Climate models suggest that human activities might weaken the Atlantic Meridional Overturning Circulation (AMOC), a key ocean current system. One important part of the AMOC is the Florida Current (FC), which has been measured almost continuously since 1982 using submarine cables between Florida and the Bahamas at 27°N. A drop in the FC strength could signal a weakening of the AMOC.
In a new study, scientists at the Cooperative Institute for Marine and Atmospheric Studies (CIMAS), the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML), and the National Oceanography Centre reassess motion-induced voltages measured on a submarine cable and reevaluate the overall trend in the inferred FC transport. They found that the strength of the Florida Current, the beginning of the Gulf Stream system, and a vital component of the global Atlantic Meridional Overturning Circulation, or AMOC, has remained stable for the past four decades.
AMOC acts as a ‘conveyor belt’ to distribute heat, salt, nutrients, and carbon dioxide across the world’s oceans. Changes in the AMOC’s strength could affect global and local climate, weather, sea levels, precipitation patterns, and marine ecosystems.
In this study, scientists reassessed the 40-year record of the Florida Current volume transport measured on a decommissioned submarine telecommunications cable in the Florida Straits, which spans the seafloor between Florida and the Bahamas.
The Earth’s magnetic field creates a detectable voltage in the cable as the Florida Current carries salt ions from the seawater over it. Scientists analyzed this cable data along with regular hydrographic surveys that measure the current’s volume and water properties. They also used satellite altimetry to infer the current transport by measuring sea level differences across the stream.
Denis Volkov, the study’s lead author and a scientist at CIMAS, which is based at the Rosenstiel School, said, “This study does not refute the potential slowdown of AMOC. It shows that the Florida Current, one of the key components of the AMOC in the subtropical North Atlantic, has remained steady over the more than 40 years of observations.”
“With the corrected and updated Florida Current transport time series, the negative tendency in the AMOC transport is indeed reduced, but it is not gone completely. The existing observational record is just starting to resolve interdecadal variability, and we need many more years of sustained monitoring to confirm if a long-term AMOC decline is happening.”
Journal Reference:
- Volkov, D.L., Smith, R.H., Garcia, R.F. et al. Florida Current transport observations reveal four decades of steady state. Nat Commun 15, 7780 (2024). DOI: 10.1038/s41467-024-51879-5
