Characterizing climate change from heating, not merely temperature
Climate change goals
Peer-Reviewed PublicationIMAGE:
COVER FOR "JOURNAL OF CLIMATE ACTION, RESEARCH AND POLICY"
view moreCREDIT: WORLD SCIENTIFIC
Current human–induced climate change arises primarily from the heating of the planet from changes in atmospheric composition. Only one manifestation of this is temperature change. Yet the focus of many media reports is on temperatures and whether the Paris Agreement targets of 1.5°C or 2°C have been breached or threatened. A new paper published in the Journal of Climate Action, Research, and Policy challenges this framing.
The increasing amount of greenhouse gases (notably carbon dioxide from burning fossil fuels) in the atmosphere leads to Earth’s Energy Imbalance (EEI) and altered flows of energy through the climate system. The dissemination of excess energy is partly what determines how climate change is manifested. Some of the extremes being experienced — especially those involving drought, convection, storms, flooding, and the water cycle — are mostly driven by aspects of heating. While temperature contributes through the water–holding capacity of the atmosphere, it is more a consequence than a cause. After all, water is the air–conditioner of the planet. Natural climate variability — such as the strong El Niño currently underway — generally determines where new extremes occur and can lead to confusion as to what is going on. Human–caused change exacerbates the weather and natural variability.
The United Nations — and especially the Intergovernmental Panel on Climate Change (IPCC) in their Summary for Policy Makers — focus on global temperature targets rather than broader facets of climate change including EEI, and do not always adequately discriminate between temperature and heating. This also has consequences for future climate control if or when heating is brought under control by cutting emissions. Improvements are needed in expressing how the climate is changing by properly accounting for the flow of energy through the climate system.
The new climate norm has a warmer ocean and less ice, and some changes on the warmer land mean less and maybe destabilized permafrost. Rainfall character changes substantially. Many changes do not relate directly to global temperature but are nonetheless physically related to the heating climate.
The new paper is authored by Kevin Trenberth, who has watched as climate change (global warming) was ignored, then dismissed, under–reported, largely missing in many disaster reports where it should have been included, to now being blamed for almost everything.
He emphasizes that increased heating often leads to more evaporation from the ocean and terrestrial surfaces. The resulting increased amount of atmospheric water vapor causes more intense storms and heavier rains, raising the risk of flooding.
About the author:
Dr. Kevin E. Trenberth is a Distinguished Scholar at the National Center for Atmospheric Research and an honorary affiliate faculty at the University of Auckland in New Zealand. He has been involved in climate and climate change research throughout his career. He has been prominent in most of the Intergovernmental Panel on Climate Change (IPCC) scientific assessments of Climate Change, including in the inter–governmental meetings that approved the second, third and fourth assessments, and has also extensively served the World Climate Research Programme (WCRP) in numerous ways.
The author is affiliated with the NSF National Center for Atmospheric Research, in Boulder, CO, and the University of Auckland, New Zealand.
Kevin Trenberth: +64 27 771 4868, trenbert@ucar.edu
The paper Characterizing Climate Change from Heating, not merely Temperature can be found in the Journal of Climate Action, Research, and Policy.
JOURNAL
Journal of Climate Action Research and Policy
METHOD OF RESEARCH
Literature review
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Characterizing Climate Change from Heating, not merely Temperature
ARTICLE PUBLICATION DATE
28-Feb-2024
Climate change disrupts seasonal flow of rivers
Climate change is disrupting the seasonal flow of rivers in the far northern latitudes of America, Russia and Europe and is posing a threat to water security and ecosystems, according to research published today.
Peer-Reviewed PublicationClimate change is disrupting the seasonal flow of rivers in the far northern latitudes of America, Russia and Europe and is posing a threat to water security and ecosystems, according to research published today.
A team of scientists led by the University of Leeds analysed historical data from river gauging stations across the globe and found that 21% of them showed significant alterations in the seasonal rise and fall in water levels.
The study used data-based reconstructions and state-of-the-art simulations to show that river flow is now far less likely to vary with the seasons in latitudes above 50°N than previously, and that this could be directly linked to changes to the climate caused by human activity.
Until now, evidence suggesting that climate change has had an impact on river flow seasonality has been limited to local studies or has failed to consider the impact of climate change brought about by humans explicitly.
In this study the team used monthly average river flow measurements from 10,120 gauging stations from 1965 to 2014.
For the first time ever, they were able to exclude direct human interventions such as reservoir management or water extraction, to show that widespread reduction in river flow seasonality was driven by climate change.
The results of the research, which was funded by the University of Leeds and the Southern University of Science and Technology in China are published today (29 February) in the journal Science.
Lead author, Hong Wang, a PhD researcher at the University of Leeds and the Southern University of Science and Technology in China, said: “Our research shows that rising air temperatures are fundamentally altering the natural patterns of river flow.
“The concerning aspect of this change is the observed weakening of river flow seasonality, and that this is as a direct consequence of historical human-induced emissions. This signals a sustained and considerable diminishment of river flow seasonality if air temperatures continue to rise.”
Human impact on river flow
Human activities are altering river flow patterns worldwide, both directly through flow regulations such as reservoirs, and indirectly through land use change and the impacts of climate change on air temperature, precipitation, soil moisture, and snowmelt.
Over two-thirds of the world’s rivers have already been altered by humans even without considering the indirect impacts of increases in greenhouse gases and aerosols.
