QBO Changes in CMIP6 Climate Projections
The Quasi-biennial Oscillation (QBO) is the dominant mode of variability in the tropical stratosphere. Many more CMIP6 models simulate a QBO than in previous CMIP phases hence it’s possible to evaluate how the QBO will change in an ensemble of models.
QBO impacts the variability of the stratosphere and troposphere, and is a source of seasonal predictability. Changes in the QBO in a warming climate will likely impact teleconnections, such as those to the troposphere and stratospheric polar vortex.
All CMIP6 models project a weakening of the QBO throughout the stratosphere for SSP370 and SSP585 scenarios between 1960 to 2010. The weakening is strongest in the lower stratosphere, ranging from 5.8 ± 0.5% to 4.3 ± 0.5 % per decade at 50 hPa for SSP585, SSP370 simulations, respectively. In both scenarios, the QBO period decreases in 7 of the 10 models.