Freeze Dates Research Articles

P-270 Analysis of patient response rates to automated cryomanagement platform communications by length of cryostorage and tissue type

Abstract Study question Does the length of storage time of cryopreserved samples impact patient response rate and is this influenced by the tissue type stored. Summary answer Patient response rates decline as storage time increases. The decline is faster and higher with sperm and testicular tissue, compared to oocytes and embryos What is known already Clinics are experiencing increasing inventories of cryopreserved samples. While clinics provide storage consents and contracts, an increasing issue has emerged of abandoned/unclaimed samples, even with provision of multiple disposition options. Cryomanagement is labour intensive, both in terms of physical and administrative maintenance, the latter further increasing when communication and payment from the patient inadvertently or deliberately ceases. Full cryomanagement automation including patient billing, education and engagement with disposition decisions reduces the workload for the embryologist and increases consistency. It may also provide data insights allowing clinics to identify issues and implement strategies to improve patient engagement Study design, size, duration Data were retrospectively analysed from an automated cryomanagement platform. In total, 418,895 patient accounts from 122 clinics based in the USA over the period 2015 to 2024 Participants/materials, setting, methods Data was extracted from the automated cryomanagement platform database - a live feed of clinic information – and encrypted. Logic was created to develop calculations utilising the coding language, Structured Query Language (SQL). Revenue collected was compared with collectable charges to generate the collection/response rate. Data was analysed by collection rate by tissue type to identify trends and differences Main results and the role of chance An inverse relationship was identified between storage duration and response rates. Collection rates fell from 97.44% to 68.44% in relation to oocytes, 94.87% to 45.08% for embryos, 87.01% to 29.41% for sperm, and 95.67% to 29.75% for testicular tissue. Patients with stored oocytes are least likely to abandon cryopreserved samples, with 68.44% of storage payments continuing to be received beyond 14yrs. Patients with stored sperm or testicular tissue are the most likely to abandon cryopreserved samples. Collection rates fall below 50% at 6-8yrs and 10-12yrs respectively, and beyond 14yrs storage have fallen to 29.41% and 29.75% Limitations, reasons for caution The storage duration does not necessarily reflect the duration of patient interaction with the automated cryomanagement platform, where freeze date preceeded platform implementation. Further research is necessary to identify if patients exclusively interacting with the platform from freeze date have altered response rates Wider implications of the findings Data held by automated cryomanagement systems allows accurate review and analysis of cryostorage and cryomanagement metrics. Mined data could be used to develop policies based on real-life data. Including patient treatment information and patient engagement with the system from freeze date may help identify and address reasons for abandonment Trial registration number Not Applicable

P-502 Mosaic embryos result in equivalent live birth rates when compared to euploid embryos following frozen embryo transfer

