What Do Latest <scp>CMIP6</scp> Global Climate Models Say About Future Arctic Sea Ice Coverage Changes?

ABSTRACT Observational evidence of rapid Arctic sea ice decline motivates the need for reliable projections of first ice‐free Arctic summer year (FIASY). Remotely sensed observations, combined with outcomes from global climate models, provide a foundation to characterise the future state of the Arctic. Modelling of sea ice dynamics has significantly improved between CMIP5 and CMIP6, with nearly three times as many models capturing realistic annual variability in sea ice extent (SIE). As such, previous analysis that was conducted with CMIP5 is updated with the improved CMIP6 model data and a longer observational period of record. What we previously thought was a non‐linear pattern of low SIE observations in 2007–2010, that would continue throughout time, now appears to be non‐record‐setting lows in an otherwise linear decline of SIE. Curve‐fitting the first 30‐year projection from CMIP6 models estimates FIASY probability to peak at 2040, 6 years later than was projected by CMIP5. The difference in mean FIASY between the medium and high scenarios was 7 years in CMIP6, a 5‐year reduction compared with CMIP5 estimates. This suggests that SIE projections in CMIP6 models may not be as sensitive to emission scenario forcings as they were in CMIP5.