River flow seasonality plays a critical role in the predicted cycle of floods and droughts. A weakening of these peaks and troughs can threaten water security and freshwater biodiversity. For example, a substantial portion of the early meltwater from snowpack depletion may quickly flow into oceans and therefore not be available for human use.
Weakening river flow seasonality - for example due to a reduction in spring and early summer river levels in snowmelt regions - can also have an impact downstream on riverbank vegetation and organisms living in the river itself.
Gauging the seasonal flow
In northern North America, the researchers found that 40% of the 119 stations observed showed a significant decrease in river flow seasonality. Similar results were also observed in sS
There was a comparable pattern in Europe, with 19% of the river gauging stations experiencing a significant decrease - mainly in northern Europe, western Russia and the European Alps.
In addition, regions in the contiguous United States (the lower 48 states in North America, including the District of Columbia) showed predominantly decreasing trends of river flow seasonality overall, except for rivers in the Rocky Mountains and Florida.
In central North America, the research showed significant decreasing river flow seasonality trends in 18% of the stations.
By contrast, the researchers found a significant increase in river flow seasonality in 25% of the gauging stations in southeast Brazil, showing that changes to the water cycle are having a different impact in some parts of the world.
Dr Megan Klaar, an Associate Professor in the University of Leeds School of Geography and a member of water@leeds, co-authored the research. She said: “The highs and lows of river flow during the different seasons provide vital cues for the species living in the water.
“For example, a lot of fish use particular increases in the water as a cue to run to their breeding areas upstream or towards the sea. If they don’t have those cues, they won’t be able to spawn.”
The research concludes that there is a need to accelerate climate adaptation efforts to safeguard freshwater ecosystems by managing flows to try to recreate some of the natural systems and processes that are being lost.
Professor Joseph Holden, the Director of water@leeds and who supervised Hong Wang’s research, added: “A lot of concern is based upon what climate change will do in the future but our research signals that it’s happening now and that increases in air temperature are driving huge changes in river flow.
“We should be very concerned about what the future holds given accelerating climate change and begin to think about mitigation strategies and adaptation planning to alleviate the future weakening of seasonal river flow, particularly in locations such as western Russia, Scandinavia, and Canada.”
Ends
Notes to editors
The DOI is 10.1126/science.adi9501
Pictures and illustrations available here
Photo of alpine river in Zinal, Switzerland: Please credit Yoal Desurmont
Illustration 1: Credit Myriam Wares
Email: contact@myriamwares.com
The rapid rise in air temperature, driven by human-induced emissions, is diminishing the seasonal variations in river flow. This weakening pattern of river flow seasonality has the potential to impact riparian vegetation, the life cycles of freshwater biota, and water security.
Illustration 2: Credit Elena Galofaro Bansh
Email: elena@elenabanshart.com
The rapid rise in air temperature, driven by human-induced emissions, is diminishing the seasonal variations in river flow. The homogenized monthly distribution of river flow throughout the year has the potential to impact freshwater ecosystems and water security.
For media enquiries or interview requests, please contact Kersti Mitchell via k.mitchell@leeds.ac.uk
Other institutions involved in the research were:
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, China
North China University of Water Resources and Electric Power, Zhengzhou, China
Henan Provincial Key Lab of Hydrosphere and Watershed Water Security, North China
University of Water Resources and Electric Power, Zhengzhou, China
Institute for Atmospheric and Climate Science, ETH Zürich, Zürich, Switzerland
University of Leeds
The University of Leeds is one of the largest higher education institutions in the UK, with more than 39,000 students from more than 137 different countries. We are renowned globally for the quality of our teaching and research.
We are a values-driven university, and we harness our expertise in research and education to help shape a better future for humanity, working through collaboration to tackle inequalities, achieve societal impact and drive change.
The University is a member of the Russell Group of research-intensive universities, and is a major partner in the Alan Turing, Rosalind Franklin and Royce Institutes www.leeds.ac.uk
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JOURNAL
Science
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Anthropogenic climate change has influenced global river flow seasonality
ARTICLE PUBLICATION DATE
29-Feb-2024
In wake of powerful cyclone, remarkable recovery of Pacific island’s forests
IMAGE:
THESE PHOTOS SHOW THE RAPID RECOVERY OF THE FOREST CANOPY ON TANNA, FOLLOWING CYCLONE PAM IN 2015.
view moreCREDIT: UH MĀNOA
After one of the most intense cyclones in world history tore through the Pacific island of Tanna in Vanuatu, new research led by the University of Hawaiʻi at Mānoa showed the resilience of the island’s forests.
In the Pacific islands, climate change is expected to increase the intensity and frequency of cyclones, causing huge potential risks to forests and the people who depend on them. In March 2015, Cyclone Pam touched down on the island of Tanna as the strongest Pacific island cyclone in history at the time. With sustained winds reaching 165 mph, Pam pounded the island for 18 hours.
A new study published on February 29 in the journal Science of the Total Environment has documented the remarkable recovery of Tanna’s forests after Cyclone Pam. The team, which included researchers from UH Mānoa, The New York Botanical Garden (NYBG), the University of the South Pacific, and the Vanuatu Cultural Centre and Vanuatu Department of Forestry, examined post-cyclone recovery across eight forested sites on Tanna over five years.
