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The Phoenix City Council expanded an ordinance to add more protections for outdoor workers of city contractors. The measure, which impacts about 10,000 people, requires city contractors to maintain a heat safety plan that provides outdoor workers with sanitized cool drinking water, regular hydration breaks, access to shaded areas or air conditioning, air conditioning in vehicles with closed cabs, and training on heat illness and first aid…
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Kathleen Stinson
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Newswise — A team of University of Bristol experts are poised to join the 2023 United Nations Climate Change Conference, which will hold the world to account in addressing humanity’s most urgent and ambitious challenge.
The annual two-week summit, starting in the United Arab Emirates on Tuesday, 30 November, is set to deliver the first-ever global stocktake of progress in achieving key international climate targets to reduce carbon emissions and limit global warming.
Dr Matt Palmer, Associate Professor of Climate Science, is among a group of academics from the University of Bristol’s renowned Cabot Institute for the Environment, who will be attending to share their expertise and insights.
“The world community stands on the edge of a burning bridge: we must act faster to reduce emissions if we are to avoid devastating impacts of climate change on humans, the environment, and vital ecosystems,” Dr Palmer said.
“2023 is set to be the warmest year on record and saw a catalogue of unprecedented and damaging extreme climate events across the globe. Current emissions reduction pledges by nations fall well short of the 1.5C Paris Agreement warming target. Immediate concerted action is imperative to lessen future climate risks and this meeting is a crucial opportunity for the global community to review progress, recognise shortcomings, and commit to stepping up mitigation actions.”
Dr Palmer has been a lead author on the UN’s Intergovernmental Panel on Climate Change (IPCC) report, covering sea-level rise and ocean warming, and he will be presenting an event focused on the latest observations on climate change.
Wide-ranging experts in hot topics including climate change policy, emissions, climate modelling, adapting to a warming world, food systems, and ensuring the shift to a net zero economy is fair, are joining the gathering.
The conference will help harness joint global efforts on climate action and identify changes needed to bridge gaps preventing being on track to meet agreed goals.
Delivering climate resilient, net zero food systems is a major global challenge which will come under discussion.
Dr Pete Falloon, Associate Professor in Climate Resilient Food Systems, is attending in this capacity, leading an event in the UK Pavilion spanning partners and youth farmers from the Global North and South amongst others.
He said: “Droughts, flooding, high temperatures and rising sea levels are increasingly threatening the security and resilience of our food systems worldwide. Food systems are also a key part of the pathway to net zero, given they are responsible for around a third of global emissions. We critically need to transform our food systems so they are well adapted to climate change but also deliver on net zero goals.
“My hope is that by bringing together scientists, young farmers and policy makers together, we will use climate science and services as a platform to accelerate food system change, innovation and practice to reduce hunger and ensure a more sustainable future.”
Dr Katharina Richter, a specialist in decolonial environmental politics and equitable development, hopes negotiations will consolidate previous multilateral plans to help emerging economy countries have swift access to financing to mitigate and adapt to the climate crisis.
“This year, extreme weather events in Africa, including drought and flooding, are thought to have been exacerbated by climate change and, tragically, have killed more than 15,000 people already. To prevent further loss of life, it’s absolutely critical developing countries can access climate finance quickly and unconditionally,” Dr Richter said.
“I will therefore be watching closely to see how G77 and Alliance of Small Island States proposals are met by the international community, especially details on operationalising last year’s negotiation highlight: the Loss and Damage Fund.”
Technology and the transition to a green economy are further important areas to be negotiated.
“Rich and oil-producing countries must honour their emission-related responsibilities and commit to phasing out fossil fuels entirely. Clean energy technology will be key to replacing fossil fuels. Without commitments to demand-side reductions by rich nations, however, a business-as-usual energy transition will continue to create sacrifice zones in indigenous, biodiverse, and/or water scarce territories of the Global South,” Dr Richter added.
“I will therefore also be looking out for how green technology supply chains are addressed in the negotiations, including outcomes for developing countries where critical raw materials are extracted.”
Climate justice specialist Dr Alix Dietzel, who also attended last year, leads work to help ensure the journey towards net zero is fully inclusive and equitable.
Dr Dietzel said: “I’ll be interested to see who is able to attend and who will have their voices heard at the negotiations and whether this represents fair and equal decision making. Substantial commitments to mitigation targets, adaptation planning, and loss and damage funding are vital requirements of the just transition to climate change.
“I hope the global community rises to such pressing challenges and that pledges are fair to all those most affected by climate change, who may be under-represented.”
Incorporating the voice of Indigenous groups will play a pivotal role in realising such aspirations.
Dr Karen Tucker, an expert in the politics of Indigenous knowledge, added: “Indigenous peoples are some of the most knowledgeable actors in global climate politics. But this doesn’t mean their expertise or rights are always recognised in international negotiations.
“I’ll therefore be paying attention to the ways in which Indigenous peoples and Indigenous knowledges are incorporated into negotiations, particularly relating to land use and nature.”
Raising the ambition of climate policies by integrating cities in national climate policies could help deliver and step-up progress in meeting demanding targets.
Energy and climate policy specialist Dr Colin Nolden is hosting an official event, which highlights the latest research development and cross-sectoral policy recommendations for ramping up climate action at urban level. It has a specific focus on using Article 6 of the Paris Agreement to generate investment, especially in the context of climate clubs and alliances.
Dr Nolden said: “Article 6 of the Paris Agreement provides a mechanism not just for trading carbon credits but also for generating investment and lowering the cost of capital, ranging from district heating systems in the global north to clean cooking projects in the global south.”
“Climate clubs and alliances, meanwhile, can increase emission mitigation ambition among participating countries if they include cross-border investment and trading arrangements for carbon emission reductions generated using Article 6.
“If appropriate Article 6 market governance arrangements are agreed on at COP28, climate clubs and alliances, ideally spanning the Global North and South, have great potential to help implement effective and just net zero policies. I will be providing insights and pitching an idea on how to make this happen.”
University of Bristol student Katie Riley, who is in the final year of her degree in politics and international relations, will be joining as an observer.
The 21-year-old has been an environmental lobbyist for several years and recently published a book about experiences of youth in climate activism. At COP27 Katie was a UK communications delegate for the Future Leaders Network and this year she is on Generation Climate’s COP28 strategy delegation.
“I mainly started because I saw a space for change and loved engaging within my community. But international politics is exciting, especially within COP, so I’m pleased to be developing my involvement more widely,” Katie said.
“I also think it’s necessary for as many young people to have a platform within big conferences like this, as our generation will be most affected by the climate crises.”
