Browsing by Subject "Temperature"

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  • Noreikiene, Kristina; Kuparinen, Anna; Merilae, Juha (2017)
    Telomeres are highly conserved nucleoprotein structures which protect genome integrity. The length of telomeres is influenced by both genetic and environmental factors, but relatively little is known about how different hereditary and environmental factors interact in determining telomere length. We manipulated growth rates and timing of maturation by exposing full-sib nine-spined sticklebacks (Pungitius pungitius) to two different temperature treatments and quantified the effects of temperature treatments, sex, timing of maturation, growth rate and family (genetic influences) on telomere length. We did not find the overall effect of temperature treatment on the relative telomere length. However, we found that variation in telomere length was related to timing of maturation in a sex- and temperature-dependent manner. Telomere length was negatively related to age at maturation in elevated temperature and early maturing males and females differed in telomere length. Variation in growth rate did not explain any variation in telomere length. The broad sense heritability (h(2)) of telomere length was estimated at h(2) = 0.31 - 0.47, suggesting predominance of environmental over genetic determinants of telomere length variability. This study provides the first evidence that age at maturation together with factors associated with it are influencing telomere length in an ectotherm. Future studies are encouraged to identify the extent to which these results can be replicated in other ectotherms.
  • Pöysa, Hannu; Vaananen, Veli-Matti (2018)
    The proportion of first-year birds in annual wing samples provided by hunters has been used as a measure of breeding success in waterfowl. The proportion of first-year birds in the wing samples of Eurasian wigeon (Mareca penelope) from Denmark and the UK shows a long-term decline, probably reflecting a decrease in breeding success. However, previous studies report conflicting results in the relationship between variation in the proportion of first-year birds and variation in climatic conditions. We used wing data of hunter-shot Eurasian wigeon from Finland to study whether the proportion of first-year birds shows a similar long-term decline and whether between-year variation in the proportion of young is associated with variation in climatic conditions. We found a long-term decline in the proportion of first-year birds. The proportion of young also varied considerably between years, but this variation was not associated with weather or the climatic variables considered for the breeding and wintering periods. More research is needed concerning factors that affect long-term changes and annual variation in the proportion of young in the hunting bag and on the suitability of this index to measure productivity in ducks.
  • Ahonen, Salla; Hayden, Brian; Leppänen, Jaakko Johannes; Kahilainen, Kimmo Kalevi (2018)
    Climate change is resulting in increased temperatures and precipitation in subarctic regions of Europe. These changes are extending tree lines to higher altitudes and latitudes, and enhancing tree growth enabling intensification of forestry into previously inhospitable subarctic regions. The combined effects of climate change and land-use intensification extend the warm, open-water season in subarctic lakes and increase lake productivity and may also increase leaching andmethylation activity of mercury within the lakes. To assess the joint effects of climate and productivity on total mercury (THg) bioaccumulation in fish, we conducted a space-for-time substitution study in 18 tributary lakes of a subarcticwatercourse forming a gradient fromcold pristine oligotrophic lakes in the northern headwaters to warmer and increasingly human-altered mesotrophic and eutrophic systems in the southern lower reaches. Increasing temperature, precipitation, and lake productivity were predicted to elevate length-and age-adjusted THg concentrations, as well as THg bioaccumulation rate (the rate of THg bioaccumulation relative to length or age) in muscle tissue of European whitefish (Coregonus lavaretus), vendace (Coregonus albula), perch (Perca fluviatilis), pike (Esox lucius), roach (Rutilus rutilus) and ruffe (Gymnocephalus cernua). A significant positive relationship was observed between age-adjusted THg concentration and lake climateproductivity in vendace (r(2) = 0.50), perch (r(2) = 0.51), pike (r(2) = 0.55) and roach (r(2) = 0.61). Higher climate-productivity values of the lakes also had a positive linear (pike; r(2) = 0.40 and whitefish; r(2)= 0.72) or u-shaped (perch; r(2) = 0.64 and ruffe; r(2) = 0.50) relationship with THg bioaccumulation rate. Our findings of increased adjusted THg concentrations in planktivores and piscivores reveal adverse effects of warming climate and increasing productivity on these subarctic fishes, whereas less distinct trends in THg bioaccumulation rate suggest more complex underlying processes. Joint environmental stressors such as climate and productivity should be considered in ongoing and future monitoring of mercury concentrations. (C) 2018 Elsevier B.V. All rights reserved.
