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While previous studies have suggested a substantial role of ozone‐depleting substances (ODSs) in historical climate change, their relative contribution to historical anthropogenic warming has not been quantified before. Analyzing all‐but‐one‐forcing, 20‐member ensembles of historical simulations with a state‐of‐the‐art Earth System Model, we find that over the 1955–2005 period ODSs are responsible for 30% of global warming, 37% of Arctic warming, and 33% of summertime Arctic sea ice loss. Effective Radiative Forcing (ERF) calculations reveal that the global warming response to ODSs per unit of ERF is about 20% larger than for CO2, which may be due to stronger feedbacks and the difference in temporal evolution with ODSs having leveled off and CO2 still increasing in 2005. While the response to both peaks in the Arctic, the ODS ERF opposes Arctic amplification more than the CO2 ERF. Our findings highlight the importance of the Montreal Protocol for mitigating future climate change. Plain Language Summary: Ozone‐depleting substances (ODSs) are chemicals developed in the 1920s and 1930s for use in spray cans, refrigerators and plastic foams. Their commercial use increased rapidly in the 1950s and 1960s, but their phase out is underway since the signing of the Montreal Protocol in the 1987, following the identification of their devastating impact on the stratospheric ozone layer. It is well known that ODSs are powerful greenhouse gases, with the second largest warming effect between 1955 and 2005. However, their relative contribution to past global warming has not been quantified previously using comprehensive climate models. Here we show that ODSs were responsible for roughly a third of late 20th Century global warming, Arctic warming and Arctic sea ice decline. In addition, we find that the impact of ODSs on global temperatures is about 20% larger than expected based on the impacts they have on the radiative balance. The impacts of ODSs peak in the Arctic, while their radiative forcing peaks in the tropics, and thus opposes Arctic warming amplification. These findings enhance our understanding of drivers of past climate change, and highlight the importance of the Montreal Protocol for future climate change mitigation. Key Points: Between 1955 and 2005, global warming from ozone‐depleting substances (ODSs) was more than half of that due to CO2, and about one third of total anthropogenic warmingODSs have been about 20% more effective than CO2 at causing global warming per unit radiative forcingODS warming peaks in the Arctic and is 66% of that due to CO2, while their Effective Radiative Forcing (ERF) opposes Arctic amplification more than the CO2 ERF [ABSTRACT FROM AUTHOR]

Major sudden stratospheric warmings (SSWs), vortex formation, and final breakdown dates are key highlight points of the stratospheric polar vortex. These phenomena are relevant for stratosphere‐troposphere coupling, which explains the interest in understanding their future changes. However, up to now, there is not a clear consensus on which projected changes to the polar vortex are robust, particularly in the Northern Hemisphere, possibly due to short data record or relatively moderate CO2 forcing. The new simulations performed under the Coupled Model Intercomparison Project, Phase 6, together with the long daily data requirements of the DynVarMIP project in preindustrial and quadrupled CO2 (4xCO2) forcing simulations provide a new opportunity to revisit this topic by overcoming the limitations mentioned above. In this study, we analyze this new model output to document the change, if any, in the frequency of SSWs under 4xCO2 forcing. Our analysis reveals a large disagreement across the models as to the sign of this change, even though most models show a statistically significant change. As for the near‐surface response to SSWs, the models, however, are in good agreement as to this signal over the North Atlantic: There is no indication of a change under 4xCO2 forcing. Over the Pacific, however, the change is more uncertain, with some indication that there will be a larger mean response. Finally, the models show robust changes to the seasonal cycle in the stratosphere. Specifically, we find a longer duration of the stratospheric polar vortex and thus a longer season of stratosphere‐troposphere coupling. Key Points: The tropospheric signal of sudden stratospheric warming (SSWs) in the North Atlantic does not change under 4xCO2 forcingThere is high uncertainty in changes of SSW frequency under 4xCO2 forcing; single models show the rate to be significantly halved or doubledThe boreal polar vortex will form earlier and disappear later under increased CO2, extending the season of stratosphere‐troposphere coupling [ABSTRACT FROM AUTHOR]