The University has been working closely with Mayor Marvin Rees and Bristol City Council to help the city achieve a just transition towards a more sustainable economy. This includes a shared commitment to deliver the UN’s Sustainable Development Goals (SDGs), which aim to deliver better health, education, economic growth, and equality while also tackling climate change.
Notes to editors
Here’s a full overview of experts from the University of Bristol Cabot Institute for the Environment who can help with media requests in the run up to and during COP28: https://environment.blogs.bristol.ac.uk/2023/10/30/are-you-a-journalist-looking-for-climate-experts-for-cop28-weve-got-you-covered/
For more information and to request an expert comment and/or media interview, please contact Victoria Tagg, University of Bristol Media & PR Manager (Research): [email protected]
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Humanity is on course to transgress multiple global “tipping points” that could lead to irreversible instability or the complete collapse of ecological and institutional systems, a United Nations report warned Wednesday.
The third annual Interconnected Disaster Risks report from the U.N. University’s Institute for Environment and Human Security in Bonn, Germany, found that drastic changes will occur if urgent actions are not taken around six moments when sociological systems are no longer able to buffer risks.
The tipping points include several issues that California is confronting head-on — groundwater depletion, rising insurance costs, extreme heat and species extinction. The other threats are melting glaciers and space debris. According to U.N. officials, “when one system tips, other systems may also be pushed over the edge.”
“The very practical consequence will be that much more people will live under very precarious conditions — so loss of life, loss of livelihood and loss of opportunities,” said Zita Sebesvari, deputy director at the U.N. University Institute and one of the lead authors of the report. “It does have cascading impacts.”
The tipping points are growing increasingly interconnected through global supply chains, trade and communications networks, the report says. Those links offer greater opportunity for cooperation, “but also expose us to greater risks and unpleasant surprises” from ripple effects when one element begins to crumble.
An aerial view of the Port of Long Beach in February.
(Allen J. Schaben / Los Angeles Times)
“We are moving perilously close to the brink of multiple risk tipping points,” the report says. The good news is that it is not too late to make changes to avoid or at least delay the worst possible outcomes.
According to the analysis, groundwater depletion is one problem with major potential consequences. Roughly 2 billion people worldwide rely on groundwater as a primary source, but 21 of the world’s 37 largest aquifers are already being depleted faster than they can be replenished.
The tipping point for groundwater occurs when existing wells are not sufficient to reach the water table and access to groundwater becomes prohibitively expensive or problematic, the report says.
By that criterion, California is already on the cliff’s edge, as industrial agriculture and other uses are sapping supplies so quickly that more than 5,700 wells are currently dry and thousands more are at risk, according to state data. Groundwater depletion is also contributing to land subsidence, with some areas sinking as quickly as 1 foot per year.
At the end of the Coachella Canal, Colorado River water is routed to ponds that are designed to replenish groundwater.
(Carolyn Cole / Los Angeles Times)
Surpassing the tipping point could have dire consequences not just for local communities but for global food production, the report says. In California, officials are attempting to rectify this through the Sustainable Groundwater Management Act — a landmark piece of legislation that seeks to limit groundwater use, but with a timeline for implementation that could take decades.
“The long-term vision is to balance out the infiltration and recharging of groundwater with the taking out of groundwater,” Sebesvari said. “At least California does have a management plan, which is quite outstanding, I must say, because many places in this group don’t have that.”
But groundwater is only one of a handful of tipping points facing California and the globe. Unbearable heat driven by climate change is also an element of concern. The U.N. report estimates that roughly 500,000 excess deaths were attributed to extreme heat annually between 2000 and 2019, and that 30% of the global population is exposed to deadly heat conditions at least 20 days per year.
This year, the planet experienced its hottest summer on record, with global surface temperatures in August 2.25 degrees above the 20th century average. Simultaneous heat waves plagued Europe, China and the Southwest, where Phoenix experienced a record 31 consecutive days of temperatures at or above 110 degrees.
Sebesvari said extreme heat is one area where adaptation, as opposed to mitigation, may be warranted, since places such as Pakistan and parts of India are regularly surpassing the threshold for livability. In Los Angeles, officials are already exploring adaptation measures such as the installation of cool pavement, the planting of trees and a possible city mandate requiring air conditioning in all rental units.
Meanwhile, Californians continue to face the looming threat of un-insurability. That tipping point will occur when the cost of hazards becomes so high that insurance is no longer accessible or affordable, leaving people without an economic safety net when disaster strikes.
Flames erupt from a home in Laguna Niguel, where a May 2022 brush fire spread to an oceanside neighborhood.
(Wally Skalij / Los Angeles Times)
California came perilously close to that point earlier this year when insurance giants State Farm, Allstate and USAA pulled out of the state, citing rising wildfire risks and other mounting threats.
In September, Insurance Commissioner Ricardo Lara struck a deal to bring them back to California in exchange for a number of concessions, including the possibility of much higher premiums.
But the fix only served to underscore a burgeoning global crisis spurred by a sevenfold increase in the cost of disasters globally since the 1970s, according to the U.N. report. Last year, global economic losses from disasters totaled $313 billion.
The report arrives just weeks ahead of COP28 — an annual international climate conference that will be held in Dubai — and in the wake of the scorching summer that spurred dire warnings from scientists about the worsening effects of climate change.
It also echoes a major study published in September in the journal Science Advances, which found that the planet has crossed six of nine boundaries that suggest “Earth is now well outside of the safe operating space for humanity.”
While the U.N. report is largely focused on irreversible socioeconomic tipping points, the Science Advances study examined planetary systems such as ozone depletion and ocean acidification that are mostly reversible, but could alter living conditions on Earth if pushed far enough, according to Katherine Richardson, the study’s lead author.
Though the findings are distinct, Richardson said she agreed with the U.N.’s assessment. Its framework is “likely a better way to communicate the urgency of the existential crisis we have created for ourselves as it can directly be translated to people’s immediate condition and wealth,” she said.
In addition to groundwater depletion, rising insurance costs and extreme heat, the U.N. report highlights melting glaciers, ecosystem collapse and space debris as systems nearing precipices.
Wildlife officials conduct a count of dead fall-run Chinook salmon in the Sacramento River in January 2022.
(Allen J. Schaben / Los Angeles Times)
This summer, global sea ice coverage reached a record low — about 550,000 square miles less than the previous low set in August 2019, according to the National Oceanic and Atmospheric Administration. The continued melting of ice and glaciers driven by human-caused global warming will have negative effects on freshwater availability for humans and other species, the U.N. report says.
Ecosystem collapse is similarly underway, with accelerating extinctions driven by land use changes, climate change, pollution and invasive species.