  • Holopainen, Jari; Helama, Samuli; Väre, Henry (2018)
    Abstract Long records of phenological observations are commonly used as data in global change and palaeoclimate research and to analyse plants' responses to climatic changes. Here we delve into the historical archives of plant phenological observations (1750–1875) compiled and published previously by Professor Adolf Moberg (Imperial Alexander University of Finland). The digitized dataset represents 44,487 observations of 450 different plant species for their 15 different phenological phases made in 193 sites across Finland, and results in 662 different phenological variables. The five most frequently observed variables are the blooming of rye, the sowing of barley, the blooming of bird cherry, the leaf outbreak of birch, and the sowing of oat. The spring and summer observations demonstrate positive relationships between the onset date and the site latitude, this relationship becoming negative for observations made in the autumn. This latitudinal effect is evident in the raw data as demonstrated by the temporal correlations between the unadjusted mean phenological records and the mean latitude of the sites. After the latitudinal effect is removed from the original data such correlations are much reduced and the new set of phenological records based on the adjusted dates can be computed. The resulting mean phenological records correlate negatively and statistically significantly with the mean temperatures from April through July. Linear trends indicate (i) summer onsets having become delayed by more than one week over the full period and (ii) shortening of the growing seasons since 1846. The dataset is made available in an open repository.
  • Vuola, Jyrki (2016)
    Ääriolosuhteissa saunavammoja voi aiheutua kontaktin ja kuuman ilman lisäksi myös vesihöyryn syrjäyttäessä hapen. Saunomisen MM-kisoissa vuonna 2010 oletettavasti nimenomaan hapenpuute esti vaarallisten merkkien havaitsemisen ja saunojat jäivät saunaan kriittisiksi viimeisiksi minuuteiksi.
  • Luoto, Tomi P.; Ojala, Antti E. K.; Zajaczkowski, Marek (2019)
    We used fossil Chironomidae assemblages and the transfer function approach to reconstruct summer air temperatures over the past 300 years from a High Arctic lake in Hornsund, Svalbard. Our aims were to compare reconstructed summer temperatures with observed (last 100 years) seasonal temperatures, to determine a potential climate warming break point in the temperature series and to assess the significance and rate of the climate warming trend at the study site. The reconstructed temperatures were consistent with a previous proxy record from Svalbard and showed good correlation with the meteorological observations from Bjornoya and Longyearbyen. From the current palaeoclimate record, we found a significant climate warming threshold in the 1930s, after which the temperatures rapidly increased. We also found that the climate warming trend was strong and statistically significant. Compared with the reconstructed Little Ice Age temperatures in late eighteenth century cooling culmination, the present day summer temperatures are >4 degrees C higher and the temperature increase since the 1930s has been 0.5 degrees C per decade. These results highlight the exceptionally rapid recent warming of southern Svalbard and add invaluable information on the seasonality of High Arctic climate change and Arctic amplification.
  • Taccone, Fabio Silvio; Lascarrou, Jean-Baptiste; Skrifvars, Markus B. (2021)
  • Valles, G.; Martin-Bragado, I.; Nordlund, K.; Lasa, A.; Björkas, C.; Safi, E.; Perlado, J. M.; Rivera, A. (2017)
    Recently, tungsten has been found to form a highly underdense nanostructured morphology ("W fuzz") when bombarded by an intense flux of He ions, but only in the temperature window 900-2000 K. Using object kinetic Monte Carlo simulations (pseudo-3D simulations) parameterized from first principles, we show that this temperature dependence can be understood based on He and point defect clustering, cluster growth, and detrapping reactions. At low temperatures (2300 K), all He is detrapped from clusters, preventing the formation of the large clusters that lead to fuzz growth in the intermediate temperature range. (C) 2017 Elsevier B.V. All rights reserved.
  • Olden, Anna; Peura, Maiju; Saine, Sonja; Kotiaho, Janne S.; Halme, Panu (2019)
    Riparian forests have cool and humid microclimates, and one aim of leaving forested buffer strips between clear-cut areas and streams is to conserve these microclimatic conditions. We used an experimental study set up of 35 streamside sites to study the impacts of buffer strip width (15 or 30 m) and selective logging within the buffer strips on summer-time air temperature, relative air humidity and canopy openness 12 years after logging. The buffer strip treatments were compared to unlogged control sites. We found that 15-meter buffer strips with or without selective logging and 30-meter buffer strips with selective logging were insufficient in maintaining temperature, relative humidity and canopy openness at similar levels than they were in control sites. In contrast, 30-meter buffer strips differed only little from control sites, although they did have significantly lower mean air humidity. Microclimatic changes were increased by southern or southwestern aspect of the clear-cut, and by logging on the opposite side of the stream. We also tested how the cover of three indicator mosses (Hylocomium splendens, Pseudobqum cinclidioides and Polytrichum commune) had changed (from pre-logging to 12 years post-logging) in relation to post-logging air temperature, relative air humidity and canopy openness. We found that each of the species responded to at least one of these physical conditions. Air humidity was the most significant variable for explaining changes in the cover of the indicator moss species, suggesting that the changes in this microclimatic component has biological impacts. We conclude that to preserve riparian microclimatic conditions and species dependent on those, buffer strips should exceed 30 m in width, and not be selectively logged. Wider buffer strips are required if the clear-cut is towards south or southwest, or if the two sides of the stream are logged at the same time or during subsequent years.
