The seasonality of moisture-sensitive tree-ring recordsScott St. George
The document discusses the seasonality of moisture-sensitive tree-ring records across North America. It finds that tree-ring records are more sensitive to winter precipitation and climate patterns in northern areas, while they are more sensitive to summer precipitation and the El Niño-Southern Oscillation in southern areas. Additionally, tree-ring analysis methods may overestimate correlations when applied to large datasets, so alternative statistical approaches are needed to accurately assess relationships to climate across the continent.
Prairie megadroughts: drought, proxies and decadal climate variability in the...Scott St. George
Slides supporting a presentation at the University of Stockholm's Department of Physical Geography and Quaternary Geology.
Canada is rightly considered a water-rich nation, but persistent drought is still a leading source of risk to agriculture and energy production, particularly in the dry western interior. During the 20th century, the Canadian Prairies were less affected by decadal-scale shifts in hydroclimate than other places in North America, but the relative brevity of instrumental records makes it difficult to evaluate the potential duration and geographic scope of severe drought. Tree-ring and other proxy records show that that parts of the the Canadian Prairies experienced, relatively recently, summer droughts that were more intense and more long lasting than those observed in instrumental records. These past droughts serve as alternative worst-case scenarios that water managers can use to evaluate the resilience of their systems to conditions outside their personal or institutional experience. Comparing regional tree-ring records against the broader North American network also indicates that studies investigating the patterns and mechanisms of past drought across the continent need to consider the potential effects of seasonality biases in paleoclimate proxies.
Tales in timber - the story of Prairie drought written in tree ringsScott St. George
This document summarizes information from tree ring studies about past drought conditions in the Canadian Prairies. It finds that droughts were more severe and persistent in the past, including droughts in the 18th and early 19th centuries that were more extreme than anything in the instrumental record from 1900 to present. Tree ring data also indicates drought probabilities were higher in the 1930s than indicated by instrumental data alone. The study suggests drought conditions may be worse in the future than what has been observed in the last 100 years of records given natural multidecadal variability and potential climate change impacts. It calls for improved access and application of paleoclimatic data from tree rings to better inform water management and planning under uncertain future conditions.
GEOG3839.14, The West, water and the Colorado RiverScott St. George
This document summarizes research on surface temperature reconstructions over the past 2,000 years and tree-ring analysis of droughts in the American Southwest. Tree rings have been used to reconstruct Colorado River flows over the past 1,200 years, showing megadroughts more severe than any in the 20th century. This long-term context challenged water management assumptions and highlighted the potential for even worse droughts under climate change.
Through the trees: The story of Prairie drought told by tree ringsScott St. George
The Canadian Prairies are Canada’s most significant dryland area and regional drought has an enormous impact on agricultural and energy production and the reliability of public water supplies. Many water managers are turning to tree rings and other natural indicators to expand their perspective on regional hydrology.
Prepared for the Department of Geography, University of Lethbridge, April 3, 2009.
Recent changes to Peruvian glaciers and their impacts:
- Peruvian glaciers have lost significant area and volume since the 1970s, with the Cordillera Blanca region losing around 25% of its glacial coverage. Approximately 20 million people depend on glacial meltwater from this region.
- Detailed observations of the La Balsa glacier show an 85.7% reduction in surface area from 1962-2008, along with over 50 meters of average surface lowering and loss of 0.233 km3 of ice volume.
- Glacier retreat is altering stream flow patterns in glacier-fed rivers like the Rio Santa, with decreasing trends observed and concerns about water availability, especially during dry seasons, as
Noah, Joseph, And High-Resolution PaleoclimatologyScott St. George
In 1968, Benoit Mandelbrot and James Wallis published an article titled ‘Noah, Joseph, and operational Hydrology’ in the journal Water Resources Research. In it, they argued that hydrological models of the day were not able to estimate the true risk of extreme floods or prolonged drought, and that rare hydrological events were much more common than usually assumed.
In this lecture, I’ll review how high-resolution paleoenvironmental archives can help us judge more accurately the risks posed by the ‘Noah’- and ‘Joseph’-style events described by Mandelbrot and Wallis. I’ll give particular emphasis to the environmental information recovered from the rings of ancient trees, and explain how dendrochronology (tree-ring research) has been used to redefine the ‘flood of record’, test potential avenues for long-lead climate predictions, and gage the performance of state-of-the-art climate models.
The seasonality of moisture-sensitive tree-ring recordsScott St. George
The document discusses the seasonality of moisture-sensitive tree-ring records across North America. It finds that tree-ring records are more sensitive to winter precipitation and climate patterns in northern areas, while they are more sensitive to summer precipitation and the El Niño-Southern Oscillation in southern areas. Additionally, tree-ring analysis methods may overestimate correlations when applied to large datasets, so alternative statistical approaches are needed to accurately assess relationships to climate across the continent.
Prairie megadroughts: drought, proxies and decadal climate variability in the...Scott St. George
Slides supporting a presentation at the University of Stockholm's Department of Physical Geography and Quaternary Geology.
Canada is rightly considered a water-rich nation, but persistent drought is still a leading source of risk to agriculture and energy production, particularly in the dry western interior. During the 20th century, the Canadian Prairies were less affected by decadal-scale shifts in hydroclimate than other places in North America, but the relative brevity of instrumental records makes it difficult to evaluate the potential duration and geographic scope of severe drought. Tree-ring and other proxy records show that that parts of the the Canadian Prairies experienced, relatively recently, summer droughts that were more intense and more long lasting than those observed in instrumental records. These past droughts serve as alternative worst-case scenarios that water managers can use to evaluate the resilience of their systems to conditions outside their personal or institutional experience. Comparing regional tree-ring records against the broader North American network also indicates that studies investigating the patterns and mechanisms of past drought across the continent need to consider the potential effects of seasonality biases in paleoclimate proxies.