Arctic sea ice loss may influence midlatitude climate by changing large-scale circulation. The extent to which climate change can be understood as greenhouse gas-induced changes that are modulated by this loss depends on how additive the responses to the separate influences are. A novel sea ice nudging methodology in a fully coupled climate model reveals that the separate effects of doubled atmospheric carbon dioxide (CO2) concentrations and associated Arctic sea ice loss are remarkably additive and insensitive to the mean climate state. This separability is evident in several fields throughout most of the year, from hemispheric to synoptic scales. The extent to which the regional response to sea ice loss sometimes agrees with and sometimes cancels the response to CO2 is quantified. The separability of the responses might provide a means to better interpret the diverse array of modeling and observational studies of Arctic change and influence. [ABSTRACT FROM AUTHOR]

Recent decades have seen significant developments in seasonal-to-interannual timescale climate prediction capabilities. However, until recently the potential of such systems to predict Arctic climate had not been assessed. This paper describes a multimodel predictability experiment which was run as part of the Arctic Predictability and Prediction On Seasonal to Inter-annual Timescales (APPOSITE) project. The main goal of APPOSITE was to quantify the timescales on which Arctic climate is predictable. In order to achieve this, a coordinated set of idealised initial-value predictability experiments, with seven general circulation models, was conducted. This was the first model intercomparison project designed to quantify the predictability of Arctic climate on seasonal to inter-annual timescales. Here we present a description of the archived data set (which is available at the British Atmospheric Data Centre) and an update of the project's results. Although designed to address Arctic predictability, this data set could also be used to assess the predictability of other regions and modes of climate variability on these timescales, such as the El Niño Southern Oscillation. [ABSTRACT FROM AUTHOR]

Detection of climate change requires a network of stable ground-based long-term measurements. Building upon earlier work, we first explore requirements of such measurements (such as maximum random uncertainty and sampling frequency) to ensure a minimum random uncertainty in monthly mean temperatures and to ensure effective detection of trends. In agreement with previous work we find that only for individual measurement random uncertainties >0.2K does the measurement random uncertainty start to contribute significantly to the random uncertainty in the monthly mean. For trend analysis, we find that the quality of the trend determination is only compromised when the measurement random uncertainty exceeds 2K and measurements are made just once or twice a month. In the second part of the study we provide guidance on how to most effectively design a measurement network. To this end we developed a method to objectively identify the optimal location of sites for detecting projected trends in upper-air temperatures and total column ozone in the shortest possible time. This is done by first estimating the spatial distribution of the minimum length of time during which measurements have to be made in order to detect projected trends in temperature and ozone. This quantity is calculated from the unforced variance in the signal and the degree of autocorrelation, both estimated from historical data sets and assumed not to change in the future, and the projected trends as estimated from chemistry-climate models. The optimal site locations are then selected by an iterative procedure based on the minimum time required to detect a trend and a minimal distance between different measurement sites. While the optimal sites identified here result from our use of only one of a wide range of objective strategies, these results provide additional incentives for initiating measurement programmes at these sites or, if already in operation, to continue to be supported. [ABSTRACT FROM AUTHOR]

The separate climate effects of middle-atmospheric and tropospheric CO2 doubling have been simulated and analyzed with the ECHAM middle-atmosphere climate model. To this end, the CO2 concentration has been separately doubled in the middle-atmosphere, the troposphere, and the entire atmosphere, and the results have been compared to a control run. During NH winter, the simulated uniformly doubled CO2 climate shows an increase of the stratospheric residual circulation, a small warming in the Arctic lower stratosphere, a weakening of the zonal winds in the Arctic middle-atmosphere, an increase of the NH midlatitude tropospheric westerlies, and a poleward shift of the SH tropospheric westerlies. The uniformly doubled CO2 response in most regions is approximately equal to the sum of the separate responses to tropospheric and middle-atmospheric CO2 doubling. The increase of the stratospheric residual circulation can be attributed for about two-thirds to the tropospheric CO2 doubling and one-third to the middle-atmospheric CO2 doubling. This increase contributes to the Arctic lower-stratospheric warming and, through the thermal wind relationship, to the weakening of the Arctic middle-atmospheric zonal wind. The increase of the tropospheric NH midlatitude westerlies can be attributed mainly to the middle-atmospheric CO2 doubling, indicating the crucial importance of the middle-atmospheric CO2 doubling for the tropospheric climate change. Results from an additional experiment show that the CO2 doubling above 10 hPa, which is above the top of many current GCMs, also causes significant changes in the tropospheric climate. [ABSTRACT FROM AUTHOR]

The article quantifying the influence of short-term emission reductions on climate. It mentions that Covid-19 (coronavirus disease 2019) pandemic has resulted in a marked slowdown in greenhouse gas and aerosol emissions. It discusses the impact of carbon dioxide and aerosol emission reductions in temporary enhancement in warming rate.

