GeoAI technologies for sustainable urban development

From heatwaves to pandemic diseases, the urban environments of the world face numerous challenges. Researchers at the Hong Kong Polytechnic University are harnessing artificial intelligence (AI) and informatics to address emerging concerns related to environmental changes and urban growth.

Innovative geospatial and AI technologies offer ground-breaking solutions and insights into the dynamic changes occurring in our natural and social surroundings. The applications of GeoAI are rapidly expanding across various fields, encompassing transportation, urban and public safety, planning, climate change and natural disasters.

Prof. Qihao WENG, Chair Professor of Geomatics and Artificial Intelligence of the Department of Land Surveying and Geo-Informatics, and Global STEM Professor, established the PolyU Research Centre for Artificial Intelligence in Geomatics (RCAIG), to focus on the development of original and innovative AI methodologies and technologies for geomatics and their applications in urban areas, with the goal of it becoming a global R&D hub in GeoAI. Prof. Weng has recently been honoured with the 2024 American Association of Geographers (AAG) Wilbanks Prize for Transformational Research in Geography and the 2024 AAG Remote Sensing Specialty Group Lifetime Achievement Honor Award for his ground-breaking contributions in geography.

Earth observations Prof. WENG said, "By leveraging the latest geospatial technology and AI, we stand at the forefront of addressing global environmental and societal challenges. Our research encompasses a wide spectrum of subjects in the fields of earth observations and geoinformatics."

Satellite observations are invaluable tools for our community, relying on satellite imagery, videos and data that are crucial for informed decision-making in urban resilience and public health. For instance, satellite observations help us understand the impact of extreme heatwave on population exposure and aid in the development of urban flood monitoring algorithms. Real-time data acquisition also facilitate applications in traffic conditions, air quality, nature disasters, population movement and urban land use.

Prof. WENG said, "Earth observation is important as a guiding compass for understanding changes in the environment and society. Our research focuses on diverse fields including Geospatial big data and AI, remote sensing, ground-based sensors, navigation and positioning, surveying and geodesy, laser scanning and photogrammetry. These technologies play a crucial role in addressing and resolving key issues."

In particular, GeoAI has revolutionised building monitoring by utilising thousands of learnable parameters. An illustration of this is its ability to automatically learn and identify general patterns of buildings such as colour and shape. This technology is crucially applied to detect disaster-damaged buildings, retrieve building height, identify structural changes, and estimate building energy consumption. As a result, GeoAI has emerged as a mainstream solution for more efficient and insightful building monitoring.

Environmental monitoring

As the world rapidly urbanises, cities become the focal point of diverse aspects of human development, including building and environmental monitoring, conservation efforts, urban safety, and the impacts of climate change.

By leveraging AI techniques like deep neural networks, alongside with remote sensing methods, these technologies have the ability to detect and track changes such as in habitats, urbanisation and deforestation patterns. Additionally, monitoring the uptake of carbon by vegetation plays a crucial role in combating climate change and developing effective mitigation strategies.

For urban resilience and public health, these technologies aim to enhance the ability of urban areas to withstand and recover from various challenges such as extreme heatwaves, while promoting the well-being and sustainable development of urban population.

In the field of urbanisation monitoring, research team of the RCAIG has developed an impervious surface area (ISA) based urban cellular automata (CA) model that can simulate the fractional change of urban areas within each grid by utilising annual urban extent time series data obtained from satellite observations. By characterising the historical pathways of urban area growth under different levels of urbanisation, the model offers more detailed insights compared to traditional binary CA models. This demonstrates its great potential in supporting sustainable development.

Research conducted by Ms Wanru HE, an RCAIG doctoral research assistant and the team, titled "Modeling gridded urban fractional change using the temporal context information in the urban cellular automata model" was published on Cities. Their model effectively capture the dynamics of urban sprawl with significantly improved computational efficiency and performance, and it enables the modelling of urban growth at regional even global level, under diverse future urbanisation scenarios.

GeoAI for traffic management

GeoAI utilises machine learning and deep learning to effectively analyse intricate information, offering applications like real-time traffic management. Through the integration of diverse data modalities, such as text, images, and knowledge graphs, GeoAI enables accurate traffic flow prediction, route optimisation, accident warnings, and the planning of an efficient traffic network. Consequently, this contributes to the advancement of smart traffic management.

To enhance the efficiency of ride-hailing platforms and achieve intelligent management of their services, research team of the RCAIG has developed a multi-agent order matching and vehicle repositioning (MAMR) approach. This innovative technology focuses on coordinating the supply and demand of ride-hailing services, ultimately aiming to improve their overall efficiency.

This approach provides a ground-breaking solution to tackle two critical aspects of efficient ride-hailing services. Firstly, it addresses order matching by efficiently assigning orders to available vehicles. Secondly, it incorporates proactive vehicle repositioning, strategically deploying idle vehicles to regions with potentially high demand. Based on multi-agent deep reinforcement learning (MARL), this innovation solves the complex planning in transportation and offers a news perspective on long-term spatiotemporal planning problem. The research conducted by Ms Mingyue XU, another RCAIG researcher and the team, titled "Multi-agent reinforcement learning to unify order-matching and vehicle-repositioning in ride-hailing services," was published on International Journal of Geographical Information Science. The study demonstrated outperforming results, including reduced passenger rejection rates and driver idle time. With a focus on geospatial artificial intelligence (GeoAI), the RCAIG and the POLEIS at PolyU are dedicated to conducting research in diverse fields, including urban building and energy, urban safety and securing, environmental monitoring and conservation and urban resilience and public health. This aligns with the 11th United Nations Sustainable Development Goal (SDG11), which aims to create inclusive, safe, resilient, and sustainable cities and human settlements.

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Multiple ecosystems in hot water after marine heatwave surges across the Pacific

Rising ocean temperatures are sweeping the seas, breaking records and creating problematic conditions for marine life. Unlike heatwaves on land, periods of abrupt ocean warming can surge for months or years. Around the world these 'marine heatwaves' have led to mass species mortality and displacement events, economic declines and habitat loss. New research reveals that even areas of the ocean protected from fishing are still vulnerable to these extreme events fueled by climate change.