Tales in timber - the story of Prairie drought written in tree ringsScott St. George
This document summarizes information from tree ring studies about past drought conditions in the Canadian Prairies. It finds that droughts were more severe and persistent in the past, including droughts in the 18th and early 19th centuries that were more extreme than anything in the instrumental record from 1900 to present. Tree ring data also indicates drought probabilities were higher in the 1930s than indicated by instrumental data alone. The study suggests drought conditions may be worse in the future than what has been observed in the last 100 years of records given natural multidecadal variability and potential climate change impacts. It calls for improved access and application of paleoclimatic data from tree rings to better inform water management and planning under uncertain future conditions.
GEOG3839.14, The West, water and the Colorado RiverScott St. George
This document summarizes research on surface temperature reconstructions over the past 2,000 years and tree-ring analysis of droughts in the American Southwest. Tree rings have been used to reconstruct Colorado River flows over the past 1,200 years, showing megadroughts more severe than any in the 20th century. This long-term context challenged water management assumptions and highlighted the potential for even worse droughts under climate change.
Through the trees: The story of Prairie drought told by tree ringsScott St. George
The Canadian Prairies are Canada’s most significant dryland area and regional drought has an enormous impact on agricultural and energy production and the reliability of public water supplies. Many water managers are turning to tree rings and other natural indicators to expand their perspective on regional hydrology.
Prepared for the Department of Geography, University of Lethbridge, April 3, 2009.
Recent changes to Peruvian glaciers and their impacts:
- Peruvian glaciers have lost significant area and volume since the 1970s, with the Cordillera Blanca region losing around 25% of its glacial coverage. Approximately 20 million people depend on glacial meltwater from this region.
- Detailed observations of the La Balsa glacier show an 85.7% reduction in surface area from 1962-2008, along with over 50 meters of average surface lowering and loss of 0.233 km3 of ice volume.
- Glacier retreat is altering stream flow patterns in glacier-fed rivers like the Rio Santa, with decreasing trends observed and concerns about water availability, especially during dry seasons, as
Noah, Joseph, And High-Resolution PaleoclimatologyScott St. George
In 1968, Benoit Mandelbrot and James Wallis published an article titled ‘Noah, Joseph, and operational Hydrology’ in the journal Water Resources Research. In it, they argued that hydrological models of the day were not able to estimate the true risk of extreme floods or prolonged drought, and that rare hydrological events were much more common than usually assumed.
In this lecture, I’ll review how high-resolution paleoenvironmental archives can help us judge more accurately the risks posed by the ‘Noah’- and ‘Joseph’-style events described by Mandelbrot and Wallis. I’ll give particular emphasis to the environmental information recovered from the rings of ancient trees, and explain how dendrochronology (tree-ring research) has been used to redefine the ‘flood of record’, test potential avenues for long-lead climate predictions, and gage the performance of state-of-the-art climate models.
Why the past matters - how tree rings and environmental history help us make ...Scott St. George
This document discusses how studying tree rings and environmental history can help with managing resources and risks related to water and climate. It provides three key points:
1) Tree rings and other climate proxies like lake sediments and ice cores provide information about past climate variability like droughts, floods, and shifts in atmospheric patterns over centuries. This helps understand the range of natural climate variations.
2) Reconstructions of past river flows and floods indicate that some past events were more extreme than what modern records show, challenging assumptions about water availability and flood risks. This provides "stress tests" for water resource systems.
3) Decadal-scale climate patterns like the Pacific Decadal Oscillation cause important swings in precipitation
The document discusses climate change impacts in the Great Lakes region based on a conference presentation. It finds that (1) the climate is already changing, with temperatures rising especially in winter and other impacts like shorter ice cover, (2) these changes will exacerbate existing problems like worsening water resources and human health issues, and (3) common sense solutions exist now but it is unclear if governments, industries and citizens are adequately preparing for these challenges.
This document discusses research by Scott St. George on droughts in the Winnipeg River basin. It uses tree ring data from over 2,800 trees to reconstruct drought records back to 1500 AD. The tree ring data shows that droughts in the early 1720s and 1910 were more persistent and severe than droughts since 1900. This paleoclimate data provides benchmarks to understand recent drought trends and starting points for climate change scenarios. It can also help assess if recent droughts may occur again in the future.
1. The document consists primarily of the word "never" repeated many times.
2. It concludes by stating one should never use Comic Sans font, unless your name is Richard Alley.
3. Bullet points, visual clutter, and overly complex slides should be avoided when creating science presentations. Clear, concise messaging is most effective.
Tree rings have been used to reconstruct streamflow in the Colorado River basin over centuries. This revealed that severe multi-year droughts were more common than shown in the instrumental record. A 1,000-year drought reconstruction for western North America also indicated droughts could last decades. Tree rings have additionally helped develop the North American Drought Atlas which provides drought context for historical events and shows Asian monsoon variability over centuries.
This document discusses water resources in the western United States, focusing on snowmelt and snow water equivalent (SWE) in the Sierra Nevada mountains. It provides information on how most runoff and recharge comes from snowmelt in areas like Arizona, New Mexico, Utah, and Colorado. It also discusses challenges measuring snow levels at high elevations and how snow redistribution and differential ablation can impact SWE measurements. Methods for reconstructing heterogeneous snow distribution in a grid cell using fractional snow-covered area data are presented. The importance of data sharing and moving toward more collaborative and data-driven approaches in hydrology is emphasized.
Boosting the Signal: Simple Strategies to Deliver Better Scientific TalksScott St. George
A good talk can open the doors to new collaborations, increase your chances of funding success, and make it more likely other people will respond to your ideas. But scientific presentations are too often confusing, boring, and overstuffed. Here are some suggestions, based on our experience as speakers, audience members, and presentation trainers, that we hope will make your next conference talk or seminar more enjoyable, engaging and effective.
Ringing true: The scientific and societal relevance of dendrochronology at th...Scott St. George
Tree rings and other natural archives empower us to extend our perspective on environmental change, resources, and hazards. But many contemporary applications of paleoclimatology and paleohydrology are useful because of the lasting disruption to our collective environmental memory caused by colonization.
