A HOTTER,
DRIER WORLD
Our planet is in crisis. Since the beginning of the Industrial Revolution, we have added more than two trillion tons of carbon dioxide into the atmosphere, threatening to forever alter the relatively stable climate system in which humanity has grown and flourished for the last ten thousand years.
A HOTTER,
DRIER WORLD
Our planet is in crisis. Since the beginning of the Industrial Revolution, we have added more than two trillion tons of carbon dioxide into the atmosphere, threatening to forever alter the relatively stable climate system in which humanity has grown and flourished for the last ten thousand years.
The disappearance of land and ocean species is progressing at rates unseen since the time of the dinosaurs. Each year, tens of thousands of people flee their homes because of extreme weather, extended droughts, wildfires and other climate-related stressors in search of stable access to food, water and safety. Societies will face these challenges for decades to come. By studying the past and by modeling the future, Lamont researchers are helping put the present into context, and helping ensure we develop smart adaptation policies and management practices to meet these challenges.
The disappearance of land and ocean species is progressing at rates unseen since the time of the dinosaurs. Each year, tens of thousands of people flee their homes because of extreme weather, extended droughts, wildfires, and other climate-related stressors searching for stable access to food, water, and safety. Societies will face these challenges for decades to come. By studying the past and by modeling the future, Lamont researchers are helping put the present into context, and working to ensure we develop smart adaptation policies and management practices to meet these challenges.
Using data from tree rings, satellites, and observational stations, Park Williams, Benjamin Cook, and Jason Smerdon confirmed that the 23-year-long megadrought currently parching southwestern North America is the worst the region has seen in at least 1,200 years.
Life-supporting reservoirs such as Lake Mead and Lake Powell are shriveling, while prolonged, triple-digit heatwaves are making cities like Phoenix and Las Vegas more dangerous during summers. While this region started experiencing cycles of megadroughts well before humans started pumping greenhouse gases into the atmosphere, climate change is increasing their severity and duration: warmer temperatures increase evaporation, which dries out soil and vegetation. These human-driven influences have made the current megadrought in the American Southwest more than 40% more severe than it would have been in a world absent the human influence.
Droughts and heat waves are also driving increased fire incidence in the American West, with complicated impacts on water resources. Williams, Smerdon, and Cook–along with Arianna Varuolo-Clarke, Justin Mankin, and Caroline Juang–analyzed stream flow and climate data from 179 river basins to show that wildfires in the western U.S. are increasingly impacting the region's rivers and streams. Fires actually elevate stream flow for years after they have burned away vegetation that would otherwise draw water out of the soil. But they could also increase the risks of catastrophic landslides and floods in the affected areas, in addition to impacting water quality. Understanding the role of wildfires will become increasingly important to the region's water-supply managers in their calculations of water availability and allocation for western communities.
Droughts and heat waves are also driving increased fire incidence in the American West, with complicated impacts on water resources. Williams, Smerdon, and Cook–along with Arianna Varuolo-Clarke, Justin Mankin, and Caroline Juang–analyzed stream flow and climate data from 179 river basins to show that wildfires in the western U.S. are increasingly impacting the region's rivers and streams. Fires actually elevate stream flow for years after they have burned away vegetation that would otherwise draw water out of the soil. But they could also increase the risks of catastrophic landslides and floods in the affected areas, in addition to impacting water quality. Understanding the role of wildfires will become increasingly important to the region's water-supply managers in their calculations of water availability and allocation for western communities.
New Way of Analyzing Tree Rings Confirms Unprecedented Central Asia Warming
By Sarah Fecht
A relatively new way of analyzing tree rings have allowed Lamont researchers and international colleagues to reconstruct historical temperatures in Mongolia back to 1269 CE. The new reconstruction confirms that summer temperatures since the 1990s are the warmest the region has seen in the past eight centuries.
Lamont Adjunct Research Scientist Nicole Davi led the project team, which included Mukund Rao, Robert Wilson, Laia Andreu-Hayles, Rose Oelkers, Rosanne D’Arrigo, Brendan Buckley and Caroline Leland of the Lamont-Doherty Tree Ring Lab.
Central Asia is one of the fastest-warming places on the planet. In just the past 15 years, summer temperatures have warmed nearly 3 degrees F, or almost three times the global average rate. Rapid warming is already causing extreme droughts, harming fragile ecosystems and causing devastating livestock losses for pastoralists, who have traditionally formed the backbone of the Mongolian economy.