A study published today in Global Change Biology, led by researchers at UC Santa Barbara, found that while California's network of marine protected areas (MPAs) provide many social and ecological benefits, they are not resilient to the effects of ocean warming. MPAs are locations in the ocean where human activities such as fishing are restricted to conserve and protect marine ecosystems, habitats, species and cultural resources. The study, part of a 10-year review of California's MPA network conducted at UCSB's National Center for Ecological Analysis & Synthesis (NCEAS), found that marine heatwaves impact ecological communities regardless of whether they are protected inside MPAs.

"MPAs in California and around the world have many benefits, such as increased fish abundance, biomass and diversity," said Joshua Smith, who led the study while he was a postdoctoral researcher at NCEAS . "But they were never designed to buffer the impacts of climate change or marine heatwaves."

Smith and co-authors from all over the world were part of an NCEAS working group formed to synthesize decades of long-term ecological monitoring data from California's diverse ocean habitats. The group, co-led by Jenn Caselle, a researcher with UCSB's Marine Science Institute, and Kerry Nickols, a professor from Cal State University Northridge who now works with the non-profit Ocean Visions, aimed to provide actionable scientific results to California's policy makers and natural resource managers, as part of a statewide Decadal Evaluation of the MPA network. Their analyses spanned the largest marine heatwave on record, which rolled through the Pacific Ocean toward California from 2014-2016. The monster marine heatwave was formed from an environmental double-whammy -- unusual ocean warming nicknamed "The Blob," followed by a major El Niño event that prolonged the sweltering sea temperatures. The marine heatwave blanketed the West Coast from Alaska to Baja and left a wake of altered food webs, collapsed fisheries, and shifted populations of marine life among various other consequences.

As MPA managers around the world face increasing climate shocks, the extent to which MPAs can buffer the worst of these events has become an important question. The working group scientists asked how the ecological communities in California's protected areas fared after such a severe and prolonged heatwave: Would the communities shift and if so, how? Would they 'bounce back' when the marine heatwave subsided? Could the marine protected areas protect sensitive populations or facilitate recovery?

To find answers to their questions, they synthesized over a decade of data collected from 13 no-take MPAs located in a variety of ecosystems along the Central Coast: rocky intertidal zones, kelp forests, shallow and deep rocky reefs. The team looked at fish, invertebrates and seaweed populations inside and outside these areas, using data from before, during and after the heatwave.

They also focused on two of these habitats, rocky intertidal and kelp forests, at 28 MPAs across the full statewide network to gauge whether these locations promoted one particular form of climate resilience -- maintaining both population and community structure.

"We used no-take MPAs as a type of comparison to see whether the protected ecological communities fared better to the marine heatwave than places where fishing occurred," said Smith, now an Ocean Conservation Research Fellow at Monterey Bay Aquarium.

The results are somewhat sobering, though not altogether unexpected.

"The MPAs did not facilitate resistance or recovery across habitats or across communities," Caselle said. "In the face of this unprecedented marine heatwave, communities did change dramatically in most habitats. But, with one exception, the changes occurred similarly both inside and outside the MPAs. The novelty of this study was that we saw similar results across many different habitats and taxonomic groups, from deepwater to shallow reefs and from fishes to algae."

The implication of these findings, according to Smith, is that every part of the ocean is under threat from climate change. "MPAs are effective in many of the ways they were designed, but our findings suggest that MPAs alone are not sufficient to buffer the effects of climate change."

The key question now is what will happen in the future? At the time of this study using data through 2020, the ecological communities have not returned to their former, pre-heatwave state. According to the paper, these ecological communities shifted toward a "pronounced decline in the relative proportion of cold-water species and an increase in warm water species." For example, increases in the abundance of the señorita fish (Oxyjulis californica), a subtropical species with warm water affinity and previously rare in central California, had an outsized influence on the shift of communities. Whether these species persist in their new locations remains to be seen.

"This study makes it clear why long-term monitoring of California's MPAs is so critical," said Caselle. "Some of these time series are longer than 25 years at this point and the data are critical to understanding and readying human communities for the changes occurring in our marine communities." Continued study will show if future shifts in marine communities occur at different rates or to different base states in MPAs compared to fished areas.

Despite the limited ability of MPAs to resist the grip of the marine heatwave, they do confer benefits, not the least of which is the ability to study the complex effects of climate change in areas not impacted by fishing. As areas of minimal human interference that are regularly monitored, they present opportunities to study the response of marine ecosystems to shifting conditions and potentially tailor management techniques accordingly. Moreover, as Smith stated, "the ecological communities in MPAs are still being protected, even if they are different as a result of the heatwave. Given that marine heatwaves are anticipated to increase in frequency and magnitude into the future, swift climate action and nature-based solutions are needed as additional pathways to enhance the health of our oceans."

Kerry Nickols adds, "With the devastating impacts of climate change already apparent, it is very important that we are upfront about climate solutions -- as long as we are burning fossil fuels and warming the globe marine ecosystems will be at risk, even if they are protected from fishing."

Read more at Science Daily

Global research reveals countries where record-breaking heatwaves are likely to cause most harm

A new study has highlighted under-prepared regions across the world most at risk of the devastating effects of scorching temperatures.

The University of Bristol-led research, published today in Nature Communications, shows that unprecedented heat extremes combined with socioeconomic vulnerability puts certain regions, such as Afghanistan, Papua New Guinea, and Central America,most in peril.

Countries yet to experience the most intense heatwaves are often especially susceptible, as adaptation measures are often only introduced after the event. A high chance of record-breaking temperatures, growing populations, and limited healthcare and energy provision, increase the risks.

Beijing and Central Europe are also on the list of hotspots, as if record-breaking heatwaves occurred in these densely populated regions millions of people would be adversely affected.

In light of the findings, the researchers are calling for policy makers in hotspot regions to consider relevant action plans to reduce the risk of deaths and associated harms from climate extremes.

Lead author, climate scientist Dr Vikki Thompson at the University of Bristol Cabot Institute for the Environment, said: "As heatwaves are occurring more often we need to be better prepared. We identify regions that may have been lucky so far -- some of these regions have rapidly growing populations, some are developing nations, some are already very hot. We need to ask if the heat action plans for these areas are sufficient."