Much of what we know regarding variations in Earth's climate during the past millennium comes from tree rings. But tree rings, like other proxies, attenuate some climate signals but amplify others, and their fidelity at longer timescales is difficult to gage. Even though dendroclimatology is well-established, questions remain about the climate clues encoded in tree rings — particularly at decadal-to-centennial timescales.
Don’t call it a comeback: Studying ancient floods to prepare for future hazardsScott St. George
How long do we need to watch a river before its behavior holds no more surprises? In this country, instrumental measurements of river stage and discharge stretch back a century or more, but this observed history still provides only a rough guide to the risks of future extreme floods. In this lecture, I’ll outline how paleoflood hydrology expands our perspective on river history by combining historical, botanical, and geological evidence of earlier (and ofttimes unknown) floods. And I’ll explain how we can interpret those physical clues left behind by ancient floods to improve hazard assessments for at-risk communities, support decisions about flood infrastructure, and investigate the long-term effects of climate or land-use changes on flooding. Because what has happened before can happen again, most everyone near a river would profit by keeping a longer memory of old floods.
Flood rings: Paleoflood evidence in tree-ring anatomyScott St. George
In low-gradient, low energy rivers, forms of tree-ring evidence such as impact scars or stem deformation do not provide useful evidence of past floods. In this talk, I explain the strengths and limitations of wood anatomy as tools in in paleoflood hydrology.
Historic accounts of extreme floods on the Red River of the NorthScott St. George
Here I explain how Canadian and American communities along the Red River of the North have developed fundamentally different responses to the threat of flooding, and argue that these differences in flood mitigation reflect disparate experiences with particular floods during the past two hundred years.
Disentangling the decadal ‘knot’ in high-resolution paleoclimatologyScott St. George
Even after more than a century of coordinated monitoring, instrumental weather observations are still too short to adequately constrain decadal or multidecadal behavior in the Earth’s climate system. Leading climatologists and climate modelers have called for the wider application of high-resolution proxy records to decadal variability and prediction studies, and our community has responded by producing new paleoclimate products that specifically target this type of ‘intermediate-term’ behavior. But we now also know our medium changes that message: the biological and geological systems that encode climate information into natural archives often also alter the original ‘input’, usually due to either seasonal filtering or non-climatic persistence. In this talk, we’ll discuss some of the challenges inherent to the use of high-resolution proxies to study decadal or multi-decadal climate variability, and suggest strategies that might clarify how climate acts on those timescales. And we’ll also present a new theoretical framework that could help paleo-scientists evaluate competing ideas about the causes of decadal- or multi-decadal events known to have occurred during the past one or two millennia.
A new framework to test the origins of western American megadroughtScott St. George
We know from tree rings and other natural drought records that the western United States has been affected by several 'megadroughts' during the past millennium. But are these exceptionally long-lasting droughts due to unusual external forcings, or are they inevitable given a sufficiently long period of time? Here we present a statistical model that combines sea surface temperature records and drought severity statistics from the western USA, and use that tool to set out an expectation for megadrought, given no other changes in the climate system. Even though this model was trained using only modern climate data (and incorporates no information from tree rings or other proxies), it still produced megadroughts. Moreover, those simulated megadroughts were just as long-lasting, covered as large an area, and were just as severe as real megadroughts estimated from tree rings. That result means that megadroughts can occur in the western United States even if nothing else changes in the climate -- they really are just a matter of time. On the other hand, the only aspect of real-world megadroughts that the model cannot duplicate was the high number of these events during the so-called Medieval Climate Anomaly (800 to 1300 CE). So that cluster of megadroughts may have been caused by some sort of unusual climate circumstances that have not been observed by us during the past few decades. The proxy record tells us that many different kinds of exceptional or unusual climate events happened in the past. But it is often difficult to determine what caused those exceptional events because even, within a period of a thousand years, we still have very few cases. So besides being an aid to understand the causes of past megadroughts, we hope this approach can be applied to other paleoclimate records to distinguish between real interrelations between separate components of the climate system and simple coincidences.
The need for new theory in global dendroclimatologyScott St. George
This document summarizes an interdisciplinary tree-ring research conference. It discusses the need for new theory in dendroclimatology, presentations on temperature and river flow reconstructions from tree rings, and principles of tree ring research site selection and replication. It also questions how to evaluate rare signals in tree growth and climate relationships and where remote teleconnections may be most evident in tree rings.
The societal value of historical and paleoflood research in Manitoba, CanadaScott St. George
1) Shared knowledge of past natural disasters has a major impact on preparation for future hazards. The document discusses the historical floods along the Red River in Manitoba, Canada.
2) Winnipeg built a large flood diversion channel in the 1960s after experiencing major floods, including in 1826 and 1950, to protect the city from future flooding of the Red River.
3) American communities like Grand Forks and Fargo were more vulnerable to Red River flooding until recently because they did not have the same long historical memory of floods that informed Winnipeg's early investment in flood protection infrastructure.
Solar ghosts: Weighing the evidence for sunspot cycles in fossil treesScott St. George
In their study of tree rings from the Chemnitz Fossil Forest (Germany), Luthardt and Rößler (2017) claim to identify a regular near-11-yr cyclicity in growth, and present that pattern as evidence of the influence of the Schwabe solar cycle (Usokin and Mursula, 2003) on climate and forest productivity during the early Permian. If correctly interpreted, these fossil tree rings would indicate the sunspot cycle was the dominant influence on interannual variability in Earth’s climate during this period and that it has been a consistent aspect of our Sun’s behavior for at least the past 300 m.y. We argue the fossil tree-ring record from Chemnitz does not constitute reliable evidence of solar activity during the Permian because the individual tree-ring sequences are not correctly aligned (dendrochronologically dated) and, as a result, the mean ring-width composite is not a meaningful estimate of year-to-year variations in tree growth in this ancient forest.
