What tree rings can reveal about hurricanes throughout history
Scientists say pencil-sized samples from a particular kind of tree have given new insights into hurricanes dating back hundreds of years — as well as the trends with powerful storms in recent years.
By
Lauren Fox, AccuWeather staff writer
Updated Nov 5, 2021 3:52 PM EDT
A processed cross-section of Longleaf pine shows the dark bands of the late-season wood. (Image courtesy of Justin Maxwell)
The rings within a tree's trunk can tell a story filled to the brim with history, and a new study suggests that they can also reveal vital information on how hurricanes have changed over the centuries.
Every year, a tree produces a ring, which scientists often use to determine the age of that tree. According to Justin Maxwell, the lead author of the study and an associate professor in the Department of Geography at Indiana University, the tree rings also respond to weather events and can reveal how much precipitation the tree experienced.
The researchers measured the width of the rings inside longleaf pine trees, which can live for 500 to even 600 years in some instances, along the coast of North Carolina and South Carolina. The researchers used drills to take out pencil-sized samples from the tree in a way that would not cause the trees any harm. Then, the samples were taken back to a lab to be measured and observed under a microscope, although, Maxwell said, the differences in ring width can also be seen by the naked eye.
“Generally speaking, more extreme events are likely to occur as you extend the record,” Maxwell told AccuWeather. However, he added, the findings contradicted their expectations, and the years with the biggest rainfalls were actually more recent. “That was a big finding, a big shocker. We were like, ‘Wow, OK -- this is weird, we’re finding all these big rain years more recently.’”
The longleaf pine was the perfect candidate for this study not only due to how long the tree lives but also because of the way its rings end up looking once they’ve formed. Longleaf pines have light rings and dark rings -- the light rings represent the beginning of the growing season and the darker rings represent the end of the growing season.
Maxwell said the presence of the two different shades of rings would allow them to narrow down the amount of precipitation that was present specifically during hurricane season, with a thicker dark ring representing more precipitation during the end of growing season and hurricane season.
The results of the study, which was published in October by the scientific journal Proceedings of the National Academy of Sciences (PNAS), revealed that tropical cyclone precipitation has increased in the last 300 years.
Researchers sample 300-year-old trees in a longleaf pine savannah. (Image courtesy of Justin Maxwell)
Since the year 1700, the maximum amount of precipitation from tropical cyclones has increased by 2 to 4 mm (0.078 to 0.157 of an inch) per decade, according to the findings of the study. Compared to the maximum amounts of precipitation from 1700, modern-day extremes have increased by 64 to 128 mm (2.5 to 5 inches).
"Our findings suggest that the maximum amount of rainfall from these storms is increasing and is likely going to continue to do so in a warmer world," Maxwell told HealthDay News.
According to AccuWeather Senior Meteorologist Dan Kottlowski, current studies on the long-term number of hurricanes do not show any drastic changes over the centuries, but the number of recorded tropical cyclones has increased. He noted that this increase could also be due to modern-day technology that is now used to observe storms.
Warmer water in parts of the Atlantic Ocean that are usually spared during hurricane season, such as the northern and far eastern portions of the ocean, has also led to storm development and activity in places that do not typically experience tropical weather.
And even though the number of hurricanes hasn't budged much, there are troubling trends in the intensity of these powerful storms that have real implications for places in the United States.
"Warmer water is leading to more intense hurricanes, which can produce not only larger regions of damaging winds but also generate more rainfall," Kottlowski said. "So, hurricane numbers have not increased significantly, but the numbers of more intense hurricanes have increased, mostly due to warmer water."
AccuWeather radar shows Hurricane Ida's eye as it approached the Louisiana coastline on Sunday, Aug. 29, 2021. (AccuWeather)
AccuWeather / NOAA
According to National Hurricane Center (NHC) Communications and Public Affairs Officer Dennis Feltgen, in the event of a 4-degree Fahrenheit global warming scenario, the number of tropical storms and hurricanes would actually be expected to decrease by about 15%, rather than increase. However, the intensity of tropical storms and hurricanes would be expected to increase by about 5%, meaning a hurricane with 100-mph winds would instead reach 105 mph.
In addition, the NHC expects that in the event of a 4-degree warming scenario, the number of Category 4 and Category 5 hurricanes would increase by around 15%. However, Feltgen told AccuWeather in an email that some studies project a decrease, not an increase, which Kottlowski explained is due to climate change causing increased vertical wind shear. The rainfall rate within about 100 miles of tropical storms' and hurricanes' centers would also be expected to increase by about 15%.