More than 400 vertebrate species have gone extinct in the last 100 years, and nearly a million plant and animal species are currently threatened with extinction, the U.N. report says. That includes several California species such as Delta smelt, Chinook salmon, California condors, gray wolves and mountain lions. California trees are also dying at a record pace due to drought, wildfires, bark beetle infestation and other threats.
Earlier this month, the U.S. Fish and Wildlife Service removed 21 species from the U.S. Endangered Species Act due to extinction, including a fruit bat, two types of fish, eight types of mussels and 10 birds.
Finally, there is space debris — the only non-terrestrial threat outlined in the report. There are roughly 8,300 satellites in orbit and nearly 35,000 other tracked objects circling the Earth. Many are used for global communications, early warning systems, weather monitoring and other purposes that help connect people and reduce disaster risk.
A tipping point will occur when there is such a critical density of objects in orbit that one collision could set off a chain reaction and take those systems offline, the report says.
Though there has been a push for space to be seen as a “global commons,” no such international agreement has been reached. (In fact, then-President Trump in 2020 issued a statement saying that the United States “does not view space as a global commons.”)
While each tipping point is a potential threat in and of itself, the interconnection between them is key to the report, according to Jack O’Connor, senior expert at the U.N. University Institute and one of the lead authors. He likened the systems to towers of wooden blocks, like in the game Jenga.
“We and our behaviors are slowly removing pieces one by one from the base, until at some point the system can no longer cope with the growing instability and it collapses,” O’Connor told reporters Wednesday.
He and other officials said their hope is that policymakers, world leaders and the public will factor the findings into decisions moving forward in order to prevent a worst-case scenario. It is important to consider the rights and opportunities of future generations in current planning processes, they said.
“Our report is not saying that we are doomed to cross these risk tipping points, but rather it’s supposed to empower us to see the paths that we have ahead of us, and to take steps toward a better future,” O’Connor said. “We are still driving the car. And we still have a choice.”
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Hayley Smith
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Newswise — Scientists ran simulations on the UK’s national supercomputer to investigate ocean-driven melting of the West Antarctic Ice Sheet: how much is unavoidable and must be adapted to, and how much melting the international community still has control over through reduction of greenhouse gas emissions.
Taking into account climate variability like El Niño, they found no significant difference between mid-range emissions scenarios and the most ambitious targets of the 2015 Paris Agreement. Even under a best-case scenario of 1.5°C global temperature rise, melting will increase three times faster than during the 20th century.
The West Antarctic Ice Sheet is losing ice and is Antarctica’s largest contributor to sea-level rise. Previous modelling finds this loss could be driven by warming of the Southern Ocean, particularly the Amundsen Sea region. Collectively the West Antarctic Ice Sheet contains enough ice to raise global mean sea-level by up to five metres.
Around the world millions of people live near the coast and these communities will be greatly impacted by sea level rise. A better understanding of the future changes will allow policymakers to plan ahead and adapt more readily.
Lead author Dr Kaitlin Naughten, a researcher at the British Antarctic Survey says:
“It looks like we’ve lost control of melting of the West Antarctic Ice Sheet. If we wanted to preserve it in its historical state, we would have needed action on climate change decades ago. The bright side is that by recognising this situation in advance, the world will have more time to adapt to the sea level rise that’s coming. If you need to abandon or substantially re-engineer a coastal region, having 50 years lead time is going to make all the difference.”
The team simulated four future scenarios of the 21st century, plus one historical scenario of the 20th century. The future scenarios either stabilised global temperature rise at the targets set out by the Paris Agreement, 1.5°C and 2°C, or followed standard scenarios for medium and high carbon emissions.
All scenarios resulted in significant and widespread future warming of the Amundsen Sea and increased melting of its ice-shelves. The three lower-range scenarios followed nearly identical pathways over the 21st century. Even under the best-case scenario, warming of the Amundsen Sea sped up by about a factor of three, and melting of the floating ice shelves which stabilise the inland glaciers followed, though it did begin to flatten by the end of the century.
The worst-case scenario had more ice shelf melting than the others, but only after 2045. The authors heed that this high fossil fuel scenario, where emissions increase rapidly, is considered unlikely to occur.
This study presents sobering future projections of Amundsen Sea ice-shelf melting but does not undermine the importance of mitigation in limiting the impacts of climate change.
Naughten cautions: “We must not stop working to reduce our dependence on fossil fuels. What we do now will help to slow the rate of sea level rise in the long term. The slower the sea level changes, the easier it will be for governments and society to adapt to, even if it can’t be stopped.”
Unavoidable future increase in West Antarctic ice-shelf melting over the 21st century by Kaitlin Naughten (BAS), Paul Holland (BAS), Jan De Rydt (Northumbria) is published in the journal Nature Climate Change.
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Newswise — RUDN University ecologists and colleagues from Algeria, Greece, Egypt, and Russia have determined the scale and causes of desertification in northern Algeria. The analysis was carried out using satellite images in different ranges. Over six years, the area of usable land has decreased by 1.5-9 times. The results were published in The Egyptian Journal of Remote Sensing and Space Science.
The loss of the biological function of land is called desertification. The composition of the soil changes, the sand content increases, and the vegetation becomes poorer. Such lands can no longer be cultivated; livestock cannot graze on them. There are several regions on Earth with a high risk of desertification. One of them is North Africa. Remote monitoring using satellite images helps track desertification. However, different soil types may be difficult to distinguish by satellite data if they have high sand content. It is important to interpret the images correctly. RUDN University ecologists and colleagues from Algeria, Greece, Egypt, and Russia determined which satellite data is best suited for determining soil composition.
“There is a problem with the similarity of reflectivity between different soils with high sand content. These are, for example, sand, loamy sand and clay. Therefore, it is necessary to develop more accurate spectral indicators to distinguish soil structures easily,” said Dmitry Kucher, Ph.D., head of the Scientific Center for Research, Integrated Design and Development of Urban and Agricultural Development of the RUDN University.
Ecologists conducted the study in the Nemamcha region in northern Algeria. This region has undergone rapid desertification. To trace spatiotemporal changes in the topsoil, RUDN University ecologists used satellite images from 2013 and 2019 and soil samples. Then they calculated the correlation between these data and analyzed the possible causes of desertification.
It turned out that blue and near-infrared images are best suited for determining the proportion of sand and clay. Using them, RUDN University ecologists built a regression model determing the composition of the soil with sufficient accuracy—the coefficient of determination (an indicator of model quality) reached 89%.
