Infectious Diseases in a Changing Climate.

This JAMA Insights in the Climate Change and Health series discusses the importance of clinicians having awareness of changes in the geographic range, seasonality, and intensity of transmission of infectious diseases to help them diagnose, treat, and prevent these diseases.

Climate Change and Stroke: A Topical Narrative Review.

The impacts of accumulating atmospheric greenhouse gases on the earth's climate are now well established. As a result, there have been increases in ambient temperatures and resultant higher frequency and duration of temperature extremes and other extreme weather events, which have been linked to a wide range of adverse health outcomes. This topical narrative review provides a summary of published evidence on the links between climate change and stroke. There is consistent evidence of associations between stroke incidence and mortality and increasing ambient temperature and air pollution. Associations have also been shown for changes in barometric pressure, wildfires, and desert dust and sandstorms, but current evidence is limited. Flooding and other extreme weather events appear to primarily cause service disruption, but more direct links to stroke may emerge. Synergies between dietary changes that reduce stroke risk and may also reduce carbon footprint are being explored. We also discuss the impact on vulnerable populations, proposed pathophysiologic mechanisms, mitigation strategies, and current research priorities. In conclusion, climate change increasingly impacts the stroke community, warranting elevated attention.

A WHO-led global strategy to control greenhouse gas emissions: a call for action.

BACKGROUND: Climate change, driven by anthropogenic greenhouse gas emissions, is among the greatest threats to human health. The World Health Organisation (WHO), has led global efforts to respond to emerging public health threats including the control of hazardous substances such as tobacco, alcohol, lead and asbestos, with remarkable health gains. BODY: Despite WHO's clear messaging on the enormous and growing health risks of climate change, greenhouse gases are not yet classified as hazardous substances, requiring control through a global strategy or framework. Additionally, WHO has not classified disease attributable to climate change as a result of the promulgation of these hazards as a Public Health Emergency of International Concern (PHEIC), despite the serious and preventable health risks it poses globally. Several historical precedents set the stage for WHO to declare excess greenhouse gases as health hazards, including the control of ozone-depleting substances and breast-milk substitutes where the public benefit of control exceeded the potential benefit of their promulgation. In addition, WHO's undertaking within the International Health Regulations to protect global health, providing imperative to declare climate change a PHEIC, with Tedros Adhanom Ghebreyesus, director-general of WHO, declaring: "The climate crisis is a health crisis, fuelling outbreaks, contributing to higher rates of noncommunicable diseases, and threatening to overwhelm our health workforce and health infrastructure". Importantly, the health sector, perhaps more than other sectors, has successfully overcome formidable, vested interests in combatting these threats to health. CONCLUSION: It is thus imperative that WHO make full use of their credibility and influence to establish a global framework for the control of greenhouse gases through the declaration of excess greenhouse gas emissions as a hazardous substance, and declaring climate change a PHEIC. Who else is better placed to drive the considerable societal transformation needed to secure a liveable future?

Seasonal advance of intense tropical cyclones in a warming climate.

Intense tropical cyclones (TCs), which often peak in autumn1,2, have destructive impacts on life and property3-5, making it crucial to determine whether any changes in intense TCs are likely to occur. Here, we identify a significant seasonal advance of intense TCs since the 1980s in most tropical oceans, with earlier-shifting rates of 3.7 and 3.2 days per decade for the Northern and Southern Hemispheres, respectively. This seasonal advance of intense TCs is closely related to the seasonal advance of rapid intensification events, favoured by the observed earlier onset of favourable oceanic conditions. Using simulations from multiple global climate models, large ensembles and individual forcing experiments, the earlier onset of favourable oceanic conditions is detectable and primarily driven by greenhouse gas forcing. The seasonal advance of intense TCs will increase the likelihood of intersecting with other extreme rainfall events, which usually peak in summer6,7, thereby leading to disproportionate impacts.

Nitrous Oxide Use in Australian Health Care: Strategies to Reduce the Climate Impact.