To date, there are only a handful of long-term climate records in Central Asia that can help to put these trends into context. Analyzing the rings from trees can tell scientists about temperature and precipitation patterns hundreds or thousands of years in the past. However, suitably old trees and logs in this region can be difficult to sample, in part due to their remoteness.
The scarcity of tree-ring data in the region makes the new reconstruction all the more important. To create it, Davi and her colleagues analyzed tree-ring cores that were originally collected in 1998 and 2005 for a project led by her mentor, Gordon Jacoby, co-founder of the Tree Ring Lab at Lamont. Jacoby had been trying to reconstruct the region’s temperature history using ring widths, but the data wasn’t strong enough, so he set it aside. Before Jacoby died in 2014, Davi asked permission to take over the project.
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Work by Corey Lesk and Radley Horton showed that climate change may cause heat and drought events to coincide more often, which could deliver a one-two punch to maize and soy farmers. They found that, when compared to previous projections of future climate risk to crops, these stronger relationships between high temperatures and low moisture could cause yields to drop an additional 20% in parts of the eastern U.S., and by up to 40% in parts of eastern Europe and southeastern Africa. Without strong and rapid cuts in greenhouse gases, overall supplies of staple foods could be increasingly damaged by compound climate extremes. This raises the risks of higher food prices and reduced food security, even in developed countries.
A hotter, drier world threatens the population and health of livestock, as well as the traditional pastoralist societies that depend on them. Below, read about the novel methods we're using to better understand the past climate of Mongolia, which happens to be located in one of the fastest-warming regions on the planet.
The disappearance of land and ocean species is progressing at rates unseen since the time of the dinosaurs. Each year, tens of thousands of people flee their homes because of extreme weather, extended droughts, wildfires, and other climate-related stressors searching for stable access to food, water, and safety. Societies will face these challenges for decades to come. By studying the past and by modeling the future, Lamont researchers are helping put the present into context, and working to ensure we develop smart adaptation policies and management practices to meet these challenges.
Using data from tree rings, satellites, and observational stations, Park Williams, Benjamin Cook, and Jason Smerdon confirmed that the 23-year-long megadrought currently parching southwestern North America is the worst the region has seen in at least 1,200 years.
Life-supporting reservoirs such as Lake Mead and Lake Powell are shriveling, while prolonged, triple-digit heatwaves are making cities like Phoenix and Las Vegas more dangerous during summers. While this region started experiencing cycles of megadroughts well before humans started pumping greenhouse gases into the atmosphere, climate change is increasing their severity and duration: warmer temperatures increase evaporation, which dries out soil and vegetation. These human-driven influences have made the current megadrought in the American Southwest more than 40% more severe than it would have been in a world absent the human influence.
Droughts and heat waves are also driving increased fire incidence in the American West, with complicated impacts on water resources. Williams, Smerdon, and Cook–along with Arianna Varuolo-Clarke, Justin Mankin, and Caroline Juang–analyzed stream flow and climate data from 179 river basins to show that wildfires in the western U.S. are increasingly impacting the region's rivers and streams. Fires actually elevate stream flow for years after they have burned away vegetation that would otherwise draw water out of the soil. But they could also increase the risks of catastrophic landslides and floods in the affected areas, in addition to impacting water quality. Understanding the role of wildfires will become increasingly important to the region's water-supply managers in their calculations of water availability and allocation for western communities.
Work by Corey Lesk and Radley Horton showed that climate change may cause heat and drought events to coincide more often, which could deliver a one-two punch to maize and soy farmers. They found that, when compared to previous projections of future climate risk to crops, these stronger relationships between high temperatures and low moisture could cause yields to drop an additional 20% in parts of the eastern U.S., and by up to 40% in parts of eastern Europe and southeastern Africa. Without strong and rapid cuts in greenhouse gases, overall supplies of staple foods could be increasingly damaged by compound climate extremes. This raises the risks of higher food prices and reduced food security, even in developed countries.
A hotter, drier world threatens the population and health of livestock, as well as the traditional pastoralist societies that depend on them. Below, read about the novel methods we're using to better understand the past climate of Mongolia, which happens to be located in one of the fastest-warming regions on the planet.
New Way of Analyzing Tree Rings Confirms Unprecedented Central Asia Warming
By Sarah Fecht
A relatively new way of analyzing tree rings have allowed Lamont researchers and international colleagues to reconstruct historical temperatures in Mongolia back to 1269 CE. The new reconstruction confirms that summer temperatures since the 1990s are the warmest the region has seen in the past eight centuries.
