Recent Climatic Fluctuations Research Articles

Stream/aquifer interactions at Great Sand Dunes National Monument, Colorado: influences on interdunal wetland disappearance

Between 1937 and 1995 a complex of more than 100 interdunal wetlands disappeared from Great Sand Dunes National Monument, Colorado. We investigated three hypotheses that could explain wetland disappearance: (1) dune movement during a severe drought in the 1950s buried the wetlands, (2) agriculture related ground water pumping lowered the regional water table, and (3) changes in local hydrologic processes led to wetland loss. We used regional stream flow records, ground water level measurements, natural stable isotope analyses, soil stratigraphy, buried seed banks, and ground water modeling to address these hypotheses. Hydrologic data and stable isotope analyses illustrated the interaction between Sand Creek, a nearby stream, and the unconfined aquifer in the area where wetlands occurred. When the intermittent Sand Creek flows, seepage through its bed creates a large ground water mound under the creek. The seasonal development and dispersion of this mound propagates pressure waves through the aquifer that influence ground water levels up to 2 km from Sand Creek. Our data suggest the primary factors contributing to wetland disappearance were recent climatic fluctuations and incision of the Sand Creek channel. Below average stream flow between 1950 and 1980 reduced the duration of Sand Creek flow across the dune complex, minimizing ground water mound development. Consequently, the water table in the unconfined aquifer dropped ∼1.0 m and interdunal wetlands dried up. Twentieth Century incision of Sand Creek's channel reduced ground water mound height ∼2.5 m, decreasing seasonal water table fluctuations at interdunal wetlands and contributing to the overall water table decline. Long-term wet and dry cycles affect the water table elevation more than channel incision, leading us to conclude that many interdunal wetlands are ephemeral features. Wetland area is maximized during consecutive years of above average Sand Creek discharge and minimized as the water table drops during dry periods.

Correlation of loess–paleosol sequences in East and Central Asia with SE Central Europe: towards a continental Quaternary pedostratigraphy and paleoclimatic history

As recent small climatic fluctuations on a 10 2–10 3 year time scale can be correlated worldwide, and represent a decline of mean annual temperature of only ⩽1°C, major climatic changes on at least a 10 5 year scale (glacial-interglacial cycles) and probably a 10 4 year scale (the approximate length of an interglacial) must be of similar ages throughout the temperate climatic belt of the Northern Hemisphere. This concept allows continental pedostratigraphical correlations. Detailed knowledge of the genesis of paleosols is needed to establish loess–paleosol stratigraphies that can be used for paleoclimatic reconstruction. Most paleosols, however, are truncated and largely recalcified from overlying loess. Micromorphological studies allow primary and secondary carbonates to be distinguished and provide unequivocal evidence of clay illuviation. This enables the recognition of typical loess, weathered loess and the recognition of different genetic soil horizons, such as CB, BC, Ah, Bw and Bt horizons. For the Brunhes epoch, the sequence at Karamaydan, Tadjikistan, is more detailed than the corresponding section in Luochuan, China, and even more than in SE Central Europe except for the last glaciation. The very good correlation with the deep-sea oxygen isotope record, which includes the development of an accurate astronomical time scale, allows a detailed chronostratigraphical subdivision of the loess–paleosol sequence in Karamaydan, which therefore should be regarded as a key sequence for reconstructing the climatic history of the Brunhes epoch. This implies that the loess–paleosol sequences in SE Central Europe are less complete than thought earlier. Pedocomplexes in Karamaydan correspond with single paleosols in SE Central Europe, e.g. the F6 paleosol in Stari Slankamen correlates with pedocomplexes PK VI and V at Karamaydan, which were formed over a period of about 140 ka , although pedogenesis was interrupted several times by loess deposition. The F6 soil is therefore an example of a welded paleosol, as are the F5, the F4 and the F2 paleosols in SE Central Europe. For most of the Matuyama epoch, the central and lower parts of the sequence at Chashmanigar show more pronounced paleosols than the equivalent parts at Luochuan; in SE Central Europe only at Stari Slankamen are three strongly developed though truncated paleosols (F9–F11) above Neogene sediments. Mineralogical investigations of the silt and clay subfractions show that there is little difference in the type and amount of pedogenic clay mineral formation between the Holocene soils and the paleosols of the Brunhes epoch at Karamaydan and of the Matuyama epoch at Chashmanigar. This suggests that the interglacial climates represented by the B or Bt horizons of the buried paleosols of late, middle, and early Pleistocene age were similar to that of the Holocene.