“Compared to cyclones on other Pacific Islands, Pam caused relatively low levels of severe damage to Tanna’s trees,” said UH Mānoa School of Life Sciences Professor Tamara Ticktin and lead author on the paper. “In addition, there was high resprouting, widespread recruitment of most tree species present, and basically no spread of invasive species.”
The latter is especially surprising, because invasive species often spread rapidly after Pacific Island cyclones.
Cyclone history, stewardship practice, key to resilience
The authors conclude that Tanna’s historical cyclone frequency likely fostered the abundance of resilient species, and that Tanna’s customary stewardship practices appear to augment the capacity for resilience. This is because they promote a diversity of tree species, life histories and life stages; as well as a wide range of pathways for regeneration.
“Tanna stewards value a wide range of species useful for food, medicines and building materials,” explained ethnobotanist and co-author Michael J. Balick, Ph.D., NYBG’s Vice President for Botanical Science and Director and Senior Philecology Curator of the Institute for Economic Botany. “And customary stewardship involves management practices that enhance the survival and reproduction of these species.”
Co-author Jean-Pascal Wahe of the Vanuatu Cultural Centre noted that after a cyclone, stewards weed around native tree species and even plant them.
These actions can help ensure their regeneration while decreasing dominance of weedy understory species.
The study also showed that forests that had previously been subject to grazing by cattle and pigs were slower to recover and will likely be more vulnerable to future cyclones.
"This highlights the key role of forest management in building resilience to climate change,” said senior author Gregory M. Plunkett, Ph.D., NYBG’s Director and Curator of the Cullman Program for Molecular Systematics. Dr. Plunkett, who has been studying the plants of Vanuatu for two decades, had been carrying out research on Tanna along with Dr. Balick and co-author Marika Tuiwawa of the University of the South Pacific when Cyclone Pam hit. They experienced the terror of the cyclone first-hand and were delighted to also witness forest recovery.
“As the world comes to grips with more frequent extreme weather events, our work suggests that the right kind of human interaction can play a significant role in the survival of forests,” said Dr. Plunkett.
This study is part of the wider Plants and People of Vanuatu program, led by Drs. Balick and Plunkett, and was supported by the National Science Foundation, the Critical Ecosystem Partnership Fund, and the National Geographic Society.
Team members monitor tree regeneration in study plots on Tanna in the aftermath of Cyclone Pam.
Fallen tree in the aftermath of Cyclone Pam.
CREDIT
UH Mānoa
JOURNAL
Science of The Total Environment
ARTICLE TITLE
High resilience of Pacific Island forests to a category- 5 cyclone
ARTICLE PUBLICATION DATE
29-Feb-2024
Hurricanes and power grids: Eliminating large-scale outages with a new approach
Large scale-power outages caused by tropical cyclones can be prevented almost entirely if a small but critical set of power lines is protected against storm damages, a new study published in Nature Energy finds.
POTSDAM INSTITUTE FOR CLIMATE IMPACT RESEARCH (PIK)
Large scale-power outages caused by tropical cyclones can be prevented almost entirely if a small but critical set of power lines is protected against storm damages, a new study published in Nature Energy finds. Scientists from the Potsdam Institute for Climate Impact Research (PIK) developed a new method that can be used to identify those critical lines and increase the system’s resilience. Based on a model of the Texas power grid on the US Gulf Coast, their analysis reveals how large-scale power outages actually occur and how to prevent them. The Texas power grid is frequently hit by hurricanes and weaker tropical storms, a risk that is expected to substantially increase under global warming.
“For the first time, our analysis shows how an electric network reacts to evolving storms. By simulating the co-evolution of wind-induced failures of high-voltage transmission lines and the resulting cascading power outages, we discovered which parts of the electricity network are most critical as their failures have cascading impacts leading to major power outages. This appears to be a property of the network itself, rather than the storm’s precise path”, says PIK scientist and study author Frank Hellmann.
The scientists coupled a model of the evolution of the wind-fields of tropical cyclones with a dynamic model of the Texas power grid in an innovative spatio-temporal approach, allowing to describe the evolution of storm-induced cascading power outages. “This is a challenging task, as the time scales at which storms and power outages evolve can be very different. By combining PIK expertise on the event-based modelling of tropical storms and power grids, we managed to identify the critical lines, whose failure can trigger large blackouts”, says scientist Mehrnaz Anvari, who conducted the research at PIK and is now group leader of “Network Evaluation Technologies” at the Fraunhofer Institute for Algorithms and Scientific Computing.
Protecting a small part of the power grid prevents major cascade fails in regions and cities
“We found that the failures of certain lines can trigger large-scale outages affecting whole regions or cities. Regions or cities fail in one major cascade, rather than gradually. Our research shows that such cascades can be avoided almost entirely if less than 1 percent of the overall grid – this is 20 lines in the case of the Texas power grid – is protected against storm damages, for example by reinforcing transmission towers or using underground cables. This way, the risk of outages in major population centers can be significantly reduced. Notably, protecting the same small set of relevant lines works for all seven historical hurricanes considered”, says study author and PIK scientist Christian Otto.
The Texas electric power system, which is frequently exposed to hurricanes and weaker tropical storms, provided the perfect context to study these complex effects and potential adaptation options in depth. The scientists developed a model that simulates the storms’ damages to the Texas power grid and studied 10.000 realizations of potential damages for each of seven historical tropical cyclones, including the major hurricanes Harvey (2017) and Ike (2008). Their approach allowed to reproduce observed supply failures.
