Tag: climate change

Categories : Environmental EffectsTags :

Climate Anomalies may Play a Major Role in Driving Cholera Pandemics

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Global climate change could create more opportunities for rise and spread of new cholera strains

Scanning electron micrograph image of cholera bacteria.

New research suggests that an El Niño event may have aided the establishment and spread of a novel cholera strain during an early 20th-century pandemic, supporting the idea that climate anomalies could create opportunities for the emergence of new cholera strains. Xavier Rodo of Instituto de Salud Global de Barcelona, Spain, and colleagues present these findings in the open-access journal PLOS Neglected Tropical Diseases.

Since 1961, more than 1 million people worldwide have died in an ongoing cholera pandemic, the seventh cholera pandemic to have occurred since 1817. The drivers of past cholera pandemics have been unclear, but one hypothesis holds that anomalous climate conditions may act synergistically with genetic changes of Vibrio cholerae—the bacterium that causes the disease—to facilitate the spread and dominance of new strains.

To help clarify potential links between climate and cholera, Rodo and colleagues applied a variety of statistical and computational tools to historical records of climate conditions and cholera deaths in various regions of former British India during the sixth cholera pandemic, which lasted from 1899 to 1923. They also compared past conditions with climate and cholera data for the ongoing pandemic.

This analysis revealed that anomalous patterns of cholera deaths from 1904 to 1907 occurred alongside out-of-the-ordinary seasonal temperatures and rainfall levels associated with an El Niño event; the timing of these occurrences correlates with the establishment of a new invasive strain during the sixth pandemic. In addition, these historical climate conditions show similarities to strong El Niño events that have been associated with cholera strain changes during the ongoing pandemic.

These findings support the possibility that anomalous climate events could help facilitate the establishment and spread of new cholera strains.

The researchers then explored future possibilities for climate-facilitated emergence of new cholera strains using standard climate prediction models. They found that climate change-driven increases in climate variability and extremes could boost the chances of emergence of novel strains through the end of the current century.

Meanwhile, to deepen understanding of this deadly disease, the scientists call for further research focused on the interplay of cholera evolution and climate anomalies.

Dr Rodó and co-author Dr Mercedes Pascual summarise: “Variation in climate conditions or the evolutionary change of a pathogen can be important drivers of major epidemics and pandemics. But these two drivers are typically considered separately in studies seeking to explain the emergence of unusually large outbreaks…here, we present indirect evidence that the two can act together to synergistically underlie the establishment and widespread transmission of a new strain.”

Provided by PLOS

Categories : Environmental EffectsTags :

Study Tallies Heatwave Deaths over Recent Decades

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Photo by Fandy Much

Between 1990 and 2019, more than 150 000 deaths around the globe were associated with heatwaves each year, according to a new study published May 14 in PLOS Medicine by Yuming Guo of Monash University, Australia, and colleagues.

Heatwaves, periods of extremely high ambient temperature that last for a few days, can impose overwhelming thermal stress on the human body.

Studies have previously quantified the effect of individual heatwaves on excess deaths in local areas, but have not compared these statistics around the globe over such a prolonged period.

In the new study, researchers used data from the Multi-Country Multi-City (MCC) Collaborative Research Network that included daily deaths and temperatures from 750 locations across 43 countries.

With the MCC data, the researchers estimated excess heatwave deaths around the world spanning 1990 to 2019 and mapped the variance in these deaths across continents.

During the warm seasons from 1990 to 2019, heatwave-related excess deaths accounted for 153 078 deaths per year, a total of 236 deaths per 10 million residents or 1% of global deaths.

While Asia had the highest number of estimated deaths, Europe had the highest population-adjusted rate, at 655 deaths per 10 million residents.

A substantial burden of estimated deaths was seen in southern and eastern Europe as well as the area between Northern Africa, the Arabian Peninsula and Southern Asia.

At the national level, Greece, Malta, and Italy had the highest excess death ratios.

Overall, the largest estimated rates of heatwaves deaths were seen in areas with dry climates and lower-middle incomes.

