Using a space-based satellite, the National Aeronautics and Space Administration (NASA) tracked the largest animal migration on Earth to find clues to potential climate change. Through the study, NASA was able to identify how the migration directly affects global warming.
In a bid to monitor the migration of small ocean animals including squid and krill, the US space agency used Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. The satellite was used by the researchers every 16 days for a span of 10 years. The study has been published findings in the journal Nature.
Diel Vertical Migration
Through the data collected by CALIPSO satellite, the researchers were able to keep track of the animals' Diel Vertical Migration (DVM), which is a natural phenomenon that occurs daily when the sea creatures swim up to the surface from the bottom of the ocean to feed on phytoplankton near the surface. Since almost all small ocean creatures participate in DVM, scientists considered it the largest migration of animals on Earth. Researchers noted that they were only able to observe this phenomenon at such a large scale through CALIPSO.
“This is the latest study to demonstrate something that came as a surprise to many: that lidars have the sensitivity to provide scientifically useful ocean measurements from space,” said Chris Hostetler, a scientist at NASA's Langley Research Center in Hampton, Virginia, and co-author on the study. "I think we are just scratching the surface of exciting new ocean science that can be accomplished with lidar.”
The cumulative effect of daily vertically migrating creatures on Earth's climate is significant. During the day, ocean phytoplankton photosynthesize and, in the process, absorb significant amounts of carbon dioxide, which contributes to the ocean's ability to absorb the greenhouse gas from the atmosphere. Animals that undergo DVM come up to the surface to feed on phytoplankton near the ocean’s surface and then swim back down, taking the phytoplankton carbon with them. Much of this carbon is then defecated at depths where it is effectively trapped deep in the ocean, preventing its release back into the atmosphere.
Reducing Carbon Dioxide in Ocean
Through their observations, the researchers learned that phytoplankton contribute to the ocean's ability to absorb carbon dioxide by photosynthesizing near the surface. This increases the amount of greenhouse gases absorbed by the ocean from the atmosphere.
Through DVM, the small animals take away the carbon on the surface by consuming the phytoplankton, which is then released into the bottom of the ocean as waste. The researchers noted that this process prevents carbon dioxide from returning to the atmosphere.
How DVM can slow down Global Warming
With lesser carbon dioxide in the atmosphere, Earth is able to experience cooler climates. The researchers noted that since the DVM is such a big phenomenon, it greatly contributes in slowing down the onset of global warming.
"What these modelers haven't had is a global dataset to calibrate these models with, to tell them where these migrators are most important, where they're most abundant, and how they change over time," said Behrenfeld.
"The new satellite data give us an opportunity to combine satellite observations with the models and do a better job quantifying the impact of this enormous animal migration on Earth’s carbon cycle," he added.
It is worth mentioning here that the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite is a joint venture between NASA and the French space agency, Centre National d'Etudes Spatiales. It was launched in 2006.