Showing papers on "Climate change published in 1979"

Can Rapid Climatic Change Cause Volcanic Eruptions

Abstract: Many major volcanic eruptions coincide with cooling trends of decadal or longer duration that began significantly before the eruptions. Dust veils provide positive feedback for short-term (less than 10 year) global cooling, but seem unlikely to trigger glaciations or even minor climate fluctuations in the 10-to 100-year range. On the contrary, variations in climate lead to stress changes on the earth9s crust—for instance, by loading and unloading of ice and water masses and by axial and spin-rate changes that might augment volcanic (and seismic) potential.

An analysis of the evidence for climatic change in New Zealand in the last thousand years: Evidence from diverse natural phenomena and from instrumental records

Abstract: An analysis is made of the diverse evidence for climatic variation in New Zealand in the last 1000 years. After a brief account of the pressure systems and circulation pattern near New Zealand, indirect evidence from a range of phenomena which have been influenced by climate is discussed. The climatological evidence derived from instrumental records and observations is then considered, with emphasis on precipitation and temperature. Little reliance may be placed on some evidence which is weak, equivocal, difficult to interpret or difficult to place in time. The most reliable evidence is summarized in two overlapping time periods, 1000 A.D. to 1900 A.D. and 1850 A.D. to the present. Dated glacial episodes, speleothem palaeotemperatures and tree palaeotemperatures demonstrate that there have been many fluctuations of temperature in the last 1000 years, over a range of not much more than ± 0.5°C. The high temperatures since about 1950 A.D. have probably not been exceeded. Expansion of glaciers in th...

Short-term climate change and New Zealand temperatures during the last millennium

Abstract: MANY theories have been proposed to explain the climatic fluctuations which produced the sequence of glacial–interglacial periods of the order of tens of thousands of years which have occurred throughout the Quaternary. These fluctuations represent temperature changes in the temperate regions of about 6 °C between a glacial and an interglacial situation. There are also climatic fluctuations with a period of the order of about a thousand years representing temperature changes of about 2 °C. These changes are believed to have had an important bearing on human history, but have been little studied because it is difficult to obtain accurate temperature records for past periods. Shorter temperature fluctuations of the order of a few decades, and representing temperature changes of perhaps as much as one degree, are of considerable economic importance and merge into the developing field of long-term meteorological forecasting. Considerable interest has recently developed in short-term climate changes. If detailed long-term climatic records could be obtained for extended periods in the past it might be possible to determine the causes for the climatic variation, and hence predict future climate trends. Even a knowledge of how hot/cold or dry/wet a particular region's climate could become, and with what probability, would be of considerable economic value to planners involved in hydroelectric development, irrigation schemes, snow clearance and the development of arid and polar regions. At present instrumental records have existed only since the mid-seventeenth century for central England, and for most other areas only over a little more than a century. Cave deposits (speleothems) provide stratigraphy which has a high inherent time resolution. Data for studying short-term temperature fluctuations can be obtained by measuring the 18O/16O ratio of suitable stalagmites1. This technique should enable a high resolution temperature curve to be produced for many regions of the globe. We report here an investigation on the 18O/16O profile through a New Zealand stalagmite which was undertaken partly to evaluate the feasibility of obtaining high time resolution data from speleothem material and partly to compare the temperature record from New Zealand (in the Southern Hemisphere and a region meteorologically unrelated to Europe) with the English climate curve, which is the most firmly established climate curve for the last millennium. Such proxy data given us the possibility of obtaining long-term high resolution temperature records from some of the critical regions of the world where meteorological records either do not exist or are of very short duration.

A Study of Climate Sensitivity Using a Simple Energy Balance Model

Abstract: The results of simple zonal energy balance climate models are rather sensitive to the parameterizations used to calculate the fluxes of solar radiation absorbed, thermal radiation emitted and energy transported by the atmosphere and oceans. For this reason results are examined for North's (1975a) constant coefficient diffusion model using climatologically consistent radiation parameterizations. With these radiation parameterizations, the calculated climate is less sensitive to changes in the incident solar radiation than was previously found using other parameterizations. In addition, how the model's results are influenced by the biofeedback mechanism recently proposed by Cess (1978) is studied. This feedback accounts for changes in the surface albedo caused by changes in the vegetation that might accompany climate change. Based on the model results, this feedback could be an important link between the climate and the earth's orbit around the sun.