Long droughts: Using natural climate archives to gage the risks of future “me...Scott St. George
In the Biblical story of Joseph, following seven years of abundance, the Kingdom of Egypt was confronted by seven years of drought and famine. In the parlance of modern climate science, intervals with several consecutive extremely dry years are described as ‘“megadroughts”. In this short talk, I’ll describe how climate scientists combine clues from natural weather archives (including corals, tree rings, lake sediments, and many other sources) to reveal the history of ancient megadroughts across our planet. And I’ll highlight new research that combines these surrogate drought records with simulations from state-of-the-art climate models to help us better anticipate the risks of unusually persistent droughts during the coming century.
Expecting the unexpected: The relevance of old floods to modern hydrologyScott St. George
This document discusses the importance of understanding past floods to properly assess modern flood risks. It provides examples of paleoflood research along rivers like the Red River of the North, which uncovered major floods in 1826 and around 700 years ago that exceeded any floods measured by modern instrumentation. Understanding a river's full history through both recorded data and geological evidence of past floods is essential for floodplain management, development planning, and infrastructure design to mitigate future flood risks.
What to expect when you’re expecting decadal variability in hydroclimatic pro...Scott St. George
Climate simulations were run for 1000 years, with 1000 total simulations conducted. The simulations modeled climate changes over long time periods. The large number of long-term simulations provided insights into potential climate variations and outcomes.
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Why the past matters - how tree rings and environmental history help us make ...Scott St. George
This document discusses how studying tree rings and environmental history can help with managing resources and risks related to water and climate. It provides three key points:
1) Tree rings and other climate proxies like lake sediments and ice cores provide information about past climate variability like droughts, floods, and shifts in atmospheric patterns over centuries. This helps understand the range of natural climate variations.
2) Reconstructions of past river flows and floods indicate that some past events were more extreme than what modern records show, challenging assumptions about water availability and flood risks. This provides "stress tests" for water resource systems.
3) Decadal-scale climate patterns like the Pacific Decadal Oscillation cause important swings in precipitation
The document discusses climate change impacts in the Great Lakes region based on a conference presentation. It finds that (1) the climate is already changing, with temperatures rising especially in winter and other impacts like shorter ice cover, (2) these changes will exacerbate existing problems like worsening water resources and human health issues, and (3) common sense solutions exist now but it is unclear if governments, industries and citizens are adequately preparing for these challenges.
This document discusses research by Scott St. George on droughts in the Winnipeg River basin. It uses tree ring data from over 2,800 trees to reconstruct drought records back to 1500 AD. The tree ring data shows that droughts in the early 1720s and 1910 were more persistent and severe than droughts since 1900. This paleoclimate data provides benchmarks to understand recent drought trends and starting points for climate change scenarios. It can also help assess if recent droughts may occur again in the future.
1. The document consists primarily of the word "never" repeated many times.
2. It concludes by stating one should never use Comic Sans font, unless your name is Richard Alley.
3. Bullet points, visual clutter, and overly complex slides should be avoided when creating science presentations. Clear, concise messaging is most effective.
Tree rings have been used to reconstruct streamflow in the Colorado River basin over centuries. This revealed that severe multi-year droughts were more common than shown in the instrumental record. A 1,000-year drought reconstruction for western North America also indicated droughts could last decades. Tree rings have additionally helped develop the North American Drought Atlas which provides drought context for historical events and shows Asian monsoon variability over centuries.
This document discusses water resources in the western United States, focusing on snowmelt and snow water equivalent (SWE) in the Sierra Nevada mountains. It provides information on how most runoff and recharge comes from snowmelt in areas like Arizona, New Mexico, Utah, and Colorado. It also discusses challenges measuring snow levels at high elevations and how snow redistribution and differential ablation can impact SWE measurements. Methods for reconstructing heterogeneous snow distribution in a grid cell using fractional snow-covered area data are presented. The importance of data sharing and moving toward more collaborative and data-driven approaches in hydrology is emphasized.
Boosting the Signal: Simple Strategies to Deliver Better Scientific TalksScott St. George
A good talk can open the doors to new collaborations, increase your chances of funding success, and make it more likely other people will respond to your ideas. But scientific presentations are too often confusing, boring, and overstuffed. Here are some suggestions, based on our experience as speakers, audience members, and presentation trainers, that we hope will make your next conference talk or seminar more enjoyable, engaging and effective.
Ringing true: The scientific and societal relevance of dendrochronology at th...Scott St. George
Tree rings and other natural archives empower us to extend our perspective on environmental change, resources, and hazards. But many contemporary applications of paleoclimatology and paleohydrology are useful because of the lasting disruption to our collective environmental memory caused by colonization.
Much of what we know regarding variations in Earth's climate during the past millennium comes from tree rings. But tree rings, like other proxies, attenuate some climate signals but amplify others, and their fidelity at longer timescales is difficult to gage. Even though dendroclimatology is well-established, questions remain about the climate clues encoded in tree rings — particularly at decadal-to-centennial timescales.
Don’t call it a comeback: Studying ancient floods to prepare for future hazardsScott St. George
How long do we need to watch a river before its behavior holds no more surprises? In this country, instrumental measurements of river stage and discharge stretch back a century or more, but this observed history still provides only a rough guide to the risks of future extreme floods. In this lecture, I’ll outline how paleoflood hydrology expands our perspective on river history by combining historical, botanical, and geological evidence of earlier (and ofttimes unknown) floods. And I’ll explain how we can interpret those physical clues left behind by ancient floods to improve hazard assessments for at-risk communities, support decisions about flood infrastructure, and investigate the long-term effects of climate or land-use changes on flooding. Because what has happened before can happen again, most everyone near a river would profit by keeping a longer memory of old floods.
Flood rings: Paleoflood evidence in tree-ring anatomyScott St. George
In low-gradient, low energy rivers, forms of tree-ring evidence such as impact scars or stem deformation do not provide useful evidence of past floods. In this talk, I explain the strengths and limitations of wood anatomy as tools in in paleoflood hydrology.
