Showing papers on "Climate change published in 1984"

Climatic changes on a yearly to millennial basis : geological, historical, and instrumental records

Abstract: Climatic changes on a yearly to millennial basis: An introduction.- Late Weichselian deglaciation and chronostratigraphy of Southern Scandinavia: Problems and present "state of the art".- Biotic response to climatic changes during the time span 13,000-10,000 BP - A case study from SW Sweden.- Climatic changes at Pleistocene/Holocene boundary in the Middle Swedish Endmoraine zone, mainly inferred from stratigraphic indications.- Cyclic lamination in proximal varves reflecting the length of summers during Late Weichsel in southernmost Sweden.- Late Weichselian sea-levels and fauna communities in northern Vendsyssel, Jutland, Denmark.- Flora, fauna and stable isotopes in Late-Wurm deposits at Lobsigensee (Swiss Plateau).- Late Weichselian fluctuations in the French Alps and Massif Central from pollen analyses.- Climatic and glacial fluctuations during the Late-Glacial and the Holocene in Oisans (Isere, France).- The classical Late Weichselian climatic fluctuations in Mexico.- Climatic variations in the low continental latitudes during the last 30,000 years.- Late-Glacial - Holocene High-frequency climatic changes in deep-sea cores from the Denmark Strait.- The reflection of abrupt climatic changes in the relief and sequence of continental deposits.- Water-level changes, climate and human impact: A palaeohydrological study of Krageholm Lake (Scania), southern Sweden.- Trees and shrubs in the Shetland Islands. Evidence for a Postglacial climatic optimum?.- Holocene palaeo-winds and climatic changes in West Greenland as indicated by long-distance transported and local pollen in lake sediments.- Peat inception and climatic change in northern Quebec.- The Nile floods as a global climatic/solar proxy.- Rainfall patterns and lake level variations at Lake Chad.- Tropical peats: Hydrogeologic and climatic control.- Causes of a Late-Atlantic swamp-forest submergence in the central Rhine/Meuse delta.- Late Postglacial beach ridges on the island of Gotland, Sweden, as indicators of a probable periodicity in the climate.- Size variations in Atlantic, Subboreal and modern moose teeth.- Climate and history in northern Europe and elsewhere.- Settlement expansion - settlement contraction: A question of war, plague, ecology or climate?.- Climatic reflection in varved lake sediments.- Sunspot cycles and global oscillations.- Dendrochronology in Sweden.- Dendrochronology, mass balance and glacier front fluctuations in northern Sweden.- Dendroclimatological studies at the northern timberline.- Limitations of 14C dates from buried soils in reconstructing glacier variations and Holocene climate.- Climate and glaciation in Kong Karls Land, eastern Svalbard.- Questions arising when using lichen for 14C measurements in climatic studies.- Some studies of the Little Ice Age of recent centuries and its great storms.- The potential of documentary data for the reconstruction of past climates. Early 16th to 19th century. Switzer land as a case study.- A contribution to the reconstruction of weather in central Europe at the end of the 16th century (with regard to me teorological observations of Tycho de Brahe on Hven).- The impact of climate on grass growth and hay yield in Iceland: A.D. 1601 to 1780.- Climatic changes during recent centuries as indicated by dendrochronological studies, Mount Baker, Washington, U.S.A..- The cold winter 1808-1809: A russian force crosses the ice-bound Gulf of Bothnia and takes (the first?) air-temperature measurements in history for purposes of a military operation.- On the availability and homogeneity of instrumentally observed climatological records.- Climate variation in northern Europe during the past century -Climatic changes on a yearly to millennial basis: An introduction.- Late Weichselian deglaciation and chronostratigraphy of Southern Scandinavia: Problems and present "state of the art".- Biotic response to climatic changes during the time span 13,000-10,000 BP - A case study from SW Sweden.- Climatic changes at Pleistocene/Holocene boundary in the Middle Swedish Endmoraine zone, mainly inferred from stratigraphic indications.- Cyclic lamination in proximal varves reflecting the length of summers during Late Weichsel in southernmost Sweden.