The researchers used extreme value statistics -- a method to estimate the return periods of rare events -- and large datasets from climate models and observations to pinpoint regions globally where temperature records are most likely to be broken soonest and the communities consequently in greatest danger of experiencing extreme heat.

The researchers also cautioned that statistically implausible extremes, when current records are broken by margins that seemed impossible until they occurred, could happen anywhere. These unlikely events were found to have transpired in almost a third (31%) of the regions assessed where observations were deemed reliable enough between 1959 and 2021, such as the 2021 Western North America heatwave.

Co-author Dann Mitchell, Professor in Atmospheric Sciences at the University of Bristol Cabot Institute for the Environment, said: "Being prepared saves lives. We have seen some of the most unexpected heatwaves around the world lead to heat-related deaths in the tens of thousands. In this study, we show that such record smashing events could occur anywhere. Governments around the world need to be prepared."

Human-induced climate change is causing an increase in the frequency, intensity, and duration of heatwaves, which have the potential to lead to thousands more excess deaths globally.

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Cities will need more resilient electricity networks to cope with extreme weather

Dense urban areas amplify the effects of higher temperatures, due to the phenomenon of heat islands in cities. This makes cities more vulnerable to extreme climate events. Large investments in the electricity network will be necessary to cool us down during heatwaves and keep us warm during cold snaps, according to a new study led by Lund University in Sweden.

"Unless we account for extreme climate events and continued urbanisation, the reliability of electricity supply will fall by up to 30%. An additional outlay of 20-60 per cent will be required during the energy transition in order to guarantee that cities can cope with different kinds of climate," says Vahid Nik, Professor of Building Physics at Lund University and one of the authors of the article in Nature Energy.

The study presents a modelling platform that ties together climate, building and energy system models in order to facilitate simulation and evaluation of cities' energy transition. The aim is to secure the cities' resilience against future climate changes at the same time as densification of urban areas is taking place. In particular, researchers have looked closely at extreme weather events (e.g. heatwaves and cold snaps) by producing simulations of urban microclimates.

"Our results show that high density areas give rise to a phenomenon called urban heat islands, which make cities more vulnerable to the effects of extreme climate events, particularly in southern Europe. For example, the outdoor temperature can rise by 17% while the wind speed falls by 61%. Urban densification -- a recommended development strategy in order to reach the UN's energy and climate goals -- could make the electricity network more vulnerable. This must be taken into consideration when designing urban energy systems, says Kavan Javanroodi, Assistant Professor in Building and Urban Physics.

"The framework we have developed connects future climate models to buildings and energy systems at city level, taking the urban microclimate into account. For the first time, we are getting to grips with several challenges around the issues of future climate uncertainty and extreme weather situations, focussing in particular on what are known as 'HILP' or High Impact Low Probability events," says Vahid Nik.

There is still a large gap between future climate modelling and building and energy analyses and their links to one another. According to Vahid Nik, the model now being developed makes a great contribution to closing that gap.

"Our results answer questions like 'how big an effect will extreme weather events have in the future, given the predicted pace of urbanisation and several different future climate scenarios?', 'how do we take them and the connections between them into account?' and 'how does the nature of urban development contribute to exacerbating or mitigating the effects of extreme events at regional and municipal level?' "

The results show that the peaks in demand in the energy system increase more than previously thought when extreme microclimates are taken into account, for example with an increase in cooling demand for 68% in Stockholm and 43% in Madrid on the hottest day of the year. Not considering this can lead to incorrect estimates of cities' energy requirements, which can turn into power shortage and even blackouts.

"There is a marked deviation between the heat and cooling requirements shown in today's urban climate models, compared to the outcomes of our calculations when urban morphology, the physical design of the city, is more complex. For example, if we fail to take into account the urban climate in Madrid, we could underestimate the need for cooling by around 28%," says Kavan Javanroodi.

Vahid Nik explains that an increasing number of countries have become interested in extreme weather events, energy issues and the impact on public health. At the same time, there are no methods of quantifying the effects of climate change and planning for adapting to them, especially when it comes to extreme weather events and climate variations across space and time.

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Palau's Rock Islands harbor heat-resistant corals

Ocean warming is driving an increase in the frequency and severity of marine heatwaves, causing untold damage to coral reefs. Tropical corals, which live in symbiosis with tiny single celled algae, are sensitive to high temperatures, and exhibit a stress response called bleaching when the ocean gets too hot. In the last 4 decades, marine heatwaves have caused widespread bleaching, and killed millions of corals. Because of this, a global search is underway for reefs that can withstand the heat stress, survive future warming, and act as sources of heat-tolerant coral larvae to replenish affected areas both naturally and through restoration.

Now, scientists studying reefs in Palau, an archipelago in the western tropical Pacific, have identified genetic subgroups of a common coral species that exhibit remarkable tolerance to the extreme heat associated with marine heatwaves. Further, the scientists found evidence that larvae from these corals are traveling from their birthing grounds deep in Palau's lagoons, to the outer reef, where they survive and grow, and maintain their heat tolerance.

Understanding both the underlying mechanisms that facilitate heat tolerance of these corals, as well as the dispersal capabilities of their larvae will go a long way toward enhancing coral reef conservation and restoration efforts in the 21st century ocean, according to scientists at the Woods Hole Oceanographic Institution (WHOI) who led the research.

In Palau's main lagoon, a network of very ancient, fossilized reefs has been uplifted to form a series of mountains known as the Rock Islands. These formations slow water flow in and around them, creating localized environments in which the water temperatures are consistently higher than other areas of Palau's reefs.

Scientists sampled the keystone coral species Porites lobata (lobe coral) across Palau, including the Rock Islands. They took skeletal biopsies and examined the cores for stress bands, which are telltale signs of bleaching, a stress response corals have to high temperatures. They found corals from the Rock Islands bleached less during the intense 1998 heatwave than corals from other areas of the reef, indicating enhanced thermal tolerance.

Scientists then investigated the genetics of the corals and discovered four distinct lineages within the same species. Within the warmer Rock Islands, certain lineages, designated as "LB" and "RD" lineages, were much more common. The scientists were able to match the genetics of each coral with its own bleaching history and found that fewer individuals from the "LB" and "RD" lineages bleached during 1998, indicating enhanced thermal tolerance.