Historic accounts of extreme floods on the Red River of the NorthScott St. George
Here I explain how Canadian and American communities along the Red River of the North have developed fundamentally different responses to the threat of flooding, and argue that these differences in flood mitigation reflect disparate experiences with particular floods during the past two hundred years.
Disentangling the decadal ‘knot’ in high-resolution paleoclimatologyScott St. George
Even after more than a century of coordinated monitoring, instrumental weather observations are still too short to adequately constrain decadal or multidecadal behavior in the Earth’s climate system. Leading climatologists and climate modelers have called for the wider application of high-resolution proxy records to decadal variability and prediction studies, and our community has responded by producing new paleoclimate products that specifically target this type of ‘intermediate-term’ behavior. But we now also know our medium changes that message: the biological and geological systems that encode climate information into natural archives often also alter the original ‘input’, usually due to either seasonal filtering or non-climatic persistence. In this talk, we’ll discuss some of the challenges inherent to the use of high-resolution proxies to study decadal or multi-decadal climate variability, and suggest strategies that might clarify how climate acts on those timescales. And we’ll also present a new theoretical framework that could help paleo-scientists evaluate competing ideas about the causes of decadal- or multi-decadal events known to have occurred during the past one or two millennia.
A new framework to test the origins of western American megadroughtScott St. George
We know from tree rings and other natural drought records that the western United States has been affected by several 'megadroughts' during the past millennium. But are these exceptionally long-lasting droughts due to unusual external forcings, or are they inevitable given a sufficiently long period of time? Here we present a statistical model that combines sea surface temperature records and drought severity statistics from the western USA, and use that tool to set out an expectation for megadrought, given no other changes in the climate system. Even though this model was trained using only modern climate data (and incorporates no information from tree rings or other proxies), it still produced megadroughts. Moreover, those simulated megadroughts were just as long-lasting, covered as large an area, and were just as severe as real megadroughts estimated from tree rings. That result means that megadroughts can occur in the western United States even if nothing else changes in the climate -- they really are just a matter of time. On the other hand, the only aspect of real-world megadroughts that the model cannot duplicate was the high number of these events during the so-called Medieval Climate Anomaly (800 to 1300 CE). So that cluster of megadroughts may have been caused by some sort of unusual climate circumstances that have not been observed by us during the past few decades. The proxy record tells us that many different kinds of exceptional or unusual climate events happened in the past. But it is often difficult to determine what caused those exceptional events because even, within a period of a thousand years, we still have very few cases. So besides being an aid to understand the causes of past megadroughts, we hope this approach can be applied to other paleoclimate records to distinguish between real interrelations between separate components of the climate system and simple coincidences.
The need for new theory in global dendroclimatologyScott St. George
This document summarizes an interdisciplinary tree-ring research conference. It discusses the need for new theory in dendroclimatology, presentations on temperature and river flow reconstructions from tree rings, and principles of tree ring research site selection and replication. It also questions how to evaluate rare signals in tree growth and climate relationships and where remote teleconnections may be most evident in tree rings.
The societal value of historical and paleoflood research in Manitoba, CanadaScott St. George
1) Shared knowledge of past natural disasters has a major impact on preparation for future hazards. The document discusses the historical floods along the Red River in Manitoba, Canada.
2) Winnipeg built a large flood diversion channel in the 1960s after experiencing major floods, including in 1826 and 1950, to protect the city from future flooding of the Red River.
3) American communities like Grand Forks and Fargo were more vulnerable to Red River flooding until recently because they did not have the same long historical memory of floods that informed Winnipeg's early investment in flood protection infrastructure.
Solar ghosts: Weighing the evidence for sunspot cycles in fossil treesScott St. George
In their study of tree rings from the Chemnitz Fossil Forest (Germany), Luthardt and Rößler (2017) claim to identify a regular near-11-yr cyclicity in growth, and present that pattern as evidence of the influence of the Schwabe solar cycle (Usokin and Mursula, 2003) on climate and forest productivity during the early Permian. If correctly interpreted, these fossil tree rings would indicate the sunspot cycle was the dominant influence on interannual variability in Earth’s climate during this period and that it has been a consistent aspect of our Sun’s behavior for at least the past 300 m.y. We argue the fossil tree-ring record from Chemnitz does not constitute reliable evidence of solar activity during the Permian because the individual tree-ring sequences are not correctly aligned (dendrochronologically dated) and, as a result, the mean ring-width composite is not a meaningful estimate of year-to-year variations in tree growth in this ancient forest.
Long droughts: Using natural climate archives to gage the risks of future “me...Scott St. George
In the Biblical story of Joseph, following seven years of abundance, the Kingdom of Egypt was confronted by seven years of drought and famine. In the parlance of modern climate science, intervals with several consecutive extremely dry years are described as ‘“megadroughts”. In this short talk, I’ll describe how climate scientists combine clues from natural weather archives (including corals, tree rings, lake sediments, and many other sources) to reveal the history of ancient megadroughts across our planet. And I’ll highlight new research that combines these surrogate drought records with simulations from state-of-the-art climate models to help us better anticipate the risks of unusually persistent droughts during the coming century.
Expecting the unexpected: The relevance of old floods to modern hydrologyScott St. George
This document discusses the importance of understanding past floods to properly assess modern flood risks. It provides examples of paleoflood research along rivers like the Red River of the North, which uncovered major floods in 1826 and around 700 years ago that exceeded any floods measured by modern instrumentation. Understanding a river's full history through both recorded data and geological evidence of past floods is essential for floodplain management, development planning, and infrastructure design to mitigate future flood risks.
What to expect when you’re expecting decadal variability in hydroclimatic pro...Scott St. George
Climate simulations were run for 1000 years, with 1000 total simulations conducted. The simulations modeled climate changes over long time periods. The large number of long-term simulations provided insights into potential climate variations and outcomes.