- Late Weichselian sea-levels and fauna communities in northern Vendsyssel, Jutland, Denmark.- Flora, fauna and stable isotopes in Late-Wurm deposits at Lobsigensee (Swiss Plateau).- Late Weichselian fluctuations in the French Alps and Massif Central from pollen analyses.- Climatic and glacial fluctuations during the Late-Glacial and the Holocene in Oisans (Isere, France).- The classical Late Weichselian climatic fluctuations in Mexico.- Climatic variations in the low continental latitudes during the last 30,000 years.- Late-Glacial - Holocene High-frequency climatic changes in deep-sea cores from the Denmark Strait.- The reflection of abrupt climatic changes in the relief and sequence of continental deposits.- Water-level changes, climate and human impact: A palaeohydrological study of Krageholm Lake (Scania), southern Sweden.- Trees and shrubs in the Shetland Islands. Evidence for a Postglacial climatic optimum?.- Holocene palaeo-winds and climatic changes in West Greenland as indicated by long-distance transported and local pollen in lake sediments.- Peat inception and climatic change in northern Quebec.- The Nile floods as a global climatic/solar proxy.- Rainfall patterns and lake level variations at Lake Chad.- Tropical peats: Hydrogeologic and climatic control.- Causes of a Late-Atlantic swamp-forest submergence in the central Rhine/Meuse delta.- Late Postglacial beach ridges on the island of Gotland, Sweden, as indicators of a probable periodicity in the climate.- Size variations in Atlantic, Subboreal and modern moose teeth.- Climate and history in northern Europe and elsewhere.- Settlement expansion - settlement contraction: A question of war, plague, ecology or climate?.- Climatic reflection in varved lake sediments.- Sunspot cycles and global oscillations.- Dendrochronology in Sweden.- Dendrochronology, mass balance and glacier front fluctuations in northern Sweden.- Dendroclimatological studies at the northern timberline.- Limitations of 14C dates from buried soils in reconstructing glacier variations and Holocene climate.- Climate and glaciation in Kong Karls Land, eastern Svalbard.- Questions arising when using lichen for 14C measurements in climatic studies.- Some studies of the Little Ice Age of recent centuries and its great storms.- The potential of documentary data for the reconstruction of past climates. Early 16th to 19th century. Switzer land as a case study.- A contribution to the reconstruction of weather in central Europe at the end of the 16th century (with regard to me teorological observations of Tycho de Brahe on Hven).- The impact of climate on grass growth and hay yield in Iceland: A.D. 1601 to 1780.- Climatic changes during recent centuries as indicated by dendrochronological studies, Mount Baker, Washington, U.S.A..- The cold winter 1808-1809: A russian force crosses the ice-bound Gulf of Bothnia and takes (the first?) air-temperature measurements in history for purposes of a military operation.- On the availability and homogeneity of instrumentally observed climatological records.- Climate variation in northern Europe during the past century - evidence from a Danish record.- Certain relationships between lake level variations and some climatic factors in Finland.- Long-term variations in some physical parameters of the Baltic Sea.- Strategies for assessing impacts of climatic change in marginal areas.- Mechanism for linking solar activity to weather-scale effects, climatic changes and glaciations in the Northern Hemisphere.- Solar ultraviolet irradiance variations and the Earth's atmosphere.- Cycles of solar flares and weather.- Planetary, solar, atmospheric, hydrospheric, and endogene processes as origin of climatic changes on the Earth.- Planetary periodicities and terrestrial climate stress.- A possible mechanism of abrupt climatic changes.- Sea surface temperature, atmospheric CO2 and the global energy budget: some comparisons between the past and present.- The effect of atmospheric and oceanic energy transports in climatic balance.- Possible CO2-induced warming effects on the cryosphere.- The nature and significance of cloud-cryosphere interactions in the marginal snow and ice zones.- Climatic belts in the case of a unipolar glaciation.- Energy-flow budgets in aquatic ecosystems and the conflict between biology and geophysics about Earth-axis tilt.- Climatic changes on a yearly to millennial basis. Concluding remarks.