Mass balance and streamflow variability at Place Glacier, Canada, in relation to recent climate fluctuations

AbstractAlthough a great deal of research has focused on the hydrologic effects of climate variability and change, relatively little research has examined the effects on streamflow of interactions between climate variability and change and resulting glacier response. Place Glacier, in the southern Coast Mountains of British Columbia, Canada, has been monitored for mass balance since 1965, and a stream gauge was operated just below the glacier terminus from 1969 to 1989. This paper presents analyses of the mass balance history and streamflow variations in relation to recorded climatic variability.Place Glacier's winter and net balances are correlated with the Pacific Decadal Oscillation (PDO). Summer balance is positively correlated with summer temperature and negatively with the preceding winter balance, which enhances the effects of changes in winter balance on net balance. The well‐documented post‐1976 shift from the PDO cold phase to the present warm phase initiated a significant and persistent period of more negative net balance and terminal retreat. A reconstruction of net balance extending back to the 1890s, based on a regression with winter precipitation and summer temperature, displays decadal‐scale fluctuations consistent with the PDO. Summer streamflow responded to interannual variations in winter snow accumulation and summer temperatures, which control the rate of rise of the glacier snowline and melt rates. After accounting for these influences via regression analysis, August streamflow displayed a negative trend in total runoff. Examination of air photographs and the reconstructed mass balance history suggest that significant firn depletion had occurred prior to 1965, such that the dominant effect of glacier changes was a reduction in ice area, resulting in decreased meltwater production. Copyright © 2001 John Wiley & Sons, Ltd.

Hydrogeology of a restored coastal dune system in northeastern Scotland

This paper reports the results of 12 years of hydrological monitoring at the St. Fergus dune system in northeastern Scotland. The site is adjacent to the UK’s largest gas terminal and the dunes are crossed in five places by North Sea gas pipelines which were constructed between 1976 and 1990. These are buried beneath the dune system which was restored after pipeline installation. The dunes include a substantial freshwater wetland which is seasonally flooded and provides an important habitat for waterfowl. The hydrogeology of the site is characterized and the hydrogeological processes that sustain this wetland feature are considered including recent climatic fluctuations.

River runoff changes and recent climatic fluctuations in Bulgaria

Some estimates of global climatic change in the next 100 years suggest a general warming and rainfall decrease on the Balkan Peninsula. Our studies suggest that in Bulgaria climatic changes have already started. Because water resources to a great extent depend upon climate dynamics, this paper develops the linkage of climatic fluctuations and water resources using time-series analysis of climatic parameters and some river runoff characteristics and their correlation. One of the main conclusions, based on the results, is that climatic change manifested in the last 15 years has significantly influenced river runoff. A study of the recent prolonged drought and the influence of changes on water resources and human activity begins with characterizing climate-hydrology linkages. The results of this study point to several problems of regional and local importance.

Spatial Pattern of Temporal Trends in Moisture Conditions in the Southeastern United States

Palmer's Drought Severity Index (PDSI) is used to represent moisture conditions in the southeastern United States. Temporal trends in annual PDSI for 53 climate divisions in the region are examined for the period 1895 to 1988. Spearman's rank correlation reveals that 19 climate divisions have increasing trends in annual PDSI at the 0.05 significance level, changing towards a wetter condition during the study period. There is no division with a significant decreasing trend. Such temporal changes also display a welldefined spatial pattern. All but one of the divisions with significant increasing trends are located in the southwestern part of the region, centered at Alabama. Climate divisions in Alabama have experienced the most consistent change towards a wetter condition. The increasing rates in the annual PDSI during the study period range from 0.021/year to 0.037/year. Further analysis indicates that the increases in annual PDSI are mostly the result of increasing annual precipitation. Introduction Recent climatic fluctuations have attracted a great attention. Many studies focus on the temporal variation of climatic variables, such as temperature and precipitation. In the southeastern United States, temporal variations in temperature have been discussed by several workers. Although there is a general warming trend corresponding to the increase of CO2 in the atmosphere since the turn of the century, the temperature in the southeast has been characterized by a cooling trend since the 1930s with more colder winters lately (Barnett 1983, McCabe 1988, Skeeter 1985, Suckling 1986 and 1988). Studies on precipitation are fewer than that on temperature. There is probably a slight increase in precipitation in the southeastern United States. For example, Plummer (1983) found an increase in statewide precipitation for Georgia. Howarth (1989) also found an increase in statewide precipitation for Kentucky. However, changes in precipitation are often highly localized Geografiska Annaler · 75 A (1993) · 1-2 and few studies have been able to generalize a regional pattern. Recently, several studies are focused on droughts in the southeastern United States, probably prompted by the severe droughts occurred in the 1980s (Eder et al. 1987, Henry and LeBoutillier 1990, Soul6 and Meentemeyer 1989). Severe droughts have been recorded in the 1930s, 1950s, and especially the 1980s. 1981 was a very dry year for Georgia and South Carolina (Carter 1983). In 1986, the southeast was hit by one of the worst droughts in the century (Karl and Young 1987). This drought was ranked as unprecedented for the past 277 years in the southern Appalachian Mountains (Cook et al. 1988). The southeast was affected again in 1988 by a drought covering a large portion of the United States (Soule and Meentemeyer 1989). 1990 saw another dry year for Georgia and Florida (LeComte 1991). These severe droughts, particularly when occurring in consecutive years, are great threats to agriculture in the region, causing crop failures and lower income to farmers. Severe droughts also cause water supply shortage in urban areas where surface water is the main source, such as Atlanta. Furthermore, frequent wild fires are often associated with droughts (Izlar 1984). After 3 years of consecutive drought years in south Florida, the Everglades were on fire in early 1990. The fire continued for more than 2 months and burned more than 20,000 acres (LeComte 1991). A wild fire broke out later in 1990 in the Okefenokee Swamp National Wildlife Refuge in south Georgia and swept over more than 5000 acres in just two days. The refuge spent $6.6 million to fight the fire (Leavenworth 1991). Palmer's Drought Severity Index (PDSI) has been widely used in regional climatic studies because it summarizes the effect of changing temperature and precipitation. Although it was originally designed to represent drought conditions, its val-