Understanding the regional disparity of heatwave-related mortality is key to planning local adaptation and risk management towards climate change.

“Heatwaves are associated with substantial mortality burden that varies spatiotemporally over the globe in the past 30 years,” the authors say.

“These findings indicate the potential benefit of government actions to enhance health sector adaptation and resilience, accounting for inequalities across communities.”

The authors add, “In the context of climate change, it is crucial to address the unequal impacts of heatwaves on human health. This necessitates a comprehensive approach that not only tackles immediate health risks during heatwaves but also implements long-term strategies to minimize vulnerability and inequality. The strategies include: climate change mitigation policy, heat action plans (e.g., heat early warning system), urban planning and green structure, social support program, healthcare and public health services, education awareness, and community engagement and participation.”

Provided by PLOS

Categories : Environmental EffectsTags :

Climate Change may Reduce Life Expectancy by Half a Year, Study Suggests

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UPDATE: Concerns have been raised about the source of the data used in the study. Details below.

On its own, a 1°C temperature rise might shave off about five months, with women and people in developing nations disproportionately affected.

Photo by Markus Spiske

The cost of climate change may be six months off the average human lifespan, according to a study published January 18, 2024, in the open-access journal PLOS Climate by Amit Roy from Shahjalal University of Science and Technology and The New School for Social Research, US.

Temperature and rainfall – two telltale signals of climate change – cause myriad public health concerns, from the acute and direct (eg, natural disasters like flooding and heat waves) to the indirect yet equally devastating (eg, respiratory and mental illnesses). While impacts like these are observable and well documented, existing research has not established a direct link between climate change and life expectancy.

To clarify this relationship, the author evaluated average temperature, rainfall, and life expectancy data from 191 countries from 1940-2020, using GDP per capita to control for drastic differences between countries.

In addition to measuring the isolated impacts of temperature and rainfall, the author designed a first-of-its-kind composite climate change index, which combines the two variables to gauge the overarching severity of climate change.

Results indicate that in isolation, a global temperature increase of 1°C  is associated with an average human life expectancy decrease of approximately 0.44 years, or about five months and one week. A 10-point increase in the composite climate change index – which accounts for both temperature and rainfall – is expected to decrease the average life expectancy by six months. Women and individuals in developing nations are disproportionately affected.

Beyond the results of this study, Dr Roy is hopeful that the composite climate change index will standardise the global conversation about climate change; become a usable metric for the nonscientific public; and encourage collaboration and even friendly competition among countries to combat the impacts of climate change.

Mitigating greenhouse gas emissions and adapting to a changing environment are of particular importance, the author says.

To complement this large-scale approach, the author suggests localised future studies that consider specific severe weather events (eg, wildfires, tsunamis, and floods), the impacts of which cannot be fully captured through analysing temperature and rainfall alone.

Dr Roy adds: “The global threat posed by climate change to the well-being of billions underscores the urgent need to address it as a public health crisis, as revealed by this study, emphasising that mitigation efforts to reduce greenhouse gas emissions and proactive initiatives are essential to safeguard life expectancy and protect the health of populations worldwide.”

IMPORTANT UPDATE: Following publication of the paper referenced below, concerns have been raised about the reliability of global mean annual temperature data that are discussed in the article and used in the study’s analyses. The source of these data is reported as [1] in the article’s Materials and methods section, and as [2] in the Fig 4 legend.

1. World Bank. The Climate Change Knowledge Portal (CCKP) 2023. The World Bank; 2023. https://climateknowledgeportal.worldbank.org/

2. Akhtar R, Palagiano C. Climate change and air pollution: an introduction. Climate Change and Air Pollution: The Impact on Human Health in Developed and Developing Countries. 2018:3–8.

PLOS Climate is looking into the concerns that have been raised. Meanwhile, readers are advised to interpret this article’s results with caution. You may direct any specific questions to onepress@plos.org. We apologise sincerely for the inconvenience and thank you for your understanding. 