The role of geographic variables in explaining paleoclimates: Results from Cretaceous climate model sensitivity studies

Abstract: Changes in geography (topography, continental positions and sea level) are one of the most frequently cited mechanisms of climatic change on geologic time scales. The role of geographic variables in paleoclimatology is investigated through a series of climate model sensitivity studies using a version of the National Center for Atmospheric Research spectral GCM and specified Cretaceous (≈ 100 million years ago) geography. The Cretaceous is investigated because it was both a large geographic and climatic contrast from the present day. The model simulations demonstrate that paleogeography was a substantial climatic forcing factor (4.8°K increase in globally averaged surface temperature compared with a present-day control). However, the warming is insufficient to explain fully the paleoclimatic data. In addition, the model is insensitive to global sea level variations (related to tectonics and not ice volume) which are well correlated with paleoclimatic data. Additional climatic forcing factors, such as increased atmospheric CO2 correlated with these sea level variations, may be required to explain the Cretaceous climate.

The Global climate

Abstract: Now in paperback, this book has succeeded in its aim to introduce the global climate problem and the complex processes and interactions which play a part in climatic change to a wide range of scientists working in climatic research or the related fields of meteorology, oceanography, glaciology and hydrology. It is centred around the World Climate Research Programme, an international enterprise jointly sponsored by the scientific community (through the International Council of Scientific Unions) and the national weather centres (through the World Meteorological Organisation). If progress is to be made in understanding climatic change, it is necessary to observe and understand all components of the climate system and the interactions between them. This book is particularly relevant to many contemporary climatic problems and to the two most important questions arising tom them: to what extent can changes in climate be predicted; and what is the extent of man's influence on climate. The Global Climate answers these questions, showing how the important processes may be -observed, evaluated and modelled by computer.

The variability of holocene climate change: evidence from varved lake sediments.

Abstract: Varved sediments from a lake near the present forest-prairie border in northwestern Minnesota provide an annual record of climate change for the last 10,400 years. Climate-sensitive mineral, chemical, and biological components show that the mid-Holocene dry interval between 8500 and 4000 years ago is asymmetrical and actually consists of two distinct drier pulses separated by a moister interval that lasted about 600 years. Cyclic fluctuations with periods of several hundred years were abrupt and persistent throughout the Holocene and are most clearly recorded within the two drier pulses.

The Identification of 10- to 20-Year Temperature and Precipitation Fluctuations in the Contiguous United States.

Abstract: A potentially fruitful approach to assessing society's sensitivity to climate change is to study the impacts, perceptions and adjustments of recent climate fluctuations. We set out to determine if the recent (1931–82) United States climate record exhibits fluctuations of sufficient scope and magnitude to be useful in a complement of retrospective, empirical studies of climate impacts. The search for fluctuations was designed specifically to identify areas and periods in which the climate within an epoch was terminated by a rather sharp transition to another epoch with a climate unlike the previous epoch. The largest 10- to 20-year temperature and precipitation climate fluctuations were identified across the contiguous United States, along with various scenarios of simultaneous change of temperature and precipitation for the four seasons and annually. All possible 10- to 20-year nonoverlapping “consecutive epochs” within 344 state climatic divisions (as defined by the National Climatic Data Center...

Chronology of palaeoclimatic change at the end of the last glaciation

Abstract: Analysis of sediments recorded in a piston core, located east of southern North Island, New Zealand, gives a detailed record of climate change at the end of the last glacial. Accumulation rates1 of both detrital (quartz) and biological (carbonate and biogenic silica) components of the sediment are much higher during glacial than post-glacial time and they all show a synchronous, rapid decline at 14,700 yr BP. We attribute this to a decline in intensity of the strong glacial westerly winds in the New Zealand region as the polar winds contracted to their present latitudes2–6. The greatest rate of quartz accumulation occurs between 16,200 and 14,700 yr BP and is not matched by any change in carbonate or silica accumulation. We believe this reflects accelerated fluvial transport of detritus out of the mountain ranges and consequently increased aeolian dust transport before the decline of the polar westerlies.

Effects of Nontropical Forest Cover on Climate

Abstract: The albedo of a forest with snow on the ground is much less than that of snow-covered low vegetation such as tundra. As a result, simulation of the Northern Hemisphere climate, when fully forested south of a suitably chosen taiga/tundra boundary (ecocline), produces a hemispheric surface air temperature 1.9 K higher than that of an earth devoid of trees. Using variations of the solar constant to force climate changes in the GLAS Multi-Layer Energy Balance Model, the role of snow-albedo feedback in increasing the climate sensitivity to external perturbations is reexamined. The effect of snow-albedo feedback is found to be significantly reduced when a low albedo is used for snow over taiga, south of the fixed latitude of the ecocline. If the ecocline shifts to maintain equilibrium with the new climate - which is presumed to occur in a prolonged perturbation when time is sufficient for trees to grow or die and fall - the feedback is stronger than for a fixed ecocline, especially at high latitudes. However, this snow/vegetation-albedo feedback is still essentially weaker than the snow-albedo feedback in the forest-free case. The loss of forest to agriculture and other land-use would put the present climate further away from that associated with the fully forested earth south of the ecocline and closer to the forest-free case. Thus, the decrease in nontropical forest cover since prehistoric times has probably affected the climate by reducing the temperatures and by increasing the sensitivity to perturbations, with both effects more pronounced at high latitudes.