Nitrous oxide is a useful inhaled analgesic. Due to its high global warming potential and ozone-depleting properties, the nitrous oxide emissions related to health care are being increasingly scrutinized. In this narrative review, we will discuss the clinical uses of nitrous oxide relevant to anesthetists, in addition to its contribution as a greenhouse gas. Using available data from Australia, we will explore potential strategies for reducing the impact of those emissions, which are likely to be applicable in other countries. These include destruction of captured nitrous oxide, minimizing nitrous oxide waste and reducing clinical use. Anesthesia clinicians are well placed to raise awareness with colleagues and consumers regarding the environmental impact of nitrous oxide and to promote cleaner alternatives. Reducing use is likely to be the most promising reduction strategy without large-scale changes to infrastructure and subsequent delay in action.

Associations of daily diet-related greenhouse gas emissions with the incidence and mortality of chronic diseases: a systematic review and meta-analysis of epidemiological studies.

OBJECTIVES: Although the entire process extending from food production to dietary consumption makes a large contribution to total greenhouse gas (GHG) emissions, little and inconsistent evidence exists on the epidemiological associations of daily diet-related GHG emissions with chronic disease risk or all-cause mortality. This systematic review and meta-analysis explored the observational epidemiological relationship between daily diet-related GHG emissions and health outcomes, including the risk of chronic diseases and all-cause mortality. METHODS: Original articles published in English until May 2022 were identified by searching PubMed, Ovid-Embase, Web of Science, CINAHL, and Google Scholar. The extracted data were pooled using both fixed-effects and random-effects meta-analyses and presented as hazard and risk ratios (RRs) with 95% confidence intervals (CIs). RESULTS: In total, 7 cohort studies (21 study arms) were included for qualitative synthesis and meta-analysis. The GHG emissions of dietary consumption showed a significant positive association with the risk of chronic disease incidence and mortality in both fixed-effects and random-effects models (fixed: RR, 1.04; 95% CI, 1.03 to 1.05; random: RR, 1.04; 95% CI, 1.02 to 1.06). This positive association was robust regardless of how daily diet-related GHG emissions were grouped. More strongly animal- based diets showed higher GHG emissions. However, there were only a few studies on specific chronic diseases, and the subgroup analysis showed insignificant results. There was no evidence of publication bias among the studies (Egger test: p=0.79). CONCLUSIONS: A higher GHG-emission diet was found to be associated with a greater risk of all-cause mortality.

Future temperature extremes threaten land vertebrates.

The frequency, duration, and intensity of extreme thermal events are increasing and are projected to further increase by the end of the century1,2. Despite the considerable consequences of temperature extremes on biological systems3-8, we do not know which species and locations are most exposed worldwide. Here we provide a global assessment of land vertebrates' exposures to future extreme thermal events. We use daily maximum temperature data from 1950 to 2099 to quantify future exposure to high frequency, duration, and intensity of extreme thermal events to land vertebrates. Under a high greenhouse gas emission scenario (Shared Socioeconomic Pathway 5-8.5 (SSP5-8.5); 4.4 °C warmer world), 41.0% of all land vertebrates (31.1% mammals, 25.8% birds, 55.5% amphibians and 51.0% reptiles) will be exposed to extreme thermal events beyond their historical levels in at least half their distribution by 2099. Under intermediate-high (SSP3-7.0; 3.6 °C warmer world) and intermediate (SSP2-4.5; 2.7 °C warmer world) emission scenarios, estimates for all vertebrates are 28.8% and 15.1%, respectively. Importantly, a low-emission future (SSP1-2.6, 1.8 °C warmer world) will greatly reduce the overall exposure of vertebrates (6.1% of species) and can fully prevent exposure in many species assemblages. Mid-latitude assemblages (desert, shrubland, and grassland biomes), rather than tropics9,10, will face the most severe exposure to future extreme thermal events. By 2099, under SSP5-8.5, on average 3,773 species of land vertebrates (11.2%) will face extreme thermal events for more than half a year period. Overall, future extreme thermal events will force many species and assemblages into constant severe thermal stress. Deep greenhouse gas emissions cuts are urgently needed to limit species' exposure to thermal extremes.

Environmental impacts and diet quality of popular diet models compared to Turkey's national nutrition guidelines.