Abstract Study question Are mosaic embryos associated with a lower live birth rate (LBR) than euploid embryos? Summary answer In this adequately powered study, mosaic embryos had nearly identical LBR and similar miscarriage rates (MR) when compared to euploid embryos. What is known already While prior data has suggested that mosaic embryos result in almost half the LBR and three-fold higher MR than euploid embryos, all prior data supports mosaic embryo transfers as safe with acceptable LBRs. Recent studies have suggested a revised selection criteria choosing either euploid or mosaic embryos for transfer based on embryo grade, day of freeze, low level (LL) versus high level (HL) mosaicism and segmental versus whole chromosome mosaicism. Given the lower LBR reported with mosaics, we initially offered double embryo transfer (DET). We initiated this study to assess our LBR, MR, aneuploidy and DET outcomes with mosaics. Study design, size, duration This was a retrospective case-control cohort study. All mosaic embryos (51) that underwent frozen embryo transfer (FET) between January 2020 and June 2023 were compared to all euploid embryos (706) among all patients with tested embryos that underwent FET in the same time frame. Our Power analysis confirmed that with the 14:1 ratio of 706/51 euploid/mosaic embryos this study is sufficiently powered to exclude a > 20% lower LBR following mosaic transfer. Participants/materials, setting, methods All patients seen at our IVF center undergoing FET of mosaic or euploid embryos tested with next generation sequencing during the study period were included. Primary outcome was LBR. Further comparison included age, MR, twin rate, freeze day and grade. Embryos were further analyzed for HL versus LL mosaicism, segmental or whole chromosomal mosaicism, freeze date and grade. Statistics employed chi-squared for categorical and student t-test for continuous data with significance set at p < 0.01 Main results and the role of chance Mosaic embryos resulted in nearly identical LBR when compared to euploid embryos, 26/51(50.9%) versus 359/706(50.85%). Implantation rate was also equivalent, 29/51(54.6%) and 376/706(53.3%). Both biochemical pregnancy [mosaics, 8/45(17.8%) versus euploid 127/683(18.6)], and MR [mosaics 3/29(10.3%) versus euploids 24/373(6.4%)] were not significantly different. Among mosaic embryos, the LBR in LL versus HL mosaics were 17/28 (60.7%) and 9/23 (39.1%), respectively. LBR following segmental only versus whole chromosomal defects were 14/27(51.9%) and 11/24(45.8%). LBR following Day 5 versus Day 6/7 freeze were 10/22(45.5%) and 16/29(55.2%) and LBR for favorably graded embryos were 19/34(55.9%) versus fair to poor graded 7/17(41.2%). None of these achieved statistical significance. While Mosaic embryos were transferred in significantly older patients (37.6 vs 36.1 p < 0.01), there was no difference in mean age associated with LBR (36.1 vs 36.3 p =.4). Additionally, there was no statistically significant difference in LBR between age groups, <35yo 143/259(55.2%), 35-37yo 96/202(47.5%), 38-40yo 96/207(46.4%) or > 40yo 50/90(55.6%) among tested embryos. DET was performed more often with mosaic 19/45 (42.2%) than euploid embryos 36/683 (5.3%) p < 0.001, resulting in significantly higher twin births/LB 5/22 (23.8%) versus 6/356 (1.7%) p < 0.001. All DET data sets included the 13 DETs where one euploid and one mosaic embryo were transferred. Limitations, reasons for caution Our small mosaic numbers may have kept the higher LBR with LL, segmental and good quality mosaic embryos from achieving statistical significance, and may be too small to confirm a higher MR with mosaics. Prospective trials are needed to confirm which euploid or mosaic embryo should be selected for transfer. Wider implications of the findings Given the equivalent LBR, mosaic embryos should be used for transfer prior to repeating IVF retrieval for euploids. The high rate of twin delivery following mosaic DET suggests only eSET should be utilized with any tested embryos. Larger prospective trials are needed to further refine euploid versus mosaic embryo selection criteria. Trial registration number not applicable

Influence of snowpack on soil organic carbon decomposition in a northern peatland

Peatlands play a significant role in maintaining the carbon balance and regulating the climate. The turnover of soil organic carbon (SOC) in peatlands is mediated by snowpack, which affects microbial decomposition through its regulation of hydrothermal conditions. However, the impact of snowpack on carbon dynamics in peatlands is not fully understood, particularly in the context of decline in snowpack due to climate warming. To address this issue, an on-site experiment was conducted involving snowpack manipulation (undisturbed and snow removal) to investigate the effects of snowpack on SOC decomposition at depths of 0–30 cm (topsoil) and 30–60 cm (subsoil). Various techniques such as X-ray absorption near-edge structure, synchrotron radiation micro computed tomography technology and microbial metagenomics were utilized to measure SOC content and fractions, pore structure and bacterial community’s structure and function. Results showed that snow removal delayed the start of soil freezing date by 27 days and advanced the start of thawing date by 39 days, increased maximum freezing depth by 27.9 cm and frequency of freeze–thaw cycles, and decreased average temperature of topsoil and subsoil by 1.48 °C and 1.34 °C, respectively. Additionally, snow removal increased SOC content by 8.27 % and 3.19 % and its stability by 53 % and 13.92 % in the topsoil and subsoil, respectively, and decreased microbial decomposition potential functioning by 55.89 % and 5.75 % in both soil layers. The three-dimensional spatial distribution of SOC and soil pores at the micro-scale indicated that snow removal significantly influenced pore structure and microbe feedback loops, thereby affecting SOC decomposition. Notably, snow removal led to an increase in the proportion of micropores by 3.44 % and 4.41 % in the topsoil and subsoil, respectively, suggesting enhanced protection of pore structure and preservation of SOC during decomposition processes. Overall, the findings suggest that snow removal may intensify the response of carbon pools to climate change in peatlands.

