Rising Summer Temperatures Research Articles

Late-Glacial and Early Holocene Environmental and Climatic Change at Lake Tambichozero, Southeastern Russian Karelia

High-resolution lithostratigraphy, mineral magnetic, carbon, pollen, and macrofossil analyses, and accelerator mass spectrometry 14C measurements were performed in the study of a sediment sequence from Lake Tambichozero, southeastern Russian Karelia, to reconstruct late-glacial and early Holocene aquatic and terrestrial environmental changes. The lake formed ca. 14,000 cal yr B.P. and the area around the lake was subsequently colonized by arctic plants, forming patches of pioneer communities surrounded by areas of exposed soil. A minor rise in lake productivity and the immigration of Betula pubescens occurred ca. 11,500 cal yr B.P. The rise in summer temperatures probably led to increased melting of remnant ice and enhanced erosion. The distinct increase in lake productivity and the development of open Betula-Populus forests, which are reconstructed based on plant macrofossil remains, indicate stable soils from 10,600 cal yr B.P. onward. Pinus and Picea probably became established ca. 9900 cal yr B.P.

The Yellow‐necked Mouse Apodemus flavicollis in Britain: status and analysis of factors affecting distribution

ABSTRACTA national survey of the Yellow‐necked Mouse (Apodemus flavicollis) in Britain was undertaken by The Mammal Society. The live‐trapping study sampled small mammal populations from 168 deciduous woodlands in autumn 1998. Within their range, Yellow‐necked Mice were widespread in deciduous woodland and were more abundant than Wood Mice in 15% of the woodlands sampled. These trapping records, as well as records solicited from local recorders, record centres and individuals, supplemented the existing distribution map, confirming the general pattern, but with minor extensions to some range borders.Yellow‐necked Mice were found in woodland of all ages, but were more common in woods of ancient origin than in younger woodland. Woodland size was not important in determining the presence or abundance of Yellow‐necked Mice, but they were more often absent from woods more than 2 km from neighbouring substantial woodland.The presence of Yellow‐necked Mice did not affect the relative abundance of Wood Mice (Apodemus sylvaticus). However, the decline in the proportion of breeding male Wood Mice at the end of the main breeding season was more marked in those woods that also contained Yellow‐necked Mice. Where their ranges overlapped, Bank Voles (Clethrionomys glareolus) were less abundant where Yellow‐necked Mice were also present.The distribution of the Yellow‐necked Mouse was explored with respect to a number of climatic, soil and habitat variables. Maximum summer temperature was the most significant variable explaining distribution, although woodland cover variables also contributed. Soil moisture and pH, mean rainfall and winter temperature parameters did not predict Yellow‐necked Mouse distribution. Low summer temperature may limit Yellow‐necked Mouse distribution through its impact on tree seed production and diversity. Climatic change leading to a rise in summer temperature might encourage range expansion by Yellow‐necked Mice, if their other habitat requirements are met.

Moisture conditions of outdoor air-ventilated crawl spaces in apartment buildings in a cold climate

The effects of air change and ground covers on crawl space moisture balance in a cold climate are discussed in this paper. The objectives were to assess the suitability of outdoor air-ventilation in the crawl spaces of apartment buildings, to determine the optimum air change rate with and without ground covers, and the effect of the ground covers’ thermal insulation on moisture behaviour. Measured data from the test building was used to develop the crawl space model in a modular simulation environment, where the parametric simulations were carried out. The air change rate was varied between 0–10 ach to study moisture behaviour with covered and uncovered ground surface. Moisture evaporation was included in the moisture balance, but moisture storage in the constructions and in the ground was not. The results show that evaporation and thermal behaviour are the key elements determining the resulting relative humidity in crawl spaces. If moisture evaporation is entirely prevented, the crawl space may be left unventilated. In other cases, ventilation is always required to remove the moisture. The higher air change rates increased moisture evaporation from uncovered ground, but still brought about lower relative humidity. The rise from 0.5 to 3 ach increased evaporation from 2.4 to 4.9 g/m 2 h and decreased the highest monthly average of relative humidity from 81 to 74%. For the uncovered ground the lowest relative humidity was achieved at 2–3 ach air change in winter, but in the summer, the higher the air change the lower the relative humidity. Ground covers made it possible to decrease relative humidity and to increase temperature significantly due to reduced moisture evaporation. Ground cover with thermal insulation was in principle more effective than without insulation as it provided a slightly higher temperature rise in summer. The studied 5 cm expanded polystyrene layer reduced moisture evaporation to 0.3–0.4 g/m 2 h, increased crawl space temperature by 2–3°C and decreased relative humidity below the 60% level when air change was 0.5–1 ach. In general, outdoor air-ventilation demonstrated very high performance in the crawl space of the studied apartment building when a ground cover was applied.

