Contributions of Anthropogenic Forcing and Internal Variability on Global Wave Height Trend during 1961-2020 - CMIP6/DAMIP Analysis

In this study, the contribution of external forcings on global ocean wave height change during 1961-2020 is investigated. Historical significant wave height (SWH) produced at Ifremer for different CMIP6 external forcing and preindustrial control conditions following the framework of Detection and Attribution Model Intercomparison Project (DAMIP) and other available multi-model simulations are employed. The linear trends (with statistical significance) in SWH computed over regional ocean basins could be mostly associated with greenhouse gas-only (GHG) and aerosol-only (AER) forcing. The SWH in Arctic and Antarctic Ocean shows remarkable trends and GHG induced change could explain most of it. Moreover, this can be attributed to clear decline in sea-ice extent with GHG induced wind speed change. The SWH weakening over North Pacific is majorly influenced by AER forcing rather than GHG, in contrast to SWH weakening over North Atlantic and North Indian Ocean. In addition to the anthropogenic forcings, internal variability estimated from control simulation has important contribution to the total change.