Convective available potential energy (CAPE) is of strong interest in climate modeling because of its role in both severe weather and in model construction. Extreme levels of CAPE (>2000 J kg⁻¹) are ...associated with high-impact weather events, and CAPE is widely used in convective parameterizations to help determine the strength and timing of convection. However, to date few studies have systematically evaluated CAPE biases in models in a climatological context, and none have addressed bias in the high tail of CAPE distributions. This work compares CAPE distributions in ~200 000 summertime proximity soundings from four sources: the observational radiosonde network Integrated Global Radiosonde Archive (IGRA), 0.125° reanalyses (ERA-Interim and ERA5), and a 4-km convection-permitting regional WRF simulation driven by ERA-Interim. Both reanalyses and the WRF Model consistently show too-narrow distributions of CAPE, with the high tail (>90th percentile) systematically biased low by up to 10% in surface-based CAPE and even more in alternate CAPE definitions. This "missing tail" corresponds to the most impacts-relevant conditions. CAPE bias in all datasets is driven by surface temperature and humidity: reanalyses and the WRF Model underpredict observed cases of extreme heat and moisture. These results suggest that reducing inaccuracies in land surface and boundary layer models is critical for accurately reproducing CAPE.
Water scarcity is a global challenge, yet existing responses are failing to cope with current shocks and stressors, including those attributable to climate change. In sub-Saharan Africa, the impacts ...of water scarcity threaten livelihoods and wellbeing across the continent and are driving a broad range of adaptive responses. This paper describes trends of water scarcity for Africa and outlines climate impacts on key water-related sectors on food systems, cities, livelihoods and wellbeing, conflict and security, economies, and ecosystems. It then uses systematic review methods, including the Global Adaptation Mapping Initiative, to analyse 240 articles and identify adaptation characteristics of planned and autonomous responses to water scarcity across Africa. The most common impact drivers responded to are drought and participation variability. The most frequently identified actors responding to water scarcity include individuals or households (32%), local government (15%) and national government (15%), while the most common types of response are behavioural and cultural (30%), technological and infrastructural (27%), ecosystem-based (25%) and institutional (18%). Most planned responses target low-income communities (31%), women (20%), and indigenous communities (13%), but very few studies target migrants, ethnic minorities or those living with disabilities. There is a lack of coordination of planned adaptation at scale across all relevant sectors and regions, and lack of legal and institutional frameworks for their operation. Most responses to water scarcity are coping and autonomous responses that showed only minor adjustments to business-as-usual water practices, suggesting limited adaptation depth. Maladaptation is associated with one or more dimension of responses in almost 20% of articles. Coordinating institutional responses, carefully planned technologies, planning for projected climate risks including extension of climate services and increased climate change literacy, and integrating indigenous knowledge will help to address identified challenges of water scarcity towards more adaptive responses across Africa.
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•Climate-induced water scarcity is a widespread trend across Africa.•Systematic review of responses to water scarcity shows many deficiencies.•Planned adaptation lacks coordination at scale across key sectors and regions.•Most responses include only minor adjustments to business-as-usual water practices.•Improving institutional responses is key to adaptation to water scarcity.
Abstract Cattle farming is a major source of global food production and livelihoods that is being impacted by climate change. However, despite numerous studies reporting local-scale heat impacts, ...quantifying the global risk of heat stress to cattle from climate change remains challenging. We conducted a global synthesis of documented heat stress for cattle using 164 records to identify temperature-humidity conditions associated with decreased production and increased mortality, then projected how future greenhouse gas emissions and land-use decisions will limit or exacerbate heat stress, and mapped this globally. The median threshold for the onset of negative impacts on cattle was a temperature-humidity index of 68.8 (95% C.I.: 67.3–70.7). Currently, almost 80% of cattle globally are exposed to conditions exceeding this threshold for at least 30 days a year. For global warming above 4°C, heat stress of over 180 days per year emerges in temperate regions, and year-round heat stress expands across all tropical regions by 2100. Limiting global warming to 2°C, limits expansion of 180 days of heat stress to sub-tropical regions. In all scenarios, severity of heat stress increases most in tropical regions, reducing global milk yields. Future land-use decisions are an important driver of risk. Under a low environmental protection scenario (SSP3-RCP7.0), the greatest expansion of cattle farming is projected for tropical regions (especially Amazon, Congo Basin, and India), where heat stress is projected to increase the most. This would expose over 500 million more cattle in these regions to severe heat risk by 2090 compared to 2010. A less resource-intensive and higher environmental protection scenario (SSP1-RCP2.6) reduces heat risk for cattle by at least 50% in Asia, 63% in South America, and 84% in Africa. These results highlight how societal choices that expand cattle production in tropical forest regions are unsustainable, both worsening climate change and exposing hundreds of millions more cattle to large increases in severe, year-round heat stress.