Remarkably, the scientists found the LB lineage was not restricted to the Rock Islands. They found some LB colonies also living on the cooler outer reefs. An examination of the bleaching histories of these colonies again revealed fewer stress bands, indicating that they maintained the thermal tolerance characteristic of their relatives in the Rock Islands.

"This suggests that the Rock Islands provide naturally tolerant larvae to neighboring areas," the scientists write in the paper titled "Palau's warmest reefs harbor thermally tolerant corals that thrive across different habitats," published in Communications Biology, a journal published by Nature. "Finding and protecting such sources of thermally-tolerant corals is key to reef survival under 21st century climate change."

"As oceans worldwide continue to warm, corals derived from extreme habitats will be at a competitive advantage and may enable the survival of otherwise vulnerable reefs," the authors continue. "Identifying and safeguarding natural breeding grounds of environmentally tolerant corals that can thrive under future climate conditions will be fundamental to the persistence of coral reef ecosystems worldwide in the coming decades."

"We found that some of Palau's reefs with the highest temperatures have corals that are more tolerant than one would expect," said the paper's lead author Hanny Rivera, a graduate of the MIT-WHOI Joint Program. Rivera, who conducted this work as part of her Ph.D. and postdoctoral research, is currently an associate director of business development at Ginko Bioworks. "In addition, they are genetically distinct from the same corals found in other parts of Palau, which suggests that there has been natural selection for hardier corals in these regions.."

Paper co-author Michael Fox added that the study is particularly exciting because it combines coral genetics with historical records of bleaching preserved in their skeletons to shed light on how corals from extreme habitats with high temperature tolerance can be dispersed across a reefscape. "This integrated perspective is essential for improving projections of coral communities in a warming ocean," said Fox, who was a postdoctoral scholar at WHOI during the research for this paper. He currently is an assistant research professor in the Red Sea Research Center at King Abdullah University of Science and Technology in Thuwal, Saudi Arabia.

The Palau research is directly related to the Super Reefs initiative WHOI launched with The Nature Conservancy and Stanford University to locate coral communities that can withstand marine heat waves, and work with local communities and governments to protect them.

"This work is the scientific basis for the Super Reefs initiative," said paper co-author Anne Cohen, a scientist at WHOI and Rivera's advisor on the study. "The Palau research demonstrates that Super Reefs exist and also provides actionable science knowledge that can be used to support their protection."

Cohen noted that there are other coral reefs, not just in Palau, where coral communities have not bleached as severely as scientists predicted based on the levels of thermal stress. "When we find the coral communities that are heat-tolerant or bleaching-resistant, and we protect them from other stresses that can kill them -- like dynamiting, overfishing, or coastal development -- they will produce millions of larvae that will travel on the currents, outside of their places of origin as we see on Palau, and they will repopulate reefs that have been devastated by heatwaves," she said. "Nature is amazing. Our job with the Super Reefs initiative is to protect these thermally resilient reefs and let nature do the rest."

Rivera added she is in awe of the immense appreciation, respect, and stewardship that the Palauan people have for their environment.

"They have been one of the pioneering countries in promoting marine conservation and ecological protection. It is wonderful to know that these special reefs are in such good hands," Rivera said. "It is my greatest hope that our research will further support the Palauan people in their efforts to maintain a healthy marine ecosystem."

Read more at Science Daily

Today's heat waves feel a lot hotter than heat index implies

If you looked at the heat index during this summer's sticky heat waves and thought, "It sure feels hotter!," you may be right.

An analysis by climate scientists at the University of California, Berkeley, finds that the apparent temperature, or heat index, calculated by meteorologists and the National Weather Service (NWS) to indicate how hot it feels -- taking into account the humidity -- underestimates the perceived temperature for the most sweltering days we're now experiencing, sometimes by more than 20 degrees Fahrenheit.

The finding has implications for those who suffer through these heat waves, since the heat index is a measure of how the body deals with heat when the humidity is high, and sweating becomes less effective at cooling us down. Sweating and flushing, where blood is diverted to capillaries close to the skin to dissipate heat, plus shedding clothes, are the main ways humans adapt to hot temperatures.

A higher heat index means that the human body is more stressed during these heat waves than public health officials may realize, the researchers say. The NWS currently considers a heat index above 103 to be dangerous, and above 125 to be extremely dangerous.

"Most of the time, the heat index that the National Weather Service is giving you is just the right value. It's only in these extreme cases where they're getting the wrong number," said David Romps, UC Berkeley professor of earth and planetary science. "Where it matters is when you start to map the heat index back onto physiological states and you realize, oh, these people are being stressed to a condition of very elevated skin blood flow where the body is coming close to running out of tricks for compensating for this kind of heat and humidity. So, we're closer to that edge than we thought we were before."

Romps and graduate student Yi-Chuan Lu detailed their analysis in a paper accepted by the journal Environmental Research Letters and posted online Aug. 12.

The heat index was devised in 1979 by a textile physicist, Robert Steadman, who created simple equations to calculate what he called the relative "sultriness" of warm and humid, as well as hot and arid, conditions during the summer. He saw it as a complement to the wind chill factor commonly used in the winter to estimate how cold it feels.

His model took into account how humans regulate their internal temperature to achieve thermal comfort under different external conditions of temperature and humidity -- by consciously changing the thickness of clothing or unconsciously adjusting respiration, perspiration and blood flow from the body's core to the skin.

In his model, the apparent temperature under ideal conditions -- an average-sized person in the shade with unlimited water -- is how hot someone would feel if the relative humidity were at a comfortable level, which Steadman took to be a vapor pressure of 1,600 pascals.

For example, at 70% relative humidity and 68 F -- which is often taken as average humidity and temperature -- a person would feel like it's 68 F. But at the same humidity and 86 F, it would feel like 94 F.

The heat index has since been adopted widely in the United States, including by the NWS, as a useful indicator of people's comfort. But Steadman left the index undefined for many conditions that are now becoming increasingly common. For example, for a relative humidity of 80%, the heat index is not defined for temperatures above 88 F or below 59 F. Today, temperatures routinely rise above 90 F for weeks at a time in some areas, including the Midwest and Southeast.