Changes in soil composition between 2013 and 2019 indicate noticable desertification: the share of land suitable for agriculture in the region fell from 31% in 2013 to 4% in 2019, and the grazing area fell from 21% to 13%. Ecologists also named the main cause of desertification in this area – aeolian processes, that is, wind erosion and the application of sand by the wind. They turn out to be strong, among other things, because of human activity – too intensive cattle breeding and agriculture.
“We found a dominant role for aeolian processes, which are exacerbated by low topography, overgrazing, climate change, and over-intensive agriculture. We recommend investigating the protective role of dry grasslands and desert shrublands against erosion and restoring degraded lands. We urge legislators to implement remote monitoring strategies and restore vegetation to combat desertification,” said Dmitry Kucher, Ph.D., Head of the Scientific Center for Research, Integrated Design and Development of Urban and Agriculture at RUDN University.
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Newswise — This summer, the planet is suffering from unprecedented heat waves and heavy rainfalls. Developing renewable energy and expanding associated infrastructure has become an essential survival strategy to ensure the sustainability of the planet in crisis, but it has obvious limitations due to the volatility of electricity production, which relies on uncertain variables like labile weather conditions. For this reason, the demand for energy storage systems (ESS) that can store and supply electricity as needed is ever-increasing, but lithium-ion batteries (LIBs) currently employed in ESS are not only highly expensive, but also prone to potential fire, so there is an urgent need to develop cheaper and safer alternatives.
A research team led by Dr. Oh, Si Hyoung of the Energy Storage Research Center at the Korea Institute of Science and Technology (KIST) has developed a highly safe aqueous rechargeable battery that can offer a timely substitute that meets the cost and safety needs. Despite of lower energy density achievable, aqueous rechargeable batteries have a significant economic advantage as the cost of raw materials is much lower than LIBs. However, inveterate hydrogen gas generated from parasitic water decomposition causes a gradual rise in internal pressure and eventual depletion of the electrolyte, which poses a sizeable threat on the battery safety, making commercialization difficult.
Until now, researchers have often tried to evade this issue by installing a surface protection layer that minimizes the contact area between the metal anode and the electrolyte. However, the corrosion of the metal anode and accompanying decomposition of water in the electrolyte is inevitable in most cases, and incessant accumulation of hydrogen gas can cause a potential detonation in long-term operation.
To cope with this critical issue, the research team has developed a composite catalyst consisting of manganese dioxide and palladium, which is capable of automatically converting hydrogen gas generated inside the cell into water, ensuring both the performance and safety of the cell. Manganese dioxide does not react with hydrogen gas under normal circumstances, but when a small amount of palladium is added, hydrogen is readily absorbed by the catalysts, being regenerated into water. In the prototype cell loaded with the newly developed catalysts, the internal pressure of the cell was maintained well below the safety limit, and no electrolyte depletion was observed.
The results of this research effectively solves one of the most concerning safety issues in the aqueous batteries, making a major stride towards commercial application to ESS in the future. Replacing LIBs by cheaper and safer aqueous batteries can even trigger a rapid growth of global market for ESS.
“This technology pertains to a customized safety strategy for aqueous rechargeable batteries, based on the built-in active safety mechanism, through which risk factors are automatically controlled.” said Dr. Oh, Si Hyoung of KIST. “Moreover, it can be applied to various industrial facilities where hydrogen gas leakage is one of major safety concerns (for instance, hydrogen gas station, nuclear power plant etc) to protect public safety.”
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KIST was established in 1966 as the first government-funded research institute in Korea. KIST now strives to solve national and social challenges and secure growth engines through leading and innovative research. For more information, please visit KIST’s website at https://eng.kist.re.kr/
This research was supported by the Ministry of Science and ICT (Minister Lee Jong-ho) through the Nano Future Material Source Technology Development Project and the Mid-Career Researcher Support Project, and the results were published on August 1 in the international journal Energy Storage Materials (IF 20.4).
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As the chair of the department of obstetrics and gynecology at UT Southwestern Medicine, Catherine Spong is used to seeing a lot of baby bumps. But through her decades of practice, she’s been fascinated by a different kind of bump: Year after year after year, she and her colleagues deliver a deluge of babies from June through September, as much as a 10 percent increase in monthly rates over what they see from February through April. “We call it the summer surge,” Spong told me.
Her hospital isn’t alone in this trend. For decades, demographers have documented a lift in American births in late summer, and a trough in the spring. I see it myself in my own corner of the world: In the past several weeks, the hospital across the street from me has become a revolving door of new parents and infants. When David Lam, an economist at the University of Michigan who helped pioneer several early U.S. studies on seasonal patterns of fertility, first analyzed his data decades ago, “we were kind of surprised how big it was,” he told me. Compare the peak of some years to their nadir, he said, and it was almost like looking at the Baby Boom squished down into 12 months.
Birth seasonality has been documented since the 1820s, if not earlier. But despite generations of study, we still don’t fully understand the reasons it exists, or why it differs so drastically among even neighboring countries. Teasing apart the contributions of biology and behavior to seasonality is messy because of the many factors involved, says Micaela Martinez, the director of environmental health at the nonprofit WE ACT for Environmental Justice, who has been studying seasonality for years. And even while researchers try to track it, the calendar of human fertility has been changing. As our species has grown more industrialized, claimed more agency over reproduction, and reshaped the climate we are living in, seasonality, in many places, is shifting or weakening.
There is no doubt that a big part of human birth seasonality is behavioral. People have more sex when they have more free time; they have less sex when they’re overworked or overheated or stressed. Certain holidays have long been known to carry this effect: In parts of the Western world with a heavy Christian presence, baby boomlets fall roughly nine months after Christmas; the same patterns have been spotted with Spring Festival and Lunar New Year in certain Chinese communities. (Why these holidays strike such a note, and not others, isn’t entirely clear, experts told me.)
In addition to free time, family-focused celebrations probably help set the mood, Luis Rocha, a systems scientist at Binghamton University, told me. Cold weather might help people get snuggly around Christmastime, too, but it’s not necessary; Rocha’s studies and others have shown the so-called Christmas effect in southern-hemisphere countries as well. No matter whether Christmas falls in the winter or summer, around the end of December, Google searches for sex skyrocket and people report more sexual activity on health-tracking apps. In a few countries, including the U.S., condom sales rise too.
But cultural norms have never been able to explain everything about the Homo sapiens birth calendar. “It’s pretty common for mammals to have a specific breeding season” dictated by all sorts of environmental cues, Martinez told me. Deer, for instance, mate in the fall, triggered by the shortening length of daylight, effectively scheduling their fawns to be born in the spring; horses, whose gestations are longer, breed as the days lengthen in the spring and into summer, so they can foal the following year.