Changes in global land surface frozen ground and freeze‒thaw processes during 1950–2020 based on ERA5-Land data

Frozen ground (FG) plays an important role in global and regional climates and environments through changes in land freeze‒thaw processes, which have been conducted mainly in different regions. However, the changes in land surface freeze‒thaw processes under climate change on a global scale are still unclear. Based on ERA5-Land hourly land skin temperature data, this study evaluated changes in the global FG area, global land surface first freeze date (FFD), last freeze date (LFD) and frost-free period (FFP) from 1950 to 2020. The results show that the current FG areas (1991–2020 mean) in the Northern Hemisphere (NH), Southern Hemisphere (SH), and globe are 68.50 × 106, 9.03 × 106, and 77.53 × 106 km2, which account for 72.4%, 26.8%, and 60.4% of the exposed land (excluding glaciers, ice sheets, and water bodies) in the NH, SH and the globe, respectively; further, relative to 1951–1980, the FG area decreased by 1.9%, 8.8%, and 2.8%, respectively. Seasonally FG at lower latitudes degrades to intermittently FG, and intermittently FG degrades to non-frozen ground, which caused the global FG boundary to retreat to higher latitudes from 1950 to 2020. The annual FG areas in the NH, SH, and globe all show significant decreasing trends (p < 0.05) from 1950 to 2020 at −0.32 × 106, −0.22 × 106, and −0.54 × 106 km2 per decade, respectively. The FFP prolongation in the NH is mainly influenced by LFD advance, while in the SH it is mainly controlled by FFD delay. The prolongation trend of FFP in the NH (1.34 d per decade) is larger than that in the SH (1.15 d per decade).

Projecting the effect of climate change on planting date and cultivar choice for South African dryland maize production

The anticipated climate change in South Africa is of great concern as Southern Africa appears to be warming at twice that of the global average, limiting maize production in the country and threatening food security in the region. The formulation of effective adaptation measures calls for understanding how projected changes in temperature, precipitation, and climate extremes might become misaligned with the critical maize developmental stages, which are likely to impact crop development. We conducted an analysis of the climate change impacts for dryland maize phenology in Bloemfontein and Lichtenburg, which represent major maize growing regions of South Africa. The climate projections generated by six Global Climate Models under the Representative Concentration Pathways (RCP) 4.5 and 8.5 were used. Analyses were performed for four representative planting dates: November 15 (early), December 15 (optimal), January 15 (late), and February 5 (very late). Days to maturity decreased (by approx. 5-10 days) as years progressed from baseline period (1991-2020) to the far future period (2051-2080), at both locations with higher rates projected under RCP 8.5. The results suggest a longer summer season with receding freeze dates in these regions and might provide additional flexibility for adaptive strategies. At the optimal planting dates, future climate will likely affect both vegetative and reproductive stages of maize leading to the decrease in the days to maturity. A major factor affecting maize productivity is extreme temperature, with the number of days above 35 °C expected to increase 20–30% at the optimal planting date as climate changes progresses, which will likely limit grain filling and yield. Exploring maize phenology in the future at later planting dates revealed a decrease in days to maturity trending towards the optimal number of days required for each cultivar (100–110 days) in both regions. This coupled with the projected receding freeze date at these planting dates under future climates suggests there may be opportunities to shift planting to later dates in the region.

Lake Heatwaves and Cold‐Spells Across Qinghai‐Tibet Plateau Under Climate Change

AbstractLake heatwaves (LHWs) and cold‐spells (LCSs), similar to marine heatwaves and cold‐spells, can have long‐term impacts on lake ecosystems and are vulnerable to climate change. Here we first comparatively assess LHW and LCS changes across the Qinghai‐Tibet Plateau (QTP) using satellite surface water temperature observations in 160 lakes over 1978–2017. Our findings reveal notable differences in the mean and trends of LHW and LCS metrics. Specifically, total days and frequency of LHW have been increasing at a rate of 8.82 ± 1.25 days per decade and 0.78 ± 0.10 counts per decade, respectively. Conversely, total days and frequency of LCS have decreased at −6.52 ± 1.46 days per decade and −0.51 ± 0.01 counts per decade, respectively. However, average duration and mean intensity show no significant difference. Additionally, the average duration of ice cover across the QTP has been decreasing (−2.60 ± 0.38 days per decade) due to the delayed freezing date (1.13 ± 0.18 days per decade) and earlier thawing date (−1.28 ± 0.27 days per decade) during 1978–2017. Furthermore, the annual mean lake surface water temperatures across the QTP exhibit a warming trend (0.00 ∼ 0.47°C per decade) from 1978 to 2017, with faster warming occurring in winter (0.00 ∼ 0.98°C per decade) compared to summer (−0.17 ∼ 0.47°C per decade). Accelerated lake warming will increase the frequency and mean intensity of LHWs while decreasing the number of LCSs. These results help to understand how QTP lakes respond to extreme temperatures under climate change.