The Riss-Würm interglacial from West to East in the Alps: an overview of the vegetational succession and climatic development

Abstract The vegetational and climatic developments during the Riss-Würm interglacial in the area on the northern flank of the Alps are reviewed. Reforestation seems to have begun over the whole region with a dwarf-shrub and ensuing shrub phase, leading to birch and/or pine woodland. The rise in summer temperatures, which δ180 values suggest to have been a two-stage event, permitted the immigration and expansion of more demanding trees (elm, oak, lime, ash, ivy, hazel, yew, etc.). Following the thermal maximum, which took place during the hazel and yew biozones, hornbeam dominated the forests in the alpine foreland, whilst fir/spruce forests formed the dominant vegetation at sites closer to the Alps or at a higher altitude. A marked climatic deterioration can only be recognised towards the end of the interglacial, which led to extensive spruce/pine and, finally, almost pure pine forests.

Younger Dryas and Allerød summer temperatures at Gerzensee (Switzerland) inferred from fossil pollen and cladoceran assemblages

Linear- and unimodal-based inference models for mean summer temperatures (partial least squares, weighted averaging, and weighted averaging partial least squares models) were applied to a high-resolution pollen and cladoceran stratigraphy from Gerzensee, Switzerland. The time-window of investigation included the Allerød, the Younger Dryas, and the Preboreal. Characteristic major and minor oscillations in the oxygen-isotope stratigraphy, such as the Gerzensee oscillation, the onset and end of the Younger Dryas stadial, and the Preboreal oscillation, were identified by isotope analysis of bulk-sediment carbonates of the same core and were used as independent indicators for hemispheric or global scale climatic change. In general, the pollen-inferred mean summer temperature reconstruction using all three inference models follows the oxygen-isotope curve more closely than the cladoceran curve. The cladoceran-inferred reconstruction suggests generally warmer summers than the pollen-based reconstructions, which may be an effect of terrestrial vegetation not being in equilibrium with climate due to migrational lags during the Late Glacial and early Holocene. Allerød summer temperatures range between 11 and 12°C based on pollen, whereas the cladoceran-inferred temperatures lie between 11 and 13°C. Pollen and cladocera-inferred reconstructions both suggest a drop to 9–10°C at the beginning of the Younger Dryas. Although the Allerød–Younger Dryas transition lasted 150–160 years in the oxygen-isotope stratigraphy, the pollen-inferred cooling took 180–190 years and the cladoceran-inferred cooling lasted 250–260 years. The pollen-inferred summer temperature rise to 11.5–12°C at the transition from the Younger Dryas to the Preboreal preceded the oxygen-isotope signal by several decades, whereas the cladoceran-inferred warming lagged. Major discrepancies between the pollen- and cladoceran-inference models are observed for the Preboreal, where the cladoceran-inference model suggests mean summer temperatures of up to 14–15°C. Both pollen- and cladoceran-inferred reconstructions suggest a cooling that may be related to the Gerzensee oscillation, but there is no evidence for a cooling synchronous with the Preboreal oscillation as recorded in the oxygen-isotope record. For the Gerzensee oscillation the inferred cooling was ca. 1 and 0.5°C based on pollen and cladocera, respectively, which lies well within the inherent prediction errors of the inference models.