Lamont Adjunct Research Scientist Nicole Davi led the project team, which included Mukund Rao, Robert Wilson, Laia Andreu-Hayles, Rose Oelkers, Rosanne D’Arrigo, Brendan Buckley and Caroline Leland of the Lamont-Doherty Tree Ring Lab.
Central Asia is one of the fastest-warming places on the planet. In just the past 15 years, summer temperatures have warmed nearly 3 degrees F, or almost three times the global average rate. Rapid warming is already causing extreme droughts, harming fragile ecosystems and causing devastating livestock losses for pastoralists, who have traditionally formed the backbone of the Mongolian economy.
To date, there are only a handful of long-term climate records in Central Asia that can help to put these trends into context. Analyzing the rings from trees can tell scientists about temperature and precipitation patterns hundreds or thousands of years in the past. However, suitably old trees and logs in this region can be difficult to sample, in part due to their remoteness.
The scarcity of tree-ring data in the region makes the new reconstruction all the more important. To create it, Davi and her colleagues analyzed tree-ring cores that were originally collected in 1998 and 2005 for a project led by her mentor, Gordon Jacoby, co-founder of the Tree Ring Lab at Lamont. Jacoby had been trying to reconstruct the region’s temperature history using ring widths, but the data wasn’t strong enough, so he set it aside. Before Jacoby died in 2014, Davi asked permission to take over the project.
The cores come from a combination of living Siberian larch trees dating back 400 to 500 years, and relict wood—ancient trees that had fallen over but hadn’t decayed, thanks to the cold and dry conditions. “When we find relict wood it’s super exciting because we know we can go back further in time,” said Davi.
To get new information out of Jacoby’s samples, the team turned to a promising method that came into use a few years ago. Called delta blue intensity, the method looks at how well each ring reflects blue light in its latewood (the darker band that forms later in the growing season) compared to in the lighter early wood. Less dense wood, which results from cooler conditions, absorbs less blue light.
The stronger results from the delta blue light technique allowed the team to build a model of summer temperatures in the region from 1269 to 2004 CE. The reconstruction matches up well with data from regional weather stations dating back to the 1950s, as well as cooling events associated with several large-scale volcanic eruptions.
For Davi, publishing these findings feels personally meaningful. “Gordon Jacoby was my Ph.D. advisor, mentor, and friend,” she said. “We had countless adventures doing fieldwork together. Bringing closure to some of the research that he started definitely feels good.”
The reconstruction also adds context to the warming of the past several decades, and to global climate models showing what it could look like in the future.
The cores come from a combination of living Siberian larch trees dating back 400 to 500 years, and relict wood—ancient trees that had fallen over but hadn’t decayed, thanks to the cold and dry conditions. “When we find relict wood it’s super exciting because we know we can go back further in time,” said Davi.
To get new information out of Jacoby’s samples, the team turned to a promising method that came into use a few years ago. Called delta blue intensity, the method looks at how well each ring reflects blue light in its latewood (the darker band that forms later in the growing season) compared to in the lighter early wood. Less dense wood, which results from cooler conditions, absorbs less blue light.
The stronger results from the delta blue light technique allowed the team to build a model of summer temperatures in the region from 1269 to 2004 CE. The reconstruction matches up well with data from regional weather stations dating back to the 1950s, as well as cooling events associated with several large-scale volcanic eruptions.
For Davi, publishing these findings feels personally meaningful. “Gordon Jacoby was my Ph.D. advisor, mentor, and friend,” she said. “We had countless adventures doing fieldwork together. Bringing closure to some of the research that he started definitely feels good.”
The reconstruction also adds context to the warming of the past several decades, and to global climate models showing what it could look like in the future.
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Editors: Francesco Fiondella, Marian Mellin, Stacey Vassallo I Contributing Writers: Kevin Krajick, Sarah Fecht, Marie DeNoia Aronsohn I Design: Carmen Neal
Columbia Climate School Lamont-Doherty Earth Observatory Annual Report FY2022
© 2022 by The Trustees of Columbia University in the City of New York, Lamont-Doherty Earth Observatory. All rights reserved.
Editors: Francesco Fiondella, Marian Mellin, Stacey Vassallo I Contributing Writers: Kevin Krajick, Sarah Fecht, Marie DeNoia Aronsohn I Design: Carmen Neal
Columbia Climate School Lamont-Doherty Earth Observatory Annual Report FY2022
© 2022 by The Trustees of Columbia University in the City of New York, Lamont-Doherty Earth Observatory. All rights reserved.