To account for these gaps in Steadman's chart, meteorologists extrapolated into these areas to get numbers that, Romps said, are correct most of the time, but not based on any understanding of human physiology.

"There's no scientific basis for these numbers," Romps said.

He and Lu set out to extend Steadman's work so that the heat index is accurate at all temperatures and all humidities between zero and 100%.

"The original table had a very short range of temperature and humidity and then a blank region where Steadman said the human model failed," Lu said. "Steadman had the right physics. Our aim was to extend it to all temperatures so that we have a more accurate formula."

One condition under which Steadman's model breaks down is when people perspire so much that sweat pools on the skin. At that point, his model incorrectly had the relative humidity at the skin surface exceeding 100%, which is physically impossible.

"It was at that point where this model seems to break, but it's just the model telling him, hey, let sweat drip off the skin. That's all it was," Romps said. "Just let the sweat drop off the skin."

That and a few other tweaks to Steadman's equations yielded an extended heat index that agrees with the old heat index 99.99% of the time, Romps said, but also accurately represents the apparent temperature for regimes outside those Steadman originally calculated. When he originally published his apparent temperature scale, he considered these regimes too rare to worry about, but high temperatures and humidities are becoming increasingly common because of climate change.

Romps and Lu published the revised heat index equation earlier this year. In the most recent paper, they apply the extended heat index to the top 100 heat waves that occurred between 1984 and 2020. The researchers find mostly minor disagreements with what the NWS reported at the time, but also some extreme situations where the NWS heat index was way off.

One surprise was that seven of the 10 most physiologically stressful heat waves over that time period were in the Midwest -- mostly in Illinois, Iowa and Missouri -- not the Southeast, as meteorologists assumed. The largest discrepancies between the NWS heat index and the extended heat index were seen in a wide swath, from the Great Lakes south to Louisiana.

During the July 1995 heat wave in Chicago, for example, which killed at least 465 people, the maximum heat index reported by the NWS was 135 F, when it actually felt like 154 F. The revised heat index at Midway Airport, 141 F, implies that people in the shade would have experienced blood flow to the skin that was 170% above normal. The heat index reported at the time, 124 F, implied only a 90% increase in skin blood flow. At some places during the heat wave, the extended heat index implies that people would have experienced an increase of 820% above normal skin blood flow.

"I'm no physiologist, but a lot of things happen to the body when it gets really hot," Romps said. "Diverting blood to the skin stresses the system because you're pulling blood that would otherwise be sent to internal organs and sending it to the skin to try to bring up the skin's temperature. The approximate calculation used by the NWS, and widely adopted, inadvertently downplays the health risks of severe heat waves."

Physiologically, the body starts going haywire when the skin temperature rises to equal the body's core temperature, typically taken as 98.6 F. After that, the core temperature begins to increase. The maximum sustainable core temperature is thought to be 107 F -- the threshold for heat death. For the healthiest of individuals, that threshold is reached at a heat index of 200 F.

Luckily, humidity tends to decrease as temperature increases, so Earth is unlikely to reach those conditions in the next few decades. Less extreme, though still deadly, conditions are nevertheless becoming common around the globe.

"A 200 F heat index is an upper bound of what is survivable," Romps said. "But now that we've got this model of human thermoregulation that works out at these conditions, what does it actually mean for the future habitability of the United States and the planet as a whole? There are some frightening things we are looking at."

Read more at Science Daily

Increasing heat waves affect up to half a billion people

Climate change is a reality and extremely high temperatures have been reported by India and Pakistan in the spring. In a new scientific journal article, researchers from the University of Gothenburg, amongst others, paint a gloomy picture for the rest of the century. Heat waves are expected to increase, affecting up to half a billion people every year. In turn, they can lead to food shortages, deaths and refugee flows when the heat reaches levels that exceed what humans can tolerate. But this does not have to happen if measures are put in place to reach the Paris Agreement targets, the researchers say.

In India and Pakistan, heat waves with temperatures above 40 degrees in the shade are a directly life-threatening form of extreme weather. In a new article in the journal Earth's Future, researchers have outlined different scenarios for the consequences of heat waves in South Asia to the year 2100.

"We established a link between extreme heat and population. In the best scenario, we succeeded in meeting the targets in the Paris Agreement, which added roughly two heat waves per year, exposing about 200 million people to the heat waves. But if countries continue to contribute to the greenhouse effect as they are still doing now, clearing and building on land that is actually helping to lower global temperatures, we believe that there could be as many as five more heat waves per year, with more than half a billion people being exposed to them, by the end of the century," says Deliang Chen, Professor of Physical Meteorology at the University of Gothenburg and one of the authors of the article.

Population growth drives emissions

The study identifies the Indo-Gigantic Plains beside the Indus and Ganges rivers as particularly vulnerable. This is a region of high temperatures, and it is densely populated. Deliang Chen points out that the link between heat waves and population works in both directions. The size of the population affects the number of future heat waves. A larger population drives emissions up as consumption and transport increase. Urban planning is also important. If new towns and villages are built in places that are less subject to heat waves, the number of people affected can be reduced.

"We hope that the leaders in the region such as India and Pakistan read our report and think about it. In our calculation model, the range for the number of people who will be exposed to heat waves is large. The actual numbers will depend on the path that these countries choose to take in their urban planning. It is future greenhouse gas and particulate emissions that will determine how many people are actually exposed. We can more than halve the population exposed to intense heat waves if we reduce emissions so that we reach the targets in the Paris Agreement. Both mitigation and adaptation measures can make a huge difference," says Deliang Chen.

Risk of a refugee wave

Heat waves are already causing major problems in India and Pakistan. Farmers have been hit hard when drought and heat has caused their wheat crops to fail, and their crops have moved to higher altitudes to escape the extreme heat. But this move has resulted in large acreages of trees being cleared; trees that have contributed to lowering temperatures.

"With a larger population, land use increases, which in itself can drive up temperatures further. Each heat wave will result in increased mortality and decreased productivity, since few people can work in 45-degree heat. I fear that if nothing is done, it can ultimately lead to a huge wave of migrations."

Read more at Science Daily

Scientists identify the most extreme heatwaves ever recorded globally

A new study has revealed the most intense heatwaves ever across the world -- and remarkably some of these went almost unnoticed decades ago.