Laboratory-induced spawning of the gastropod Gibbula cineraria as an indicator of field spawning

The t r o c l d gastropod Gibbula cinerana spawns in response to a rlse in sea water temperature A simple laboratory bioassay a warm water shmulus can therefore be employed to de t e rm~ne the competence of adult s n a ~ l s to spawn at any given tlme d u r ~ n g the year The bioassay has been used over 1 yr, at approximately monthly intervals to estabhsh the spawning season of a population of G clnerarla in NE England The main spawning season was indicated between late June and early September Spawning could also be induced in females in winter Results are discussed in relation to previous, contrasting, reports regarding the spawning season of G cinerarla Gibbula cjneraria ( L . ) is gonochoristic and spawns directly to the sea where fertilisation occurs. Reports of the spawning season of G. cineraria present a confusing picture of events (see Underwood 1972 for a review). For example, Fretter & Graham (1962) consider that G. cineraria spawns throughout the year at Plymouth (SW England), while in Scotland (Elmhirst 1922) and North Wales (Thompson cited in Underwood 1972), spawning reportedly occurs in spring. To clarify this situation, a laboratory study was performed using a simple and rapid bioassay (Clare 1987). The assay employs a 'warm water stimulus' and is based upon Underwood's (1972) observation that Gibbula cineraria spawns when the sea water temperature rises above 12°C. The assay involves transferring 30 specimens, which have been maintained below 12C, to individual bowls containing 100 m1 of sea water (also below 12°C) and allowing them to equilibrate to room temperature (ca 20°C). The bowls are examined after 24 h for spawned gametes and all snails are dissected to determine the condition of the gonad. The gonads are scored in 3 categories based on a visual examination. These categones are: (1) spent, i.e. the digestive ' Present address: Duke University Marlne Laboratory, Pivers Island, Beaufort, North Carolina 28516, USA gland is clearly visible through the gonad; (2) partly spent, i.e. patches of digestive gland are visible, and (3) gravid, i.e, the gonad is either entirely green in females or cream/white in males. This method allows the gonad condition to be rapidly evaluated. The specimens used in this study were collected at low water from the intertidal zone at Cullercoats, NE England, throughout 1986 and during the early months of 1987. Fig. 1 shows the results of bioassays performed on the day of collection. Fenlale snails had 2 potential spawning periods; one during the summer and the other during late winter. Male snails, however, spawned in response to a temperature rise in summer, but not during late winter.

Phenology of high-altitude plants of Kumaun in Central Himalaya, India

The various developmental stages of 184 species of high-altitude plants were studied during 1987 and 1988 in the Pindari glacial moraine area of Kumaun Himalaya in the Central Himalaya. The initiation of growth was synchronised with the beginning of the spring/or summer temperature rise and snowmelt. In this high-altitude zone, the peaks of various phenophases succeeded one after another over about 4 months from early June to October. It is suggested that the plants complete various growth cycles within a very short period of favourable conditions to ensure the survival of their progeny.

Studies on Competition between Grass and Legume in Mixed Sward : VI. Effects of the growth stage and the temperature on the upward growth of orchardgrass and Ladino clover in summer.

In order to clarify the effects of the growth stage and the temperature on the upward growth of orchardgrass and Ladino clover in summer, the tests were attempted on the two species grown separately in each own sward. The test results are summarilzed as follows: 1) The tiller number per square meter of orchardgrass was larger in spring, while smaller in summer. In spring, 70 to 90 per cent of all tillers were at the reproductive stage, while in summer, most of the tillers were at the vegetative stage. 2) Smallness in the tiller number in summer can be ascribed to the follwing two reasons: -(1): most of the tillers observed in spring have died out after heading by late June. (2): the tillering rate was lower in summer. 3) The plant height of tillers at the reproductive stage in spring was approximately twice as high as that at the vegetative stage in summer, while the plant height of the tillers at the vegitative stage showed almost no difference between spring and summer. 4) Judging from the facts stated in l), 2) and 3), it is concluded that the decrease in the upward growth rate of orchardgrass in summer can be ascribed to the fact that the tillers at the reprodutive stage have been replaced, by early summer, by the tillers which put forth at the vegetative stage. 5) The petiole length of Ladino clover was not related with the growth stage. With regard to the effect of the growth stage, it can be said that the flower buds which reached a peak of the formation in June-July months suppressed the formation of branches in the same season, thus resulting in the decrease in the stolon number per square meter in summer. 6) The petiole length was related with temperature. It has become longer according to the rise in summer temperature. 7) Judging from the facts stated in 5 and 6, it is concluded that the increase in upward growth rate of Ladino clover in summer can be ascribed chiefly to the high temperature in summer.

