A pseudoproxy emulation of the PAGES 2k database using a hierarchy of proxy system models.

Paleoclimate reconstructions are now integral to climate assessments, yet the consequences of using different methodologies and proxy data require rigorous benchmarking. Pseudoproxy experiments (PPEs) provide a tractable and transparent test bed for evaluating climate reconstruction methods and their sensitivity to aspects of real-world proxy networks. Here we develop a dataset that leverages proxy system models (PSMs) for this purpose, which emulates the essential physical, chemical, biological, and geological processes that translate climate signals into proxy records, making these synthetic proxies more relevant to the real world. We apply a suite of PSMs to emulate the widely-used PAGES 2k dataset, including realistic spatiotemporal sampling and error structure. A hierarchical approach allows us to produce many variants of this base dataset, isolating the impact of sampling bias in time and space, representation error, sampling error, and other assumptions. Combining these various experiments produces a rich dataset ("pseudoPAGES2k") for many applications. As an illustration, we show how to conduct a PPE with this dataset based on emerging climate field reconstruction techniques.

Forced changes in the Pacific Walker circulation over the past millennium.

The Pacific Walker circulation (PWC) has an outsized influence on weather and climate worldwide. Yet the PWC response to external forcings is unclear1,2, with empirical data and model simulations often disagreeing on the magnitude and sign of these responses3. Most climate models predict that the PWC will ultimately weaken in response to global warming4. However, the PWC strengthened from 1992 to 2011, suggesting a significant role for anthropogenic and/or volcanic aerosol forcing5, or internal variability. Here we use a new annually resolved, multi-method, palaeoproxy-derived PWC reconstruction ensemble (1200-2000) to show that the 1992-2011 PWC strengthening is anomalous but not unprecedented in the context of the past 800 years. The 1992-2011 PWC strengthening was unlikely to have been a consequence of volcanic forcing and may therefore have resulted from anthropogenic aerosol forcing or natural variability. We find no significant industrial-era (1850-2000) PWC trend, contrasting the PWC weakening simulated by most climate models3. However, an industrial-era shift to lower-frequency variability suggests a subtle anthropogenic influence. The reconstruction also suggests that volcanic eruptions trigger El Niño-like PWC weakening, similar to the response simulated by climate models.

An increase in marine heatwaves without significant changes in surface ocean temperature variability.

Marine heatwaves (MHWs)-extremely warm, persistent sea surface temperature (SST) anomalies causing substantial ecological and economic consequences-have increased worldwide in recent decades. Concurrent increases in global temperatures suggest that climate change impacted MHW occurrences, beyond random changes arising from natural internal variability. Moreover, the long-term SST warming trend was not constant but instead had more rapid warming in recent decades. Here we show that this nonlinear trend can-on its own-appear to increase SST variance and hence MHW frequency. Using a Linear Inverse Model to separate climate change contributions to SST means and internal variability, both in observations and CMIP6 historical simulations, we find that most MHW increases resulted from regional mean climate trends that alone increased the probability of SSTs exceeding a MHW threshold. Our results suggest the need to carefully attribute global warming-induced changes in climate extremes, which may not always reflect underlying changes in variability.

Climate change increases risk of extreme rainfall following wildfire in the western United States.

Post-wildfire extreme rainfall events can have destructive impacts in the western United States. Using two climate model large ensembles, we assess the future risk of extreme fire weather events being followed by extreme rainfall in this region. By mid-21st century, in a high warming scenario (RCP8.5), we report large increases in the number of extreme fire weather events followed within 1 year by at least one extreme rainfall event. By 2100, the frequency of these compound events increases by 100% in California and 700% in the Pacific Northwest in the Community Earth System Model v1 Large Ensemble. We further project that more than 90% of extreme fire weather events in California, Colorado, and the Pacific Northwest will be followed by at least three spatially colocated extreme rainfall events within five years. Our results point to a future with substantially increased post-fire hydrologic risks across much of the western United States.

Twenty-first century hydroclimate: A continually changing baseline, with more frequent extremes.