The research, led by the University of Bristol, also shows heatwaves are projected to get hotter in future as climate change worsens.

The western North America heatwave last summer was record-breaking with an all-time Canadian high of 49.6 °C in Lytton, British Columbia, on June 29, an increase of 4.6 °C from the previous peak.

The new findings, published today in Science Advances, uncovered five other heatwaves around the world which were even more severe, but went largely underreported.

Lead author, climate scientist Dr Vikki Thompson at the University of Bristol, said: "The recent heatwave in Canada and the United States shocked the world. Yet we show there have been some even greater extremes in the last few decades. Using climate models, we also find extreme heat events are likely to increase in magnitude over the coming century -- at the same rate as the local average temperature."

Heatwaves are one of the most devastating extreme weather events. The western North America heatwave was the most deadly weather event ever in Canada, resulting in hundreds of fatalities. The associated raging wildfires also led to extensive infrastructure damage and loss of crops.

But the study, which calculated how extreme heatwaves were relative to the local temperature, showed the top three hottest-ever in the respective regions were in Southeast Asia in April 1998, which hit 32.8 °C, Brazil in November 1985, peaking at 36.5 °C, and Southern USA in July 1980, when temperatures rose to 38.4 °C.

Dr Vikki Thompson, from the university's Cabot Institute for the Environment, said: "The western North America heatwave will be remembered because of its widespread devastation. However, the study exposes several greater meteorological extremes in recent decades, some of which went largely under the radar likely due to their occurrence in more deprived countries. It is important to assess the severity of heatwaves in terms of local temperature variability because both humans and the natural eco-system will adapt to this, so in regions where there is less variation, a smaller absolute extreme may have more harmful effects."

The team of scientists also used sophisticated climate model projections to anticipate heatwave trends in the rest of this century. The modelling indicated levels of heatwave intensity are set to rise in line with increasing global temperatures.

Although the highest local temperatures do not necessarily cause the biggest impacts, they are often related. Improving understanding of climate extremes and where they have occurred can help prioritise measures to help tackle this in the most vulnerable regions.

Co-author Professor Dann Mitchell, Professor in Climate Sciences at the University of Bristol, said: "Climate change is one of the greatest global health problems of our time, and we have showed that many heatwaves outside of the developed world have gone largely unnoticed. The country-level burden of heat on mortality can be in the thousands of deaths, and countries which experience temperatures outside their normal range are the most susceptible to these shocks."

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Precipitation trends determine how often droughts and heat waves will occur together

The fact that global warming will increase temperatures over land masses, increasing the frequency of droughts and heat waves, is a certainty -- as is the fact that climate change will alter the average amount of precipitation on land. However, it has remained unclear until now under what conditions both extreme events will occur together, known as 'compound hot-dry-events'. The UFZ researchers have defined these events as summers in which the average temperature was higher than in 90 percent of the summers between 1950 and 1980, and precipitation was simultaneously lower than in 90 percent of those years.

"In the past, periods of drought and heat waves were often considered separately; there is, however, a strong correlation between the two events, which can be seen in the extremes experienced in 2003 and 2018 in Europe. The negative consequences of these compound extremes are often greater than with one single extreme," says UFZ climate researcher Dr Jakob Zscheischler, last author of the study. Until now, however, it was not known what the future simultaneous occurrence of these extremes depends on -- the uncertainties in the occurrences estimated via routinely used climate model simulations were too large to arrive at robust pronouncements.

The researchers have now used a novel model ensemble, comprising seven climate models, to reduce and better understand these uncertainties. Each model simulation was carried out up to 100 times in order to account for natural climate variability. They examined the historical period between 1950 and 1980, comparing the results with those of a potential future climate that is two degrees warmer than preindustrial conditions. "The advantage of these multiple simulations is that we have a much larger volume of data than with conventional model ensembles, enabling us to better estimate compound extremes," explains Dr Emanuele Bevacqua, first author and climate researcher at the UFZ. The researchers were able to confirm the previous assumption that the average frequency of compound hot-dry events will increase with global warming: while the frequency lay at 3 percent between 1950 and 1980, which statistically is an occurrence every 33 years, in a climate that is two degrees warmer, this figure will be around 12 percent. This would be a fourfold increase compared to the historical period studied.

The climate researchers were also able to determine from the simulations that the frequency of compound hot-dry events in the future will be determined not by temperature trends, but by precipitation trends. The reason for this is that, even with a moderate warming of two degrees, local temperature increase will be so great that in the future, every drought anywhere in the world will be accompanied by a heat wave, regardless of the exact number of degrees by which the temperature increases locally. The uncertainty in the warming leads to an uncertainty in the prediction of compound hot-dry event frequencies of only 1.5 percent. This discounts temperature as a decisive factor for uncertainty. For precipitation, however, the researchers calculated an uncertainty of up to 48 percent. "This demonstrates that local precipitation trends determine whether periods of drought and heat waves will occur simultaneously," explains Emanuele Bevacqua. For Central Europe, for example, this implies that in the case of a 'wet storyline' with increasing precipitation, concurrent droughts and heat waves will occur on average every ten years, whereas in the case of a 'dry storyline' with decreasing precipitation, they will occur at least every four years. For Central North America, these events would be expected every nine years ('wet storyline') and six years ('dry storyline'). These regional storylines for precipitation trends can be used as a basis for decisions on adaptation, for example to evaluate best and worst case-scenarios.

However, even if we know that precipitation trends are decisive for the occurrence of concurrent droughts and heat waves, it is still difficult to predict them any more reliably: "Climate change may shift the distribution of precipitation in certain regions. The pattern of precipitation depends on atmospheric circulation, which determines regional weather dynamics through numerous interactions over large parts of the globe," says Emanuele Bevacqua. Since the dynamic of many of these processes is not yet fully understood, it is difficult to reduce these uncertainties any further. 

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Concurrent heatwaves seven times more frequent than in 1980s

Multiple large heatwaves the size of Mongolia occurred at the same time nearly every day during the warm seasons of the 2010s across the Northern Hemisphere, according to a study led by Washington State University researchers.