AIMS: This study aimed to compare the environmental impacts and diet qualities of popular diet models with the recommendations of the Turkish national dietary guidelines. METHODS: Seven-day isocaloric (8368 kJ) diet models were created taking into account the Mediterranean, Atkins (20/40/100), Ornish, Zone diets, and Turkey Dietary Guidelines-2015 recommendations with different food and nutrient contents. Water footprints were evaluated using the global water footprint standards. Greenhouse gas emissions were evaluated using carbon footprint factors compiled as a result of meta-analyses of life cycle analysis studies in the literature. In addition, the quality of diets was evaluated with the Diet Quality Index-International. RESULTS: Atkins20 diet model had the most harmful environmental impact (greenhouse gas emissions 8.74 kg CO2 -eq/per/day and total water footprint 7731 L/per/day), whereas Ornish and Mediterranean diet models (greenhouse gas emissions 2.2/3.07 kg CO2 -eq/per/day and total water footprints 3184/3675 L/per/day, respectively) had less harmful environmental impact. The highest Diet Quality Index-International score was in the Ornish diet model while the lowest Diet Quality Index-International was in the Atkins20 diet model. CONCLUSION: Ornish and Mediterranean diet models had less harmful environmental impacts, which contributed to sustainable nutrition. The importance of diet quality and environmental impacts should be kept in mind when evaluating diet models to ensure sustainable nutrition.

Diet-Attributable Greenhouse Gas Emissions and Acute Myocardial Infarction in Costa Rica Heart Study.

Adopting sustainable dietary patterns is essential for planetary and human health. As data to address this issue are lacking in Latino populations, this study examined the association between diet-attributable greenhouse gas emissions (GHGEs) and myocardial infarction (MI) in a Costa Rica Heart Study. This analysis included 1817 cases of a first non-fatal acute MI during hospitalization and their matched population-based controls, by age, sex, and area of residence. A validated food frequency questionnaire was used to quantify habitual dietary intake and diet-attributable GHGEs (kg CO2 equivalent (eq.)/year). Due to the matching design, conditional logistic regression was used. Red meat consumption contributed approximately 50% to the total diet-attributable GHGEs among both cases and controls. Higher diet-attributable GHGEs were associated with increased odds of acute MI. The odds of MI were 63% higher (OR = 1.63; 95% CI 1.20-2.21) among participants in the highest quintile (median diet-attributable GHGEs = 6247 kg CO2 eq./year) compared to the lowest quintile (median diet-attributable GHGEs = 2065 kg CO2 eq./year). An increasing linear trend in the odds of acute MI and diet-attributable GHGEs was detected (p-trend 0.0012). These findings highlight the importance of reducing red meat consumption to sustainably mitigate the incidence of MI and improve planetary health.

Health and environmental impacts of plant-rich dietary patterns: a US prospective cohort study.

BACKGROUND: Diets that are rich in animal-based foods threaten planetary and human health, but plant-rich diets have varied health and environmental effects. We aimed to characterise a healthy dietary index and three plant-based indices by their environmental impacts and associations with risk of cardiovascular disease. METHODS: In this prospective cohort study, we used data from a food-frequency questionnaire in the US-based Nurses' Health Study II. Participants were categorised by quintiles of four dietary indices, including the alternative healthy eating index-2010 (AHEI), plant-based diet index (PDI), unhealthy PDI, and healthy PDI. We calculated environmental impacts (greenhouse gas emissions and irrigation water, nitrogenous fertiliser, and high-quality cropland needs), and relative risks (RRs) of cardiovascular disease from 1991-2017, comparing quintiles. FINDINGS: We included 90 884 participants in the health-impact analysis and 65 625 participants in the environmental-impact analysis. Comparing the top and bottom quintiles, higher AHEI scores were associated with a decreased cardiovascular disease risk (relative risk 0·77 [95% CI 0·66-0·89]); 30% lower greenhouse gas emissions (Q5 2·6 kg CO2 equivalent vs Q1 3·7 kg CO2 equivalent); and lower fertiliser, cropland, and water needs (all ptrends<0·0001). Similarly, the highest healthy PDI and PDI quintiles were associated with a decreased cardiovascular disease risk (healthy PDI 0·71 [0·60-0·83] and PDI 0·74 [0·63-0·85]) and lower environmental impacts (PDI water needs ptrend=0·0014; all other ptrends<0·0001). Conversely, the highest unhealthy PDI quintile had a higher cardiovascular disease risk compared with the lowest unhealthy PDI quintile (1·15 [1·00-1·33]; ptrend=0·023) and required more cropland (ptrend<0·0001) and fertiliser (ptrend=0·0008). INTERPRETATION: Dietary patterns that are associated with better health had lower greenhouse gas emissions and nitrogenous fertiliser, cropland, and irrigation water needs. Not all plant-based diets conferred the same health and environmental benefits. US dietary guidelines should include nuanced consideration of environmental sustainability. FUNDING: US National Institutes of Health.