Effect of Woodland Clearance on Stream Temperature

A study was made of the temperature characteristics of a stream which flowed first through open fields and then through woodland. When the woodland was felled, that section of the stream showed a marked rise in summer temperature. It is argued that the presence or absence of tree shading can be the decisive factor in determining the temperature of small streams.

DISSOLVED OXYGEN IN SWEETWATER LAKE

In Sweetwater Lake, near San Diego, California, vertical distribution of dissolved oxygen was observed to be highly stratified during the early summer months. With the lake at a maximum depth of about 32 ft, the lower 5 to 10 ft were devoid of oxygen by early July but mid‐depths and upper levels remained well‐oxygenated throughout the period of observation. The pattern of oxygen distribution in the lake appeared to reflect the prevailing summer circulation which consisted of rapid down‐wind movement at the surface with counter‐currents at mid‐depths and smaller circulation cells at lower depths. Rising summer temperatures caused an increase in the depth of the upper layer of water saturated or supersaturated with oxygen. The drop in solubility of oxygen due to heating of the surface layers of water was proportionally greater than the decrease in oxygen content, producing an increase in saturation values. Thermal stratification seemed to be sufficient, by reduced vertical mixing, to maintain the lake in a condition of oxygen‐rich epilimnion and oxygen‐depleted hypolimnion.Serial observations showed a diurnal cycle of rising oxygen content in the surface layers in late afternoon and evening, probably the results of the photosynthetic activity of the phytoplankton and the circulation of high oxygen water from the shallow end of the lake.Simultaneous sampling of the water at various depths for oxygen analysis and measurement of light transmission with a hydrophotometer produced no correlation between oxygen content and turbidity. Simultaneous measurement of sound velocity, attenuation and oxygen content also produced no conclusive results.

Variability of Summer Temperature in Sweden and its Connection with Changes in the General Circulation

A method of calculating moving standard deviations to give an idea of long-periodic fluctuations in the interannual variability of summer temperature is described and discussed from a statistical point of view. The method was applied to summer temperature records from 15 stations in Sweden and changes in the variability at those stations are treated. In addition the actual variability during the period 1920–39 is determined and compared to the interdiurnal variability of the same period. In the second part of this investigation are studied frequency fluctuations of different circulation patterns over southern Scandinavia based upon the catalogue of daily weather situations during the period 1881–1950 published by the German Weather Service of the U.S. Zone in 1952. These fluctuations are compared with changes in the summer-temperature and its variability in South Sweden during the same period. It is found that the recent rise of summer temperature has been connected with a definite decrease in frequency of north-meridional situations over Europe and with an increase of south and warm-meridional cases as well as zonal situations. High variability seems to be connected with meridional circulation, low variability with zonal circulation. In a special chapter the fluctuations in variability of the Stockholm summer temperature since 1756 are discussed. DOI: 10.1111/j.2153-3490.1953.tb01046.x

Variability of Summer Temperature in Sweden and its Connection with Changes in the General Circulation

A method of calculating moving standard deviations to give an idea of long-periodic fluctuations in the interannual variability of summer temperature is described and discussed from a statistical point of view. The method was applied to summer temperature records from 15 stations in Sweden and changes in the variability at those stations are treated. In addition the actual variability during the period 1920—39 is determined and compared to the interdiurnal variability of the same period.
 In the second part of this investigation are studied frequency fluctuations of different circulation patterns over southern Scandinavia based upon the catalogue of daily weather situations during the period 1881—1950 published by the German Weather Service of the U.S. Zone in 1952. These fluctuations are compared with changes in the summer-temperature and its variability in South Sweden during the same period. It is found that the recent rise of summer temperature has been connected with a definite decrease in frequency of north-meridional situations over Europe and with an increase of south and warm-meridional cases as well as zonal situations. High variability seems to be connected with meridional circulation, low variability with zonal circulation. In a special chapter the fluctuations in variability of the Stockholm summer temperature since 1756 are discussed.