Worldwide marine temperature fluctuations 1856–1981

Paltridge and Woodruff1 found a warming of global mean sea-surface temperatures (SSTs) of ∼1°C in the first half of the present century, but there are doubts about its reality because spurious temperature fluctuations can arise from changes in measuring instruments2,3 and because inter-annual fluctuations may contain sufficient variance to allow the observed inter-decadal variations to fall within the limits of sampling error of a stationary series3. We present here the results of analyses of worldwide SSTs and night near-surface marine air temperature (MAT) for the period 1856–1981 with the aim of estimating the magnitudes of recent climatic fluctuations of temperature at the ocean surface, taking account of changes in observing procedures. Our results show a worldwide temperature fluctuation of range ≃0.6 °C (in broad agreement with a preliminary analysis of global SST2), with the coldest period being centred around 1905–10 and the warmest occurring in the 1940s. The fluctuation has a similar magnitude to, and is nearly in phase with, climatic warmings and coolings near the surface of the Northern Hemisphere land masses for the period after 1900. Before 1900 the trends are sharply different.

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...

Environmental Influences on Yield and In Vitro True Digestibility of Warm‐Season Perennial Grasses and the Relationships to Fiber Components1

AbstractIn recent years climatic fluctuations have been increasingly associated with seasonal variation in yield and quality of forage crops. Although considerable information is available concerning environmental influences on yield and quality of many temperate and tropical grasses, very little is known about these relationships in the major grasses grown in the southern U.S.A. The objectives of this study were to determine the relative influences of temperature (T) and photon flux density (L) on dry matter yield (DMY) and in vitro true digestibility (IVD) of four warm‐season perennial grasses grown at two soil moisture levels and to relate the differences in IVD to fiber component concentrations. Coastal and common hermudagrass [Cynodon dactylon (L.) Pers.], Pensacola hahiagrass (Paspalurn notatum Flugge), and dallisgrass (P. dilatatum Poir.) were grown in an artificial growth medium at 4 day/night temperatures (35/24, 32/21, 29/18, 26/15 C), four photon Aux densities (1,050, 840, 630, 420 µEm−2 sec−1 PAR) and two soil moisture levels in growth cabinets. After 14 and 21 days regrowth, DMY and IVD were measured. Regression equations were developed to predict DMY and IVD as functions of T and L at each soil moisture level and regrowth period.The study clearly showed that DMY of all grasses increased with increasing T and L. The imposed moisture stress sharply reduced DMY of dallisgrass (DAL) hut not of the other grasses. In all grasses IVD consistently decreased as T increased, resulting in maximum IVD at the lowest T. The effect of L on IVD ranged from positive to negative, depending on the grass and T. Maximum IVD values occurred at the high soil moisture (HM) level after 14 days regrowth. At the HM level maximum IVD of Coastal bermudagrass (COA), common hermudagrass (COM), and Pensacolabahia grass (BAH), respectively, was 5.7, 4.9, and 3.6 percentage units higher after 14 than after 21 days regrowth. In DAL at the HM level and in all grasses at the low soil moisture level, these differences due to age were only about one percentage unit or less. The Paspalum spp. averaged about seven percentage units higher in IVD than the Cynodon spp. Significant (P ≤ 0.01) negative correlations were obtained between IVD and previously reported concentrations of acid detergent fiber (ADF), cellulose, permaganate lignin (LIG), and silica in all grasses and concentrations of neutral‐detergent fiber in COA and COM. Although correlation coefficients were ≤ 0.50, hemicellulose concentration and IVD were positively correlated in all grasses. Strongest correlations were obtained between IVD and concentrations of ADF and LIG.