Using climate data from 1979 to 2019, the researchers found that the number of heatwaves occurring simultaneously in the mid- to high-latitudes of the Northern Hemisphere was seven times greater in the 2010s than in the 1980s. On average, there were concurrent heatwaves on 143 days each year of the 2010s -- almost every day of the 153 days of the warm months of May through September.

The concurrent heat events also grew hotter and larger: their intensity rose by 17% and their geographic extent increased 46%.

"More than one heatwave occurring at the same time often has worse societal impacts than a single event," said Cassandra Rogers, a WSU post-doctoral researcher and lead author of the study in Journal of Climate. "If certain regions are dependent on one another, for instance for agriculture or trade, and they're both undergoing stresses at the same time, they may not be able to respond to both events."

Heatwaves can cause disasters from crop failures to wildfires. Concurrent heatwaves can multiply those threats, the authors pointed out, exhausting the ability of countries to provide mutual aid in crises as was seen during the multiple wildfires in the U.S., Canada and Australia associated with the 2019 and 2020 heatwaves. A previous study also found that concurrent heatwaves caused about a 4% drop in global crop production.

This study defined large heatwaves as high temperature events lasting three days or more and covering at least 1.6 million square kilometers (about 620,000 square miles), which is roughly equivalent to the size of Mongolia or Iran.

The researchers analyzed ERA5 data produced by the European Center for Medium-Range Weather Forecasts, which blends vast amounts of observational data from weather stations on land, water buoys and aircraft as well as data from satellites with weather forecasting models. ERA5 provides globally complete estimates of hourly data for various climate variables from 1979, when satellite data became available, which is why the study focused on this time period.

Using these observational data, the researchers found that the primary driver of the heatwaves was the overall rise in global mean temperature due to climate change. The world has warmed 1 degree Celsius (about 1.8 degrees Fahrenheit) over the last century with the vast majority of the rise, two-thirds, occurring since 1975. The researchers also found that increasing occurrence of two hemisphere-wide circulation patterns made particular areas more vulnerable to concurrent heatwaves, including eastern North America, eastern and northern Europe, East Asia and eastern Siberia.

The study adds more evidence for the need to curb greenhouse gas emissions and mitigate climate change, the researchers said, and the continued rise in temperature means the world should prepare for more concurrent heatwaves.

"As a society, we are not currently adapted to the types of climate events we're experiencing right now," said co-author Deepti Singh, WSU associate professor in the School of the Environment.

"It's important to understand how we can reduce our vulnerability and adapt our systems to be more resilient to these kind of heat events that have cascading societal impacts."

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Heatwaves like ‘the Blob' could decrease role of ocean as carbon sink

Researchers have found the two-year heatwave known as 'the Blob' may have temporarily dampened the Pacific's 'biological pump,' which shuttles carbon from the surface ocean to the deep sea where it can be stored for millennia.

Canadian and European researchers, in collaboration with the U.S. Department of Energy Joint Genome Institute, conducted a large-scale study of the impact of one of the largest marine heatwaves on record -- colloquially known as the Blob -- on Pacific Ocean microorganisms. Their observations suggest that it's not just larger marine life that is affected by abrupt changes in sea temperature.

"Heatwaves such as the Blob may decrease the ocean's biological role as a carbon sink for fixed atmospheric carbon," said Dr. Steven Hallam (he/him), a microbiologist at the University of British Columbia and author of the paper published in Nature Communications Biology.

This 'biological pump' process is an important mechanism for buffering the impact of human activity on Earth's climate, said co-author Dr. Colleen Kellogg (she/her), a research scientist with the Hakai Institute. "The ocean is a huge global reservoir for atmospheric carbon dioxide. If marine heatwaves reduce the capacity for carbon dioxide to be absorbed into the ocean, then this shrinks this reservoir and leaves more of this greenhouse gas in the atmosphere."

Microbes form the base of the marine food web, performing critical functions such as synthesizing and recycling organic matter. Very little is known about how these invisible community members are affected by marine heatwaves, but understanding their responses can provide a vital sign for the rest of the marine food web.

"Marine heatwaves are one of the big challenges of climate change," explains Dr. Sachia Traving (she/her), lead author on the study at the University of Southern Denmark. "Knowing how they affect microbes -- some of the smallest but most abundant organisms on earth -- will help us understand how heatwaves will impact life in our future oceans."

To investigate these responses, the study brought together researchers from UBC, Fisheries and Oceans Canada's Institute of Ocean Sciences, and the Hakai Institute. They combined seven years of DNA sequencing and oceanographic measurements from an open-sea buoy known as Ocean Station Papa (OSP) to chart how microbial communities were structured before and during the most severe marine heatwave in recent time.

OSP is the terminal station of the Line P transect. Running continuously since 1956, Line P is one of the longest running oceanographic time series in the world, and is composed of 26 hydrographic stations originating in the coastal waters of British Columbia and heading westward to OSP, over 1,400 km from the coast.

A major impact researchers observed during the Blob, which began in 2013, was a rise in microbes specialized to survive under more nutrient limiting conditions. That shift was likely a response to changes in the composition of the region's phytoplankton, which saw a decline in larger cells that contribute to the formation of organic matter particles. That decrease in large particles in turn hinders the ocean's biological pump and ability to act as a carbon sink.

Research has shown that marine heatwaves are a direct consequence of climate change. These anomalous warm water bodies are occurring with increasing frequency as global temperatures rise, and disrupt the ecosystems in which they appear. Previous work on the Blob has documented its extensive impacts on life in the Northeastern Pacific Ocean, from phytoplankton, zooplankton and fish populations to marine mammals and birds.

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July 2019 was hottest month on record for the planet

Thermometer showing high temperature in summer

Much of the planet sweltered in unprecedented heat in July, as temperatures soared to new heights in the hottest month ever recorded. The record warmth also shrank Arctic and Antarctic sea ice to historic lows.

Here's a closer look into NOAA's latest monthly global climate report:

Climate by the numbers: July 2019

The average global temperature in July was 1.71 degrees F above the 20th-century average of 60.4 degrees, making it the hottest July in the 140-year record, according to scientists at NOAA's National Centers for Environmental Information. The previous hottest month on record was July 2016.