Categories : Environmental EffectsTags :

Air Conditioning Kept Heat-related Deaths Down in Spain – for Those who Could Afford it

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Photo by Fandy Much

Air conditioning and heating systems have contributed considerably to reducing mortality linked to extreme temperatures in Spain, according to a new observational study. The findings, published in Environment International, provide valuable insights for designing policies to adapt to climate change.

Rising temperatures but lower mortality

Spain, like many parts of the world, has experienced rising temperatures in recent decades, with the average annual mean temperature increasing at an average rate of 0.36°C per decade.

The warming trend is even more pronounced in the summer months (0.40°C per decade). Surprisingly, this increase in temperature has coincided with a progressive reduction in mortality associated with heat.

In addition, cold-related mortality has also decreased.

“Understanding the factors that reduce susceptibility to extreme temperatures is crucial to inform health adaptation policies and to combat the negative effects of climate change,” says first author of the study, Hicham Achebak, researcher at ISGlobal and Inserm (France) and holder of a Marie Sklodowska-Curie Postdoctoral Fellowship from the European Commission.

Effective societal adaptations

In this study led by the Barcelona Institute for Global Health (ISGlobal), Achebak and colleagues analysed the demographic and socioeconomic factors behind the observed reduction in heat and cold-related mortality, despite rising temperatures.

They found that the increase in air conditioning (AC) prevalence in Spain was associated with a reduction in heat-related mortality, while the rise in heating prevalence was associated with a decrease in cold-related mortality.

Specifically, AC was found to be responsible for about 28.6% of the decline in deaths due to heat and 31.5% of the decrease in deaths due to extreme heat between the late 1980s and the early 2010s.

Heating systems contributed significantly, accounting for about 38.3% of the reduction in cold-related deaths and a substantial 50.8% decrease in extreme cold-related fatalities during the same period.

The decrease in mortality due to cold would have been larger had there not been a demographic shift towards a higher proportion of people aged over 65, who are more susceptible to cold temperatures.

The authors conclude that the reduction in heat-related mortality is largely the result of the country’s socioeconomic development over the study period, rather than specific interventions such as heat-wave warning systems.

Four decades of data

For the statistical analysis, the research team collected data on daily mortality (all causes) and weather (temperature and relative humidity) for 48 provinces in mainland Spain and the Balearic Islands, between January 1980 and December 2018.

These data were then linked to 14 indicators of context (demographic and socioeconomic variables such as housing, income and education) for these populations over the same period.

Implications for climate adaptation

The results of the study extend previous findings on heat-related mortality in Spain and underscore the importance of air conditioning and heating as effective adaptation measures to mitigate the effects of heat and cold.

“However, we observed large disparities in the presence of AC across provinces. AC is still unaffordable for many Spanish households,” says Achebak.

The authors also point out that the widespread use of AC could further contribute to global warming depending on the source of electricity generation, which is why other cooling strategies, such as expanding green and blue spaces in cities, are also needed.

“Our findings have important implications for the development of adaptation strategies to climate change. They also inform future projections of the impact of climate change on human health,” concludes Joan Ballester, ISGlobal researcher and study coordinator.

Source: Barcelona Institute for Global Health (ISGlobal)

Categories : Cardiovascular Disease Environmental EffectsTags :

Cardiovascular Risk from Extreme Hot and Cold Days

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Source: Pixabay CC0

Extremely hot and cold temperatures both increased the risk of death among people with cardiovascular diseases, such as ischaemic heart disease, stroke, heart failure and arrhythmia, according to new research published today in journal Circulation.

Among the cardiovascular diseases examined in this study, heart failure was linked to the highest excess deaths from extreme hot and cold temperatures.

“The decline in cardiovascular death rates since the 1960s is a huge public health success story as cardiologists identified and addressed individual risk factors such as tobacco, physical inactivity, Type 2 diabetes, high blood pressure and others. The current challenge now is the environment and what climate change might hold for us,” said Barrak Alahmad, MD, MPH, PhD, research fellow at Harvard University and Kuwait University.