An Attempt to Address the Question, “Are Weather patterns Changing?” for a Nonspecialist Audience

This paper is derived from an address at an Illinois agricultural conference on the specified topic, “Are weather patterns changing?” It examines three contrasting perspectives on the weather and climate of the recent past and immediate future evident in the contemporary literature. One standpoint has interpreted recent weather extremes and climatic fluctuations as evidence that the earth is undergoing a larger-scale climatic change towards a cooler and more variable regime, while an alternative view considers these extremes and fluctuations to be part of normal climate. The third perspective results from the recent pronounced increase in atmospheric CO2, which may induce a warm climate change. The request to provide this address offered the additional opportunity of drawing agriculturalists' attention to the research their scientists, economists, and sociologists must perform before the adverse socioeconomic effects of weather and climate variability can be minimized. It was also stressed, however, that the atmospheric sciences will have to demonstrate credibility to win and retain this vital support required from other specialists.

RELATIONSHIP BETWEEN THE VARIATION OF PRECIPITATION DISTRIBUTION AND OF 500mb FLOW PATTERN IN WINTER OVER NORTH AMERICA

Precipitation distribution is in general fairly complex, because many factors are involved in it. To classify such complicated distribution a principal component analysis is a useful means. This paper aims to clarify the relationship between the variation of precipitation distribution and that of upper flow pattern, which is considered to govern the variation of precipitation distribution in winter (January and February) over North America, Monthly data during 1951_??_1978 were analysed for this purpose. Besides, some new findings with regard to the recent climatic fluctuations were obtained. The results are summarized as follows: 1. Four principal components were obtained by the principal component analysis of month ly precipitation for 38 stations (Fig. 3). The first and the second components mainly explain precipitation fluctuation of the eastern part of the United States and that of the western coast of North America respectively. Both the third and the fourth components explan more local fluctuations. 2. The values of correlation coefficients between component scores and 500 mb height prove that the first two components are closely related to the 500 mb height distribution (Fig. 5). 3. On the other hand, four components were obtained with regard to monthly mean height of 500 mb for 39 stations (Fig. 6). Both the first and the second components determine either meridional or tonal flow type (Fig. 7), and the third and the fourth components mainly explain meridional movement of 500 mb contour lines. 4. Months of high component score were chosen with respect to the first two components, e. e. four types of precipitation anomaly distribution (1 WA, 1 WB, 2 WA 2 WB) and composite maps of 500 mb height distribution were made for these four types. These maps indicate that four types of precipitation anomaly distribution are prescribed by the four different 503 erent 50 mb flow patterns respectively (Fig. 9). 5. The first two components of 500 mb height give four 500 mb flow types (1Wa 1Wb, 2Wa 2Wb ; Fig. 7). They almost coincide with the four different 500 mb flow patterns (Fig. 9) which are considered to prescribe the four different precipitation anomaly distribution types. 6. Four types of precipitation anomaly distribution correspond to four different 540 mb flow types (1 WA-1Wb, 1 WB-1 Wa, 2.WA-2Wa, 2 WB-2 Wb) . The dominant feature of 1 WA-1 Wb (Fig. 9-a) is the prevailing tonal flow with stronger middle latitude westerlees. The eastern part of the United States is a positive precipitation anomaly area. In the case of 1 WB1 Wa (Fig. 9-b), the meridional flow is dominant with a ridge over the Rocky Mountains and a trough over the eastern part of North America or the adjacent Atlantic Ocean. The eastern part of the United States is a negative precipitation anomaly area. The 2 WA-2Wa type (Fig. 9-c) is characterized by the dominant meridional flow. A ridge is formed over the area from Alaska to the Pacific Ocean and a trough is over the eastern part of North America. As for precipitation, the vicinity of 45-N of the western coast is a negative anomaly area, while Alaska and the northeastern part of Canada is a positive anomaly area. In the case of 2WB-2Wb (Fig. 9-d), the zonal flow is dominant but with weaker middle lattitude westerlies. Characteristics of precipitation distribution are contrary to the case of 2 WA-2 Wa. 7. Examination of time series of 500 mb height component scores (Fig. 8) elucidates the following tendency of flow pattern. The zonal flow was prevalent in the former half of the 1950's, whereas the meridional flow appeared in the former half of the 1960's and in the latter half of the 1970's. The circumpolar vortex has expanded southward since about 1963. 8. Judging from time series of precipitation component scores (Fig. 4), precipitation was intend to decrease in the eastern part of the United States through the investigated period.

