Storylines for unprecedented heatwaves based on ensemble boosting.

Recent temperature extremes have shattered previously observed records, reaching intensities that were inconceivable before the events. Could the possibility of an event with such unprecedented intensity as the 2021 Pacific Northwest heatwave have been foreseen, based on climate model information available before the event? Could the scientific community have quantified its potential intensity based on the current generation of climate models? Here, we demonstrate how an ensemble boosting approach can be used to generate physically plausible storylines of a heatwave hotter than observed in the Pacific Northwest. We also show that heatwaves of much greater intensities than ever observed are possible in other locations like the Greater Chicago and Paris regions. In order to establish confidence in storylines of 'black swan'-type events, different lines of evidence need to be combined along with process understanding to make this information robust and actionable for stakeholders.

An Assessment of Earth's Climate Sensitivity Using Multiple Lines of Evidence.

We assess evidence relevant to Earth's equilibrium climate sensitivity per doubling of atmospheric CO2, characterized by an effective sensitivity S. This evidence includes feedback process understanding, the historical climate record, and the paleoclimate record. An S value lower than 2 K is difficult to reconcile with any of the three lines of evidence. The amount of cooling during the Last Glacial Maximum provides strong evidence against values of S greater than 4.5 K. Other lines of evidence in combination also show that this is relatively unlikely. We use a Bayesian approach to produce a probability density function (PDF) for S given all the evidence, including tests of robustness to difficult-to-quantify uncertainties and different priors. The 66% range is 2.6-3.9 K for our Baseline calculation and remains within 2.3-4.5 K under the robustness tests; corresponding 5-95% ranges are 2.3-4.7 K, bounded by 2.0-5.7 K (although such high-confidence ranges should be regarded more cautiously). This indicates a stronger constraint on S than reported in past assessments, by lifting the low end of the range. This narrowing occurs because the three lines of evidence agree and are judged to be largely independent and because of greater confidence in understanding feedback processes and in combining evidence. We identify promising avenues for further narrowing the range in S, in particular using comprehensive models and process understanding to address limitations in the traditional forcing-feedback paradigm for interpreting past changes.

Strong hemispheric coupling of glacial climate through freshwater discharge and ocean circulation.

The climate of the last glacial period was extremely variable, characterized by abrupt warming events in the Northern Hemisphere, accompanied by slower temperature changes in Antarctica and variations of global sea level. It is generally accepted that this millennial-scale climate variability was caused by abrupt changes in the ocean thermohaline circulation. Here we use a coupled ocean-atmosphere-sea ice model to show that freshwater discharge into the North Atlantic Ocean, in addition to a reduction of the thermohaline circulation, has a direct effect on Southern Ocean temperature. The related anomalous oceanic southward heat transport arises from a zonal density gradient in the subtropical North Atlantic caused by a fast wave-adjustment process. We present an extended and quantitative bipolar seesaw concept that explains the timing and amplitude of Greenland and Antarctic temperature changes, the slow changes in Antarctic temperature and its similarity to sea level, as well as a possible time lag of sea level with respect to Antarctic temperature during Marine Isotope Stage 3.

[Narcotic gas burden of personnel in pediatric anesthesia]. / Narkosegasbelastung des Personals in der Kinderanästhesie.

METHODS: To assess the occupational exposure of the anaesthetist to anaesthetic gases, a total of 1 German and 25 Swiss hospitals were investigated. A Brüel & Kjaer Type 1302 multi-gas monitor was used to measure concentrations of nitrous oxide and halogenated anaesthetic agents in the anaesthetist's breathing zone. Measurements were performed during 114 general anaesthetic, 55 of which were in patients under 11 years of age. In these 55 patients, the influence of various factors on the exposure (time-weighted average concentrations) was estimated by comparing different data groups. The efficiency of the applied scavenging equipment was examined by surveying the exhalation valve with a leak detector (type TIF 5600, TIF Instruments, Miami). RESULTS: Sessions with patients under 11 years of age revealed much higher anaesthetic gas exposures compared to older patients. The concentrations of nitrous oxide were on average threefold (Fig. 1), those of the halogenated anaesthetics fivefold higher (Fig. 2) for the younger patients. In 11- to 16-year-old patients the exposure level was the same as in adult patients. The measurements showed a reduction of 85% in exposure if an efficient scavenging system (i.e., no waste gas discharge to room air through the exhalation valve) or lower fresh gas flow were used (Fig. 4); 42% of the inspected scavengers were inefficient, and reduced the exposure on average by only 30%. In operating theatres with a ventilation rate of at least ten air changes per h, the measured concentrations of anaesthetic gases in the inhalation zone of the anaesthetists were reduced more than 50% compared to poorly ventilated rooms (Figs. 4 and 5). The use of tracheal intubation or laryngeal mask airway (LMA) anaesthesia resulted in a reduction of 80% in exposure compared to standard face masks if efficient scavenging was used. The exposures during sessions with inefficiently scavenged Bain coaxial systems or unscavenged semi-open delivery systems of the Jackson-Rees type were tenfold higher than with scavenged rebreathing circuit systems (Fig. 6). During anaesthesia with IV or double-mask induction, the average levels of inhalation anaesthetics were reduced by about 80% compared to inhalational induction with standard masks (Fig. 7). The anaesthetist's working technique is a very important factor that strongly influences the concentrations. Poor work practices, like lifting off the face mask with anaesthetic gas flow turned on, increased the exposure of the anaesthetist and other operating room personnel drastically, even if the other conditions (scavenger and room ventilation) were good. DISCUSSION: The exposure levels of anaesthetic gases are generally higher during anaesthesia in children up to 10 years of age than in older patients. Nevertheless, the measurements showed that exposure during paediatric anaesthesia can be kept below the recommended limit (8-h TWA in Switzerland) of 100 ppm nitrous oxide and 5 ppm halothane or 10 ppm enflurane or isoflurane. Causes of high exposures were particularly high fresh gas flows often applied without scavenging or together with inefficient scavenging devices and the high part of mask anaesthesia and inhalation induction with a loosely held mask. To achieve an effective reduction of occupational exposure, well-adjusted and maintained scavenging systems and low-leakage work practices are of primary importance. As leakage can never be completely avoided, a ventilation rate of at least ten air changes per h should be maintained in operating rooms and rooms where anaesthesia is induced to keep down concentrations of waste anaesthetic gases. High exposure during mask anaesthesia and inhalation induction can be prevented by further measures. Using a LMA instead of a standard mask reduces the exposure to the same level as endotracheal intubation.

