Today, a total solar eclipse was visible across North America in a narrow path ranging from Sonora, Mexico to Newfoundland and Labrador, Canada. While environmental scientists understand what happens during a total solar eclipse – the moon entirely blocks incoming radiation from the sun – an interesting question remains unanswered: What happens to terrestrial ecosystems in the sudden absence of solar radiation?
EESA Postdoctoral Scientist Leila Hernandez Rodriguez leads an international effort to close this knowledge gap, collaborating with more than 20 institutions and organizing 50 field sites across the path of totality and nearby. Many of the field sites are part of AmeriFlux, a network of PI-managed sites across the Americas measuring carbon, water, and energy fluxes using the eddy covariance technique.
This week during the total solar eclipse, site teams from AmeriFlux as well as the MexFlux Networks coordinated collection of high-frequency data at 10 or 20 measurements per second. This time, though, the meteorological instruments acquired data such as solar radiation, air temperature, and humidity, at five-second intervals rather than the typical practice of several minutes intervals. This data can help scientists understand how processes like photosynthesis, respiration, and transpiration instantaneously respond to a sudden lack of solar radiation.
Based at Berkeley Lab under the leadership of Margaret Torn and Sebastien Biraud, the AmeriFlux Management Project supports the AmeriFlux Network with technical support, site visits, and an extensive data infrastructure to ensure quality and availability of continuous, long-term ecosystem measurements. Torn and Biraud, in addition to Stephen Chan and Housen Chu, were instrumental in helping the community-led Working Group on Solar Eclipse Impact on Ecosystems take shape.
Hernandez Rodriguez also strategically sought out field sites that were not completely in the path of totality, but also nearby it, meaning that some sites would still receive some level of solar radiation since the sun would not be completely blocked by the moon at these locations. This will allow for a gradient understanding of solar radiation, or lack thereof, and its critical role in ecosystem function.
Measurements of solar radiation are necessary for many reasons; for example, solar radiation fuels the process of photosynthesis, an ecosystem service critical for other ecosystem processes and human life. It also fuels the entire water cycle, as solar radiation is needed for evapotranspiration that transfers and transforms water throughout the planet. While earth scientists begin to explore geoengineering ideas that block incoming solar radiation as a potential measure to limit warming temperatures, understanding what happens to ecosystems without the sun is a critical fundamental question that needs to be answered.
“The solar eclipse allows us to conduct a kind of large-scale experiment on ecosystems that would not otherwise be possible, enabling us to explore the behavior and dynamics of these systems,” Hernandez Rodriguez said.
While it’s difficult to change one environmental variable on a large spatial scale, the solar eclipse presented a unique opportunity to collect data on entire ecosystems undergoing change in a natural setting. Hernandez Rodriguez also worked to ensure a coordinated effort where different types of ecosystems were included in the study, such as wetlands, grasslands, forests, and agricultural lands. This will provide insight as to how various types of ecosystems may rely on solar radiation, and respond to the lack of it, differently.
This solar eclipse will be the last for 20 years across the United States. Therefore, the team of scientists representing organizations across the United States, Mexico, and Canada was eager to collect this data and see what environmental knowledge gaps they can close. Taking advantage of the opportunity for discovery that the solar eclipse provided will add fundamental insights to our understanding of ecosystem functioning.