Humans, of course, aren’t horses or deer. Our closest relatives among primates “are much more flexible” about when they mate, Élise Huchard, a behavioral ecologist at the University of Montpellier, in France, told me. But those apes are not immune to their surroundings, and neither are we. All sorts of hormones in the human body, including reproductive ones, wax and wane with the seasons. Researchers in the United States and Australia have found that couples hoping to conceive via in vitro fertilization have a higher chance of success if the eggs are retrieved during the summer. At the same time, summer conceptions appear to be less common, or less successfully carried to term, in some countries, a trend that sharpens at lower latitudes and, Lam told me, during hotter years. The subsequent spring lulls may be explained in part by heat waves dissuading people from sex. But Alan Barreca, an economist at UCLA, suspects that ultrahigh temperatures may also physiologically compromise fertility, potentially by affecting factors such as sperm quantity and quality, ovulation success, or the likelihood of early fetal loss.
No matter its exact drivers, seasonality is clearly weakening in many countries, Martinez told me; in some parts of the world, it may be entirely gone. The change isn’t uniform or entirely understood, but it’s probably to some extent a product of just how much human lifestyles have changed. In many communities that have historically planted and harvested their own food, people may have been more disinclined to, and less physically able to, conceive a child when labor demands were high or when crops were scarce—trends that are still prominent in certain countries today. People in industrial and high-income areas of the modern world, though, are more shielded from those stressors and others, in ways that may even out the annual birth schedule, Kathryn Grace, a geographer at the University of Minnesota, told me. The heat-driven dip in America’s spring births, for instance, has softened substantially in recent decades, likely due in part to increased access to air-conditioning, Lam said. And as certain populations get more relaxed about religion, the cultural drivers of birth times may be easing up, too, several experts told me. Sweden, for example, appears to have lost the “Christmas effect” of December sex boosting September births.
Advances in contraception and fertility treatments have also put much more of fertility under personal control. People in well-resourced parts of the world can now, to a decent degree, realize their preferences for when they want their babies to be born. In Sweden, parents seem to avoid November and December deliveries because that would make their child among the youngest in their grade (which carries a stereotype of potentially having major impacts on their behavioral health, social skills, academics, and athletic success). In the U.S., people have reported preferring to give birth in the spring; there’s also a tax incentive to deliver early-winter babies before January 1, says Neel Shah, the chief medical officer of Maven Clinic, a women’s health and fertility clinic in New York.
Humans aren’t yet, and never will be, completely divorced from the influences of our surroundings. We are also constantly altering the environment in which we reproduce—which could, in turn, change the implications of being born during a particular season. Births are not only more common at certain times of the year; they can also be riskier, because of the seasonal perils posed to fetuses and newborns, Mary-Alice Doyle, a social-policy researcher at the London School of Economics, told me. Babies born during summer may be at higher risk of asthma, for instance—a trend that’s likely to get only stronger as heat waves, wildfires, and air pollution become more routine during the year’s hottest months.
The way we manage infectious disease matters too. Being born shortly after the peak of flu season—typically winter, in temperate parts of the world—can also be dangerous: Infections during pregnancy have been linked to lower birth weight, preterm delivery, even an increased likelihood of the baby developing certain mental-health issues later on. Comparable concerns exist in the tropics, where mosquitoes, carrying birth-defect-causing viruses such as dengue or Zika, can wax and wane with the rainy season. The more humans allow pathogens to spill over from wildlife and spread, the bigger these effects are likely to be.
Children born in the spring—in many countries, a more sparsely populated group—tend to be healthier on several metrics, Barreca told me. It’s possible that they’re able to “thread the needle,” he said, between the perils of flu in winter and extreme heat in summer. But these infants might also thrive because they are born to families with more socioeconomic privilege, who could afford to beat the heat that might have compromised other conceptions. As heat waves become more intense and frequent, people without access to air-conditioning might have an even harder time getting pregnant in the summer.
The point of all this isn’t that there is a right or wrong time of year to be born, Grace told me. If seasonality will continue to have any sway over when we conceive and give birth, health-care systems and public-health experts might be able to use that knowledge to improve outcomes, shuttling resources to maternity wards and childhood-vaccination clinics, for instance, during the months they might be in highest demand.
Humans may never have had as strict a breeding season as horses and deer. But the fact that so many people can now deliver safely throughout the year is a testament to our ingenuity—and to our sometimes-inadvertent power to reshape the world we live in. We have, without always meaning to, altered a fundamental aspect of human reproduction. And we’re still not done changing it.
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Katherine J. Wu
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Newswise — Philadelphia, August 22, 2023 – Researchers report a statistically significant and clinically important increase in heat related illnesses among patients at US Department of Veteran Affairs (VA) health facilities across the United States between 2002 and 2019. The study, which appears in The Journal of Climate Change and Health, published by Elsevier, documents far-reaching negative consequences of extreme-weather.
Lead investigator Thomas F. Osborne, MD, VA Palo Alto Healthcare System and Stanford University School of Medicine, commented, “Our goal is to provide the best care for our patients, and understanding health risk is critical to our mission. Our team has incredible analytics staff, which, combined with expertise from partners at the CDC, has empowered us to uncover important insights. The data are a call to action as they expose a steady increase in the incidence of severe heat related illnesses in our US Veteran patient population. Although no one is immune from this danger, those who are traditionally the most vulnerable face the greatest risk of heat related illnesses.”
Not surprisingly, the study found that specific groups of patients, such as those with existing health conditions and within specific ethnic groups, experienced higher rates of heat related illness.
Co-investigator Zachary Veigulis, MS, US Department of Veterans Affairs, Palo Alto Healthcare System, and Department of Business Analytics, Tippie College of Business, University of Iowa, noted, “The extensive electronic health records from the VA, the US’s largest healthcare system, made it possible to understand the scope and scale of the growing danger and predict and identify individuals at greatest risk so we can target interventions.”
While every state had residents that suffered heat related illnesses during the study period, the state-by-state numbers did not mirror geographic climate trends, possibly because the traditionally warmer states had already adopted policies, procedures, and practices to mitigate the health consequences of environmental heat. Another finding that suggested interventions reduce the growing health risk was the declining rate of heat related illness for homeless US Veterans in the second half of the study’s timeframe, a period after the launch and expansion of additional VA homeless health and wellness programs.
Dr. Osborne added, “This assessment represents a critical first step in understanding the challenge, which is required to inform optimal care and prevention strategies. However, there is much more work to be done. While the physical impact of environmental heat is critically important, it is only one of many climate-related health dangers. Climate change-related health risks such as the unprecedented spread of infectious disease, wildfires, migration, infrastructure damage, as well as food and water insecurity are now central issues of our time. Urgent collaborative action is required to avoid additional suffering.”