Characterization of Oncology Clinical Trials Using Germline Genetic Data

The recent successes of poly-ADP ribose polymerase (PARP) inhibitors and belzutifan support germline genetic data as an exciting, accessible source for biomarkers in cancer treatment. This study hypothesizes, however, that most oncology clinical trials using germline data largely prioritize BRCA1/2 as biomarkers and PARP inhibitors as therapy. To characterize past and ongoing oncology trials that use germline data. This retrospective cross-sectional study of oncology trials used the Informa Trialtrove database to evaluate trial attributes. Trials using germline information (including the terms germline, hereditary, or inherited in the title, treatment plan, interventions, end points, objectives, results, or notes) and conducted globally between December 1, 1990, and April 4, 2022 (data freeze date), were included. Trials by cancer type, phase, participants, sponsor type, end points, outcomes, and locations were described. Associated biomarkers and mechanisms of action for studied therapeutic interventions were counted. How germline data in trial inclusion and exclusion criteria are associated with end points, outcomes, and enrollment were also examined. A total of 887 of 84 297 (1.1%) oncology clinical trials in the Trialtrove database that use germline data were identified. Most trials were conducted in cancer types where PARP inhibitors are already approved. A total of 74.8% (672) of trials were performed in the phase 2 setting or above. Trials were primarily sponsored by industry (523 trials [59.0%]), academia (382 trials [43.1%]), and the government (274 trials [30.9%]), where trials may have multiple sponsor types. Among 343 trials using germline data with outcomes in Trialtrove, 180 (52.5%) reported meeting primary end points. Although BRCA1/2 are the most frequent biomarkers seen (BRCA1, 224 trials [25.3%]; BRCA2, 228 trials [25.7%]), trials also examine pharmacogenomic variants and germline mediators of somatic biomarkers. PARP inhibitors or immunotherapy were tested in 69.9% of trials; PARP inhibition was the most frequently studied mechanism (367 trials [41.4%]). An overwhelming number of trials using germline data were conducted in the US, Canada, and Europe vs other countries, mirroring disparities in cancer genetics data. Germline data in inclusion and exclusion criteria are associated with altered end point, outcomes, and enrollment compared with oncology trials with no germline data use. Examples of inclusion and exclusion criteria regarding germline data that may unintentionally exclude patients were identified. These findings suggest that for germline biomarkers to gain clinical relevance, trials must expand biomarkers, therapies, and populations under study.

Climate warming shortens ice durations and alters freeze and break-up patterns in Swedish water bodies

Abstract. Increasing air temperatures reduce the duration of ice cover on lakes and rivers, threatening to alter their water quality, ecology, biodiversity, and physical, economical and recreational function. Using a unique in situ record of freeze and break-up dates, including records dating back to the beginning of the 18th century, we analyze changes in ice duration (i.e., first freeze to last break-up), freeze and break-up patterns across Sweden. Results indicate a significant trend in shorter ice duration (62 %), later freeze (36 %) and earlier break-up (58 %) dates from 1913–2014. In the latter 3 decades (1985–2014), the mean observed ice durations have decreased by about 11 d in northern (above 60∘ N) and 28 d in southern Sweden relative to the earlier three decades. In the same period, the average freeze date occurred about 10 d later and break-up date about 17 d earlier in southern Sweden. The rate of change is roughly twice as large in southern Sweden as in the northern part. Sweden has experienced an increase in occurrence of years with an extremely short ice cover duration (i.e., less than 50 d), which occurred about 8 times more often in southern Sweden than previously observed. Our analysis indicates that even a 1 ∘C increase in air temperatures in southern (northern) Sweden results in a mean decrease of ice duration of 22.5 (±7.6) d. Given that warming is expected to continue across Sweden during the 21st century, we expect increasingly significant impacts on ice cover duration and hence, ecology, water quality, transportation, and recreational activities in the region.