SignificanceTwenty-first century trends in hydroclimate are so large that future average conditions will, in most cases, fall into the range of what we would today consider extreme drought or pluvial states. Using large climate model ensembles, we remove the background trend and find that the risk of droughts and pluvials relative to that (changing) baseline is fairly similar to the 20th century risk. By continually adapting to long-term background changes, these risks could therefore perhaps be minimized. However, increases in the frequency of extremely wet and dry years are still present even after removing the trend, indicating that sustainably managing hydroclimate-driven risks in a warmer world will face increasingly difficult challenges.

Human-driven greenhouse gas and aerosol emissions cause distinct regional impacts on extreme fire weather.

Attribution studies have identified a robust anthropogenic fingerprint in increased 21st century wildfire risk. However, the risks associated with individual aspects of anthropogenic aerosol and greenhouse gases (GHG) emissions, biomass burning and land use/land cover change remain unknown. Here, we use new climate model large ensembles isolating these influences to show that GHG-driven increases in extreme fire weather conditions have been balanced by aerosol-driven cooling throughout the 20th century. This compensation is projected to disappear due to future reductions in aerosol emissions, causing unprecedented increases in extreme fire weather risk in the 21st century as GHGs continue to rise. Changes to temperature and relative humidity drive the largest shifts in extreme fire weather conditions; this is particularly apparent over the Amazon, where GHGs cause a seven-fold increase by 2080. Our results allow increased understanding of the interacting roles of anthropogenic stressors in altering the regional expression of future wildfire risk.

Marine wild-capture fisheries after nuclear war.

Nuclear war, beyond its devastating direct impacts, is expected to cause global climatic perturbations through injections of soot into the upper atmosphere. Reduced temperature and sunlight could drive unprecedented reductions in agricultural production, endangering global food security. However, the effects of nuclear war on marine wild-capture fisheries, which significantly contribute to the global animal protein and micronutrient supply, remain unexplored. We simulate the climatic effects of six war scenarios on fish biomass and catch globally, using a state-of-the-art Earth system model and global process-based fisheries model. We also simulate how either rapidly increased fish demand (driven by food shortages) or decreased ability to fish (due to infrastructure disruptions), would affect global catches, and test the benefits of strong prewar fisheries management. We find a decade-long negative climatic impact that intensifies with soot emissions, with global biomass and catch falling by up to 18 ± 3% and 29 ± 7% after a US-Russia war under business-as-usual fishing-similar in magnitude to the end-of-century declines under unmitigated global warming. When war occurs in an overfished state, increasing demand increases short-term (1 to 2 y) catch by at most ∼30% followed by precipitous declines of up to ∼70%, thus offsetting only a minor fraction of agricultural losses. However, effective prewar management that rebuilds fish biomass could ensure a short-term catch buffer large enough to replace ∼43 ± 35% of today's global animal protein production. This buffering function in the event of a global food emergency adds to the many previously known economic and ecological benefits of effective and precautionary fisheries management.

The bolster technique utilising small intestinal submucosa wound matrix: A novel approach to wound treatment.

Managing acute wounds with soft tissue loss can be very challenging for both patients and physicians. Successful wound healing depends on several factors including exudate control, prevention of infection, and moisture balance. In this case series, we describe a novel combination treatment method utilising small intestinal submucosa wound matrix (SISWM) with the bolster technique as a way of assisting the integration of collagen-based wound treatment products into the base of complex wounds with the intent of restoring a dysfunctional extracellular matrix. In case 1, a 44-year-old female presented with an acute wound resulting from a spider bite to the posterior aspect of the right knee. In case 2, a 12-year-old male sustained multiple injuries to his right foot from an all-terrain vehicle accident. In case 3, an 80-year-old female on anticoagulants sustained an avulsion injury to her left lower leg. In case 4, a 41-year-old female sustained a severe complex avulsion injury to the dorsal left forearm sustained from a dog bite. All patients were successfully treated with SISWM and the bolster technique, and their wounds healed completely within 6 weeks. The bolster technique, when combined with an SISWM, is a novel method designed to enable the SISWM to impart its wound healing properties to these complex traumatic wounds. This case series presents treating clinicians with a different treatment methodology to assist the patient in achieving a successful outcome.