Researchers analysed health data for more than 32 million cardiovascular deaths that occurred in 567 cities in 27 countries on 5 continents between 1979 and 2019.

Climate change is associated with substantial swings in extreme hot and cold temperatures, so the researchers examined both in the current study. For this analysis, researchers compared cardiovascular deaths on the hottest and the coldest 2.5% of days for each city with cardiovascular deaths on the days that had optimal temperature (the temperature associated with the least rates of deaths) in the same city.

For every 1000 cardiovascular deaths, the researchers found that:

  • Extreme hot days accounted for 2.2 additional deaths.
  • Extreme cold days accounted for 9.1 additional deaths.
  • Of the types of heart diseases, the greatest number of additional deaths was found for people with heart failure (2.6 additional deaths on extreme hot days and 12.8 on extreme cold days).

“One in every 100 cardiovascular deaths may be attributed to extreme temperature days, and temperature effects were more pronounced when looking at heart failure deaths,” said Haitham Khraishah, MD, co-author of the study. “While we do not know the reason, this may be explained by the progressive nature of heart failure as a disease, rendering patients susceptible to temperature effects. This is an important finding since one out of four people with heart failure are readmitted to the hospital within 30 days of discharge, and only 20% of patients with heart failure survive 10 years after diagnosis.”

Researchers suggest targeted warning systems and advice for vulnerable people may be needed to prevent cardiovascular deaths during temperature extremes.

“We need to be on top of emerging environmental exposures. I call upon the professional cardiology organisations to commission guidelines and scientific statements on the intersection of extreme temperatures and cardiovascular health. In such statements, we may provide more direction to health care professionals, as well as identify clinical data gaps and future priorities for research,” Alahmad said.

The underrepresentation of data from South Asia, the Middle East and Africa limits the ability to apply these findings to make global estimates about the impact of extreme temperatures on cardiovascular deaths.

Source: American Heart Association

Categories : Diseases, Syndromes and Conditions Environmental EffectsTags :

Lassa Virus Endemic Area may Grow in Coming Decades

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Pictured are projections of the ecological niche suitability for Lassa virus based on climate models and other data. Credit: Scripps Research and University of Brussels

Analysing decades of environmental data associated with Lassa virus outbreaks, researchers projected that areas hospitable to Lassa virus spread may extend from West Africa into Central and East Africa in the next several decades. With this expansion and expected African population growth, the human population living in the areas where the virus should theoretically be able to circulate may rise by more than 600 million.

“Our analysis shows how climate, land use, and population changes in the next 50 years could dramatically increase the risk of Lassa fever in Africa,” says first author Raphaëlle Klitting, PhD, a postdoctoral researcher at Scripps Research during the study, which is published in Nature Communications.

Lassa virus is a zoonotic pathogen found in the Natal multimammate rat (Mastomys natalensis), most likely transmitted to humans via its droppings. While an estimated 80% of infections are mild or asymptomatic, the remaining cases are more severe, with signs and symptoms that can include haemorrhaging from the mouth and gut, hypotension, and potentially permanent hearing loss. Mortality rate in hospitalised patients can be up to 80%.

An estimated several hundred thousand infections occur each year, chiefly in Nigeria and several other West African countries. So far there is no approved vaccine or highly effective drug treatment.

Although the primary animal reservoir for Lassa virus is known, the virus spreads in only a subset of the areas where the animal is found. Thus, it is possible that environmental factors also help determine whether and where significant viral transmission can occur. In the study, the researchers developed an ‘ecological niche’ model of Lassa virus transmission, using environmental data at sites of known spread.

Combining the model with projections of climate and land-use changes in Africa in the next several decades, as well as the known range of the Natal multimammate rat, the researchers estimated the areas of Africa that could support Lassa virus transmission currently, and in the years 2030, 2050, and 2070. The projected current areas corresponded well to known endemic areas in West Africa, but the estimates for future decades suggested a vast expansion within and beyond West Africa.