Impacts of Climatic Variability in Australian Agriculture: A Review

Abstract: A framework is sketched for exploring the pervasive impacts of variations in climate on the uncertainties and instabilities of the Australian rural sector Low rainfall is identified as the dominating climatic variable Effects of climatic variation are investigated and measured at farm, regional, industrial, sectoral and national levels Where possible, sensitivities to climate are measured by elasticities of production with respect to rainfall indexes Some consequences of possible climatic change are discussed

Clouds and the long-term stability of the Earth's atmosphere and climate

Abstract: CLOUDS dominate the albedo of the Earth and hence have a vital role in the global radiation balance. They are one of the most important physical properties of the atmosphere but the most difficult to parameterise. The forecasting of short-term climatological excursions (weather) requires numerical integration of complex dynamical models. However, over longer time periods it may be possible to include cloud cover without resorting to explicit atmospheric dynamics. Here we suggest that over evolutionary time periods (108–109 yr) the Earth's percentage cloud cover has remained approximately constant. This is in general agreement with present ideas about the stability of the Earth's evolution1–3. Over medium-term climatological periods (104–107 yr) we have found that the position of large cloud masses may be directly related to the changing surface configuration, caused, for example, by continental drift. Global cloud cover fluctuates about a mean, which is near the present-day value and reinforces albedo changes caused by surface configuration; this could be highly significant for theories of climatic change.

Nile River Discharge

Abstract: Based on 106 years of measured streamflow of the Nile River above Aswan, Egypt, and on readings of the annual high river flow at Cairo from the year 1700, the question of possible short-period climate changes in the source region for the water is examined. The problem of random time series is discussed., the runoff record of the Colorado River is considered in comparison. A 115-year cycle from 1725 to 1840 is compared with the still continuing subsequent regime of high flow followed by low flow. The difference between high- and low-flow periods is near 25% of average in both cases, representing a large change in available water supply. Mean annual discharge was measured as 91 km3 year−1 from 1870 to 1976 and estimated as slightly less, 87 km3 year−1, for 1725–1840, due to lower computed annual discharge in about half of the years with high flow. Variability in Nile discharge is thought to be mainly related to changes in precipitation over the Ethiopian mountains. Preliminary analysis of satellite...

On the Role of Zonal Asymmetries in Climate Change

Abstract: The potential of zonal asymmetry as a sensitivity mechanism for the earth's climate is investigated through a simple extension of an energy balance climate model. The results of this model are compared with the reconstruction of climate during the last major glaciation. The comparison suggests that it is quite possible that the last glaciation was in near equilibrium with the present solar constant and that zonal asymmetry plays a very important role in the transitions between glacial and interglacial conditions. On the basis of these inferences, the planetary wave structure during summer and the transition seasons would appear to be very important for climatic change.

Ice ages and the Milankovitch theory: A study of interactive climate feedback mechanisms

Abstract: Several climate feedback mechanisms, which are not conventionally incorporated within climate models, are investigated to illustrate their potential role in enhancing the sensitivity of the earth's climate to changes in orbital parameters; i.e., for application to the astronomical or Milankovitch theory of ice ages. For illustrative purposes changes only in obliquity angle are considered. Specifically the feedback mechanisms which have been incorporated are: (1) Zenith-angle feedback, which constitutes a latitudinal change in the earth's zonal albedo due to the alteration in latitudinal distribution of insolation, and thus solar zenith angle, with changes in obliquity angle. (2) Bio-albedo feedback, comprising a climate-related change in surface albedo as a consequence of altered precipitation patterns modifying the vegetation of land surfaces. (3) Latent-heat feedback, which involves climate-induced changes in the poleward transport of latent heat. Employing crude parameterizations for these three feedback mechanisms within a simple climate model, it is suggested that collectively these feedback mechanisms could, by several factors, amplify climate change associated with orbital parameter variability. DOI: 10.1111/j.2153-3490.1979.tb00897.x