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Phoenix is writhing.
For the past 31 days, temperatures in the desert city have reached or exceeded 110 degrees, sizzling the previous record of 18 days set in June 1974.
The historic heatwave blasted the Southwest in late June, stretching from Texas into California’s desert. But it’s been the city of Phoenix that’s felt it the worse.
The heat is taxing hospitals, the city’s infrastructure, and residents’ patience.
“It’s wearing on people,” Kevin Conboy, a physician assistant with Circle the City told the New York Times. “Everyone’s temperatures are hovering at 100. Everyone is complaining of feeling so fatigued and tired.”
But some parts of the city aren’t getting so hot, thanks partly to a new cool pavement technology designed to reflect the sun’s rays back into the atmosphere rather than absorb the heat as dark asphalt does.
The city has painted over 100 miles of road with this coating material, according to the city’s website. City officials said cool pavements “had an average surface temperature 10.5 to 12 degrees lower than traditional asphalt at noon and during the afternoon hours.”
The website also says that the nighttime air temperatures over cool pavement are half a degree lower than on non-coated surfaces.
Related: No More AC? Scientist Invents the ‘World’s Whitest Paint’ To Cool Down Your House
The Washington Post recently used infrared technology to examine if the city’s claims about cooling pavement were accurate. On one street, the average surface temperature on asphalt was about 154 degrees Fahrenheit. The road treated with special coating had a cooler average temperature reading of 130 degrees.
“With the deployment of cool surfaces and smart technology, we can at least offset some of the urban heat effect, if not fully offset it, moving forward,” said David Hondula, director of the Office of Heat Response and Mitigation.
Phoenix is the first U.S. city with an office dedicated to managing extreme heat.
The water-based cooling pavement treatment is two to three times more expensive than the standard seal. The city eventually wants to treat 4,000 miles of residential roads.
The city pavement isn’t the only public space Phoenix is treating for heat. Researchers at Arizona State University, adhesives company 3M, and the city of Phoenix are experimenting with a new ramada in a dog park coated with Passive Daytime Radiative Cooling, or PDRC.
The material has higher solar reflectance and thermal emittance than typical roofs, reflecting the heat into the atmosphere.
“What we found from initial studies were some pretty substantial positive results in terms of these coated shelters’ ability to provide a better environment for pedestrians,” Dave Sailor, director of the School of Geographical Sciences and Urban Planning and the main investigator on the project, told ASU News.
“It reduced what’s known as the mean radiant temperature, but also convected much less heat into the urban airshed, so it’s a winning solution from several perspectives.”
The program has also experimented with PRDC at bus stops in the Phoenix area.
“There’s not a single blanket solution that’s going to work everywhere, but by testing these design strategies, we can put together a portfolio of solutions that work well for providing cooling for the Phoenix metro area,” Sailor said.
He says more research is still needed to understand the full benefit and consequences to cool pavement.
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Jonathan Small
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By: Bill Wellock | Published:
The United States has already experienced record-breaking high temperatures this summer, heat that threatens the lives of thousands of people.
Extreme heat is the leading weather-related cause of death in the United States. Vulnerable populations, such as older adults, infants, outdoor workers and others, are at the greatest risk.
Florida State University Associate Professor Chris Uejio studies extreme heat and public health. He is available to speak to reporters about the dangers of excessive heat and ways to lessen its impact.
Chris Uejio, associate professor, College of Social Sciences and Public Policy
Uejio researches how the physical environment influences human health and well-being. He co-authored the Centers for Disease Control and Prevention’s Building Resilience Against Climate Effects (BRACE) Framework, which was part of the 2012 President’s Climate Action Plan. He frequently works with health departments to understand and adapt to climate change. He is also a member of NASA’s Health and Air Quality Applied Sciences Team, which rapidly responds to public health and air quality problems. Uejio has been quoted in NBC News, Science Friday and elsewhere.
“Extreme heat contributes to more than 5,000 excess U.S. deaths per year – more than any other weather hazard. For the health care community, extreme heat is like our sea-level rise. We know it’s already happening, and we have a pretty clear understanding that if we don’t do things differently, it’s going to get worse.”
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The heat—miserable and oppressive—is not abating. Today, a third of Americans are under a heat alert as temperatures keep breaking records: Phoenix has hit 110 degrees Fahrenheit for two weeks straight, while this weekend Death Valley in California could surpass the all-time high of 130 degrees.
Even less extreme heat than that can be dangerous. Recently, in Texas, Louisiana, part of Arizona, and Florida, there have been reports of deaths from heat, and many more hospitalizations. The toll of a heat wave is not always clear in the moment: A new report suggests that last summer’s historic heat wave in Europe killed more than 60,000 people.
Ideally, you’d stay in the air-conditioned indoors as much as possible. That’s not an option for everyone. The other thing to do is stay hydrated. The importance of getting enough fluid is hard to overstate—and often underappreciated: Last month, the Texas state legislature banned local governments from mandating water breaks for construction workers. In the heat, hydration “impacts everything,” Stavros Kavouras, the director of the Hydration Science Lab at Arizona State University, in Phoenix, told me. And with temperatures continuing to rise, it’s essential to get it right.
Serious dehydration is really, really bad for you. Your blood volume decreases, which makes your heart work less effectively. “Your ability to thermoregulate declines,” Kavouras told me, “so your body temperature is getting higher and higher.” You might feel weak or dizzy. Your heart rate rises; it gets harder to focus. The worst-case scenario is heatstroke, when your body stops being able to cool itself—a potentially fatal medical emergency.
In extreme temperatures, heat injuries can happen quicker than you might think. Given that the human body is mostly water, you might assume that there is some to spare, but inconveniently, this is not the case. “If you lose even 10 percent of [the water] your body has, you are entering the zone of serious clinical dehydration,” Kavouras said. “And if you look at optimal health, even losing just 1 percent of your body weight impacts your ability to function.” There are two basic ways your body cools itself when it gets hot. One is to send more blood to the skin, which releases heat from the core of your body, and is the reason you turn red when you’re overheated. The other is to sweat. It evaporates off your body, and in the process, your body loses excess heat. You can’t cool yourself as effectively if you’re not properly hydrated. At the same time, one of your main cooling mechanisms is actively dehydrating, which means the goal is not just to be hydrated, but to stay that way.
What that takes depends on many factors rather than a single universal rule, but in general, the danger zone is “high humidity with anything above 90 degrees,” Kavouras said, at which point, “it’s actually dangerous” just to be outside. The more active you are in the heat, and the hotter and more humid it is, the greater the risk—and the more important proper hydration becomes. The standard water target in the U.S. during non-heat-wave times is 3.7 liters a day for men and 2.7 liters for women. When it’s very, very hot out, you need more. Even if you spend most of the day in the bliss of AC, you are almost certainly leaving the house at some point.