[DMSP treatment in acute sublimate (mercury chloride) poisoning]. / DMSP-Behandlung bei einer akuten Sublimat-(Quecksilberchlorid-) Vergiftung.

A 19-year-old girl was treated for a heavy mercury chloride intoxication (3 g HgCl2) with 2,3-dimercaptopropane-1-sulfonate (DMSP) and dialyses. The anuric stage lasted for 10 days. With DMSP the mercury clearance by hemodialysis was 3,5-5,0 ml/min, with BAL 0,6 ml/min. DMSP is an effective watersoluble mercury-chelator and is subjectively better tolerated and less toxic than BAL. The anuric stage was probably not shortened.

The effect of pregnancy on the pharmacokinetics of caffeine.

Caffeine is eliminated mainly by metabolism to demethylated and oxidised derivatives. High individual variability is therefore expected from variations and changes in the capability of the organism to metabolize xenobiotics. An increase of the half-life of elimination of caffeine has been reported during the final weeks of pregnancy. In this study, the half-lifes of caffeine were determined by HPLC-analysis of samples of saliva in male and non-pregnant females and in women during pregnancy and after parturition. The half-life of caffeine increases from an average of 3 h for non-pregnant women to 10.5 h during the last 4 weeks of pregnancy. This increase is already occurring during the first part of pregnancy. The individual values could not be correlated with age, weight, consumption of coffee or smoking habits. An increase of the apparent volume of distribution can also be ruled out as an explanation for the marked increase of the half-life. The main effect of a prolonged half-life is the accumulation of caffeine in the body, unless the consumption is reduced appropriately. Thus, the greatly increased half-life of caffeine during pregnancy could produce adverse effects at a consumption which although considered as high is not excessive under normal conditions. This possibly explains the observation that heavy coffee drinking during pregnancy is linked to a low birthweight in the neonate. Due to the non-specificity of some of the symptoms of caffeine toxicity, pregnant women with such symptoms might be unable to trace the reason for their discomfort if they are not instructed by their physician about the higher susceptibility to caffeine during pregnancy.

Distribution of aflatoxin in whole peanut kernels, sampling plans for small samples.

It is well known that the distribution of aflatoxin in a lot of whole peanut kernels is extremely heterogeneous. Several different statistical distribution models have been proposed, fitting the experimental data reasonably well as long as the samples are very large, but differing considerably when applied to small samples. Therefore, it is important to know the real distribution between single kernels for the evaluation of the effectiveness of sampling plans for small samples. It is shown by the analysis of 368 samples of 1-10,000 kernels from the same lot of peanuts that the negative binomial distribution represents a good statistical model. The variance can be estimated from the mean concentration of the analysed samples, as confirmed by the comparison of data from several independent investigations. Decisions based on small samples are especially unfavourable to the consumer, as even a lot with a high mean concentration will tend to give negative results. A reasonably small risk of a false decision, both to the consumer and to the producer, can be reached only if very large samples are analysed.

Effect of pregnancy on the pharmacokinetics of caffeine.

Individual variation in the half-life of caffeine in the body was measured by HPLC analysis of saliva samples. The mean for adult males and non-pregnant females was 3.4 h (range 2-5 h, n = 25), and 8.3 h (range 3-16 h, n = 57) for pregnant women. After delivery, in most cases the values returned to normal within one month. The individual values could not be correlated with age, weight or consumption of coffee. Women drinking large quantities of coffee should be aware of the side effects of coffee during pregnancy, as they may occur at a lower rate of consumption than in the non-pregnant state.