A decade of cold Eurasian winters reconstructed for the early 19th century

Annual-to-decadal variability in northern midlatitude temperature is dominated by the cold season. However, climate field reconstructions are often based on tree rings that represent the growing season. Here we present cold-season (October-to-May average) temperature field reconstructions for the northern midlatitudes, 1701-1905, based on extensive phenological data (freezing and thawing dates of rivers, plant observations). Northern midlatitude land temperatures exceeded the variability range of the 18th and 19th centuries by the 1940s, to which recent warming has added another 1.5 °C. A sequences of cold winters 1808/9-1815/6 can be explained by two volcanic eruptions and unusual atmospheric flow. Weak southwesterlies over Western Europe in early winter caused low Eurasian temperatures, which persisted into spring even though the flow pattern did not. Twentieth century data and model simulations confirm this persistence and point to increased snow cover as a cause, consistent with sparse information on Eurasian snow in the early 19th century.

Thermal regime variations of the uppermost soil layer in the central Tibetan Plateau

Permafrost degradation related to global warming has been widespread in the Tibetan Plateau (TP), manifesting prominently as variations in the soil thermal regime, an essential characteristic of permafrost. Altered soil thermal conditions can influence the energy and water balance between the atmosphere and land, leading to the release of stored carbon dioxide and methane. In this study, reanalysis and observed soil temperature data were combined to analyse the long-term changes in the thermal regime of the uppermost soil layer at six sites in the central TP. MERRA2 and ERA5-Land had the highest quality in matching the observed data at each site. The mean annual soil temperature ranged from −0.11 °C to 4.75 °C (averaging 1.73 °C) and warms at 0.059°Ca-1. The mean annual first dates of freezing and thawing and the mean duration of freezing were 123.23 ± 10.85 d, 285.67 ± 10.34 d, and 161.44 ± 20.54 d, respectively, indicating lagged, advanced, and shortened trends with 0.54 ± 0.49 da-1, 0.50 ± 1.06 da-1, and 1.05 ± 1.16 da-1, respectively. The mean annual freezing and thawing N-factors were 0.53 ± 0.13 and 2.43 ± 2.09, respectively. The maximum and minimum monthly average soil temperatures were 11.81 ± 2.17 °C in July and −9.54 ± 3.24 °C in January, respectively. Partial correlation analysis was used to quantify the influences of factors (including surface air temperature, snow depth, rainfall, normalised difference vegetation index [NDVI], shortwave radiation, and soil moisture) on soil temperature implicated surface air temperature as the most significant influencing factor in the increased soil temperature. Rainfall and NDVI were implicated as being likely to suppress the soil temperature warming. This study provides detailed information about the thermal regime of the uppermost soil in the central TP and facilitates validation of the land surface model.

Spatiotemporal characteristics of the soil freeze-thaw state and its variation under different land use types - A case study in Northeast China

With global warming, the soil freeze-thaw state has greatly changed, which has profoundly impacted the balance between water resources, ecological security and regional agriculture and forestry production in frozen regions. Based on daily soil freezing/thawing depth data in Heilongjiang Province over the last 60 years, Mann-Kendall trend analysis, Sen's slope and Hurst exponent were performed to analyze the spatiotemporal characteristics of the soil freeze-thaw state, and the effects of nonclimatic factors "land use types" and snow cover on the change in the soil freeze-thaw state were discussed. The results indicated that (1) the soil freeze-thaw state significantly changed over the past 60 years. The maximum seasonally frozen depth decreased approximately by 48 cm, the first freezing date was delayed by approximately 10 d, the first thawing date and last date advanced approximately by 6 and 27 d, respectively, the freezing and thawing periods decreased by approximately 17 and 21 d, respectively, and the duration and actual number of freezing days decreased by 38 and 34 d, respectively. (2) The soil freeze-thaw state changed abruptly in 1988 and exhibited a significant trend after the 1990s. The Hurst exponent of the soil freeze-thaw state variables at approximately 2/3 of the stations reached the strong persistence level. (3) In forestland and grassland areas, vegetation coverage reduced the climate warming impact on the soil freeze-thaw state. In addition, the maximum snow depth was significantly correlated with the soil freezing depth and first thawing date, and the change in snow depth also offset the effects of temperature rise on soil freezing depth and first thawing date to a certain extent. Changes in the soil freeze-thaw state have both advantages and disadvantages on agricultural production. Therefore, it is necessary to strengthen agricultural monitoring and use territorial knowledge to reasonably regulate agricultural production.

