Here are a few key points about the global distribution of tree-ring data based on reviewing it in Google Earth:
- Much of the data comes from North America, particularly western North America with sites in California, the Rocky Mountains, and Alaska/Canada. There are also many sites in the eastern U.S.
- Europe also has a significant amount of data, especially from Scandinavia and the Alps. Sites also exist across Spain, France, Germany, and other countries.
- Asia has tree-ring data primarily from Siberia and the Himalayas/Tibetan Plateau. There are also some sites in China, Japan, and other parts of Asia.
- South America has a fair
Mackenzie Nelsen, a junior at Watauga High School, collected tree core samples from high and low elevation areas to analyze how climate change may affect high altitude carbon sequestration. She found that trees at elevations over 3,000 feet showed significantly more growth variation from 1990-2013 compared to low elevation trees. This suggests climate change will have a greater impact on mountain ecosystems. Higher CO2 levels may boost high elevation tree growth through fertilization but also make them more vulnerable to climate extremes.
Many of the decisions we make about environmental issues are based on experience. Whether we're setting limits for the use of scarce resources, estimating the risks posed by natural hazards, or deciding how to manage protected areas, our plans for the future often reflect our understanding of the past. The problem is that, when it comes to the environment, our society has a fairly short memory. In this presentation, Dr. St. George will discuss how the study of ancient trees is expanding our perspective on the natural history of the northern Plains and helping to answer questions about what the future may hold for Minnesota's environment.
This document discusses tree ring dendroclimatology and how tree ring records can be used to understand past climates. Tree ring growth is influenced by climate factors like temperature and precipitation. Multiple tree ring records from a region can be combined and correlated with observed climate data to develop climate reconstructions spanning centuries. However, tree ring growth can be affected by non-climatic factors as well, and some recent studies have found a divergence or weakening correlation between tree growth and temperatures in some northern sites. Overall, tree ring records are a valuable but imperfect proxy for understanding past climate variability over centuries to millennia when used carefully.
Building tree-ring chronologies and Program ARSTANScott St. George
The document discusses dendroclimatology and paleoclimatology, including how tree rings can be used as climate proxies to reconstruct past climate variations. It explains how tree-ring measurements are standardized and aggregated to extract climate signals and maximize the environmental information while minimizing noise. Methods like COFECHA, detrending, and ARSTAN are used to process tree-ring data and develop high-quality tree-ring chronologies suitable for climate reconstruction.
The annual growth rings from trees provide us with an incredibly powerful and adaptable tool to study Earth’s history. The rings tell us much more than just the age of tree. They also provide clues that help us understand how our environment has changed in the past, and provide insights into how key processes in atmosphere, biosphere and geological systems operate over long timescales.
This course will teach students the fundamental principles of dendrochronology through a combination of formal lectures, class discussion and laboratory exercises. Students will work in the University of Minnesota’s Center for Dendrochronology, where they will learn how to collect, prepare and date tree-ring specimens. By the end of the course, they will be able to explain both the key concepts underlying dendrochronology and discuss how evidence from tree rings is used to address contemporary issues in natural history, resource management and Earth Systems Science.
This document discusses tree ring data and standardization techniques. It introduces the linear aggregate model of tree growth and its components. It describes downloading tree ring width data from several sites in New Mexico and the principle of detrending the raw ring width data. It recommends using the ARSTAN program and different detrending methods like horizontal line, negative exponential curve, and flexible splines to standardize the chronologies and compare the results.
Tree rings can be used to determine the age of trees and study environmental conditions in different years. Each year a tree forms a new growth ring, with wider rings indicating better growing conditions and narrower rings indicating drought or other difficulties. By matching ring patterns between trees, scientists have developed tree-ring chronologies that can date back thousands of years. The field of dendrochronology uses these ring patterns to date wood and study past climate patterns, as well as applications in archaeology, geology, and environmental science.