Strong variance at decadal and multidecadal timescales is a common feature of most tree-ring width records. But does this aspect of tree growth exhibit such long-memory behavior due to biology, climate, or some combination of the two factors? Understanding the origins of this behavior is crucial for efforts to evaluate the causes of decadal variability in the climate system.
Presentation at Johann Gutenburg University (Mainz) on February 16, 2017.
Five Things You Can Do Right Now To Make Your Research Presentations Just A L...Scott St. George
The ability to deliver effective and engaging oral presentations is a critical skill for all researchers. Unfortunately, despite the importance of clear communication, too many scientific presentations at conferences and workshops are confusing, abstract, and boring. In this short workshop, participants learn several key strategies and tips that will make their professional presentations just a little bit better than the rest. We discuss strategies for presentation planning, show how basic design principles can create more memorable slides, and point towards an outstanding set online tools and resources. Become a presentation superstar!
Scott St. George is Associate Professor in the Department of Geography, Environment and Society at the University of Minnesota and a Resident Fellow at UMN's Institute on the Environment. Prior to joining the faculty at Minnesota, he was a research scientist with the Geological Survey of Canada. Scott shares some of his experiences ‘doing presentations differently’ at conferences, outreach opportunities, and the classroom.
In many settings, trees growing on floodplains provide an important source of indirect evidence that may be used to infer the occurrence, extent, and magnitude of floods prior to direct observations. That evidence may take several forms, including external scars caused by abrasion or impact from floating debris, anatomical changes within the annual growth increment following prolonged stem or root inundation, or tilting or uprooting due to the hydraulic pressure of floodwaters. Likely the most useful characteristic of paleoflood studies based on floodplain trees is their relatively high temporal resolution and dating accuracy compared to most other methods. Dendrochronological methods can routinely date past floods to the year of their occurrence and, in rare cases, can estimate the timing of floods that occur during the growing season to within two weeks. This high degree of chronological control, which is surpassed only by that provided by direct observation or instrumentation, can be used to determine whether floods in separate watersheds were synchronous or offset by several years and test hypotheses that suppose linkages between extreme floods and specific forcing mechanisms. Furthermore, the wide geographic distribution of tree species with dateable rings combined with the broad suite of methods available to examine interconnections between floods and tree growth allow this style of paleoflood hydrology to be applied to many settings that are not suitable for techniques that depend on geological evidence. Future paleoflood research involving tree rings will need to strike a balance between improving our understanding of the biological and fluvial processes that link tree growth to past events, and providing answers to questions about flood dynamics and hazards that are needed to safeguard people and property from future floods.
Expanding the window - the past, present, and future of Minnesota's waterScott St. George
Nearly all decisions about water in Minnesota relate either directly or indirectly to data collected by the state’s hydrological observing network. Because most gauges were installed in early 20th century, as a whole the network provides us with roughly a 100-year ‘window’ to estimate flood risks, develop worst-case scenarios for drought, and set maximum allowable withdrawals for aquifers. But when we rely exclusively on observations made during this relatively brief interval, we may inadvertently increase our exposure to hydrological ‘surprises’. In order to make sound decisions about water in Minnesota, we need to expand this window: into the past, drawing upon historical accounts and natural archives; and into the future, via projections from climate and hydrological models. By cultivating a broader perspective on hydrological variability and extremes across the state, we will be better prepared to ensure adequate water supplies and mitigate the impacts of future floods and droughts.
These visuals were prepared to support a string quartet performance and panel on climate change at Northwestern University in February 2106.
A well-designed graphic can help audiences to quickly understand the main message embedded within a complex set of climate data and to retain those ideas longer than they would have if they were conveyed by words alone. But the visual aids used regularly by climate scientists also have their limitations: they are most easily understood by people who are already fluent in technical illustrations; they're usually static and sometimes do not tell an obvious story; and for many, they don't elicit a strong emotional response.
Music, by contrast, is inherently narrative and is known to exert a powerful influence on human emotions. Because of this, sonification — the transformation of data into acoustic signals — may have considerable promise as a tool to enhance the communication of climate science.
Daniel Crawford and Scott St. George report on a collaboration between scientists and artists that uses music to transmit the evidence of climate change in an engaging and visceral way.
Large-scale dendrochronology and low-frequency climate variabilityScott St. George
Large-scale low-frequency variability has emerged as a priority for climate research, but instrumental observations are not long enough to characterize this behavior or gage its impacts on dependent geophysical or ecological systems. As the leading source of high-resolution paleoclimate information in the middle- and high-latitudes, tree rings are essential to understand low-frequency variability prior to the instrumental period. But even though tree rings possess several advantages as climate proxies, like other natural archives they also have their own particular impediments. In this lecture, Dr. St. George will describe the structure and characteristics of the Northern Hemisphere tree-ring width network, and outline how the fingerprint of decadal and multidecadal climate variability encoded within ancient trees varies across the hemisphere.
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
In the realm of cybersecurity, offensive security practices act as a critical shield. By simulating real-world attacks in a controlled environment, these techniques expose vulnerabilities before malicious actors can exploit them. This proactive approach allows manufacturers to identify and fix weaknesses, significantly enhancing system security.
This presentation delves into the development of a system designed to mimic Galileo's Open Service signal using software-defined radio (SDR) technology. We'll begin with a foundational overview of both Global Navigation Satellite Systems (GNSS) and the intricacies of digital signal processing.
The presentation culminates in a live demonstration. We'll showcase the manipulation of Galileo's Open Service pilot signal, simulating an attack on various software and hardware systems. This practical demonstration serves to highlight the potential consequences of unaddressed vulnerabilities, emphasizing the importance of offensive security practices in safeguarding critical infrastructure.
Ivanti’s Patch Tuesday breakdown goes beyond patching your applications and brings you the intelligence and guidance needed to prioritize where to focus your attention first. Catch early analysis on our Ivanti blog, then join industry expert Chris Goettl for the Patch Tuesday Webinar Event. There we’ll do a deep dive into each of the bulletins and give guidance on the risks associated with the newly-identified vulnerabilities.