Land cover composition, climate, and topography drive land surface phenology in a recently burned landscape: An application of machine learning in phenological modeling

Land surface phenology (LSP) characterizes the seasonal dynamics of vegetation communities that compose individual satellite pixels and its interannual and spatial variations have been widely associated with climate. However, increasing evidence shows an effect of land cover composition within a pixel on LSP, but it remains unclear the extent of impacts relative to other drivers. To fill this gap, this study quantitatively assessed the contributions of land cover composition, climate, and topography on the spatial and interannual variation in LSP throughout the 2002 Ponil Complex Fire in New Mexico, USA, using a machine learning approach of Boosted Regression Trees (BRT). As the fire mainly converted ponderosa pine and Douglas-fir (evergreen tree) to soil ground and Gambel Oak (deciduous shrub), we computed both the proportion of tree cover to all vegetation cover (PTV) and vegetation fractional cover (VFC) as the metrics of land cover composition from high-resolution images in 2018 and from MODIS growing season greenness from 2001-2018. Start (SOS) and end (EOS) of growing season were derived from 500-m MODIS data from 2001-2018 and 30-m Harmonized Landsat Sentinel-2 data in 2018. BRT models showed that PTV was the most important predictor of spatial variations in SOS and EOS in 2018, despite the different contributions (20.3% - 42.9%) at 30-m and 500-m spatial scales. Although the growing degree days (28.6%) and the first freeze date (19.6%) were the most important predictors of interannual variations in SOS and EOS from 2001-2018, respectively, VFC also presented an important contribution for SOS (8.4%) and EOS (12.2%). This study demonstrates the utility of machine learning in modeling phenology and highlights the essential role of land cover composition in understanding the spatial and interannual variations of LSP that have been widely associated with topography and climate.

An indicator of freeze-kill damages to fruit trees during flowering.

This paper demonstrates the use of climatological data and published information to develop a thaw-freeze/freeze-kill indicator for fruit trees during flowering. In fruit-producing regions, when budding and flowering occur before the last spring freeze, a freeze-kill event can cause substantial losses. As spring onset is occurring earlier with climate change, thaw-freeze events have the potential to become more of a hazard both in terms of current production and in terms of potential adaptation strategies. To model the spring thaw-freeze and its magnitude or intensity, we proposed an indicator based on the accumulation of daily minimum temperature between successive freezing dates and its maximum value over the spring. This indicator was tested on apple and peach production in southern Ontario, Canada, using data from eight climate stations in southern Ontario. The indicator showed promise in its utility in that its magnitude was greater when freezing occurred after blooming and it was demonstrated to be correlated to the estimated blooming dates of apple and peach fruits grown in southern Ontario. The annual series was shown to fit the generalized extreme value distribution thereby allowing the extreme risk to be modelled and the return period to be calculated. It was also shown that the reported thaw-freeze events that caused significant apple and peach losses had a return period on the order of 10 years.

Seasonality of biological and physical systems as indicators of climatic variation and change

Evidence-based responses to climate change by society require operational and sustained information including biophysical indicator systems that provide up-to-date measures of trends and patterns against historical baselines. Two key components linking anthropogenic climate change to impacts on socio-ecological systems are the periodic inter- and intra-annual variations in physical climate systems (seasonality) and in plant and animal life cycles (phenology). We describe a set of national indicators that reflect sub-seasonal to seasonal drivers and responses of terrestrial physical and biological systems to climate change and variability at the national scale. Proposed indicators and metrics include seasonality of surface climate conditions (e.g., frost and freeze dates and durations), seasonality of freeze/thaw in freshwater systems (e.g., timing of stream runoff and durations of lake/river ice), seasonality in ecosystem disturbances (e.g., wildfire season timing and duration), seasonality in vegetated land surfaces (e.g., green-up and brown-down of landscapes), and seasonality of organismal life-history stages (e.g., timings of bird migration). Recommended indicators have strong linkages to variable and changing climates, include abiotic and biotic responses and feedback mechanisms, and are sufficiently simple to facilitate communication to broad audiences and stakeholders interested in understanding and adapting to climate change.