The impacts of harsher hurricanes carry far beyond rings in trees. Infectious diseases can be carried in floodwater containing bacteria and disease-carrying organisms. In industrialized areas, possible chemical spills can release toxic chemicals into the air, especially when flooded, HealthDay News reported. Flood-related casualties are also a risk.
Coastal cities are at an increased danger, especially ones with a lot of hard surfaces that do not allow water to be easily absorbed into the ground. As hurricane intensity increases over the next few decades, cities farther inland will also experience more tropical conditions as storms remain stronger over land for longer, and flooding rainfall will remain a concern well inland, Kottlowski said.
FILE - People travel through a torrential downpour caused by Tropical Rainstorm Ida, near Columbus Circle Wednesday, Sept. 1, 2021. As the weather becomes more extreme and unpredictable caused by climate change, transit officials say that more needs to be done to prepare the East Coast's vital transit systems. (AP Photo/Craig Ruttle, File)
According to Feltgen, damage from tropical storms and hurricanes is doubling in the U.S. every 20 to 30 years, which he said is likely a result of population growth along the coast, per capita wealth and inflation.
The effects of more intense cyclone activity especially pose a risk for those living in buildings that have not been constructed well enough to withstand the storm's powers. Those living along coastlines and in poorly constructed homes will need to make some difficult decisions, Kottlowski explained.
"People need to build and re-build strong. No longer can people and government [officials] gamble living in and working in poorly built homes and businesses and poorly maintained infrastructure," Kottlowski said.
Relocation and rebuilding homes to be stronger and more hurricane-proof are options, but both are costly and in many cases not feasible. Hurricane damage that has occurred in Louisiana over the last few years serves as an example of the destruction the powerful storms can inflict on people's lives and property.
Aside from homes and other living structures like apartment buildings, Maxwell explained that the amount of rainfall that comes from hurricanes, which is increasing, plays a powerful role in how levees and flood plains are constructed and evacuation plans are made, especially in cities along coastlines that do not have as much green space to absorb the extra rainfall.
“We have to be prepared for something we haven’t seen yet because we keep getting more and more rainfall," Maxwell said. "We’re breaking the record continuously,"
For the latest weather news check back on AccuWeather.com. Watch AccuWeather Network on DIRECTV, DIRECTVstream, Frontier, Spectrum, fuboTV, Philo, and Verizon Fios. AccuWeatherNOW is streaming on Roku and XUMO.
Report a Typo
News / Hurricane
What tree rings can reveal about hurricanes throughout history
Scientists say pencil-sized samples from a particular kind of tree have given new insights into hurricanes dating back hundreds of years — as well as the trends with powerful storms in recent years.
By Lauren Fox, AccuWeather staff writer
Updated Nov 5, 2021 3:52 PM EDT
A processed cross-section of Longleaf pine shows the dark bands of the late-season wood. (Image courtesy of Justin Maxwell)
The rings within a tree's trunk can tell a story filled to the brim with history, and a new study suggests that they can also reveal vital information on how hurricanes have changed over the centuries.
Every year, a tree produces a ring, which scientists often use to determine the age of that tree. According to Justin Maxwell, the lead author of the study and an associate professor in the Department of Geography at Indiana University, the tree rings also respond to weather events and can reveal how much precipitation the tree experienced.
The researchers measured the width of the rings inside longleaf pine trees, which can live for 500 to even 600 years in some instances, along the coast of North Carolina and South Carolina. The researchers used drills to take out pencil-sized samples from the tree in a way that would not cause the trees any harm. Then, the samples were taken back to a lab to be measured and observed under a microscope, although, Maxwell said, the differences in ring width can also be seen by the naked eye.
“Generally speaking, more extreme events are likely to occur as you extend the record,” Maxwell told AccuWeather. However, he added, the findings contradicted their expectations, and the years with the biggest rainfalls were actually more recent. “That was a big finding, a big shocker. We were like, ‘Wow, OK -- this is weird, we’re finding all these big rain years more recently.’”
The longleaf pine was the perfect candidate for this study not only due to how long the tree lives but also because of the way its rings end up looking once they’ve formed. Longleaf pines have light rings and dark rings -- the light rings represent the beginning of the growing season and the darker rings represent the end of the growing season.
Maxwell said the presence of the two different shades of rings would allow them to narrow down the amount of precipitation that was present specifically during hurricane season, with a thicker dark ring representing more precipitation during the end of growing season and hurricane season.
The results of the study, which was published in October by the scientific journal Proceedings of the National Academy of Sciences (PNAS), revealed that tropical cyclone precipitation has increased in the last 300 years.