Can we delay a greenhouse warming

Abstract: This article reviews a book published by the Environmental Protection Agency. The book discussed the Greenhouse Effect which is a warming of the earth's atmosphere caused by the doubling of the atmospheric carbon dioxide concentration. The excess carbon dioxide is pollution derived from the burning of fossil fuels. The report suggested that the warming of the atmosphere would cause thawing of the polar regions which in turn would cause a rise in sea levels and flooding of the coastal lowlands. In addition to the flooding, the report predicted climate changes that would effect the productivity of croplands in the west. The authors of the report stressed that there was no way to avoid this warming of the earth. They suggested that people should start preparing for the inevitable.

On modelling the seasonal thermodynamic cycle of sea ice in studies of climatic change

Abstract: Recent work in modelling climatic changes due to increased atmospheric CO2 has shown the maximum change to occur in the polar regions as a result of seasonal reductions in sea ice coverage. Typically, sea ice thermodynamics is modelled in a very simple way, whereby the storage of both sensible and latent heat within the ice is ignored, and the effects of snow cover on conductivity and on surface albedo and of oceanic heat flux on bottom ablation may also be neglected. This paper considers whether omission of these processes is justified within the context of quantitatively determining regional climatic changes. A related question, whether omission of ice dynamics can be justified, is not considered.