Recent Climatic Fluctuations of the Canadian High Arctic and Their Significance for Glaciology

Various measures of the character of ablation season conditions in the Canadian High Arctic (north of 74°N) are discussed based on an analysis of daily climatic data from Alert, Eureka, Isachsen, R...

Recent Climatic Fluctuations of the Canadian High Arctic and Their Significance for Glaciology

Recent Climatic Fluctuations of the Canadian High Arctic and Their Significance for Glaciology

Note on the recent climatic fluctuation in the United States

The monthly, seasonal, and annual temperature means and the annual precipitation totals are compared for the two 25-year periods 1906–1930 and 1931–1955. The data from rural stations with homogeneous records were used. The temperatures in most places show significant rises. Annual rises of 1.5°F are noted over the Great Lakes region and in the mountain states. The average of 48 stations shows an annual rise of 0.8°F between the two time intervals. For the most part, precipitation changes are probably not significant, but a tendency toward lower totals is noted over the mountain states, parts of the Great Plains, and in a sector west of the Appalachians.

The Recent Climatic Fluctuation in Lower Latitudes and the General Circulation of the Pleistocene

In order to compensate for the somewhat secondary interest commonly devoted to the problems related to general circulation anomalies of the Pleistocene in lower latitudes, the present writer (K. W. BUTZER 1957 b) has already discussed the meteorological significance of the pluvials in subtropical latitudes. In this essay it shall be attempted to analyze the character of the recent climatic fluctuation in the subtropics and tropics in order to assess its applicability to some further problems connected with the atmospheric circulation of the Quaternary, namely with interpluvial and interglacial epochs. A general warming up of the northern Atlantic region has been of great interest in the past decades, but the trends of precipitation in different geographical areas have not been given a deserving attention. These precipitation anomalies are of an equally striking nature and equal palaeoclimatological implication as the recent temperature changes. Consequently the emphasis here shall be upon the circulation changes related to precipitation in lower latitudes. The large number of well-qualified and important articles considering our present climatic fluctuation have also only paid passing attention to the mediterranean climatic province and the trade wind deserts of the Old World; and largescale maps of barometric pressure and precipitation anomalies have been based on too few stations in this area, with often misleading results. To help bridge this deficiency, pressure and rainfall changes in lower latitudes between 2zo0E and 750 W have been computed from the World Weather Records and presented in the form of three maps. Firstly January and July barometric pressure changes are summarized in Fig. I and 2. The differences are based on the records of 37 stations for the period before 192o and 1921-1940. This apparently inhomogeneous comparison is necessitated by the scarcity of stations, but largely eliminated by the fairly uniform trends between 1881 (earlier limit of records applied) and 192o. This procedure has already been employed by K. KRAMES (1951, 1952) for temperature fluctuations. Almost all of the stations used begin recording between 1881 and 1900oo. Based on 72 stations, Fig. 3 illustrates the rainfall anomalies for the 3o-year means before and after 191o for the greater

The Recent Climatic Fluctuation in Lower Latitudes and the General Circulation of the Pleistocene

The Recent Climatic Fluctuation in Lower Latitudes and the General Circulation of the Pleistocene

Geomorphic Evidences of Recent Climatic Fluctuation in the Peruvian Coastal Desert

Geomorphic Evidences of Recent Climatic Fluctuation in the Peruvian Coastal Desert

The Recent Climatic Fluctuation in Finland and Its Consequences

The Recent Climatic Fluctuation in Finland and Its Consequences Get access THE RECENT CLIMATIC FLUCTUATION IN FINLAND AND ITS CONSEQUENCES. A symposium edited by ILMARI HUSTICH for the Geographical Society of Finland.Fennia, 75. 128 pp. Helsinki, 1952. Donald S. Farner Donald S. Farner Search for other works by this author on: Oxford Academic Google Scholar Annals of the Entomological Society of America, Volume 45, Issue 4, 1 December 1952, Page 542, https://doi.org/10.1093/aesa/45.4.542 Published: 01 December 1952

Recent Climatic Fluctuations

Recent Climatic Fluctuations

On the Correlation Between Growth and the Recent Climatic Fluctuation

On the Correlation Between Growth and the Recent Climatic Fluctuation