“Tropical cyclones are one of the most destructive category of extreme weather events. As peak wind speeds of the most intense storms are projected to increase with global warming, the damage caused by these storms is likely to increase unless we adapt accordingly. Our new method gives grid operators a crucial tool to identify effective adaptation options and can help make our infrastructure networks fit for a new climate reality”, says Katja Frieler, scientist and Head of the Research Department “Transformation Pathways” at PIK.
Article: Julian Stürmer, Anton Plietzsch, Thomas Vogt, Frank Hellmann, Jürgen Kurths, Christian Otto, Katja Frieler & Mehrnaz Anvari (2024): Increasing the resilience of the Texas power grid against extreme storms by hardening critical lines. Nature Energy. [DOI: 10.1038/s41560-023-01434-1]
Large scale-power outages caused by tropical cyclones can be prevented almost entirely if a small but critical set of power lines is protected against storm damages, a new study published in Nature Energy finds.
POTSDAM INSTITUTE FOR CLIMATE IMPACT RESEARCH (PIK)
Large scale-power outages caused by tropical cyclones can be prevented almost entirely if a small but critical set of power lines is protected against storm damages, a new study published in Nature Energy finds. Scientists from the Potsdam Institute for Climate Impact Research (PIK) developed a new method that can be used to identify those critical lines and increase the system’s resilience. Based on a model of the Texas power grid on the US Gulf Coast, their analysis reveals how large-scale power outages actually occur and how to prevent them. The Texas power grid is frequently hit by hurricanes and weaker tropical storms, a risk that is expected to substantially increase under global warming.
“For the first time, our analysis shows how an electric network reacts to evolving storms. By simulating the co-evolution of wind-induced failures of high-voltage transmission lines and the resulting cascading power outages, we discovered which parts of the electricity network are most critical as their failures have cascading impacts leading to major power outages. This appears to be a property of the network itself, rather than the storm’s precise path”, says PIK scientist and study author Frank Hellmann.
The scientists coupled a model of the evolution of the wind-fields of tropical cyclones with a dynamic model of the Texas power grid in an innovative spatio-temporal approach, allowing to describe the evolution of storm-induced cascading power outages. “This is a challenging task, as the time scales at which storms and power outages evolve can be very different. By combining PIK expertise on the event-based modelling of tropical storms and power grids, we managed to identify the critical lines, whose failure can trigger large blackouts”, says scientist Mehrnaz Anvari, who conducted the research at PIK and is now group leader of “Network Evaluation Technologies” at the Fraunhofer Institute for Algorithms and Scientific Computing.
Protecting a small part of the power grid prevents major cascade fails in regions and cities
“We found that the failures of certain lines can trigger large-scale outages affecting whole regions or cities. Regions or cities fail in one major cascade, rather than gradually. Our research shows that such cascades can be avoided almost entirely if less than 1 percent of the overall grid – this is 20 lines in the case of the Texas power grid – is protected against storm damages, for example by reinforcing transmission towers or using underground cables. This way, the risk of outages in major population centers can be significantly reduced. Notably, protecting the same small set of relevant lines works for all seven historical hurricanes considered”, says study author and PIK scientist Christian Otto.
The Texas electric power system, which is frequently exposed to hurricanes and weaker tropical storms, provided the perfect context to study these complex effects and potential adaptation options in depth. The scientists developed a model that simulates the storms’ damages to the Texas power grid and studied 10.000 realizations of potential damages for each of seven historical tropical cyclones, including the major hurricanes Harvey (2017) and Ike (2008). Their approach allowed to reproduce observed supply failures.
“Tropical cyclones are one of the most destructive category of extreme weather events. As peak wind speeds of the most intense storms are projected to increase with global warming, the damage caused by these storms is likely to increase unless we adapt accordingly. Our new method gives grid operators a crucial tool to identify effective adaptation options and can help make our infrastructure networks fit for a new climate reality”, says Katja Frieler, scientist and Head of the Research Department “Transformation Pathways” at PIK.
Article: Julian Stürmer, Anton Plietzsch, Thomas Vogt, Frank Hellmann, Jürgen Kurths, Christian Otto, Katja Frieler & Mehrnaz Anvari (2024): Increasing the resilience of the Texas power grid against extreme storms by hardening critical lines. Nature Energy. [DOI: 10.1038/s41560-023-01434-1]
JOURNAL
Nature Energy
Nature Energy
DOI
METHOD OF RESEARCH
Computational simulation/modeling
Computational simulation/modeling
SUBJECT OF RESEARCH
Not applicable
Not applicable
ARTICLE TITLE
Increasing the resilience of the Texas power grid against extreme storms by hardening critical lines.
Increasing the resilience of the Texas power grid against extreme storms by hardening critical lines.
