from 9.4 to 20.8 kg C m−2). In northern latitudes where the two data sets overlapped, agreement between the HWSD and the NCSCD was poor (Pearson correlation coefficient 0.33), indicating uncertainty in empirical estimates of soil carbon. We found that a reduced complexity model dependent on NPP and soil temperature explained much of the 1° spatial variation in soil carbon within most ESMs (R2 values between 0.62 and 0.93 for 9 of 11 model centers). However, the same reduced complexity model only explained 10% of the spatial variation in HWSD soil carbon when driven by observations of NPP and temperature, implying that other drivers or processes may be more important in explaining observed soil carbon distributions. The reduced complexity model also showed that differences in simulated soil carbon across ESMs were driven by differences in simulated NPP and the parameterization of soil heterotrophic respiration (inter-model R2 = 0.93), not by structural differences between the models. Overall, our results suggest that despite fair global-scale agreement with observational data and moderate agreement at the biome scale, most ESMs cannot reproduce grid-scale variation in soil carbon and may be missing key processes. Future work should focus on improving the simulation of driving variables for soil carbon stocks and modifying model structures to include additional processes.

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Causes of variation in soil carbon simulations from CMIP5 Earth system models and comparison with observations

PART ONE: THE PERIGLACIAL DOMAIN. 1. INTRODUCTION. 1.1. The periglacial concept. 1.2. Disciplinary considerations. 1.3. The growth of periglacial knowledge. 1.4. The periglacial domain. 1.5. The scope of periglacial geomorphology. Advanced reading. Discussion topics. 2. PERIGLACIAL LANDSCAPES? 2. 1 Introduction. 2. 2 Proglacial, paraglacial or periglacial? 2. 3 Unglaciated periglacial terrain. 2. 4 Relict periglacial landscapes. 2. 5. Conclusions. Advanced reading. Discussion topics. 3. PERIGLACIAL CLIMATES. 3.1 Boundary conditions. 3.2 Regional climates. 3.3 Ground climates. 3.4. Periglacial climates and the cryosphere. Advanced reading. Discussion topics. PART TWO: PRESENT-DAY PERIGLACIAL ENVIRONMENTS. 4. COLD-CLIMATE WEATHERING. 4. 1 Introduction. 4. 2 Ground freezing. 4. 3 Freezing and thawing. 4. 4. The ground temperature regime. 4. 5. Rock (frost?) shattering. 4. 6. Chemical weathering. 4. 7. Cryogenic weathering. 4. 8. Cryobiological weathering. 4. 9. Cryopedology. Advanced reading. Discussion topics. 5. PERMAFROST. 5. 1. Introduction. 5. 2. Thermal and physical properties. 5. 3. How does permafrost aggrade? 5. 4. Distribution of permafrost. 5. 5. Relict permafrost. 5. 6. Permafrost hydrology. 5. 7 Permafrost and terrain conditions. 5. 8. The active layer. Advanced reading. Discussion topics. 6. SURFACE FEATURES OF PERMAFROST. 6. 1. Introduction. 6. 2. Thermal-contraction-crack polygons. 6. 3. Organic terrain. 6. 4. Rock glaciers and permafrost creep. 6. 5. Frost mounds. 6. 6. Active-layer phenomena. Advanced reading. Discussion topics. 7. GROUND ICE. 7. 1. Definition and description. 7. 2. Classification. 7. 3. Ice distribution. 7. 4. Cryolithology and cryostratigraphy. 7.5 Ice wedges. 7. 6. Massive ice and massive-icy bodies. 8. THERMOKARST. 8. 1 Introduction. 8. 2. Causes of thermokarst. 8. 3. Thaw-related processes. 8. 4. Thermokarst sediments and structures. 8.5. Ice-wedge thermokarst relief. 8. 6. Thaw lakes and depressions. 8. 7. Thermokarst-affected terrain. 8. 8. Man-Induced thermokarst Advanced reading. Discussion topics. 9. HILLSLOPE PROCESSES AND SLOPE EVOLUTION. 9. 1. Introduction. 9. 2. Slope morphology. 9. 3. Mass wasting. 9. 4. Slow mass-wasting. 9. 5. Rapid mass-wasting. 9.6 Slopewash. 9.7. Frozen and thawing slopes. 9. 8. Cold-climate slope evolution. Advanced reading. Discussion topics. 10. AZONAL PROCESSES AND LANDFORMS. 10. 1. Introduction. 10. 2. Fluvial processes and landforms. 10.3. Aeolian processes and sediments. 10.4 Coastal processes and landforms. PART THREE: WUATERNARY AND LATE-PLEISTOCENE PERIGLACIAL ENVIRONMENTS. 11. QUATERNARY PERIGLACIAL CONDITIONS. 11. 1. Introduction. 11. 2. The time scale and climatic fluctuations. 11. 3. Global (eustatic) considerations. 11. 4. Pleistocene periglacial environments of high latitude. 11. 5. Pleistocene periglacial environments of mid-latitude. 11. 6. Conclusions. Advanced reading. Discussion topics. 12. EVIDENCE FOR PAST PERMAFROST. 12. 1. Introduction. 12. 2. Past permafrost aggradation. 12. 3. Past permafrost degradation. 12. 4. Summary. Advanced reading. Discussion topics. 13. PERIGLACIAL LANDSCAPE MODIFICATION. 13. 1. Introduction. 13. 2. Intense frost action. 13. 3. Intense wind action. 13. 4. Fluvial activity. 13. 5. Slope modification. Advanced reading. Discussion topics. PART FOUR: APPLIED PERIGLACIAL GEOMORPHOLOGY. 14. GEOTECHNICAL AND ENGINEERING ASPECTS. 14. 1. Introduction. 14. 2. Cold-regions engineering. 14. 3. Provision of municipal services and urban infrastructure. 14. 4. Construction of buildings and houses. 14. 5. Problems of water supply. 14. 6. Roads, bridges, railways and airstrips. 14. 7. Oil and gas development. 14. 8. Mining activities. Advanced reading. Discussion topics 15. CLIMATE CHANGE AND PERIGLACIAL ENVIRONMENTS. 15. 1. Global change and cold regions. 15. 2. Climate change and permafrost. 15. 3. Future responses. 15. 4. The urban infrastructure. 15. 5. Conclusions. Advanced reading. Discussion topics. References. Index.