Connector Corner: Seamlessly power UiPath Apps, GenAI with prebuilt connectorsDianaGray10
Join us to learn how UiPath Apps can directly and easily interact with prebuilt connectors via Integration Service--including Salesforce, ServiceNow, Open GenAI, and more.
The best part is you can achieve this without building a custom workflow! Say goodbye to the hassle of using separate automations to call APIs. By seamlessly integrating within App Studio, you can now easily streamline your workflow, while gaining direct access to our Connector Catalog of popular applications.
We’ll discuss and demo the benefits of UiPath Apps and connectors including:
Creating a compelling user experience for any software, without the limitations of APIs.
Accelerating the app creation process, saving time and effort
Enjoying high-performance CRUD (create, read, update, delete) operations, for
seamless data management.
Speakers:
Russell Alfeche, Technology Leader, RPA at qBotic and UiPath MVP
Charlie Greenberg, host
What is an RPA CoE? Session 1 – CoE VisionDianaGray10
In the first session, we will review the organization's vision and how this has an impact on the COE Structure.
Topics covered:
• The role of a steering committee
• How do the organization’s priorities determine CoE Structure?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
Skybuffer SAM4U tool for SAP license adoptionTatiana Kojar
Manage and optimize your license adoption and consumption with SAM4U, an SAP free customer software asset management tool.
SAM4U, an SAP complimentary software asset management tool for customers, delivers a detailed and well-structured overview of license inventory and usage with a user-friendly interface. We offer a hosted, cost-effective, and performance-optimized SAM4U setup in the Skybuffer Cloud environment. You retain ownership of the system and data, while we manage the ABAP 7.58 infrastructure, ensuring fixed Total Cost of Ownership (TCO) and exceptional services through the SAP Fiori interface.
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/how-axelera-ai-uses-digital-compute-in-memory-to-deliver-fast-and-energy-efficient-computer-vision-a-presentation-from-axelera-ai/
Bram Verhoef, Head of Machine Learning at Axelera AI, presents the “How Axelera AI Uses Digital Compute-in-memory to Deliver Fast and Energy-efficient Computer Vision” tutorial at the May 2024 Embedded Vision Summit.
As artificial intelligence inference transitions from cloud environments to edge locations, computer vision applications achieve heightened responsiveness, reliability and privacy. This migration, however, introduces the challenge of operating within the stringent confines of resource constraints typical at the edge, including small form factors, low energy budgets and diminished memory and computational capacities. Axelera AI addresses these challenges through an innovative approach of performing digital computations within memory itself. This technique facilitates the realization of high-performance, energy-efficient and cost-effective computer vision capabilities at the thin and thick edge, extending the frontier of what is achievable with current technologies.
In this presentation, Verhoef unveils his company’s pioneering chip technology and demonstrates its capacity to deliver exceptional frames-per-second performance across a range of standard computer vision networks typical of applications in security, surveillance and the industrial sector. This shows that advanced computer vision can be accessible and efficient, even at the very edge of our technological ecosystem.
Driving Business Innovation: Latest Generative AI Advancements & Success StorySafe Software
Are you ready to revolutionize how you handle data? Join us for a webinar where we’ll bring you up to speed with the latest advancements in Generative AI technology and discover how leveraging FME with tools from giants like Google Gemini, Amazon, and Microsoft OpenAI can supercharge your workflow efficiency.
During the hour, we’ll take you through:
Guest Speaker Segment with Hannah Barrington: Dive into the world of dynamic real estate marketing with Hannah, the Marketing Manager at Workspace Group. Hear firsthand how their team generates engaging descriptions for thousands of office units by integrating diverse data sources—from PDF floorplans to web pages—using FME transformers, like OpenAIVisionConnector and AnthropicVisionConnector. This use case will show you how GenAI can streamline content creation for marketing across the board.
Ollama Use Case: Learn how Scenario Specialist Dmitri Bagh has utilized Ollama within FME to input data, create custom models, and enhance security protocols. This segment will include demos to illustrate the full capabilities of FME in AI-driven processes.
Custom AI Models: Discover how to leverage FME to build personalized AI models using your data. Whether it’s populating a model with local data for added security or integrating public AI tools, find out how FME facilitates a versatile and secure approach to AI.
We’ll wrap up with a live Q&A session where you can engage with our experts on your specific use cases, and learn more about optimizing your data workflows with AI.
This webinar is ideal for professionals seeking to harness the power of AI within their data management systems while ensuring high levels of customization and security. Whether you're a novice or an expert, gain actionable insights and strategies to elevate your data processes. Join us to see how FME and AI can revolutionize how you work with data!
zkStudyClub - LatticeFold: A Lattice-based Folding Scheme and its Application...Alex Pruden
Folding is a recent technique for building efficient recursive SNARKs. Several elegant folding protocols have been proposed, such as Nova, Supernova, Hypernova, Protostar, and others. However, all of them rely on an additively homomorphic commitment scheme based on discrete log, and are therefore not post-quantum secure. In this work we present LatticeFold, the first lattice-based folding protocol based on the Module SIS problem. This folding protocol naturally leads to an efficient recursive lattice-based SNARK and an efficient PCD scheme. LatticeFold supports folding low-degree relations, such as R1CS, as well as high-degree relations, such as CCS. The key challenge is to construct a secure folding protocol that works with the Ajtai commitment scheme. The difficulty, is ensuring that extracted witnesses are low norm through many rounds of folding. We present a novel technique using the sumcheck protocol to ensure that extracted witnesses are always low norm no matter how many rounds of folding are used. Our evaluation of the final proof system suggests that it is as performant as Hypernova, while providing post-quantum security.
Paper Link: https://eprint.iacr.org/2024/257
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/temporal-event-neural-networks-a-more-efficient-alternative-to-the-transformer-a-presentation-from-brainchip/
Chris Jones, Director of Product Management at BrainChip , presents the “Temporal Event Neural Networks: A More Efficient Alternative to the Transformer” tutorial at the May 2024 Embedded Vision Summit.