The Nature of the Environment

Abstract: Preface. Acknowledgements. Part I: The Global Framework: 1. Global Geological Background. The Ancient Earth. Core, Mantle and Crust. The Nature of the Ocean Floors. The Surface of the Land. Earthquakes. The Shape of the Continents. The Question of Plates. Microplates and Exotic Terraces. The Earth's Rock Types. The Subdivisions of the Earth's History. Conclusions. Key Terms and Concepts. Points for Review. Further Reading for Chapter 1. 2. Global Climatic Background. A Vertical Profile Through the Atmosphere. Global Climate. World Patterns of Precipitation. World Patterns of Temperature. The Major Climatic Zones. The Hydrological Cycle. Ocean Currents. Ocean Atmosphere Interactions. Climatic Change. Causes Long-Term Climatic Change. Sea-Level Changes. Future Climates. Conclusions. Key Terms and Concepts. Points for Review. Further Reading for Chapter 2. 3. The Organic World. Major Vegetation Types. Human Modifications of Major Vegetation Types. Floral Realms. Faunal Realms. The World's Great Soil Orders. Human Modifications of Soil. Climatic Geomorphology: The Influence of Climate, Soil and Vegetation. Key Terms and Concepts. Points for Review. Further Reading for Chapter 3. Part II: Major World Zones: 4. Cold Environments. Polar Climates. Vegetation and Wildlife. Glacier Types. The Formation of Glacier Ice. How Glaciers Move. Glacial Erosion. Glacial Deposits. Glacier Ice and Sea-Level Changes. Permafrost. Ground Ice. Thermokarst. Ice Segregation and Frost Heaving. Frost Shattering and Soil Formation. Slope Processes, Avalanches and River Regimes. Key Terms and Concepts. Points for Review. Further Reading for Chapter 4. 5. The Mid-latitudes. The Westerlies. Cyclones and Anticyclones. Air Masses. Cool Temperate Climates. Western Margin Warm Temperate Climates (The Mediterranean Type). Eastern Margin Warm Temperate Climates. Boreal Forest. Deciduous Forests. Mid-Latitude Grasslands. Mediterranean Evergreen Woodlands. Soils of Cool Temperate Climates. Soils of Warm Temperate Climates. The Impact of Climatic Change on the Landscape. Loess Sheets. Dry Valleys and Mis Fit Stream. Tors. Natural Hazards in Western Europe. Key Terms and Concepts. Points for Review. Further Reading for Chapter 5. 6. Deserts. Introduction. What Causes Aridity? Desert Rainfall. Desert Temperatures. Past Climates in Deserts. Desert Vegetation and Animals. Soils and Surface Materials. Insolation and Salt Weathering. Wind Action in Deserts. Sand Deposition - Dunes. The Work of Rivers. Desert Slopes . Dams, Reservoirs and Inter-Basin Water Transfer. Land Degradation. Problems of the Desert Realm. Key Terms and Concepts. Points for Review. Further Reading for Chapter 6. 7. The Tropics. The General Atmospheric Circulation. The Wet Tropics. Tropical Season Climates. Monsoons. Tropical Disturbances. Tropical Rainforests. Secondary Forest. Tropical Seasonal Forest and Savannah. Mangrove Swamps. Coral Reefs. Weathering of Rocks. Slope Movements. Some Problems of the Humid Tropics. Key Terms and Concepts. Points for Review. Further Reading for Chapter 7. Part III: Mountain and Maritime Environments: 8. Mountains. Introduction. Mountain Climates. Snow and the Snow-Line. Mountain Vegetation. The Timber-Line. Alpine Tundra. Mountain Hazards. Changing Climates. Key Terms and Concepts. Points for Review. Further Reading for chapter 8. 9. Coasts. Coastlines. Waves. Barrier Beaches and Related Forms. Tides. Storm Surges. Estuaries. Coastal Dunes. Salt Marshes. Coast Erosion. The Human Impact on the Coastline. Key Terms and Concepts. Points for Review. Further Reading for Chapter 9. Part IV: Landscapes and Ecosystems: 10. Plants and Animals. Ecology and Ecosystems. Plants and Their Habitats. Life in the Oceans. Community. Succession. Dispersal and Migration of Plants. Dispersal and Migration of Animals. The Importance of Area. Human Impact on Plants and Animals. Domestication. Introductions. Pollution. Habitat Change. Extinction. Conservation. Key Terms and Concepts. Points for Review. Further Reading for Chapter 10. 11. Tectonic Features. Introduction. Volcanoes. Intrusive Igneous Rocks. Earthquakes. Man-Made Seismic Activity. Faults. Folding. Key Terms and Concepts. Points for Review. Further Reading for Chapter 11. 12. Slopes. Mass Movements. Slope Instability. Other Processes Operating on Slopes. Slope Forms. Slope Development Through Time. Key Terms and Concepts. Points for Review. Further Reading for Chapter 12. 13. Soils and Weathering. Factors of Soil Formation. Soil Profiles. Types of Weathering. Mechanical Weathering. Chemical Weathering. Accelerated Soil Erosion. Key Terms and Concepts. Points for Review. Further Reading for Chapter 13. 14. The Hydrological Cycle. Introduction. Precipitation. Interception. Evapotranspiration. Infiltration. Surface Runoff. Groundwater. Streamflow and the Hydrograph. Annual River Regimes. Lakes. Key Terms and Concepts. Points for Review. Further Reading for Chapter 14. 15. Rivers. Introduction. Morphometry of Drainage Basins. Drainage Basin Patterns. Concave Long Profiles. Channel Cross-Section and Hydraulic Geometry. Channel Patterns. Flood Plains. Terraces. Deltas. Stream Transport. Rates of Fluvial Denudation. Floods. The Human Impact on Rivers. Key Terms and Concepts. Points for Review. Further Reading for Chapter 15. 16. Cities. Introduction. The Climate of Cities. Air Pollution and its Problems. Urbanisation and River Flow. Thermal Pollution River Water. Soil Erosion and Sediment Yield Associated with Construction and Urbanisation. Animals in Cities. Key Terms and Concepts. Points for Review. Further Reading for Chapter 16. Part V: Conclusion: 17. Nature, Humans and the Environment. Introduction. Environmental Complexity. Environmental Interactions. The Importance of Scale. The Influence of Environment on Humans. The Human Impact. The Ever-Changing Environment. Humans or Nature? Equifinality. The Relevance and Application of Physical Geography. Index.

Fluvial Responses to Small Scale Climate Changes

Abstract: Climate, either directly through its expression as temperature and precipitation or indirectly through its influence on vegetation is a major control on the type and intensity of the various geographic processes (Peltier 1950). Although it is traditional in most engineering practices to assume that climate fluctuates randomly about a stationary long-term mean condition, such an assumption is invalid for long-term scales such as, for example, in designing stable disposal sites for uranium mill tailings where time scales of 1000 years and longer are under concern. Changes of climate can be particularly significant to the long-term stability of a land surface because the recurrence intervals of natural events that control geomorphic processes have a strong dependency on the direct and indirect effects of climate. The purpose of this chapter is to illustrate how climate influences the recurrence intervals of hydrologic events that control fluvial geomorphic processes, and to show that landform sensitivity to climate change varies significantly between various physical environments. Since Holocene (post-glacial) climates have deviated significantly from present-day climates, and geomorphic responses to Holocene climates are in many places preserved in sedimentary sequences and related landforms, the Holocene record serves as a useful index of potential future hydrogeomorphic responses to climate change.