Mackenzie Nelsen, a junior at Watauga High School, collected tree core samples from high and low elevation areas to analyze how climate change may affect high altitude carbon sequestration. She found that trees at elevations over 3,000 feet showed significantly more growth variation from 1990-2013 compared to low elevation trees. This suggests climate change will have a greater impact on mountain ecosystems. Higher CO2 levels may boost high elevation tree growth through fertilization but also make them more vulnerable to climate extremes.
Many of the decisions we make about environmental issues are based on experience. Whether we're setting limits for the use of scarce resources, estimating the risks posed by natural hazards, or deciding how to manage protected areas, our plans for the future often reflect our understanding of the past. The problem is that, when it comes to the environment, our society has a fairly short memory. In this presentation, Dr. St. George will discuss how the study of ancient trees is expanding our perspective on the natural history of the northern Plains and helping to answer questions about what the future may hold for Minnesota's environment.
This document discusses tree ring dendroclimatology and how tree ring records can be used to understand past climates. Tree ring growth is influenced by climate factors like temperature and precipitation. Multiple tree ring records from a region can be combined and correlated with observed climate data to develop climate reconstructions spanning centuries. However, tree ring growth can be affected by non-climatic factors as well, and some recent studies have found a divergence or weakening correlation between tree growth and temperatures in some northern sites. Overall, tree ring records are a valuable but imperfect proxy for understanding past climate variability over centuries to millennia when used carefully.
Building tree-ring chronologies and Program ARSTANScott St. George
The document discusses dendroclimatology and paleoclimatology, including how tree rings can be used as climate proxies to reconstruct past climate variations. It explains how tree-ring measurements are standardized and aggregated to extract climate signals and maximize the environmental information while minimizing noise. Methods like COFECHA, detrending, and ARSTAN are used to process tree-ring data and develop high-quality tree-ring chronologies suitable for climate reconstruction.
The annual growth rings from trees provide us with an incredibly powerful and adaptable tool to study Earth’s history. The rings tell us much more than just the age of tree. They also provide clues that help us understand how our environment has changed in the past, and provide insights into how key processes in atmosphere, biosphere and geological systems operate over long timescales.
This course will teach students the fundamental principles of dendrochronology through a combination of formal lectures, class discussion and laboratory exercises. Students will work in the University of Minnesota’s Center for Dendrochronology, where they will learn how to collect, prepare and date tree-ring specimens. By the end of the course, they will be able to explain both the key concepts underlying dendrochronology and discuss how evidence from tree rings is used to address contemporary issues in natural history, resource management and Earth Systems Science.
This document discusses tree ring data and standardization techniques. It introduces the linear aggregate model of tree growth and its components. It describes downloading tree ring width data from several sites in New Mexico and the principle of detrending the raw ring width data. It recommends using the ARSTAN program and different detrending methods like horizontal line, negative exponential curve, and flexible splines to standardize the chronologies and compare the results.
Tree rings can be used to determine the age of trees and study environmental conditions in different years. Each year a tree forms a new growth ring, with wider rings indicating better growing conditions and narrower rings indicating drought or other difficulties. By matching ring patterns between trees, scientists have developed tree-ring chronologies that can date back thousands of years. The field of dendrochronology uses these ring patterns to date wood and study past climate patterns, as well as applications in archaeology, geology, and environmental science.
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.
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.
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
বিসিএস ও ব্যাংক এর লিখিত পরীক্ষা ...+এছাড়া মাধ্যমিক ও উচ্চমাধ্যমিকের স্টুডেন্টদের জন্য অনেক কাজে আসবে ...
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
Chapter wise All Notes of First year Basic Civil Engineering.pptx
Class 8, Sampling strategies
1.
2. KEVIN ANCHUKAITIS
COLUMBIA UNIVERSITY
FRI MAR 4, 2011
BLEGEN 445
3:30 PM
A THOUSAND YEARS OF
HUMAN HISTORY AND THE
ASIAN MONSOON FROM
TROPICAL TREE RINGS
10. THE PRINCIPLE OF
ECOLOGICAL AMPLITUDE
A tree species may grow and reproduce over a certain range of
habitats; that range is described as its ecological amplitude.