ARTICLE PUBLICATION DATE
1-Mar-2024
1-Mar-2024
Lake ecosystems: Nitrogen has been underestimated
Study shows: Algae growth in shallow lakes around the world is affected not only by phosphorus but also by nitrogen
Peer-Reviewed Publication
The input of phosphorus and nitrogen from agricultural sources and sewage treatment plants can have a strong effect on phytoplankton growth in rivers and lakes. "However, it was previously assumed that phytoplankton growth in lakes is mostly limited and driven by the availability of phosphorus," says lead author Dr. Daniel Graeber from the UFZ. The underlying theory: If only small quantities of phosphorus are available in a lake, phytoplankton growth is correspondingly limited. In contrast, large quantities of phosphorous will massively drive phytoplankton growth. "In this explanatory model, nitrogen plays no role," says Graeber. "This is based on the fact that specific cyanobacteria in the water can bind the nitrogen contained in the air and introduce it into the lake. This would therefore preclude a long-term nitrogen deficiency in lakes." Nor could an excess supply of nitrogen promote phytoplankton growth – and therefore could not ultimately give rise to eutrophication. "This model forms the basis for lake management worldwide, where the emphasis has been on controlling phosphorus inputs to counteract lake eutrophication," explains Dr. Thomas A. Davidson, limnologist at Aarhus University and last author of the study. "Reducing phosphorus inputs repeatedly fails to prevent eutrophication. This therefore gave rise to the question of whether the water equation included yet another unknown." In its present study, the research team has now clearly identified nitrogen as such a factor, and is thus indicating new directions for inland water science (limnology) and lake management.
Roughly 89 percent of lakes worldwide are so-called shallow lakes with an average depth of up to six metres. The researchers performed their statistical investigations with long-term monitoring data from 159 shallow lakes in North America, Europe and New Zealand. For each lake, they determined the relationship between the ratio of total nitrogen to total phosphorus and the concentration of chlorophyll-a as a measure of phytoplankton biomass over periods of 5 year. "We wanted to determine the long-term relationships between the ratio of the two nutrients and phytoplankton growth," explains Daniel Graeber. "The idea for our study originated with several outliers in a prior study of the ecology of shallow lakes. In some of the lakes, we did not see a linear correspondence between the measured nutrient and a respective increased or decreased chlorophyll-a concentration," says the limnologist. "We asked ourselves: Could this possibly be due to the nutrient ratio of phosphorus and nitrogen? There had already been a few studies hinting that nitrogen could potentially play a more important role in phytoplankton growth in lakes than was previously assumed."
The statistical analyses in their current study support the theory of these studies and clearly contradict the traditional limnological consensus: 60 percent of the water bodies investigated exhibit a very high probability of a dual-nutrient limitation. This would mean that both nutrients – phosphorous and nitrogen – have a limiting effect on phytoplankton growth in the majority of the lakes. "The relationships were so clear that I couldn't even believe it at first. They corresponded exactly to what was known from laboratory experiments – this was truly astounding," says Graeber. "The result withstood thorough testing of the statistics: The data were robust. Our results confirm the hypothesis that nitrogen is not a passive participant in lake ecology. And we were able to prove with a broad database for the first time that this clearly applies to lakes worldwide." The research team is now spurring further investigations, both in the field and through modelling, with which the results of their data analysis can be tested.
With their study, the researchers have figuratively pulled nitrogen into the equation of lake ecology. They recommend that, in practice, nitrogen now be given more focus in lake management. "We need a long-term investigation of the nutrient ratios to ensure the success of efficient and effective eutrophication management," says Graeber. "This requires a greater focus on inputs from agriculture, which generally have a high nitrogen content."
Study shows: Algae growth in shallow lakes around the world is affected not only by phosphorus but also by nitrogen
The input of phosphorus and nitrogen from agricultural sources and sewage treatment plants can have a strong effect on phytoplankton growth in rivers and lakes. "However, it was previously assumed that phytoplankton growth in lakes is mostly limited and driven by the availability of phosphorus," says lead author Dr. Daniel Graeber from the UFZ. The underlying theory: If only small quantities of phosphorus are available in a lake, phytoplankton growth is correspondingly limited. In contrast, large quantities of phosphorous will massively drive phytoplankton growth. "In this explanatory model, nitrogen plays no role," says Graeber. "This is based on the fact that specific cyanobacteria in the water can bind the nitrogen contained in the air and introduce it into the lake. This would therefore preclude a long-term nitrogen deficiency in lakes." Nor could an excess supply of nitrogen promote phytoplankton growth – and therefore could not ultimately give rise to eutrophication. "This model forms the basis for lake management worldwide, where the emphasis has been on controlling phosphorus inputs to counteract lake eutrophication," explains Dr. Thomas A. Davidson, limnologist at Aarhus University and last author of the study. "Reducing phosphorus inputs repeatedly fails to prevent eutrophication. This therefore gave rise to the question of whether the water equation included yet another unknown." In its present study, the research team has now clearly identified nitrogen as such a factor, and is thus indicating new directions for inland water science (limnology) and lake management.
Roughly 89 percent of lakes worldwide are so-called shallow lakes with an average depth of up to six metres. The researchers performed their statistical investigations with long-term monitoring data from 159 shallow lakes in North America, Europe and New Zealand. For each lake, they determined the relationship between the ratio of total nitrogen to total phosphorus and the concentration of chlorophyll-a as a measure of phytoplankton biomass over periods of 5 year. "We wanted to determine the long-term relationships between the ratio of the two nutrients and phytoplankton growth," explains Daniel Graeber. "The idea for our study originated with several outliers in a prior study of the ecology of shallow lakes. In some of the lakes, we did not see a linear correspondence between the measured nutrient and a respective increased or decreased chlorophyll-a concentration," says the limnologist. "We asked ourselves: Could this possibly be due to the nutrient ratio of phosphorus and nitrogen? There had already been a few studies hinting that nitrogen could potentially play a more important role in phytoplankton growth in lakes than was previously assumed."