Nine of the 10 hottest Julys have occurred since 2005 -- with the last five years ranking as the five hottest. Last month was also the 43rd consecutive July and 415th consecutive month with above-average global temperatures.

Year to date: January through July

The period from January through July produced a global temperature that was 1.71 degrees F above the 20th-century average of 56.9 degrees, tying with 2017 as the second-hottest year to date on record.

It was the hottest year to date for parts of North and South America, Asia, Australia, New Zealand, the southern half of Africa, portions of the western Pacific Ocean, western Indian Ocean and the Atlantic Ocean.

More notable stats and facts

Record-low sea ice: Average Arctic sea ice set a record low for July, running 19.8% below average -- surpassing the previous historic low of July 2012.

Average Antarctic sea-ice coverage was 4.3% below the 1981-2010 average, making it the smallest for July in the 41-year record.

Some cool spots: Parts of Scandinavia and western and eastern Russia had temperatures at least 2.7 degrees F below average.

NOAA's full climate report is available at: https://www.ncdc.noaa.gov/sotc/global/201907

From Science Daily

Heat-related deaths likely to increase significantly as global temperatures rise, warn researchers

Thermometer in a heat wave

The world needs to keep global temperatures in check by meeting the goals set out in the Paris Agreement, or more people could die because of extreme temperatures, say authors of a new study in the letters section of Springer's journal Climatic Change.

The Paris Agreement, adopted in 2015 under the auspices of the United Nations Framework Convention on Climate Change (UNFCCC), binds nations to hold warming well below 2 degrees Celsius (°C) in global mean temperature, relative to pre-industrial levels. It also urges countries to make additional efforts to limit warming to 1.5°C.

Led by researchers at the London School of Hygiene & Tropical Medicine (LSHTM), this is the first study that evaluates global temperature-related health impacts under scenarios consistent with the Agreement. The researchers assessed the mortality impacts projected for a range of temperature increases, either compatible with the thresholds set in Paris (1.5°C and 2°C) or higher (3°C and 4°C). These projections took into account how an increase in heat-related deaths might be offset against a decrease in deaths due to cold, as global temperatures rise.

The scope of the study allowed global comparisons across various areas of the world. The team at LSHTM first analyzed historical data on temperature-related deaths from 451 locations in 23 countries with different socio-economic and climatic conditions. They then projected changes in mortality under climate scenarios consistent with the various increases in global temperature, while keeping demographic distributions and temperature-health risks constant.

The results indicated dramatic increases of heat-related deaths under extreme warming (3°C and 4°C) compared to the mildest threshold (1.5°C), with additional excess mortality ranging from +0.73 per cent to +8.86 per cent across all regions. The net difference remained positive and high in most of the areas, even when potential decreases in cold-related deaths were considered.

The picture was more complex when comparing 2°C versus 1.5°C warming. A net increase in deaths was still projected for warmer regions such as South America, South Europe, and South-East Asia (with changes ranging from +0.19 per cent to +0.72 per cent), while in cooler regions the excess mortality was predicted to stay stable or drop slightly.

The results support the assessment of an upcoming Special Report of the Intergovernmental Panel on Climate Change, scheduled for approval in October, that evaluates the health risks associated with 1.5°C and 2°C of warming.

"Our projections suggest that large increases in temperature-related deaths could be limited in most regions if warming was kept below 2°C," explains Ana Maria Vicedo-Cabrera, the first author of the study. "Under extreme changes in climate, large parts of the world could experience a dramatic increase in excess mortality due to heat. This would not be balanced by decreases in cold-related deaths. Efforts to limit the increase in global temperature to below 1.5°C could provide additional benefits in tropical or arid regions, including the most populous and often poorest countries."

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Heatwave and climate change having negative impact on our soil say experts

Drought alters soil at microbial level.

The recent heatwave and drought could be having a deeper, more negative effect on soil than we first realised say scientists.

This could have widespread implications for plants and other vegetation which, in turn, may impact on the entire ecosystem.

That's because the organisms in soil are highly diverse and responsible not only for producing the soil we need to grow crops, but also other benefits such as cleaning water and regulating greenhouse gas emissions.

The new study, led by researchers at The University of Manchester and published today (02/08/2018) in Nature Communications, provides new insight into how a drought alters soil at microbial level. It shows that expected changes in climate will affect UK soil and that soil is not as tough as previously thought.

Due to climate change, disturbances such as drought are increasing in intensity and frequency. These extreme weather conditions change vegetation composition and soil moisture, which in turn impacts the soil's underlying organisms and microbial networks.

By studying how microbes react to severe drought, the study provides a better understanding of how underground soil networks respond to such environmental disturbances.

Lead author, Dr Franciska de Vries, from Manchester's School of Earth and Environmental Sciences, explains: "Soils harbour highly diverse microbial communities that are crucial for soil to function as it should.

"A major challenge is to understand how these complex microbial communities respond to and recover from disturbances, such as climate extremes, which are predicted to increase in frequency and intensity with climate change.

"These microbial communities within the soil play a crucial role in any ecosystem. But it wasn't known how soil networks respond to such disturbances until now."

Sequencing of soil DNA for the study was conducted at the Centre for Ecology & Hydrology (CEH). Dr Robert Griffiths, a molecular microbial ecologist at CEH, said: "This study further identifies those key organisms affected by drought, which will guide future research to predict how future soil microbial functions are affected by climate change."

The research team tested the effects of summer drought on plant communities consisting of four common grassland species. They found that drought increased the abundance of a certain fast-growing, drought-tolerant grass. With greater aboveground vegetation comes an increased rate of evapotranspiration, or cycling of water from plants to the atmosphere, lowering the overall soil moisture.

Science conducted as part of Lancaster University's Hazelrigg grassland experiment was key to the findings.

Professor Nick Ostle, from the Lancaster Environment Centre, said: "Our hot and dry summer this year is a 'wake up' to prepare for future weather stresses. We have just had the hottest ten years in UK history. This work shows that continued summer droughts will change soil biology. This matters as we plan for ensuring food security that depends on healthy soil."

Unlike past research, this study considered the multitude of direct and indirect interactions occurring between different microbial organisms in soil. Rather than focusing on select attributes of bacteria and fungi, this research takes a comprehensive approach to studying soil ecosystems.

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