Trees that grow near the margins or limits of their ecological
amplitude are o en sensitive to changes in their environment.
17. High
Low
Forest interior Semiarid forest border
DECREASING EFFECTIVE PRECIPITATION
INCREASING VARIABILITY IN ANNUAL PRECIPITATION
MORE DAYS WHERE MOISTURE IS LIMITING TO PROCESSES IN TREE
c.f. Fri s, 1976
18. High Av
era
ge
r ing
-w
idt
Ar h
bo
ria
ld
om
ina
nc
e
Low
Forest interior Semiarid forest border
DECREASING EFFECTIVE PRECIPITATION
INCREASING VARIABILITY IN ANNUAL PRECIPITATION
MORE DAYS WHERE MOISTURE IS LIMITING TO PROCESSES IN TREE
c.f. Fri s, 1976
19. High
S
NG
RI
N T
Low B SE
PERCENT A
Forest interior Semiarid forest border
DECREASING EFFECTIVE PRECIPITATION
INCREASING VARIABILITY IN ANNUAL PRECIPITATION
MORE DAYS WHERE MOISTURE IS LIMITING TO PROCESSES IN TREE
c.f. Fri s, 1976
20. High
E S
R E
T
N
EE
TW
BE
N
T IO
LA
RE
O R
Low C
Forest interior Semiarid forest border
DECREASING EFFECTIVE PRECIPITATION
INCREASING VARIABILITY IN ANNUAL PRECIPITATION
MORE DAYS WHERE MOISTURE IS LIMITING TO PROCESSES IN TREE
c.f. Fri s, 1976
23. COMPLACENT SENSITIVE
High
E S
R E
T
N
EE
TW
BE
N
T IO
LA
RE
O R
Low C
Forest interior Semiarid forest border
DECREASING EFFECTIVE PRECIPITATION
INCREASING VARIABILITY IN ANNUAL PRECIPITATION
MORE DAYS WHERE MOISTURE IS LIMITING TO PROCESSES IN TREE
c.f. Fri s, 1976
25. THE PRINCIPLE OF
SITE SELECTION
Dendrochronologists should apply the principles of
limiting factors and ecological amplitude to determine
which trees are most likely to provide information about a
specific environmental signal.
26. THE PRINCIPLE OF AGGREGATE TREE GROWTH
Rt = At + Ct + δD1t + δD2t + Et
29. ecotone a transitional area where one plant community
changes into another, usually caused by changes in the
environment such as changes in elevation or soil
characteristics.
57. IDENTIFYING CHARACTERISTICS OF PONDEROSA PINE TREES AT DIFFERENT LIFE STAGES
Live crown Trunk Likely
Crown shape Branches Bark
ratio shape injuries
Old trees fla ened, ‘bonsai’ shape,
sparse and open, may be
small; o en fire-pruned few but large columnar smooth,
small flakes,
fire scars, dead
tops, broken
(>200 yr) lopsided. pale orange
or grey
branches, lightning
scars, rot, burls,
exposed roots
Young trees pointed top, ‘teardrop’ or
‘Christmas tree’ shape,
large many fine branches,
dense foliage near
tapered large, coarse
flakes, deep
very few, possible
mistletoe or
(<150 yr) dense foliage the trunk fissures, dark
gray or black
lightening scars
with dark orange
Source: Huckaby et al., 2003
63. Pederson, N. 2010. External characteristics of
old trees in the Eastern Deciduous Forest.
Natural Areas Journal 30, 396:407.
64. SIX
CHARACTERISTICS OF OLD TREES
smooth bark
low stem taper
high stem sinuosity
crowns with few, thick, twisting limbs
low crown volume
low ratio of leaf area to trunk volume