Modelling the global climate response to orbital forcing and atmospheric carbon dioxide changes

Abstract: At least part of the record of climate change during the past million years may be attributed to forcing by changes in the geometry of the Earth's orbital system. Several attempts have been made to model the record of climate change (usually represented by the record of global ice volumes as recorded in marine sediments) using astronomical forcing1,2. These models have, in general, concentrated on the direct response of the ice sheets to changes in solar insolation resulting from orbital variations. So far no fully successful simulation of the climate record has been made. We investigate here the operation of a model which is forced simultaneously by changes in the distribution of solar insolation caused by orbital variations and by changes in the atmospheric carbon dioxide (CO2) concentration which are themselves forced by orbital parameters. The model results show the potential importance of other components in the climate system and their associated response to changing orbital parameters.

The influence of clouds on climate with A focus on high latitude interactions

Abstract: The global cloud distribution is recognized as forming a major component of the Earth's climate through its influence on both the energy and moisture exchanges in the earth-atmosphere system. This review concentrates on the radiative effects of clouds and examines a number of modelling and empirical studies that have addressed the possible significance of the role of cloud cover in climate change. This question is still not fully resolved. One reason for this is inadequate data and, therefore, some of the cloud climatologies available and the associated problems of data collection and interpretation are discussed. The review focuses specifically on interactions at high latitudes and describes recent studies which suggest that there may be a relationship between sea ice extent and cloud cover. Some possible consequences of this are discussed in the context of a high latitude response to climate change.

Climate Model Simulations of CO2-Induced Climatic Change

Abstract: Publisher Summary This chapter focuses on climate model simulations of CO 2 -induced climatic change. It describes the current issues concerning the study of possible CO 2 -induced climatic change by the physical method, that is, by the use of mathematical climate models. An explanation of mathematical climate models is presented, followed by a comparison of the results of these models for the climatic change resulting from increased levels of atmospheric CO 2 . The focus is on the general circulation models and their simulations of CO 2 -induced climatic change because it is the geographical distribution of that change, which is of importance to humanity, and because the general circulation models (GCMs) simulate geographical distribution. The equilibrium simulations of eight GCMs for both doubled and quadrupled concentrations of CO 2 are considered and the geographical distributions, zonal means, and global means of the CO 2 -induced changes in surface air temperature, precipitation rate, and soil moisture are compared. The issues that are raised by that comparison are described, and recommendations for resolving those issues are presented.

Multiple thermal maxima during the holocene.

Abstract: The astronomical theory of climatic change provides an alternative to the traditional chronology for Holocene climatic change, which calls for one thermal maximum about 6000 years ago. The theory predicts a series of maxima during the Holocene, one for each season. Because the relation of the perihelion to the spring equinox changes with a 22,000-year period, late summer insolation would have been greatest 5000 years ago, whereas early summer insolation would have been greatest 13,000 years ago. Climatic reconstructions based on the response of ecosystems to late summer climate indicate a later Holocene thermal maximum than paleoclimatic data sensitive to early summer climate. In southern Idaho, three different vegetation types indicate thermal maxima at different times during the Holocene, depending on the climatic variable controlling each type.

Response of unmanaged forests to CO/sub 2/-induced climate change: available information, initial tests, and data requirements

Abstract: The scientific literature is reviewed to determine how tree recruitment, growth, and mortality are related to climate directly and indirectly through climate's modulation of plant competition, succession, and migration. The resulting potential responses of forest communities to climate changes expected under increased atmospheric CO/sub 2/ concentrations are described. Empirical data sets, containing measurements of climate variables and tree densities in the eastern United States, are evaluated for their potential use in statistical projections of forest responses to climate change. Also evaluated for projection purposes is a forest-stand simulation model based on many of the processes which determine forest dynamics. The ability of the model to reproduce extant forests at 21 sites in eastern North America was first verified. Then, a model experiment simulated responses of forests at those 21 locations to a scenario in which climate responds to doubling and quadrupling of CO/sub 2/. The implications of the forest simulations are discussed in terms of internal forest dynamics and requirements for specified information from climate projections, as well as for additional model developments that could address remaining ecological uncertainties. 236 references, 35 figures, 4 tables.