How Should We Respond to Health Sector Emissions That Exacerbate Climate Change and Inequity?

A warming climate poses substantial risk to public health and worsens existing health inequity. As a contributor to greenhouse gas emissions and air pollution, the health sector has obligations and ample opportunities to protect health by decreasing waste and motivating more system-wide sustainable clinical practices. Such efforts will have important ethical implications for health equity.

A weakened AMOC may prolong greenhouse gas-induced Mediterranean drying even with significant and rapid climate change mitigation.

The Mediterranean region has been identified as a climate hot spot, with models projecting a robust warming and rainfall decline in response to increasing greenhouse gases. The projected rainfall decline would have impacts on agriculture and water resources. Can such changes be reversed with significant reductions in greenhouse gases? To explore this, we examine large ensembles of a high-resolution climate model with various future radiative forcing scenarios, including a scenario with substantial reductions in greenhouse gas concentrations beginning in the mid-21st century. In response to greenhouse gas reductions, the Mediterranean summer rainfall decline is reversed, but the winter rainfall decline continues. This continued winter rainfall decline results from a persistent atmospheric anticyclone over the western Mediterranean. Using additional numerical experiments, we show that the anticyclone and continued winter rainfall decline are attributable to greenhouse gas-induced weakening of the Atlantic Meridional Overturning Circulation (AMOC) that continues throughout the 21st century. The persistently weak AMOC, in concert with greenhouse gas reductions, leads to rapid cooling and sea ice growth in the subpolar North Atlantic. This cooling leads to a strong cyclonic atmospheric circulation anomaly over the North Atlantic subpolar gyre and, via atmospheric teleconnections, to the anticyclonic circulation anomaly over the Mediterranean. The failure to reverse the winter rainfall decline, despite substantial climate change mitigation, is an example of a "surprise" in the climate system. In this case, a persistent AMOC change unexpectedly impedes the reversibility of Mediterranean climate change. Such surprises could complicate pathways toward full climate recovery.

Imperatives for integrated science and policy in managing greenhouse gas risks to the Southern Polar Region.

The Southern Polar Region (Antarctica and the Southern Ocean) is threatened by climate change, and ocean warming and acidification. Reducing climate risks through direct human interventions in the region or through biological adaptation is not possible. Resilience of the region to global warming needs the establishment of climate refugia and science-based, climate-informed, ecosystem-based management, but long-term conservation will only be assured by global reduction in greenhouse gas emissions.

Climate change and global issues in allergy and immunology.

The steady increase in global temperatures, resulting from the combustion of fossil fuels and the accumulation of greenhouse gases (GHGs), continues to destabilize all ecosystems worldwide. Although annual emissions must be halved by 2030 and reach net zero by 2050 to limit some of the most catastrophic impacts associated with a warming planet, the world's efforts to curb GHG emissions fall short of the commitments made in the 2015 Paris Agreement. To this effect, July 2021 was recently declared the hottest month ever recorded in 142 years. The ramifications of these changes for global temperatures are complex and further promote outdoor air pollution, pollen exposure, and extreme weather events. Besides worsening respiratory health, air pollution promotes atopy and susceptibility to infections. The effects of GHGs on pollen affect the frequency and severity of asthma and allergic rhinitis. Changes in temperature, air pollution, and extreme weather events exert adverse multisystemic health effects and disproportionally affect disadvantaged and vulnerable populations. This review article is an update for allergists and immunologists about the health impacts of climate change that are already evident in our daily practices. It is also a call to action and advocacy, including to integrate climate change-related mitigation, education, and adaptation measures to protect our patients and avert further injury to our planet.