Climate change affects global agricultural production and threatens food security. Faster phenological development of crops due to climate warming is one of the main drivers for potential future ...yield reductions. To counter the effect of faster maturity, adapted varieties would require more heat units to regain the previous growing period length. In this study, we investigate the effects of variety adaptation on global caloric production under four different future climate change scenarios for maize, rice, soybean, and wheat. Thereby, we empirically identify areas that could require new varieties and areas where variety adaptation could be achieved by shifting existing varieties into new regions. The study uses an ensemble of seven global gridded crop models and five CMIP6 climate models. We found that 39% (SSP5‐8.5) of global cropland could require new crop varieties to avoid yield loss from climate change by the end of the century. At low levels of warming (SSP1‐2.6), 85% of currently cultivated land can draw from existing varieties to shift within an agro‐ecological zone for adaptation. The assumptions on available varieties for adaptation have major impacts on the effectiveness of variety adaptation, which could more than half in SSP5‐8.5. The results highlight that region‐specific breeding efforts are required to allow for a successful adaptation to climate change.
Variety adaptation could potentially outweigh climate change induced production losses and increase global production by 19%. Therefore, new adapted crop varieties are required. In 2100, about 40% of global cropland could require new adapted crop varieties to avoid yield losses from climate change. However, under high level of warming, the risk increases that adapted crop varieties are not available, because regional temperatures could exceed temperature ranges of currently grown cultivars. Thus, regional breeding efforts are required to face the challenge.
Large population studies of immune system genes are essential for characterizing their role in diseases, including autoimmune conditions. Of key interest are a group of genes encoding the killer cell ...immunoglobulin-like receptors (KIRs), which have known and hypothesized roles in autoimmune diseases, resistance to viruses, reproductive conditions, and cancer. These genes are highly polymorphic, which makes typing expensive and time consuming. Consequently, despite their importance, KIRs have been little studied in large cohorts. Statistical imputation methods developed for other complex loci (e.g., human leukocyte antigen HLA) on the basis of SNP data provide an inexpensive high-throughput alternative to direct laboratory typing of these loci and have enabled important findings and insights for many diseases. We present KIR∗IMP, a method for imputation of KIR copy number. We show that KIR∗IMP is highly accurate and thus allows the study of KIRs in large cohorts and enables detailed investigation of the role of KIRs in human disease.
In young adults, blood flow restricted exercise (BFRE) at relatively low intensities can increase muscle strength as effectively as conventional high intensity training. Ischemic exercise can also ...increase collateral blood flow in skeletal muscle. However, the effects of chronic BFRE on muscle strength and blood flow in older adults remain unknown. The purpose of this study was to compare the effects of 4weeks of BFRE training on skeletal muscle strength and blood flow between young and older subjects and between older adults performing BFRE and conventional high intensity resistance exercise.
Maximum voluntary contraction (MVC), forearm girth, peak forearm blood flow (FBF) and forearm vascular conductance (FVC) were assessed before and after 4weeks of forearm resistance training with BFRE in older adults (O-BFRE, 63±1 y, n=9) and younger adults (Y-BFRE, 22±1 y, n=8) and with high intensity training at 75% maximum voluntary contraction in older adults (O-HI, 63±1 y, n=10).