Climate model simulations of the effects of the el chichon eruption

Abstract: An energy balance climate model is used to calculate the effect of the 4 April 1982 eruption of the El Chichon volcano on surface air temperature for the next 10 years. The maximum cooling of 1.0 - 1.4 C occurs at the North Pole in the spring and fall of 1984 and 1985. The Northern Hemisphere annual average response is largest in 1984 and 1985 with a cooling of 0.4 - 0.5 C. The separate land and ocean responses as functions of latitude and time of year are shown. The particular patterns that result are caused by the snow-albedo and ice-thermal inertia feedbacks. These results have important implications for the detection of CO 2 -induced climate change.

Background tropospheric aerosols: Incorporation within a statistical‐dynamical climate model

Abstract: To evaluate the possible influence of natural background tropospheric aerosols upon the earth's present climate, we have incorporated aerosol radiation models for continental and maritime aerosols into the Lawrence Livermore National Laboratory statistical-dynamical climate model. The model results suggest that background tropospheric aerosols produce 3°–4°C global surface cooling, with maximum cooling occurring at high latitudes, results which are essentially consistent with an energy balance climate model study by Coakley et al. (1983). To specifically delineate effects caused directly by the aerosols, as opposed to indirect effects resulting from aerosol-induced climate change, a second climate perturbation was considered that consisted of reducing the solar constant so as to give exactly the same initial reduction in surface-atmosphere solar absorption as for the inclusion of tropospheric aerosols. These separate climate perturbations produced nearly identical climate feedback effects, together with similar changes in atmospheric stability and hydrological cycle, despite the fact that the two perturbations have quite different latitudinal and vertical distributions. This finding is consistent with a general circulation model study by Manabe and Wetherald (1980) concerning perturbations of both atmospheric CO2 and the solar constant. A related conclusion is that the model's climate response to tropospheric aerosols is insensitive to the manner in which the aerosols are vertically distributed.

Seasonal climate scenarios for Europe and North America in a high-CO2, warmer world

Abstract: As a result of man's activities, the concentration of CO/sub 2/ in the atmosphere has risen substantially since pre-industrial times. Future increases in atmospheric carbon dioxide may be expected to cause extensive disruptions of the global circulation system, accompanied by continuing and eventually substantial changes in climate. This report presents work done in the Climatic Research Unit to determine possible patterns of climatic change in Europe and North America associated with a global CO/sub 2/-induced warming. Although numerical models and analogues based on warm periods in the geological past have been used to simulate the effects of increasing CO/sub 2/ on climate, they cannot provide the necessary detail to allow scenario development on a regional scale. The scenarios presented here are based on warm and cold periods from the twentieth-century instrumental record. Four sets of scenarios were prepared, each using different criteria for the selection of data used in the construction process.

An Evaluation of Ocean-Climate Theories on the North Atlantic

Abstract: The role of the oceans in ice-age climatic change has been conceived differently in various publications over the last two decades. Figure 1 summarizes three broad categories into which these viewpoints might be divided. The focus here is on the role of the mid-latitude to high-latitude North Atlantic Ocean.

Atmospheric Transmission and Climate: Results from Smithsonian Measurements

Abstract: A combination of published and archival observations from the Smithsonian Institution's Astrophysical Observatory (APO) is presented and analyzed. This paper concentrates on the data from the two primary sites—Mount Montezuma, Chile, and Table Mountain, California, from 1923 to 1957. Baseline values and their variations are presented for solar aureole brightness, precipitable water vapor, pyrheliometry, corrected pyrheliometry, and spectrobolometry. In addition to clouds and water vapor, possible causes for the observed variations in atmospheric transmission are volcanic eruptions, nuclear weapons testing, and aerosols from plants. Physical theories may not be sufficient to explain climate change, and considerations of biological processes may be required.

First observations of the interaction of ocean swell with sea ice using satellite radar altimeter data

Abstract: The action of ocean waves and swell on sea ice in the marginal ice zone (MIZ) controls the size distribution of ice floes and thus affects ice dynamics and the thermodynamics of ice growth and decay. An understanding of ice processes is important because of the influence of the sea-ice cover on high latitude weather and global climate1. Also, long-term changes in average sea ice extent could provide a sensitive indication of climatic change if the degree of shorter term variability were better understood2. Previous observations of the propagation of swell within the ice pack have been limited in spatial and temporal extent3–6. Here we present new results from the US Seasat satellite which suggest that radar altimetry can provide a powerful means of global synoptic monitoring of the interaction between ocean and ice.