The Periglacial Environment

The principles of cryostratigraphy.

This paper accompanies a map that shows the extent of permafrost in the Northern Hemisphere between 25 and 17 thousand years ago. The map is based upon existing archival data, common throughout the Northern Hemisphere, that include ice-wedge pseudomorphs, sand wedges and large cryoturbations. Where possible, a distinction is made between areas with continuous permafrost and areas where permafrost is either spatially discontinuous or sporadic. The associated mean annual palaeo-temperatures that are inferred on the basis of present-day analogues increase understanding of the possible changes in permafrost extent that might accompany current global warming trends. Areas with relict permafrost and areas that were formerly exposed due to lower sea level (submarine permafrost) are also mapped. Mapping is mostly limited to lowland regions (areas approximately <1000m a.s.l.). Striking features that appear from the map are (i) the narrow permafrost zone in North America, which contrasts with the broader LPM permafrost zone in Eurasia (that may be related to different snow thickness or vegetation cover), (ii) the zonal extent of former LPM permafrost (that may reflect sea-ice distribution), which contrasts with the present-day pattern of permafrost extent (especially in Eurasia) and (iii) the relatively narrow zones of LPM discontinuous permafrost (that may indicate strong temperature gradients).

https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12070

The Last Permafrost Maximum (LPM) map of the Northern Hemisphere: permafrost extent and mean annual air temperatures, 25–17 ka BP

The shape and distribution of ice and sediment within frozen ground constitute its cryostructure. Observations on perennially frozen sediments in the Tuktoyaktuk coastlands enable six cryostructures to be identified: (1) structureless, (2) lenticular, (3) layered, (4) reticulate, (5) crustal, and (6) suspended. These cryostructures can be transitional or composite. Five cryofacies types can also be identified according to volumetric ice content and grain size. They can be grouped into cryofacies assemblages. The utility of the descriptive classification of ice-rich sediments is illustrated from a palaeothaw layer at Crumbling Point.

Hugh M. French

Papers

The Periglacial Environment

The Periglacial Environment

The principles of cryostratigraphy.

The Last Permafrost Maximum (LPM) map of the Northern Hemisphere: permafrost extent and mean annual air temperatures, 25–17 ka BP

Cryostructures in permafrost, Tuktoyaktuk coastlands, western arctic Canada