“We found that several regions will likely become ecologically suitable for virus spread in Central Africa, including in Cameroon and the Democratic Republic of the Congo, and even in East Africa, in Uganda,” Klitting said.

Currently Africa’s population is undergoing rapid growth; the researchers therefore considered projections of this population growth for the areas of current and potential future Lassa virus circulation. They found that the number of people potentially exposed to the virus could increase from about 92 million today to 453 million by 2050, and 700 million by 2070 – an increase of over 600%.

More hopefully, the researchers examined the dynamics of the spread of Lassa virus using data on sequenced viral genomes sampled at various locations in West Africa and found that virus dispersal appeared to be slow. They concluded that, unless transmission dynamics change drastically in the new location where the virus circulates, the virus’s spread into new ecologically suitable areas in the coming decades may also be slow.

The authors say that the findings should inform African public health policies, for example, by encouraging officials to add Lassa virus to lists of viruses under epidemiologic surveillance in parts of Central and East Africa.

“With the ongoing climate change and increasing impact of human activities on the environment, further comprehensive studies of the ecology and spread of zoonotic and vector-borne diseases are needed to anticipate possible future changes in their distribution as well as their impact on public health,” said senior author Simon Dellicour, PhD, of the University of Brussels.

Source: Scripps Research Institute

Categories : Dentistry Environmental EffectsTags :

Study Gives Water Fluoridation a Green Thumbs Up

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Teeth and toothbrush
Photo by Diana Polekhina on Unsplash

For the first time, researchers have demonstrated the low environmental footprint of water fluoridation compared to other preventive measures for tooth decay while still retaining effectiveness. The study is published in the British Dental Journal.

Water fluoridation is regarded as one of the most significant public health interventions of the twentieth century. But as the climate crisis worsens, the contribution of healthcare and the prevention of disease to the crisis must be considered.

Influenced by this urgency, Trinity College Dublin researchers collaborating with University College London quantified the environmental impact of water fluoridation for an individual five year-old child over a one-year period and compared this to the traditional use of fluoride varnish and toothbrushing programmes, which take place in selected schools across the UK, and internationally.

Over 35% of the world’s population has access to water fluoridation, with studies showing significant reductions in dental caries. Whilst data on the clinical effectiveness and cost analysis of water fluoridation are available, there has been no data regarding its environmental impact up to now.

To quantify this impact, the research team performed a Life Cycle Assessment by carefully measuring the combined travel, the weight and amounts of all products and the processes involved in all three preventive programmes (toothbrushing, fluoride varnish programmes and water fluoridation). Data was inputted into specialised environmental software and the team used the Ecoinvent database, enabling them to calculate environmental outputs, including the carbon footprint, the amount of water used for each product and the amount of land use.

The results of the study, led by Brett Duane, Associate Professor in Dental Public Health at Trinity College, concluded that water fluoridation had the lowest environmental impact in all categories studied, and had the lowest disability-adjusted life years impact when compared to all other community-level caries prevention programmes. The study also found that water fluoridation gives the greatest return on investment.

Considering the balance between clinical effectiveness, cost effectiveness and environmental sustainability, researchers believe that water fluoridation should be the preventive intervention of choice.

This research strengthens the case internationally for water fluoridation programmes to reduce dental decay, especially in the most vulnerable populations.

Assoc Prof Duane said: “As the climate crisis starts to worsen, we need to find ways of preventing disease to reduce the environmental impact of our health systems. This research clearly demonstrates the low carbon impact of water fluoridation as an effective prevention tool.”

Source: Trinity College Dublin

Categories : Obstetrics & Gynaecology Pain ManagementTags :

Study Finds No Adverse Effects Denying Nitrous Oxide in Labour

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Photo by Jonathan Borba on Unsplash

Birthing women denied nitrous oxide(N20) to relieve labour pain as a result of the COVID pandemic received opioids instead, without any adverse outcomes for mother or child, according to a new study published in the Australian and New Zealand Journal of Obstetrics and Gynaecology. Some anaesthetists have also argued for reducing N20 use as it is a greenhouse gas.