The genesis of ideas about ice phenomena: from the first fixations to the beginning of the XVIII century

The study of ice events on rivers is of great importance, especially in our country where some rivers are covered by ice for months. The needs of shipping, the construction and operation of hydraulic structures, the study of channel deformations caused by ice phenomena and other purposes require knowledge of the ice regime of the rivers. The article explores the beginning of visual observations of ice phenomena and their consequences on the rivers of Russia in the XI-XVII centuries. The study is based on numerous annalistic sources describing the passage of high water, floods, and also indicate the dates of opening and freezing of rivers. It also analyzes notes of foreigners travelling throughout Russia in the 15th - early 18th centuries. The authors separately examined the observation of the passage of spring floods on the Moscow River in the second half of the 17th century.

Spatiotemporal characteristics of hydrothermal processes of the active layer on the central and northern Qinghai–Tibet plateau

The spatial and temporal variations of the seasonal freeze–thaw cycles are important in understanding the ecological and hydrological processes and biogeochemical cycle associated with permafrost degradation caused by climate change, although observational data on the soil hydrothermal dynamics within the active layer of the permafrost region at the central and northern Qinghai–Tibet Plateau (QTP) are extremely scarce. In this study, soil temperature and moisture date from 11 observational sites along the Qinghai–Tibet Highway from 2010 to 2014 were used to analyze the freeze-thaw cycles of the active layer. The results revealed that mean annual ground surface temperature (MAGST) and mean annual temperature at the top of permafrost (TTOP) were the most closely related to the onset dates of soil freezing and thawing. The onset dates of soil freezing from bottom to top did not occur earlier than those from top to bottom. The differences between the onset dates of the two freezing directions and the proportion of bottom-up freezing depth increased with decreasing TTOP. The unfrozen water content of the cooling process was always higher than that of the warming process during the freezing stage. The hysteresis effect of the unfrozen water content could also be observed in the field experiment, and the maximum hysteresis levels occurred at their corresponding soil freezing points. Soil organic matter and soil moisture associated with vegetation cover are essential for water-heat exchanges between atmosphere and permafrost beneath active layer. We suggest that a better protected plant ecosystem, helps preserving the underlying permafrost on the Qinghai–Tibet Plateau.

FALL AVAILABLE TROPICAL MILKWEED (ASCLEPIAS CURASSAVICA L.) MAY BE A POPULATION SINK FOR THE MONARCH BUTTERFLY

Native plants provide the best habitat for pollinators, but non-native plants can supply resources to native pollinators. The non-native tropical milkweed (bloodflower or scarlet milkweed), Asclepias curassavica L., is a larval food source for the native monarch butterfly (Danaus plexippus). Asclepias curassavica has been widely planted in the southern U.S. where it blooms until late fall, retains healthy vegetation until frost, and does not die back until a hard freeze. In contrast, native Asclepias species senesce and are usually not suitable for monarch larvae consumption in the fall. The late availability of the non-native milkweed may trigger monarchs, normally migrating to Mexico, to break reproductive diapause and lay eggs on their host plant. To determine if non-native A. curassavica was more likely than native Asclepias species to attract egg-laying monarchs, we grew native Asclepias viridis Walter and Asclepias speciosa Torr. along with A. curassavica in Oklahoma and recorded the number of monarch eggs and caterpillars on each plant. From August 2019 until the first freeze, we observed 145 eggs and 39 caterpillars on 40 of 48 A. curassavica plants and one egg on one of 19 native Asclepias plants. First freeze occurred on 12 October. A majority of eggs were laid after 12 September resulting in most eggs having insufficient time to mature. This freeze date was nearly 3 weeks earlier than the average for this area. Our evidence suggests that the monarchs are differentially reacting to the availability of non-native and native Asclepias during late summer and fall.