MVC increased in all groups (O-BFRE, 33.4±4.7 to 36.3±4.7kg; Y-BFRE, 37.2±4.9 to 43.0±5.0kg; O-HI, 34.0±4.4 to 39.8±4.4kg; all p<0.05). Forearm girth increased in O-BFRE (26.3±1.1 to 26.7±1.1cm; p<0.05) and Y-BFRE (23.9±0.9 to 25.1±1.5cm; p<0.05) but not in O-HI (25.9±1.0 to 26.1±1.0cm; p=0.26). Peak forearm vascular conductance increased in Y-BFRE (0.190±0.016 to 0.311±0.031units; p=0.01) but not in O-BFRE (0.157±0.024 to 0.193±0.029units; p=0.48) and O-HI (0.188±0.035 to 0.227±0.035units; p=0.18).
These data suggest that chronic BFRE training is effective in increasing muscular strength, muscle size and vascularity in young adults but, in older adults, increases only muscular strength and size. Longer training durations or higher volumes may be required to evoke similar vascular adaptations in older adults.
Key points
Remote ischaemic preconditioning (RIPC), induced by brief bouts of ischaemia followed by reperfusion, confers vascular adaptations that protect against subsequent bouts of ischaemia; ...however, the effect of RIPC repeated over several days on the human microcirculation is unknown.
Using skin as a model, microvascular function was assessed at a control and a NO‐inhibited area of skin before 1 day after and 1 week after administering seven consecutive days of repeated RIPC on the contralateral arm.
Maximal vasodilatation was increased by ∼20–50% following 7 days of repeated RIPC, and this response remained elevated 1 week after stopping RIPC; however, NO‐mediated vasodilatation was not affected by the RIPC stimulus.
These data indicate that repeated RIPC augments maximal vasodilatation, but the underlying mechanism for this improvement is largely independent of NO.
This finding suggests a role for other endothelium‐derived mediators and/or for endothelium‐independent adaptations with repeated RIPC.
Remote ischaemic preconditioning (RIPC), induced by intermittent periods of ischaemia followed by reperfusion, confers cardiovascular protection from subsequent ischaemic bouts. RIPC increases conduit and resistance vessel function; however, the effect of RIPC on the microvasculature remains unclear. Using human skin as a microvascular model, we hypothesized that cutaneous vasodilatory (VD) function elicited by localized heating would be increased following repeated RIPC. Ten participants (23 ± 1 years, 6 males, 4 females) performed RIPC for seven consecutive days. Each daily RIPC session consisted of 4 repetitions of 5 min of arm blood flow occlusion interspersed by 5 min reperfusion. Before, 1 day after and 1 week after the 7 days of RIPC, two microdialysis fibres were placed in ventral forearm skin for continuous infusion of Ringer solution or 20 mM l‐NAME. Red blood cell flux was measured by laser Doppler flowmetry at each fibre site during local heating (Tloc = 39°C) and during maximal VD elicited by heating (Tloc = 43°C) and 28 mM sodium nitroprusside infusion. Data were normalized to cutaneous vascular conductance (flux/mmHg). Seven days of RIPC did not alter the nitric oxide (NO) contribution to the VD response to local heating (P > 0.05). However, the maximal VD was augmented (Pre: 2.5 ± 0.2, Post: 3.8 ± 0.5 flux/mmHg; P < 0.05) and remained elevated 1 week post RIPC (3.3 ± 0.4 flux/mmHg; P < 0.05). Repeated RIPC improves maximal VD but does not affect NO‐mediated VD in the cutaneous microvasculature. This finding suggests that other factors may explain the vasodilatory adaptations that occur following repeated RIPC.
Key points
Remote ischaemic preconditioning (RIPC), induced by brief bouts of ischaemia followed by reperfusion, confers vascular adaptations that protect against subsequent bouts of ischaemia; however, the effect of RIPC repeated over several days on the human microcirculation is unknown.
Using skin as a model, microvascular function was assessed at a control and a NO‐inhibited area of skin before 1 day after and 1 week after administering seven consecutive days of repeated RIPC on the contralateral arm.
Maximal vasodilatation was increased by ∼20–50% following 7 days of repeated RIPC, and this response remained elevated 1 week after stopping RIPC; however, NO‐mediated vasodilatation was not affected by the RIPC stimulus.
These data indicate that repeated RIPC augments maximal vasodilatation, but the underlying mechanism for this improvement is largely independent of NO.