Male Caregivers Report Problems in Caring at Home After Spouses Survive Stroke.

STROKE is sudden and often traumatic with results that affect both the patient and family members who provide care. Approximately 40% of individuals caring for family members/friends are male. Transitioning from the noncaregiver role to caregiver can be unsettling. Guided by Friedemann's framework of systemic organization, this secondary data analysis examined problems reported by men caring for spouses in the first year after stroke. Using a mixed methods design, 73 caregivers (CGs) participated in bimonthly telephone interviews for 1 year. For this analysis, only the males caring for spouses (n = 12 married and n = 1 unmarried partner) were examined. These data were analyzed using Colaizzi's rigorous method of content analysis. Five problem themes emerged: 1) adjusting to multitasking in everyday living (Friedemann's system maintenance and individuation), 2) recognizing physical and mental disabilities (coherence), 3) dealing with outside forces and limited resources (individuation), 4) struggling to return to normal (system maintenance), and 5) feeling physically, mentally, and emotionally exhausted (system maintenance). These problem themes demonstrated incongruence as the men sought to maintain their prior lives.Theory-based themes of male stroke CGs' problems were uncovered that can be used to target interventions to help them achieve balance between incongruence and congruence in their lives.

Role of eruption season in reconciling model and proxy responses to tropical volcanism.

The response of the El Niño/Southern Oscillation (ENSO) to tropical volcanic eruptions has important worldwide implications, but remains poorly constrained. Paleoclimate records suggest an "El Niño-like" warming 1 year following major eruptions [Adams JB, Mann ME, Ammann CM (2003) Nature 426:274-278] and "La Niña-like" cooling within the eruption year [Li J, et al. (2013) Nat Clim Chang 3:822-826]. However, climate models currently cannot capture all these responses. Many eruption characteristics are poorly constrained, which may contribute to uncertainties in model solutions-for example, the season of eruption occurrence is often unknown and assigned arbitrarily. Here we isolate the effect of eruption season using experiments with the Community Earth System Model (CESM), varying the starting month of two large tropical eruptions. The eruption-year atmospheric circulation response is strongly seasonally dependent, with effects on European winter warming, the Intertropical Convergence Zone, and the southeast Asian monsoon. This creates substantial variations in eruption-year hydroclimate patterns, which do sometimes exhibit La Niña-like features as in the proxy record. However, eruption-year equatorial Pacific cooling is not driven by La Niña dynamics, but strictly by transient radiative cooling. In contrast, equatorial warming the following year occurs for all starting months and operates dynamically like El Niño. Proxy reconstructions confirm these results: eruption-year cooling is insignificant, whereas warming in the following year is more robust. This implies that accounting for the event season may be necessary to describe the initial response to volcanic eruptions and that climate models may be more accurately simulating volcanic influences than previously thought.

Patient Perspectives About Follow-Up Care and Weight Regain Following Sleeve Gastrectomy.

BACKGROUND: Weight regain following sleeve gastrectomy is an increasingly recognised and important problem. Similar to other centres, we have noticed an association between the onset of weight regain and discharge from the bariatric service. We aimed to elucidate this further from the patient perspective. METHODS: Patients at least 2 years from sleeve gastrectomy, who had experienced weight regain, were invited to participate in a focus group discussion. Participants were asked to complete a demographic survey and discussions were audio-recorded. Transcripts underwent content analysis using an inductive approach. RESULTS: Thirty-eight participants participated in one of seven focus group discussions. The majority of participants were female, European and satisfied with the surgery and follow-up care. Participants described positive and negative aspects of the surgery, their follow-up care and causes of weight regain. Important emergent themes included the desire for more support, that is delivered within the overarching principles of providing individualised, specialised care by providers that maintain good rapport and assist in maintaining motivation. Furthermore, this follow-up support may be delivered in non-traditional ways rather than conventional face-to-face consultations. CONCLUSION: Explorative focus group discussions in a group of patients who had regained weight following sleeve gastrectomy revealed a desire for more support after discharge from the bariatric service.