Uncertainties associated with global effects of atmospheric carbon dioxide

Abstract: Although the evidence is quite clear that the increase in atmospheric CO/sub 2/ is at least to a large degree a result of fossil fuel burning, and it is equally clear that this increase will result in some change in the global climate, there are quantitative uncertainties that require additional understanding before full assessments can be made There are also quantitative uncertainties regarding the natural carbon cycle, the behavior of the various reservoirs when perturbed by man, the terrestrial biosphere, and the rate at which the oceans can assimilate and store carbon There are uncertainties in regard to the climate change that can result from increased atmospheric CO/sub 2/ Progress in modeling the atmosphere must continue to narrow these uncertainties before the impacts of climate change on man can be adequately determined The future demands for fossil fuels are uncertain The growth of the developing world will be closely linked to fossil energy for the next five to eight decades Only the observed increase in the atmospheric concentration and the present (and recent past) rate of production of CO/sub 2/ from fossil fuels provide data without uncertainties

World Climate Conference: Climate at the Millennium

Abstract: The World Climate Conference, sponsored by the World Meteorological Organization, a United Nations agency, met in Geneva, Switzerland, February 12–13. It was attended by some 300 climate specialists from 40 nations. Their findings and recommendations are to be transmitted to the Congress of the World Meteorological Organizations, which is scheduled to meet in Geneva in May and will recommend what activities should be included in a new international World Climate Program. The World Climate Program will have three major objectives: better climate data collection and application throughout the world; improved understanding and prediction of climate change; and better understanding of the effects changes of climate have on society. “Climate at the Millennium” has been excerpted from Robert M. White's opening address to the Conference. Dr. White, who has served as head of the climate research board of the National Academy of Sciences, was the Conference chairman.

The causes of waterlevel changes of the aral sea in the holocene

Abstract: A specialist in loess geomorphology and arid-zone hydrology distinguishes three categories of factors accounting for waterlevel changes in the Aral Sea. She judges the most significant to be changes in inflow resulting from changes in the course of the Amudarya, the more important of the two tributary streams. The Amudarya at various times emptied into the Sarykamysh depression, southwest of the Aral Sea, giving rise to a flow of water through the now dry Uzboy channel to the Caspian Sea. Climatic change, involving alternations of wet and dry cycles, is said to have accounted for only minor water level fluctuations, of the order of 4 to 6 m, against the background of the major fluctuations produced by the Amudarya course migrations. Human activity, notably irrigation, is regarded as having become significant only in modern times as a result of an expansion of irrigation works. The present abrupt decline in the Aral waterlevel (6 m from 1960 to 1977, including 2 m in the last three years) is attributed to ...

Solar-geomagnetic-climatic relationships at Bombay

Abstract: Geomagnetic and meteorological data consisting of annual mean values for the period 1848 -1967 from ,A~ Colaba and Alibag Observatories, Bombay, situated on the sea-coast in the tropics and under the strong , influence of the Indian monsoon, are studied and their long-period variations examined against similar trends in the corresponding annual mean sunspot numbers. The increasing secular trend of the geomagnetic total intensity at Alibag appears to be inversely related to the surface atmospheric pct'1sure trend and directly to the air temperature and the annual total rainfall trends at Colaba, contrary to the results given by some workers for various other stations around the world, particularly in the higher latitudes. Climatic modulations, if any, .

Secular Trend in Extreme Rainfalls

Abstract: Increasing attention has recently been given to many facets of climate change. This study focuses on a possible trend in extreme rainfalls in the past two decades based on the records of 135 National Weather Service stations in the eastern United States. The standard used to compare the recent data is Weather Bureau Technical Paper No. 40. The two frequencies examined are the 2- and 100-year 24 h return periods. No trend is discernible.

Prediction of a global cooling

Abstract: Ice or Fire? Surviving Climatic Change. By D. S. Halacy, Jr. Pp. 212. (Harper and Row: New York and London, 1979.) $9.95; £5.95.

Climatic Changes and Numerical Modeling

Abstract: The physical basis for modeling climatic change is considered in connection with the construction of global circulation models (GCM) for simulation of the climate itself and geophysical aspects of the interaction between man and climate. A retrospective review of the basic assumptions with respect to the nature of the major course of climate behavior in the past, is given with a brief survey of paleoclimatic approaches. The main features of the two advanced numerical climate models are discussed and the role of the world oceans in maintaining the climate is considered. The author's point of view on the geophysical aspects of global climate simulation for IIASA's purposes in studying the socio-economic effect of man-climate interactions is presented.