The expansion of AI services necessitates enhanced computational capabilities on edge devices. Temporal Event Neural Networks (TENNs), developed by BrainChip, represent a novel and highly efficient state-space network. TENNs demonstrate exceptional proficiency in handling multi-dimensional streaming data, facilitating advancements in object detection, action recognition, speech enhancement and language model/sequence generation. Through the utilization of polynomial-based continuous convolutions, TENNs streamline models, expedite training processes and significantly diminish memory requirements, achieving notable reductions of up to 50x in parameters and 5,000x in energy consumption compared to prevailing methodologies like transformers.
Integration with BrainChip’s Akida neuromorphic hardware IP further enhances TENNs’ capabilities, enabling the realization of highly capable, portable and passively cooled edge devices. This presentation delves into the technical innovations underlying TENNs, presents real-world benchmarks, and elucidates how this cutting-edge approach is positioned to revolutionize edge AI across diverse applications.
HCL Notes und Domino Lizenzkostenreduzierung in der Welt von DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-und-domino-lizenzkostenreduzierung-in-der-welt-von-dlau/
DLAU und die Lizenzen nach dem CCB- und CCX-Modell sind für viele in der HCL-Community seit letztem Jahr ein heißes Thema. Als Notes- oder Domino-Kunde haben Sie vielleicht mit unerwartet hohen Benutzerzahlen und Lizenzgebühren zu kämpfen. Sie fragen sich vielleicht, wie diese neue Art der Lizenzierung funktioniert und welchen Nutzen sie Ihnen bringt. Vor allem wollen Sie sicherlich Ihr Budget einhalten und Kosten sparen, wo immer möglich. Das verstehen wir und wir möchten Ihnen dabei helfen!
Wir erklären Ihnen, wie Sie häufige Konfigurationsprobleme lösen können, die dazu führen können, dass mehr Benutzer gezählt werden als nötig, und wie Sie überflüssige oder ungenutzte Konten identifizieren und entfernen können, um Geld zu sparen. Es gibt auch einige Ansätze, die zu unnötigen Ausgaben führen können, z. B. wenn ein Personendokument anstelle eines Mail-Ins für geteilte Mailboxen verwendet wird. Wir zeigen Ihnen solche Fälle und deren Lösungen. Und natürlich erklären wir Ihnen das neue Lizenzmodell.
Nehmen Sie an diesem Webinar teil, bei dem HCL-Ambassador Marc Thomas und Gastredner Franz Walder Ihnen diese neue Welt näherbringen. Es vermittelt Ihnen die Tools und das Know-how, um den Überblick zu bewahren. Sie werden in der Lage sein, Ihre Kosten durch eine optimierte Domino-Konfiguration zu reduzieren und auch in Zukunft gering zu halten.
Diese Themen werden behandelt
- Reduzierung der Lizenzkosten durch Auffinden und Beheben von Fehlkonfigurationen und überflüssigen Konten
- Wie funktionieren CCB- und CCX-Lizenzen wirklich?
- Verstehen des DLAU-Tools und wie man es am besten nutzt
- Tipps für häufige Problembereiche, wie z. B. Team-Postfächer, Funktions-/Testbenutzer usw.
- Praxisbeispiele und Best Practices zum sofortigen Umsetzen
16. 100%
Woodhouse et al., 2006
Meko et al., 2001
80% Sacramento River
Upper Colorado River
Meko et al., 2007
Colorado River
Woodhouse, 2007
Middle Boulder Creek
60%
explained
variance
40%
20%
0%
Canada USA
17. 100%
Woodhouse et al., 2006
Meko et al., 2001
80% Sacramento River
Upper Colorado River
Meko et al., 2007
Colorado River
Woodhouse, 2007
Middle Boulder Creek
60% Case and MacDonald, 2003
explained
Saskatchewan River
Beriault and Sauchyn, 2006
Churchill River
variance
Bonin and Burn, 2005
Athabasca River
40%
Watson and Luckman, 2005 Gedalof et al., 2007
Bow River Columbia River
20%
0%
Canada USA
19. Janice Lough and Hal Fritts
The Southern Oscillation and tree rings: 1600 - 1961
Journal of Applied Meteorology 24, 1985
Roseanne D’Arrigo and Gordon Jacoby
A thousand year record of northwestern New
Mexico winter precipitation reconstructed from tree
rings and its relation to El Niño and the Southern
Oscillation
The Holocene 1, 1991
David Stahle and collaborators
Experimental dendroclimatic reconstruction of the
Southern Oscillation Stahle et al., 1998
Bulletin of the American Meteorological Society 79, 1998
28. DROUGHT AND SEASONALITY
How does the connection between reconstructed drought
1
and seasonal precipitation vary across North America?
29. DROUGHT AND SEASONALITY
How does the connection between reconstructed drought
1 and seasonal precipitation vary across North America?
CLIMATE MODES AND TREE RINGS
In which regions are drought reconstructions most strongly
2 connected to remote climate forcings (ENSO, PDO, AMO)?
30. The North American
Drought Atlas
Cook et al., 2007, Earth Science Reviews
47. “
...the regional summer precipitation signal is strong in
Pseudotsuga menziesii latewood-width [in southeastern
Arizona].
David Meko and Chris Baisan
Pilot study of latewood-width of conifers as an indicator of variability of summer rainfall in
the North American monsoon region
International Journal of Climatology 21, 2001
54. Julia Cole and Ed Cook
The changing relationship between ENSO variability
and moisture balance in the continental United States
Geophysical Research Letters 25, 1998
76. IMPLICATIONS
what/where OK
what/where/why NOT OK
77. IMPLICATIONS
tree ring model output
Celine Herwiejer, Richard Seager and Ed Cook
North American droughts of the mid to late nineteenth century:
a history, simulation and implication for Mediaeval drought
The Holocene 16, 2006