Researchers sample 300-year-old trees in a longleaf pine savannah. (Image courtesy of Justin Maxwell)
Since the year 1700, the maximum amount of precipitation from tropical cyclones has increased by 2 to 4 mm (0.078 to 0.157 of an inch) per decade, according to the findings of the study. Compared to the maximum amounts of precipitation from 1700, modern-day extremes have increased by 64 to 128 mm (2.5 to 5 inches).
"Our findings suggest that the maximum amount of rainfall from these storms is increasing and is likely going to continue to do so in a warmer world," Maxwell told HealthDay News.
According to AccuWeather Senior Meteorologist Dan Kottlowski, current studies on the long-term number of hurricanes do not show any drastic changes over the centuries, but the number of recorded tropical cyclones has increased. He noted that this increase could also be due to modern-day technology that is now used to observe storms.
Warmer water in parts of the Atlantic Ocean that are usually spared during hurricane season, such as the northern and far eastern portions of the ocean, has also led to storm development and activity in places that do not typically experience tropical weather.
And even though the number of hurricanes hasn't budged much, there are troubling trends in the intensity of these powerful storms that have real implications for places in the United States.
"Warmer water is leading to more intense hurricanes, which can produce not only larger regions of damaging winds but also generate more rainfall," Kottlowski said. "So, hurricane numbers have not increased significantly, but the numbers of more intense hurricanes have increased, mostly due to warmer water."
AccuWeather radar shows Hurricane Ida's eye as it approached the Louisiana coastline on Sunday, Aug. 29, 2021. (AccuWeather)
According to National Hurricane Center (NHC) Communications and Public Affairs Officer Dennis Feltgen, in the event of a 4-degree Fahrenheit global warming scenario, the number of tropical storms and hurricanes would actually be expected to decrease by about 15%, rather than increase. However, the intensity of tropical storms and hurricanes would be expected to increase by about 5%, meaning a hurricane with 100-mph winds would instead reach 105 mph.
In addition, the NHC expects that in the event of a 4-degree warming scenario, the number of Category 4 and Category 5 hurricanes would increase by around 15%. However, Feltgen told AccuWeather in an email that some studies project a decrease, not an increase, which Kottlowski explained is due to climate change causing increased vertical wind shear. The rainfall rate within about 100 miles of tropical storms' and hurricanes' centers would also be expected to increase by about 15%.
The impacts of harsher hurricanes carry far beyond rings in trees. Infectious diseases can be carried in floodwater containing bacteria and disease-carrying organisms. In industrialized areas, possible chemical spills can release toxic chemicals into the air, especially when flooded, HealthDay News reported. Flood-related casualties are also a risk.
Coastal cities are at an increased danger, especially ones with a lot of hard surfaces that do not allow water to be easily absorbed into the ground. As hurricane intensity increases over the next few decades, cities farther inland will also experience more tropical conditions as storms remain stronger over land for longer, and flooding rainfall will remain a concern well inland, Kottlowski said.
FILE - People travel through a torrential downpour caused by Tropical Rainstorm Ida, near Columbus Circle Wednesday, Sept. 1, 2021. As the weather becomes more extreme and unpredictable caused by climate change, transit officials say that more needs to be done to prepare the East Coast's vital transit systems. (AP Photo/Craig Ruttle, File)
According to Feltgen, damage from tropical storms and hurricanes is doubling in the U.S. every 20 to 30 years, which he said is likely a result of population growth along the coast, per capita wealth and inflation.
The effects of more intense cyclone activity especially pose a risk for those living in buildings that have not been constructed well enough to withstand the storm's powers. Those living along coastlines and in poorly constructed homes will need to make some difficult decisions, Kottlowski explained.
"People need to build and re-build strong. No longer can people and government [officials] gamble living in and working in poorly built homes and businesses and poorly maintained infrastructure," Kottlowski said.
Relocation and rebuilding homes to be stronger and more hurricane-proof are options, but both are costly and in many cases not feasible. Hurricane damage that has occurred in Louisiana over the last few years serves as an example of the destruction the powerful storms can inflict on people's lives and property.
Aside from homes and other living structures like apartment buildings, Maxwell explained that the amount of rainfall that comes from hurricanes, which is increasing, plays a powerful role in how levees and flood plains are constructed and evacuation plans are made, especially in cities along coastlines that do not have as much green space to absorb the extra rainfall.
“We have to be prepared for something we haven’t seen yet because we keep getting more and more rainfall," Maxwell said. "We’re breaking the record continuously,"
In other news:
For the latest weather news check back on AccuWeather.com. Watch AccuWeather Network on DIRECTV, DIRECTVstream, Frontier, Spectrum, fuboTV, Philo, and Verizon Fios. AccuWeatherNOW is streaming on Roku and XUMO.
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