Author: Allyson Ropp, Historic Preservation Archaeology Specialist
This month, North Carolina begins preparing for hurricane season, which starts on June 1. National Hurricane Preparedness Week (April 30 – May 6) is a time to get ready for the impacts of hurricanes and learn how to interpret hurricane forecasts and know what to do before, during, and after storms. Hurricanes vary in size and strength, depending on the waters they move through, bringing strong storm surges and winds. In March, we explored the effects of water, including hurricane-driven storm surges. Now, we'll focus on the effects of wind, particularly hurricane-force gales.
Wind is caused by changes in atmospheric temperature and pressure. As air molecules warm and cool, their speed changes. Warmer temperatures lead to more air molecule movement, warming the air, and causing it to rise. This rising air leaves behind a pocket of low pressure, which is cooler and has fewer molecules than the warmer, high-pressure areas. Wind forms as air molecules diffuse from high to low-pressure areas. The bigger the difference between high and low-pressure areas in speed and temperature, the faster the air moves. Hurricanes and tornadoes are extreme weather events driven by wind, with very high wind speeds due to significant pressure differences. While climate change will lead to more uniform air temperatures, resulting in a decrease in average wind speeds worldwide by up to 10% by 2100, uncertainty about climate change's impact on extreme weather events might still cause increases in wind speeds during specific events.
If winds are generally slowing, what does that mean for archaeological sites? The slowing of daily winds due to climate change might have a positive effect on these resources. Wind can move materials, including cultural artifacts. On the beach, windy days can lead to aeolian erosion, where sand blows and erodes physical structures. Inland, winds have less daily impact on sites. Slower wind speeds will reduce daily aeolian erosion and burial-exposure cycles of sites, providing some protection against other climate change effects.
However, climate-driven changes may result in periods of high-speed winds during extreme weather events like hurricanes and tornadoes. These events will have a greater impact on archaeological resources than the daily slower winds. Hurricanes are expected to become stronger and more intense, bringing faster, more powerful, and sustained winds. The winds can drive storm surge further inland, causing more flooding. Additionally, uprooted trees during hurricanes can damage sites by falling on them and disturbing buried deposits or pulling them out of the ground, altering the context of the site and how artifacts are scattered.
While daily wind speeds may slow down with climate change, extreme weather events like hurricanes and tornados are expected to become more powerful. It's crucial to remember that winds, especially during extreme weather, can cause serious damage to archaeological sites.
Main image: Old Burying Ground in Beaufort, NC. This falling tree has pulled up parts of a burial crypt. (Image by NCOSA, 2019)
This material was produced with assistance from the Emergency Supplemental Historic Preservation Fund, administered by the National Park Service, Department of the Interior. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of the Interior.
Sources:
NOAA
2023 Why Does Wind Blow? SciJinks, National Oceanic and Atmospheric Administration. 14 April 2023.
Robbins, Jim
2022 Global ‘Stilling’: Is Climate Change Slowing Down the Wind? YaleEnvironment360, Yale School of the Environment. 13 September 2022.