Instead of trying to figure out what that precise amount should be, Kavouras recommends you focus on two things instead. “No. 1, keep water close to you. If you have water close to you, or whatever healthy beverage, you’ll end up drinking more, just because it’s closer,” he said. And second: Keep an eye on how often you pee—pale urine, six to seven times a day, or every two to three hours, is good. You want it to be “basically like a Chablis, a Riesling, Pinot Grigio, or champagne-colored,” John Higgins, a sports cardiologist at McGovern Medical School at UTHealth, in Houston, told me. “If you notice the urine is getting darker, like a Chardonnay- or Sauvignon Blanc–type of thing, that generally means you are dehydrated.”
Certain groups are especially at risk. Older adults are more prone to dehydration, as are young children, people who are pregnant, and people taking certain medications—blood-pressure medications, for example. None of this requires you to take in extra fluids per se, just that you need to be even more careful that you’re getting enough.
As for what to drink, as a go-to beverage, straight water is hard to beat. Water with fruit slices floating in it has the benefit of feeling like something from a luxury hotel. Carbonated water is also good—you might not be able to drink quite as much of it, which is a potential drawback, but “there is no mechanism in your GI system that will make sparkling water less effective at hydrating you,” Kavouras said. You probably want to avoid downing giant buckets of coffee—caffeine is a diuretic in large quantities and Higgins warns against sugary drinks for the same reason. (A daily iced coffee is fine.) If you’re doing hours of heavy sweating, then you might work in some (less sugary) sports drinks. But for the majority of people, water remains the ideal. Food can also be a fluid source: “Make sure you’re eating a diet that’s rich in vegetables and fruits that have water content,” William Adams, the director of the University of North Carolina at Greensboro’s Hydration, Environment and Thermal (H.E.A.T) Stress Lab, advised. Alcohol, which causes you to lose fluid, is definitively unhelpful.
There are lots of water myths out there. Can you go too hard? Technically, it’s possible to over-hydrate, causing an electrolyte imbalance, but all three experts agreed that for most people, this isn’t really a concern. You can find arguments for drinking hot drinks in the summer—the idea being that they increase the amount you sweat, thereby promoting cooling. But Kavouras is emphatic that you’re better off with cold drinks, which cool your body, he said. In the moments before a race, marathon runners will sometimes take it one step further, slurping ice slurries to lower their body temperature. For good old-fashioned drinking water, about 50 degrees Fahrenheit is best—roughly the temperature of cool water from the tap.
One final key to staying hydrated: Start early. A lot of people, Higgins said, are lightly dehydrated all the time, heat wave or not. “So particularly when you first wake up in the morning, typically you are in a dehydrated state.” Accordingly, he recommends that people drink about a standard water bottle’s worth—roughly 17 ounces—as soon as they wake up. The other thing people forget about, he said, is what happens when they come back inside after enduring the outdoors. “You keep sweating,” he pointed out. In other words: hydrate, and then keep hydrating.
As crucial as hydration is, it is not a miracle. “It doesn’t mean that you can say, ‘I hydrate well, so I’ll go out for a run in the 120-degree weather, and I’ll be fine because I’m drinking a lot,’” Kavouras said. “It doesn’t work this way.” Still, it is a simple but effective tool. As heat waves like this one become even more frequent, many more people will need to learn how to become attuned to their hydration. And perhaps adequate water can be a perverse sort of comfort: You can’t control the unrelenting heat, but you likely can control your water intake. In a heat wave, it helps to have a glass-half-full attitude—and an emptied glass of water.
This story is part of the Atlantic Planet series supported by HHMI’s Science and Educational Media Group.
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Rachel Sugar
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Newswise — RICHLAND, Wash.— From densely built urban cores to sprawling suburbia, cities are complex. This complexity can lead to temperature hot spots within cities, with some neighborhoods (and their residents) facing more heat than others.
Understanding this environmental disparity forms the spirit of new research led by scientists at the Department of Energy’s Pacific Northwest National Laboratory. In a new paper examining all major cities in the U.S., the authors find that the average Black resident is exposed to air that is warmer by 0.28 degrees Celsius relative to the city average. In contrast, the average white urban resident lives where air temperature is cooler by 0.22 degrees Celsius relative to the same average.
The new work, published last week in the journal One Earth, involved a two-part effort. The study’s authors aimed to produce a more useful nationwide estimate of urban heat stress—a more accurate account of how our body responds to outdoor heat. By creating and comparing these estimates against demographic data, they also tried to better understand which populations are most exposed to urban heat stress.
The findings reveal pervasive income- and race-based disparities within U.S. cities. Nearly all the U.S. urban population—94 percent, or roughly 228 million people—live in cities where summertime peak heat stress exposure disproportionately burdens the poor.
The study’s authors also find that people who now live within historically redlined neighborhoods, where loan applicants were once denied on racially discriminatory grounds, would be exposed to higher outdoor heat stress than their neighbors living in originally non-redlined parts of the city.
The work also highlights shortcomings in the typical approach scientists take in estimating urban heat stress at these scales, which frequently relies on satellite data. This conventional satellite-based method can overestimate such disparities, according to the new work. As the world warms, the findings stand to inform urban heat response plans put forward by local governments who seek to help vulnerable groups.
What is heat stress?
The human body has evolved to operate within a relatively narrow temperature range. Raise your core body temperature beyond just six or seven degrees and drastic physiological consequences soon follow. Cellular processes break down, the heart is taxed, and organs begin to fail.
Sweating helps. But the cooling power of sweating depends partly on how humid the environment is. When both heat and humidity are omnipresent and difficult to escape, the body struggles to adapt.
How is heat stress measured?
To measure heat stress, scientists use a handful of indicators, many of which depend on air temperature and humidity. Weather stations provide such data. Because most weather stations are outside of cities, though, scientists often rely on other means to get some idea about urban heat stress, including using sensors on satellites.
Those sensors infer the temperature of the land surface from measurements of thermal radiation. But such measurements fall short of delivering a full picture of heat stress, said lead author and Earth scientist TC Chakraborty. Measuring just the skin of the Earth, like the surface of a sidewalk or a patch of grass, said Chakraborty, offers only an idea of what it’s like to lay flat on that surface.
“Unless you’re walking around barefoot or lying naked on the ground, you’re not really feeling that,” said Chakraborty. “Land surface temperature is, at best, a crude proxy of urban heat stress.”