Ancient climates: investigation with climate models

Abstract: Mathematical models of the climate system have recently become an important aspect of the study of ancient climates. Three geologic climate problems have received particular attention: (i) the faint early Sun paradox; (ii) the warm apparently ice-free Cretaceous period and (iii) the glacial-interglacial cycles of the last 700000 yr. There are three basic limitations in investigating geologic climate problems: (i) limitations in reconstructing the climate state; (ii) limitations in specifying the forcing factors which influenced the climate and (iii) limitations in determining the climate sensitivity to specific forcing factors. The three climate problems which are described here are widely different in terms of the degree to which the climatic record can be reconstructed, the importance of specific factors and in the types of models which have been applied to investigate climate sensitivity. Each time period is sufficiently different in terms of the climatic record and in terms of the evidence for a particular forcing factor to be a well-posed climate modelling problem. For the most part a simulation or replica of these climates is not yet possible, but based on sensitivity experiments there has been a convergence toward understanding the climatic response forcing factors and describing the causes of climatic change during Earth history.

Climate fluctuations in Illinois, 1901-1980

Abstract: Changes in climate directly affect four areas of major activity and concern in Illinois – water, energy, agriculture, and transportation. This report presents selected Illinois records for 1901-1980 on a variety of atmospheric conditions that allow assessment of climate fluctuations, climate trends, variability around the trends, and impacts of these changes on the four areas of concern. Documented are changes in statewide and regional precipitation and temperature, plus selected point (station) data. Also presented are changes in other atmospheric conditions including relative humidity, sky cover and sunshine, visibility and related air quality, severe local storms, and wind speed and direction. The historical records are carefully evaluated as to quality. Analyses of the data indicate changes in the more recent 20 years (1961-1980 vs 1901-19601 to wetter and cooler conditions: more rain and snow and fewer droughts; decreases in temperatures especially in summer and winter, with fewer extremely warm days and many more extremely cold days; increases in cloudiness and decreases in sunshine and clear days especially in summer; and increases in wind speeds with more diverse wind directions. All trends are more marked in the extreme seasons of summer and winter than in the transition seasons of spring and fall. Mixed regional changes are noted in other atmospheric conditions, and no trend is seen for relative humidity. Reference: Changnon, Stanley A., Jr. Climate Fluctuations in Illinois: 1901-1980. Illinois State Water Survey, Champaign, Bulletin 68. Indexing Terms: air quality, climate change, Illinois, precipitation, relative humidity, severe local storms, sky cover, sunshine, temperature, visibility, wind speed and direction. STATE OF ILLINOIS HON. JAMES R. THOMPSON, Governor DEPARTMENT OF ENERGY AND NATURAL RESOURCES MICHAEL B. WITTE, B.A., Director BOARD OF NATURAL RESOURCES AND CONSERVATION Michael B. Witte, B.A., Chairman Walter E. Hanson, M.S., Engineering Laurence L. Sloss, Ph.D., Geology H. S. Gutowsky, Ph.D., Chemistry Lorin I. Nevling, Ph.D., Forestry Robert L. Metcalf, Ph.D., Biology Daniel C. Drucker, Ph.D. University of Illinois John C. Guyon, Ph.D. Southern Illinois University STATE WATER SURVEY DIVISION STANLEY A. CHANGNON, JR., M.S., Chief

Climatic Changes on a Yearly to Millennial Basis an Introduction

Abstract: The climate changes and shifts in a broad spectrum of cycles and time ranges (Fig. 1). The effects of such changes may be local, regional, hemispherical or global, as illustrated in Figs. 1 and 2.

What if increases in atmospheric CO2 have an inverse greenhouse effect? I: Energy balance considerations related to surface albedo

Abstract: An analysis of northern, low and southern latitude temperature trends of the past century, along with available atmospheric CO2 concentration and industrial carbon production data, suggests that the true climatic effect of increasing the CO2 content of the atmosphere may be to cool the Earth and not warm it, contrary to most past analyses of this phenomenon. A physical mechanism is thus proposed to explain how CO2 may act as an inverse greenhouse gas in Earth's atmosphere. However, a negative feedback mechanism related to a lowering of the planet's mean surface albedo, due to the migration of more mesic-adapted vegetation onto arid and semi-arid lands as a result of the increased water use efficiency which most plants experience under high levels of atmospheric CO2, acts to counter this inverse greenhouse effect. Quantitative estimates of the magnitudes of both phenomena are made, and it is shown that they are probably compensatory. This finding suggests that we will not suffer any great climatic catastrophe but will instead reap great agricultural benefits from the rapid increase in atmospheric CO2 which we are currently experiencing and which is projected to continue for perhaps another century or two into the future.