The statistical analyses in their current study support the theory of these studies and clearly contradict the traditional limnological consensus: 60 percent of the water bodies investigated exhibit a very high probability of a dual-nutrient limitation. This would mean that both nutrients – phosphorous and nitrogen – have a limiting effect on phytoplankton growth in the majority of the lakes. "The relationships were so clear that I couldn't even believe it at first. They corresponded exactly to what was known from laboratory experiments – this was truly astounding," says Graeber. "The result withstood thorough testing of the statistics: The data were robust. Our results confirm the hypothesis that nitrogen is not a passive participant in lake ecology. And we were able to prove with a broad database for the first time that this clearly applies to lakes worldwide." The research team is now spurring further investigations, both in the field and through modelling, with which the results of their data analysis can be tested.
With their study, the researchers have figuratively pulled nitrogen into the equation of lake ecology. They recommend that, in practice, nitrogen now be given more focus in lake management. "We need a long-term investigation of the nutrient ratios to ensure the success of efficient and effective eutrophication management," says Graeber. "This requires a greater focus on inputs from agriculture, which generally have a high nitrogen content."
JOURNAL
Nature Communications
Nature Communications
DOI
METHOD OF RESEARCH
Data/statistical analysis
Data/statistical analysis
SUBJECT OF RESEARCH
Not applicable
Not applicable
ARTICLE TITLE
Consistent stoichiometric long-term relationships between nutrients and chlorophyll-a across shallow lakes
Consistent stoichiometric long-term relationships between nutrients and chlorophyll-a across shallow lakes
Climate: 2023 – 24 El Niño likely to cause record-breaking average temperatures in some areas
Peer-Reviewed Publication
Several areas of the globe — including the Bay of Bengal, the Philippines, and the Caribbean Sea — are likely to experience record-breaking average surface air temperatures in the year period up to June 2024 as a result of the ongoing El Niño phenomenon. The modelling results, published in Scientific Reports, also suggest that there is an estimated 90 percent chance of record-breaking global mean surface temperatures occurring over the same period under a moderate or strong El Niño scenario.
The El Niño-Southern Oscillation, centred in the tropical Pacific, is a key driver of climate variability around the world. Both its warm phase, El Niño, and its colder phase, La Niña, influence weather conditions, with the heat released to the atmosphere from the western Pacific Ocean during an El Niño leading to an accelerated rise in annual global mean surface temperatures (GMST). A slight increase in GMST has been strongly linked to significant increases in surface air temperatures during extreme regional heating events.
Congwen Zhu and colleagues modelled the effects of the 2023 – 24 El Niño on the regional variation in average surface air temperatures from the 1951 – 1980 mean between July 2023 and June 2024. They used this period to ensure that the typical peak of an El Niño event, between November and January, was always included. The authors found that under a moderate El Niño scenario, the Bay of Bengal and the Philippines were predicted to experience record-breaking average surface air temperatures over the period. Under a strong El Niño, the Caribbean Sea, South China Sea, and areas of the Amazon and Alaska were also predicted to experience record-breaking average surface air temperatures. The authors also modelled the effects of El Niño on GMST over the same period and found that under a moderate or stronger El Niño, there was a 90% chance that GMST would break the historical record. In the moderate scenario, the authors estimated the 2023 – 24 GMST as being 1.03 – 1.10 °C above the benchmark 1951 – 1980 mean, whilst for the strong scenario, they estimated GMST as 1.06 – 1.20 °C above that mean.
The authors warn that record-breaking average temperatures will likely challenge regions’ current capability to cope with the consequences of excess heat. They also note that high surface air temperatures can lead to a significant increase in the likelihood of extreme climate events — including wildfires, tropical cyclones, and heatwaves — particularly in oceanic and coastal areas where the higher heat capacity of the ocean leads to climate conditions persisting for extended periods of time.
***
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Several areas of the globe — including the Bay of Bengal, the Philippines, and the Caribbean Sea — are likely to experience record-breaking average surface air temperatures in the year period up to June 2024 as a result of the ongoing El Niño phenomenon. The modelling results, published in Scientific Reports, also suggest that there is an estimated 90 percent chance of record-breaking global mean surface temperatures occurring over the same period under a moderate or strong El Niño scenario.
The El Niño-Southern Oscillation, centred in the tropical Pacific, is a key driver of climate variability around the world. Both its warm phase, El Niño, and its colder phase, La Niña, influence weather conditions, with the heat released to the atmosphere from the western Pacific Ocean during an El Niño leading to an accelerated rise in annual global mean surface temperatures (GMST). A slight increase in GMST has been strongly linked to significant increases in surface air temperatures during extreme regional heating events.
Congwen Zhu and colleagues modelled the effects of the 2023 – 24 El Niño on the regional variation in average surface air temperatures from the 1951 – 1980 mean between July 2023 and June 2024. They used this period to ensure that the typical peak of an El Niño event, between November and January, was always included. The authors found that under a moderate El Niño scenario, the Bay of Bengal and the Philippines were predicted to experience record-breaking average surface air temperatures over the period. Under a strong El Niño, the Caribbean Sea, South China Sea, and areas of the Amazon and Alaska were also predicted to experience record-breaking average surface air temperatures. The authors also modelled the effects of El Niño on GMST over the same period and found that under a moderate or stronger El Niño, there was a 90% chance that GMST would break the historical record. In the moderate scenario, the authors estimated the 2023 – 24 GMST as being 1.03 – 1.10 °C above the benchmark 1951 – 1980 mean, whilst for the strong scenario, they estimated GMST as 1.06 – 1.20 °C above that mean.