Indeed, most of us are upright, moving through a world where air temperature and moisture dictate how heat actually feels. And these satellite data are only available for clear-sky days—another limiting factor. More complete and physiologically relevant estimates of heat stress incorporate a blend of factors, which models can provide, said Chakraborty.
To better understand differences between satellite-derived land surface temperature and ambient heat exposure within cities, Chakraborty’s team examined 481 urbanized areas across the continental United States using both satellites and model simulations.
NASA’s Aqua satellite provided the land surface temperature; and through model simulations that account for urban areas, the authors generated nationwide estimates of all variables required to calculate moist heat stress. Two such metrics of heat stress—the National Weather Service’s heat index and the Humidex, often used by Canadian meteorologists—allowed the scientists to capture the combined impacts of air temperature and humidity on the human body.
They then identified heat stress hotspots across the country for summer days between 2014 and 2018. Overlaying maps of both historically redlined neighborhoods and census tracts, the team identified relationships between heat exposure and communities.
How is heat distributed within cities?
Residents in poorer neighborhoods often face greater heat stress. And a greater degree of income inequality in any given city often means greater heat stress exposure for its poorer residents.
Most U.S. cities, including heavily populated cities like New York, Los Angeles, Chicago, and Philadelphia, show this disparity. But the relationship between heat stress and race-based residential segregation is even more stark.
Roughly 87.5 percent of the cities studied show that Black populations live in parts of the city with higher land surface temperatures, warmer air, and greater moist heat stress. Moreover, the association between the degree of heat stress disparity and the degree of segregation between white and non-white populations across cities is particularly striking, said Chakraborty.
“The majority—83 percent—of non-white U.S. urban residents live in cities where outdoor moist heat stress disproportionately burdens them,” said Chakraborty, “Further, higher percentages of all races other than white are positively correlated with greater heat exposure no matter which variable you use to assess it.”
In the 1930s, the U.S. federal government’s Home Owners’ Loan Corporation graded neighborhoods in an effort to rank the suitability of real estate investments. This practice is known as “redlining,” where lower grades (and consequently fewer loans) were issued to neighborhoods composed of poorer and minority groups. The authors find that these redlined neighborhoods still show worse environmental conditions.
Neighborhoods with lower ratings face higher heat exposure than their non-redlined neighbors. Neighborhoods with higher ratings, in contrast, generally get less heat exposure.
This is consistent with previous research on originally redlined urban neighborhoods showing lower tree cover and higher land surface temperature. Chakraborty, however, notes that using land surface temperature would generally overestimate these disparities across neighborhood grades compared to using air temperature or heat index.
“Satellites give us estimates of land surface temperature, which is a different variable from the temperature we feel while outdoors, especially within cities,” said Chakraborty. “Moreover, the physiological response to heat also depends on humidity, which satellites cannot directly provide, and urbanization also modifies.”
What can be done?
Planting more trees often comes up as a potential solution to heat stress, said Chakraborty. But densely built urban cores, where poorer and minority populations in the U.S. often live, have limited space for trees. And many previous estimates of vegetation’s potential to cool city surroundings are also based solely on land surface temperature—they are perhaps prone to similar overestimation, the authors suggest.
More robust measurements of urban heat stress would help, they added. Factors like wind speed and solar insolation contribute to how heat actually affects the human body. But those factors are left out of most scientific assessments of urban heat stress because they are difficult to measure or model at neighborhood scales.
In addition to Chakraborty, PNNL authors of the new work include Yun Qian. Andrew Newman at the National Center for Atmospheric Research, Angel Hsu at the University of North Carolina-Chapel Hill, and Glenn Sheriff at Arizona State University are also authors. This work was supported by DOE’s Office of Science and the National Institutes of Health.
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The writers on The Atlantic’s Science, Technology, and Health desks have learned a lot this year. Our coverage of the ongoing coronavirus pandemic has continued, but this year, more so than in 2020 and 2021, we’ve also had the chance to report on topics that have filled us with awe and delight. Though the past 12 months have not been free of concerns about infectious disease, climate change, and even nuclear war, we’ve embraced more fascination and curiosity in our coverage this year, and we wanted to share and reflect on some of the most compelling tidbits we’ve stumbled across. We hope you find these facts as mind-blowing as we did.
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Dec. 13, 2022 — Extremely hot and extremely cold days are tied to an increase in the risk of death from heart disease, a new study suggests.
People with heart failure were most at risk when temperatures were extremely hot or cold.
Climate change, which is linked to substantial swings in extreme hot and cold temperatures, is likely a key culprit, according to lead study author Barrak Alahmad, MD, PhD, of the Harvard T.H. Chan School of Public Health in Boston.
“Investigating the burden of extreme temperatures from now on will enable us to further understand what climate change might hold for cardiovascular risks,” he says. “In this rapidly changing climate and unprecedented pace of warming, it is not the time to be asleep at the wheel.”
No specific temperatures are considered extreme, Alahmad notes. “Heat and cold are context-specific and location-specific.” For example, a 104 F day in Kuwait is a typical summer day, whereas a 104 F day in London resulted in “widespread, incalculable damage.”
For the study, published Dec. 12 in the journal Circulation, the researchers looked at more than 32 million cardiovascular deaths over 4 decades in countries around the world. They compared cardiovascular deaths on the hottest and coldest 2.5% of days in each city with cardiovascular deaths on the days with optimal temperatures.
The relative risks of death increased gradually for cold temperatures, but somewhat faster for hot temperatures – especially for heart failure, where the risk in extremely hot weather climbed quickly to as much as 12% higher, according to the analysis.
Extremely cold temperatures appeared even more dangerous. They were associated with a 33% greater risk of dying from ischemic heart disease (caused by narrowed arteries); a 32% greater risk of death from ischemic strokes caused by blood clots in the brain; and a 37% greater risk of dying from heart failure.
Overall, extreme temperatures accounted for 2.2 additional deaths per 1,000 on hot days and 9.1 additional deaths per 1,000 on cold days.
The results were similar even after the researchers adjusted for temperature variability, heatwaves, long-term trends, relative humidity, and air pollutants, including ozone, nitrogen dioxide, and particulate matter.
Protect Your Heart
American Heart Association expert volunteer Nieca Goldberg, MD, medical director of Atria New York and a professor at the New York University School of Medicine in New York City, says everyone needs to take steps to stave off the effects of climate change.
To protect your heart on extremely hot and cold days, “avoid outdoor activities,” she advises. “If you must go out for an appointment on a very cold day, remember to bundle up, wear gloves, and a hat and a scarf that covers your mouth. Keep your outdoor time to a minimum.”
“On hot days, do not exercise outdoors, stay indoors as much as possible, and stay hydrated,” she says.
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