Abstract
In this paper we assessed the representation of Arctic sea surface
salinity (SSS) and liquid freshwater content (FWC) in the historical
simulation of 31 CMIP6 models with comparison to 39 CMIP5 models, and
investigated the projected changes in Arctic liquid FWC and freshwater
budget in two scenarios (SSP245 and SSP585) of the CMIP6 models. While
CMIP6 multi-model mean (MMM) shows an amelioration in representing
Arctic SSS compared to CMIP5, no significant reduction is found in the
overestimation of FWC and overall model spreads of future changes of
Arctic freshwater budget. CMIP6 MMM projects a SSS decrease in most
parts of the Arctic Ocean, a slight SSS increase in the Eurasian Basin,
and the strongest increase in FWC along the periphery of the Arctic
Basin. In the historical simulation, the MMM river runoff, net
precipitation, Bering Strait and Barents Sea Opening freshwater
transports are 93±34 mSv, 58±109 mSv, 80±32 mSv, and -20±17 mSv,
respectively. In the last decade of the 21st century,
these budget terms will increase to 138±47 mSv, 123±93 mSv, 83±35 mSv,
and 33±47 mSv in the SSP585 scenario. Sea ice meltwater flux will
decrease to about zero in the mid-21st century in both
SSP245 and SSP585. Freshwater exports through Fram and Davis straits
will be higher in the future, and the Fram Strait export will remain
larger. The Arctic Ocean is projected to hold a total of 160,300±62,330
km3 freshwater in the SSP585 scenario by 2100, about
60% more than its historical climatology.