The study, conducted at Lyell McEwin Hospital in Australia, looked at the impact of withholding nitrous oxide (N20), a decision adopted by many hospitals worldwide over fears of virus transmission from the aerosol-generating procedure.

Anaesthetist Professor Bernd Froessler and colleagues compared patient notes for all 243 women birthing at Lyell McEwin over a seven week period in March/April 2020, half of whom did not have access to N20.

They found that although opioid use “significantly increased” when N20 was withheld, there was no increase in epidural use and no change in labour duration, Caesarean section rates, birthing complications or newborn alertness.

Nitrous oxide is used by more than 50% of Australian women to relieve pain in labour, followed by epidurals (40%) and opioids (12%), according to the Australian Institute of Health and Welfare.

However, N20 represents 6% of global greenhouse gas emissions, with 1% due to medical use (ie, around 0.06% of total global warming is due to medical N20). This has led to a debate in medical circles whether it should be replaced with other methods of pain relief.

Many obstetricians argue that effective pain relief in childbirth should be the priority, particularly given the low percentage of emissions, but the Australian and New Zealand College of Anaesthetists has advocated for a reduction in N20 use in a bid to improve environmental sustainability in anaesthesia.

“Obviously no-one wants to deprive labouring women of adequate and easy pain relief but given there are other analgesic options, including epidurals and opioids, perhaps these could be considered,” said Prof Froessler.

UniSA statistician and researcher Dr Lan Kelly said that the findings should reassure women that pain relief besides N20 does not compromise their health or their baby’s.

However, in a recent Sydney Morning Herald article, principal midwifery officer at the Australian College of Midwives, Kellie Wilton, said mothers should not be made to feel guilty about their pain relief choices and suggested hospitals could introduce nitrous oxide destruction systems to allow for its ongoing use.

When nitrous oxide destruction systems were introduced in Swedish hospitals, the carbon footprint from the gas was halved.

Source: University of South Australia

Categories : Environmental EffectsTags :

Increase in Excessively Hot Nights Will Raise Mortality Rate

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Sleeping woman
Photo by Cottonbro on Pexels

With the number of excessively hot nights expected to double due to climate change, it is predicted that their associated mortality rate will rise by up to 60% by the end of the century, according to the latest research published in published in The Lancet Planetary Health.

Ambient heat during the night may interrupt the normal physiology of sleep, leading to immune system damage and a higher risk of cardiovascular disease, chronic illnesses, inflammation and mental health conditions. The average intensity of hot night events will nearly double by 2090, from 20.4℃ to 39.7℃ across 28 cities from east Asia, increasing the burden of disease due to excessive heat that disrupts normal sleeping patterns.

This is the first study to estimate the impact of hotter nights on climate change-related mortality risk. The findings show that the burden of mortality could be significantly higher than estimated by average daily temperature increase, suggesting that warming from climate change could have a troubling impact, even under restrictions from the Paris Climate Agreement.

“The risks of increasing temperature at night were frequently neglected,” said study co-author Yuqiang Zhang, PhD, a climate scientist in the Department of Environmental Sciences and Engineering at the Gillings School. “However, in our study, we found that the occurrences of hot night excess are projected to occur more rapidly than the daily mean temperature changes. The frequency and mean intensity of hot nights would increase more than 30% and 60% by the 2100s, respectively, compared with less than 20% increase for the daily mean temperature.”

The team estimated the mortality due to excess heat in 28 cities in China, South Korea and Japan between 1980 and 2015 and applied it to two climate change modelling scenarios that aligned with carbon-reduction scenarios adapted by the respective national governments.

Through this model, the team was able to estimate that between 2016 and 2100, the risk of death from excessively hot nights would increase nearly six-fold. This prediction is much higher than the mortality risk from daily average warming suggested by climate change models.