An apparent increase in observed cold extremes over recent decades in the northern midlatitudes has been reported, in contrast to robust decreases predicted by climate models. This discrepancy has led to suggestions that models fail to accurately simulate changes in weather patterns caused by Arctic warming. Here, we show that the observed frequency and intensity of midlatitude cold extremes have strongly decreased since 1990 and are consistent with modeled trends. The previously reported increase in cold extremes was overestimated due to an artifact of changing data coverage. We also show that the fraction of land with observed cold extreme increases over recent decades is consistent with model internal variability on top of a near-uniform forced reduction in cold extremes across the midlatitudes. Our results provide strong evidence of a decrease in midlatitude cold extremes over recent decades and consistency between models and observations.

Background: Patients newly-diagnosed with diabetes require self-management education to help them understand and manage the disease. The goals of the study were to determine the frequency of diabetes self-management education program utilization by newly-diagnosed patients, and to evaluate whether there were any demographic or clinical disparities in utilization., Methods: Using population-level health care data, all 46,553 adults who were diagnosed with any type of non-gestational diabetes in Ontario, Canada between January and June 2006 were identified. They were linked with a diabetes self-management education program registry to identify those who attended within 6 months of diagnosis. The demographic and clinical characteristics of attendees and non-attendees were compared., Results: A total of 9,568 (20.6%) patients attended a diabetes self-management education program within 6 months of diagnosis. Younger age, increasing socioeconomic status, and the absence of mental health conditions or other medical comorbidity were associated with attendance. Patients living in rural areas, where access to physicians may be limited, were markedly more likely to attend. Recent immigrants were 40% less likely to attend self-management education programs than longer-term immigrants or nonimmigrants., Conclusion: Only one in five newly-diagnosed diabetes patients attended a diabetes self-management education program. Demographic and clinical disparities in utilization persisted despite a publicly-funded health care system where patients could access these services without direct charges. Primary care providers and education programs must ensure that more newly-diagnosed diabetes patients receive self-management education, particularly those who are older, poorer, sicker, or recent immigrants.

Objective: To describe the quality of diabetes care delivered by academic endocrinologists practicing at 4 teaching hospitals affiliated with a single medical school., Methods: Up to 30 patients who first saw an endocrinologist for an ambulatory consultation for diabetes between January 2004 and December 2005 were randomly selected for chart review. Process and intermediate measures of quality of care were abstracted., Results: There were 417 patient charts available for analysis. Quality of care was generally high, with 61% of patients achieving a glycated hemoglobin of ≤7.0%, 77% achieving blood pressure ≤130/80 mm Hg and 73% achieving a low-density lipoprotein cholesterol level of ≤2.5 mmol/L. More than 80% of patients had had eye examinations, microalbuminuria screening and foot examinations. There were no significant differences in quality between hospitals., Conclusions: The quality of diabetes care delivered by academic endocrinologists in this setting was high and approached the "ideal" levels of care recommended by practice guidelines. Compared to past studies in both the primary and specialist care settings, the results show that high-quality care can be delivered in routine academic clinical practice without having previously instituted a specific quality improvement program., (Copyright © 2009 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.)

Of 36 fractures of the talar neck without comminution of the body, eight were undisplaced, treated closed, and 28 were displaced and treated by open reduction. Twenty of the operations were less than 12 hours after injury. Nineteen of 20 were performed through a medial approach, six with a medial malleolar osteotomy. The long-term results were evaluated by a standard rating system based on classification by the fracture. A protective brace was developed for non-weight-bearing in two patients with complete avascular necrosis, and ankle protection with weight-bearing in ten with partial necrosis. Prompt open reduction and internal fixation, malleolar osteotomy, and protected weight-bearing are recommended in selected cases.