The authors warn that record-breaking average temperatures will likely challenge regions’ current capability to cope with the consequences of excess heat. They also note that high surface air temperatures can lead to a significant increase in the likelihood of extreme climate events — including wildfires, tropical cyclones, and heatwaves — particularly in oceanic and coastal areas where the higher heat capacity of the ocean leads to climate conditions persisting for extended periods of time.
***
Springer Nature is committed to boosting the visibility of the UN Sustainable Development Goals and relevant information and evidence published in our journals and books. The research described in this press release pertains to SDG 13 (Climate Action). More information can be found here.
JOURNAL
Scientific Reports
Scientific Reports
DOI
METHOD OF RESEARCH
Computational simulation/modeling
Computational simulation/modeling
SUBJECT OF RESEARCH
Not applicable
Not applicable
ARTICLE TITLE
Enhanced risk of record-breaking regional temperatures during the 2023–24 El Niño
Enhanced risk of record-breaking regional temperatures during the 2023–24 El Niño
ARTICLE PUBLICATION DATE
29-Feb-2024
29-Feb-2024
Extreme weather events tied to increased mortality and emergency department activity
Mass General Brigham study reveals that ED visits and death are heightened weeks after major climate-driven extreme weather events – highlighting the long-lasting impacts these events may have on health and infrastructure
Peer-Reviewed Publication
Climate change is increasing the frequency and intensity of severe weather events, which may particularly endanger vulnerable populations such as the elderly. Researchers from Mass General Brigham and colleagues examined how weather disasters between 2011 and 2016 influenced healthcare delivery and mortality among Medicare beneficiaries in affected counties, finding that one week after major weather events, emergency department (ED) use and mortality remained elevated by 1.22% and 1.4%, respectively, from pre-disaster levels. Importantly, this study also found that deaths remained elevated for as much as six weeks. Results are published in Nature Medicine.
Researchers from Massachusetts General Hospital and Brigham and Women’s Hospital, founding members of the Mass General Brigham healthcare system, collaborated on the study. Identifying events from the National Oceanographic and Atmospheric Administration (NOAA)’s National Centers for Environmental Information (NCEI), the team analyzed acute disasters such as floods, storms and hurricanes that caused $1 billion or more in damages. Severe storms, compared to other disasters, were associated with the highest mortality rates that persisted for six weeks. Counties with the greatest economic losses were found to have two to four times higher mortality rates – and higher ED usage – compared to all affected counties, highlighting how infrastructure destruction, such as power outages and transportation challenges, may compound both economic and healthcare tolls.
“Taken together, these findings suggest that the biggest weather disasters have broad and long-lasting impacts on health emergencies and deaths among those who have Medicare,” said lead author Renee Salas, MD, MS, MPH, of the Department of Emergency Medicine at Massachusetts General Hospital. “Tracking these outcomes is important to better protect patients and communities – and to strengthen our health systems.”
Authorship: Mass General Brigham affiliated co-authors include E. John Orav (BWH). Additional co-authors include Laura G. Burke, Jessica Phelan, Gregory A. Wellenius, and Ashish K. Jha.
Disclosures: Salas reports no disclosures. Additional author disclosures are included in the article.
Funding: This research was funded by the Burke Global Health Fellowship at the Harvard Global Health Institute, the Clinician-Teacher Development Award at the Center for Diversity and Inclusion at Massachusetts General Hospital, and the Yerby Fellowship at the Harvard T.H. Chan School of Public Health. A full list of funding to individual authors is included in the article.
Paper cited: Salas RN et al. “Impact of extreme weather events on healthcare utilization and mortality in the United States” Nature Medicine DOI: 10.1038/s41591-024-02833-x.
###
About Mass General Brigham
Mass General Brigham is an integrated academic health care system, uniting great minds to solve the hardest problems in medicine for our communities and the world. Mass General Brigham connects a full continuum of care across a system of academic medical centers, community and specialty hospitals, a health insurance plan, physician networks, community health centers, home care, and long-term care services. Mass General Brigham is a nonprofit organization committed to patient care, research, teaching, and service to the community. In addition, Mass General Brigham is one of the nation’s leading biomedical research organizations with several Harvard Medical School teaching hospitals. For more information, please visit massgeneralbrigham.org.
Mass General Brigham study reveals that ED visits and death are heightened weeks after major climate-driven extreme weather events – highlighting the long-lasting impacts these events may have on health and infrastructure
Climate change is increasing the frequency and intensity of severe weather events, which may particularly endanger vulnerable populations such as the elderly. Researchers from Mass General Brigham and colleagues examined how weather disasters between 2011 and 2016 influenced healthcare delivery and mortality among Medicare beneficiaries in affected counties, finding that one week after major weather events, emergency department (ED) use and mortality remained elevated by 1.22% and 1.4%, respectively, from pre-disaster levels. Importantly, this study also found that deaths remained elevated for as much as six weeks. Results are published in Nature Medicine.
Researchers from Massachusetts General Hospital and Brigham and Women’s Hospital, founding members of the Mass General Brigham healthcare system, collaborated on the study. Identifying events from the National Oceanographic and Atmospheric Administration (NOAA)’s National Centers for Environmental Information (NCEI), the team analyzed acute disasters such as floods, storms and hurricanes that caused $1 billion or more in damages. Severe storms, compared to other disasters, were associated with the highest mortality rates that persisted for six weeks. Counties with the greatest economic losses were found to have two to four times higher mortality rates – and higher ED usage – compared to all affected counties, highlighting how infrastructure destruction, such as power outages and transportation challenges, may compound both economic and healthcare tolls.