“From our study, we highlight that, in assessing the disease burden due to non-optimum temperature, governments and local policymakers should consider the extra health impacts of the disproportional intra-day temperature variations. A more complete health risk assessment of future climate change can help policymakers for better resource allocation and priority setting,” said Haidong Kan, PhD, who is a professor at Fudan University in China and the study’s corresponding author.

In this study, the authors also found that regional differences in temperature accounted for many of the variances in nighttime temperature, and areas with the lowest average temperature were projected to have the largest warming potential.

“To combat the health risk raised by the temperature increases from climate change, we should design efficient ways to help people adapt,” said Dr Zhang. “Locally, heat during the night should be taken into account when designing the future heatwave warning system, especially for vulnerable populations and low-income communities who may not be able to afford the additional expense of air conditioning. Also, stronger mitigation strategies, including global collaborations, should be considered to reduce future impacts of warming.”

Since the study only included 28 cities from three countries, Dr Zhang said that “extrapolation of these results to the whole East Asia region or other regions should be cautious. Currently, based on these findings, authors are trying to extend the analysis to a global dataset. Then we could have a global picture of the deadly nighttime heat on health under climate change scenarios.”

Source: University of North Carolina at Chapel Hill

Categories : Environmental EffectsTags :

Climate Change Will Increase Deaths Linked to Extreme Temperatures

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Heat cracked earth
Photo by Joshua Woroniecki on Unsplash

The death rate linked to extreme temperatures will increase significantly under global warming of 2°C, with even steeper rises for each degree of warming, finds a report published in Environmental Research Letters.

With a warming scenario of just 2°C from pre-industrial levels, temperature-related mortality in England and Wales during the hottest days of the year will increase by 42%. This means an increase from present-day levels of around 117 deaths per day, averaged over the 10 hottest days of the year, to around 166 deaths per day. The findings underline the importance of keeping global warming levels to below 2°C.

At current global warming levels of around 1.21°C there would be a slight decrease in temperature-related mortality in winter and a minimal net effect in summer, meaning that overall, at this level of warming we see a slight decrease in temperature-related mortality rate.

The researchers assessed the impact of climate change on mortality rates England and Wales, specifically risk from heat in summer and cold in winter. They found that as the global mean temperature increases, temperature-related mortality in summer will increase at a much faster, non-linear rate.

The rate of increase particularly speeds up at 2°C of warming, with a much higher risk appearing beyond 2.5°C. The researchers say that 3°C warming could lead to a 75% increase in mortality risk during heatwaves.

The relationship between temperature and mortality on a graph is roughly U-shaped, meaning that at extremely high temperatures, mortality risk increases sharply for each degree rise of daily mean temperature.

The rate in winter will continue to decrease, although this leaves out extreme weather events such as storms.

Lead author Dr Katty Huang said: “The increase in mortality risk under current warming levels is mainly notable during heatwaves, but with further warming, we would see risk rise on average summer days in addition to escalating risks during heatwaves. What this means is that we shouldn’t expect past trends of impact per degree of warming to apply in the future. One degree of global warming beyond 2°C would have a much more severe impact on health in England and Wales than one degree warming from pre-industrial levels, with implications for how the NHS can cope.”

In England and Wales, temperature is associated with around 9% of total population mortality, meaning that 9% of all deaths during 2021 could be associated with the temperature. Most of those deaths are related to the side effects of cold weather.

The team analysed the 2018 UK Climate Projections (UKCP18) with data on present-day temperature and mortality in order to predict changes in temperature-related mortality relative to degrees of global warming.

In order to isolate the effects of global warming on mortality risk, the researchers looked at the potential impact for the current population, and not attempting to predict future age distributions and medical conditions.

Project lead Professor Andrew Charlton-Perez said: “As the Intergovernmental Panel on Climate Change impacts report recently showed, it is increasingly common to examine how different levels of mean global warming raise the risk of significant harm to people and society. Our study shows that because death rates will go up significantly if countries experience very high temperatures, limiting the average global rise in temperatures is likely to have substantial benefits for the overall health of the population.”

Source: University College London