2014/03/31 by Christopher D. Roberts, Laura Jackson, Doug McNeall · 5 citations
Environmental Science · Earth and Planetary Sciences · #Climate variability and models #Atmospheric and Environmental Gas Dynamics #Oceanographic and Atmospheric Processes
paper · doi:10.1002/2014gl059473
openalex publication_date 2014/03/31 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
The Atlantic meridional overturning circulation (AMOC) at 26.5°N weakened by −0.53 sverdrup (Sv)/yr between April 2004 and October 2012. To assess whether this trend is consistent with the expected “noise” in the climate system, we compare the observed trend with estimates of internal variability derived from 14 control simulations from the Climate Model Intercomparison Project 5 (CMIP5). Eight year trends of −0.53 Sv/yr are relatively common in two models but are extremely unusual (or out of range) in the other 12. However, all 14 models underestimate AMOC variability on interannual time scales. To account for this bias, we estimate plausible upper limits of internal AMOC variability by combining the temporal correlation characteristics of the AMOC from CMIP5 models with an observational estimate of interannual variability. We conclude that the observed AMOC trend is not significantly different (p> 0.01) from plausible estimates of internal variability. Detecting the influence of external climate forcings on the AMOC will require more than one decade of continuous observations.