“Taken together, these findings suggest that the biggest weather disasters have broad and long-lasting impacts on health emergencies and deaths among those who have Medicare,” said lead author Renee Salas, MD, MS, MPH, of the Department of Emergency Medicine at Massachusetts General Hospital. “Tracking these outcomes is important to better protect patients and communities – and to strengthen our health systems.”
Authorship: Mass General Brigham affiliated co-authors include E. John Orav (BWH). Additional co-authors include Laura G. Burke, Jessica Phelan, Gregory A. Wellenius, and Ashish K. Jha.
Disclosures: Salas reports no disclosures. Additional author disclosures are included in the article.
Funding: This research was funded by the Burke Global Health Fellowship at the Harvard Global Health Institute, the Clinician-Teacher Development Award at the Center for Diversity and Inclusion at Massachusetts General Hospital, and the Yerby Fellowship at the Harvard T.H. Chan School of Public Health. A full list of funding to individual authors is included in the article.
Paper cited: Salas RN et al. “Impact of extreme weather events on healthcare utilization and mortality in the United States” Nature Medicine DOI: 10.1038/s41591-024-02833-x.
###
About Mass General Brigham
Mass General Brigham is an integrated academic health care system, uniting great minds to solve the hardest problems in medicine for our communities and the world. Mass General Brigham connects a full continuum of care across a system of academic medical centers, community and specialty hospitals, a health insurance plan, physician networks, community health centers, home care, and long-term care services. Mass General Brigham is a nonprofit organization committed to patient care, research, teaching, and service to the community. In addition, Mass General Brigham is one of the nation’s leading biomedical research organizations with several Harvard Medical School teaching hospitals. For more information, please visit massgeneralbrigham.org.
JOURNAL
Nature Medicine
Nature Medicine
DOI
ARTICLE TITLE
Salas RN et al. “Impact of extreme weather events on healthcare utilization and mortality in the United States”
Salas RN et al. “Impact of extreme weather events on healthcare utilization and mortality in the United States”
ARTICLE PUBLICATION DATE
29-Feb-2024
29-Feb-2024
PSU study sheds light on 2020 extreme weather event that brought fires and snow to western US
The same weather system that led to the spread of the devastating Labor Day wildfires in 2020 brought record-breaking cold and early-season snowfall to parts of the Rocky Mountains. Now, new research from Portland State is shedding light on the meteorology behind what happened and the impacts of such an extreme weather event.
“It’s really interesting to see such an amplified pattern result in opposing extremes in the Pacific Northwest and the Rocky Mountains,” said Emma Russell, a master’s student in geography and lead author of the study published in the journal Weather and Climate Extremes.
A high-pressure ridge was responsible for the extremely warm temperatures leading up to the event. Russell said the primary atmospheric driver was a highly amplified wave pattern — the strongest on record for that time of year — that persisted for several days. The wave broke, much like an ocean wave breaks, bringing about a strong wind event over western Oregon.
“Even for winter, that would have been a very strong wind event, but for early September, there’s nothing in the observational record quite that strong,” said Paul Loikith, an associate professor of geography and director of PSU’s Climate Science Lab.
The warm temperatures coupled with the strong and dry easterly winds fueled several large wildfires, which ultimately led to the evacuation of over 40,000 people, the destruction of 5,000 homes and businesses and the loss of nine lives in Oregon. The widespread wildfire smoke then led to abnormally high levels of air pollution across the region for the following two weeks. An analysis of air parcel backward trajectories found that the dry air over the Pacific Northwest, which exacerbated the fire danger, originated in western Canada at heights over 5,000 meters.
“The air is very dry at these high altitudes and as it descends to the surface, it begins to warm which increases the dryness,” Russell said. “That helps explain where the dry air was coming from.”
That same weather system brought record-setting cold temperatures for the time of year to parts of the Rocky Mountains, the Southwest and the Great Plains, just days after record-setting warmth.
“South of the jet stream is where the air is warmer and north is colder,” Loikith said. “When the peak of the wave is over a region, that’s where you get warm air surging north, and where you have the trough of the wave is where you have cold air surging south. Both were going on adjacent to one another.”
Russell said the event was a confluence of record-breaking intense patterns — and while it’s not outside the realm of possibility that it can happen again, it’s not evident that events like these are becoming more common. One thing we know for sure is that everything’s getting warmer.
“If a similar event does happen again, the warm side will be warmer and the cold side will be less cold,” Loikith said. “We can just assume that it’s always going to be a little bit warmer than it otherwise would have been. The temperature factor is always there.”
The study’s co-authors are Idowu Ajibade, a former PSU professor now at Emory University; James Done from the National Center for Atmospheric Research (NCAR); and Chris Lower, a master’s student in geography at PSU. The study was funded by Ajibade’s NCAR Early Career Innovator Fellow Program project on resilience planning for climate-related disasters in the Portland metro region.
JOURNAL
Weather and Climate Extremes
METHOD OF RESEARCH
Computational simulation/modeling
ARTICLE TITLE
The meteorology and impacts of the September 2020 Western United States extreme weather event
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