  • Janatuinen, Miia (Helsingin yliopisto, 2021)
    The electricity sector plays a central role in climate change mitigation and adaptation policies. At the same time, it is also affected by the climate. The ongoing clean energy transition has made the link between electricity sector and weather even stronger since the increasing intermittent renewable energy production is increasingly weather dependent and cannot respond to abrupt changes in demand. Therefore, understanding how the electricity demand reacts to the changes in the climate is crucial for designing policies that support sustainable transition to the net zero economy. The thesis sheds light on these challenges and studies the effects of temperature on the intra-day electricity load in four European countries, Finland, Germany, France and Spain. The research questions are how temperature affects the hourly electricity consumption and whether these effects are different at different hours of the day. The sample consists of data on aggregate hourly electricity load and hourly population weighted temperatures over a period of over 10 years. The hour-specific effects of temperature on electricity load are estimated with a linear regression model of high-frequency fixed effects that allows credible identification of the short-run effects. However, the approach can not address the role of changing behavioural, economic or technological factors which are left for future work. The effects are estimated for each country separately, which also allows to capture the heterogeneity between countries. The results confirm the finding in the previous literature of the non-linear relationship between temperature and electricity load. In particular, electricity load is estimated to be more sensitive to temperature at the extreme temperatures and a comfort zone at which the electricity consumption is estimated to be insensitive to changes in temperatures is found for all countries. However, in Finland and France, the temperature effects are more pronounced at the cold temperatures, whereas in Germany and Spain, the effects are more symmetric. Moreover, in France, Germany and Spain, a comfort zone is estimated to be at colder temperatures in the morning and to shift to warmer temperatures in the afternoon. This implies that, at temperatures approximately between 10℃ and 20℃, heating is more sensitive to changes in temperature at the afternoon hours whereas cooling is more sensitive to changes in temperature at the early morning hours in the three countries. In Finland, the effects of temperature are relatively constant between hours. In conclusion, the results imply that temperatures contribute to the changing dynamics in the electricity sector, affecting both the intra-day variability and the level of the electricity consumption. However, the role of temperatures in these dynamics is relatively moderate.
  • Huang, Wenfeng; Zhang, Jinrong; Leppäranta, Matti; Li, Zhijun; Cheng, Bin; Lin, Zhanju (2019)
    A large number of lakes and ponds are unevenly distributed over the Qinghai-Tibet Plateau (QTP). Little is known about their ice processes and thermal regimes. Seasonal ice mass balance, thermal regime and stratification of under-ice water were investigated in a shallow thermokarst lake in central QTP using in situ observations and global reanalysis data. Congelation ice grew to 60–70 cm depth while continuous surface sublimation caused a total ice loss of over 30 cm. The bulk lake temperature below ice remained above 3.0 °C through the ice freezing period and rose gradually up to 7–9 °C during the melting period. The vertical thermal structure of under-ice water consisted of a stable strongly stratified interfacial layer (IL) and an underlying convective layer reaching the lake bottom. A warm layer existed just beneath the IL since the middle equilibrium period and increased in thickness and temperature. There was seasonal variation of IL depth and temperature gradient in response to the ice thermodynamics and atmospheric conditions. The calculated daily water-ice heat flux (Fw) was of 10 W m–2 magnitude. Seasonal variation of Fw manifested both diffusive and convective heat transport to the ice-water interface. This study suggests that strong penetration of solar radiative flux is the dominant contributor to high Fw, which results in a relatively thin ice compared with other equivalent high-latitude climate.
  • Guan, Yanlong; Lu, Hongwei; Yin, Chuang; Xue, Yuxuan; Jiang, Yelin; Kang, Yu; He, Li; Heiskanen, Janne (2020)
    Extensive research has focused on the response of vegetation to climate change, including potential mechanisms and resulting impacts. Although many studies have explored the relationship between vegetation and climate change in China, research on spatiotemporal distribution changes of climate regimes using natural vegetation as an indicator is still lacking. Further, limited information is available on the response of vegetation to shifts in China's regional climatic zones. In this study, we applied Mann-Kendall, and correlation analysis to examine the variabilities in temperature, precipitation, surface soil water, normalised difference vegetation index (NDVI), and albedo in China from 1982 to 2012. Our results indicate significant shifts in the distribution of Koppen-Geiger climate classes in China from 12.08% to 18.98% between 1983 and 2012 at a significance level of 0.05 (MK). The percentage areas in the arid and continental zones expanded at a rate of 0.004%/y and 0.12%/y, respectively, while the percentage area in the temperate and alpine zones decreased by -0.05%/y and - 0.07%/y. Sensitivity fitting results between simulated and observed changes identified temperature to be a dominant control on the dynamics of temperate (r(2)= 0.98) and alpine (r(2)= 0.968) zones, while precipitation was the dominant control on the changes of arid (r(2) = 0.856) and continental (r(2) = 0.815) zones. The response of the NDVI to albedo infers a more pronounced radiative response in temperate (r = -0.82, p