Climate Variability and Change in the North Atlantic and Arctic since 1980

This report highlights the patterns and drivers of climate variability and change in the North Atlantic and Arctic regions since 1980. Using a combination of observational datasets and climate indices such as the North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO), and El Niño–Southern Oscillation (ENSO), the study indicates various multiscale variability in the ocean temperatures, surface air temperature, sea ice extent, and cyclone activity. The trend analysis signifies warming in the Arctic with surface air temperature anomalies more than +6°C after 2015, which indicates Arctic amplification. Also, the study of the detrended AMO confirms that since the mid-1990s, a persistent positive AMO phase has led to enhanced sea surface temperature (SST) and increased instances of Atlantic cyclonic days. A negative correlation (r = -0.228) between NAO index values and SST anomalies highlights the role of the NAO in ocean heat content modulation. Looking at the sea ice trend confirms that in the high latitudes, sea ice extent in November has a declining trend of approximately –0.0518 million km² per year, while the Greenland Ice sheet continues to lose over 270 -300 Gt of ice annually. ENSO teleconnections highlight the role of NAO phase and storm track in amplifying interannual variability. Further, the study evaluates climate variability impacts on the carbon cycle in the North Atlantic, revealing weakening of AMOC and shifts in NAO phases, which may reduce the oceanic CO₂ uptake, particularly in the subpolar North Atlantic.Overall, the results highlight that both internal variability and anthropogenic forcing are causing the physical and biogeochemical changes across the North Atlantic-Arctic system. These shifts have a prominent impact on the ocean circulation pattern, carbon sequestration, and the trajectory of future climate change.