This finding suggests a role for other endothelium‐derived mediators and/or for endothelium‐independent adaptations with repeated RIPC.
The optimal frequency and duration of remote ischemic preconditioning (RIPC) that augments microvascular function is unknown. A single bout of RIPC increases cutaneous endothelial function for ∼48 h, ...whereas 1 week of daily RIPC bouts improves more sustained endothelium-independent function. We hypothesized that 3 days of RIPC separated by rest days (3QOD RIPC) would result in sustained increases in both endothelium-dependent and endothelium-independent functions. Cutaneous microvascular function was assessed in 13 healthy young participants (aged 20.5 ± 3.9 years; 5 males, 8 females) before 3QOD and then 24, 48, and 72 h and a week after 3QOD. RIPC consisted of four repetitions of 5 min of blood flow occlusion separated by 5 min of reperfusion. Skin blood flow responses to local heating (
= 42°C), acetylcholine (Ach), and sodium nitroprusside (SNP) were measured using laser speckle contrast imaging and expressed as cutaneous vascular conductance (CVC = PU⋅mmHg
). Local heating-mediated vasodilation was increased 72 h after 3QOD and the increased responsivity persisted a week later (1.08 ± 0.24 vs. 1.34 ± 0.46, 1.21 ± 0.36 PU⋅mmHg
; ΔCVC, pre-RIPC vs. 72 h, a week after 3QOD;
= 0.054). Ach-induced cutaneous vasodilation increased a week after 3QOD (0.73 ± 0.41 vs. 0.95 ± 0.49 PU⋅mmHg
; ΔCVC, pre-RIPC vs. a week after 3QOD;
< 0.05). SNP-induced cutaneous vasodilation increased 24 h after 3QOD (0.47 ± 0.28 vs. 0.63 ± 0.35 PU⋅mmHg
; ΔCVC, pre-RIPC vs. 24 h;
< 0.05), but this change did not persist thereafter. Thus, 3QOD induced sustained improvement in endothelium-dependent vasodilation but was not sufficient to sustain increases in endothelium-independent vasodilation.
One week of daily remote ischemic preconditioning (RIPC) improves cutaneous vasodilatory (VD) function. However, the underlying mechanisms and the number of sessions needed to optimize this adaptive ...response remain unclear. We hypothesized that the responses to localized heating of the skin will be greater after 2 wk as opposed to 1 wk of RIPC. Furthermore, 2 wk of repeated RIPC will augment cutaneous VD responses to thermal and pharmacological stimuli. In methods, twenty-four participants (24 ± 2 yr; 13 men, 11 women) performed repeated RIPC (7 daily sessions over 1 wk,
= 11; 12 sessions over 2 wk,
= 13), consisting of four repetitions of 5 min of arm blood flow occlusion separated by 5 min reperfusion. Laser speckle contrast imaging was used to measure skin blood flow responses, in perfusion units (PU), to local heating (T
= 42°C), acetylcholine (ACh), and sodium nitroprusside (SNP) before and after repeated RIPC. Data were expressed as cutaneous vascular conductance (CVC, in PU/mmHg). In results, the VD response to local heating increased after RIPC (∆CVC from baseline; 1 wk: 0.94 ± 0.11 to 1.19 ± 0.15, 2 wk: 1.18 ± 0.07 to 1.33 ± 0.10 PU/mmHg;
< 0.05) but the ∆CVC did not differ between weeks. SNP-induced VD increased after 2 wk of RIPC (∆CVC; 0.34 ± 0.07 to 0.63 ± 0.11 PU/mmHg;
< 0.05), but ACh-induced VD did not. In conclusion, repeated RIPC improves local heating- and SNP-mediated cutaneous VD. When compared with 1 wk of RIPC, 2 wk of RIPC does not induce further improvements in cutaneous VD function.
Repeated RIPC increases the cutaneous vasodilatory response to local heating and to sodium nitroprusside but not to acetylcholine. Thus, endothelial-independent and local heating-mediated cutaneous vasodilation are improved following RIPC. However, 2 wk of RIPC sessions are not more effective than 1 wk of RIPC sessions in enhancing local heating-mediated cutaneous vasodilation.
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