Changes in growing season in the Northeastern United States

ABSTRACT Changes in growing season length (GSL) are of concern for agricultural, phenological, economic, epidemiological, and bioclimatological reasons. This research identifies spatial and temporal changes over the last several decades in GSL, along with the day-of-year of the last spring freeze and first autumn freeze, for the northeastern United States – a region particularly susceptible to such changes due to the large population and intense economic activities. Results suggest that growing season has significantly increased in length since 1980 as compared to prior to 1980, and both spatial and temporal variation in GSL has decreased for the region over time. Changes to GSL for this region are driven more by a shift in the first autumn freeze date than the last spring freeze date. The areas of greatest increase in GSL in the pre- vs. post-1980 period tend to be in the high elevations, near large water bodies, and near the largest cities. Results will assist environmental planners as they prepare mitigation and adaptation strategies amid a changing environment.

Водный и ледовый режим реки Майма в условиях современных изменений климата (Горный Алтай)

The paper considers changes in the annual and seasonal runoff, as well as the ice regime of the Mayma River in response to changing climatic conditions in the catchment area during the period of 1940–2016. Significant positive trends, especially occurring during the winter months, have been identified in the long-term course of annual and seasonal air temperatures. A significant decrease in precipitation rate is observed in the cold period of the year. According to the analysis of the hydrological characteristics for the periods of 1940–1975 (the background period) and of 1976–2016 (the period of contemporary climate change), the annual runoff for the Mayma River basin shows a downward trend against the background of the observed climatic changes. The decrease in annual flow is the result of a decrease in the flood flow. Thus, with the observed winter warming and a decrease in the amount of solid precipitation, the average maximum discharge for the wettest month (April) decreased by 35 % in the period of 1976–2016 with respect to the background level of the 1940–1976 period. Winter warming contributes to less soil freezing and replenishment of groundwater during periods of winter thaw and intensive snowmelt, which lead to an increase in runoff in the last winter months and the first months of summer-autumn low-flow periods. Winter warming manifested itself in the ice mode of the river Mayma. Since the beginning of the period of the current climate change (1976) there has been an observed decrease in the duration of ice freeze-up and a shift towards later freezing dates and earlier break-up dates.

Long-term phenoclimatic averages of the Yuganskiy Nature Reserve territory and changes for 1961-2016

In light of the observed global climate changes in recent decades, we studied the local climate indicators and explored the possible links between the spring and autumn phenophases and climate data changes in the Yuganskiy nature reserve (N 600 17’; E74054’ – N590 23’; E74000’) in 1982-2016. The collected climate data include daily average, maximum and minimum temperatures, daily precipitation amount and intensity, and number of days with precipitation of 0.1mm or more, monthly average of snow depths, dates of first and last occurrence of daily mean temperatures 0, +5, +10°С through the year. Timing of sap movement and leaf fall start were used as the spring and autumn indicators of birch (Bétula péndula ) phenology. The mean value of weather averages in the 30-year period of 1961-1990 was used as reference. Trends were calculated using linear least squares regression. Statistical significance was determined by calculating the standard error of the trend estimate.&#x0D; We found that the annual mean temperature has increased from –1.9°С (1961-1990) to –0.8° С (1982-2016), with corroborating indicators including increased temperature of the coldest night of the year from –53°С (1961-1990) to –51.3° С (1982-2016) and increased frequency of significant positive temperature anomalies from 21% (1961-1990) to 37% (1982-2016). May, June, August and October nights have become successively warmer. The air temperature increase was not accompanied by a corresponding increase in precipitation.&#x0D; Statistically significant trends toward earlier onset of spring and summer from 1982 to 2016 were observed. The date of the last spring freeze has been advancing by 6.1 days per decade since 1982. A freeze-free season has lengthened by 7.7 days per decade. Linear trend of the snowmelt timing was –3.7 days per decade. Permanent snow cover period has been shortening by 7.7 days per decade. The date of the first occurrence of the daily mean temperatures of +10° С has been advancing by 5.1 days per decade. However, the 0 -+5° С lag has been lengthening significantly by 9.2 days per decade, and the number of biologically effective degree days (base +5C) has not statistically changed.&#x0D; Sap flux and leaf fall timing of B. pendula have been advancing almost simultaneously by 4.0 and 4.2 days per decade since 1985. Sap flux beginning and last spring freeze date have been found to be linearly correlated (r=0.904). The average lag of them was 5±1 days and has been lengthening by 3 days per decade (1985–2016).