[A-CG42] Projection and detection of global environmental change

[ACG42-08] Detection of anthropogenically-induced environmental changes in the interior ocean

★Invited Papers

*Jerry Tjiputra¹ (1.Norwegian Research Centre, Bjerknes Centre for Climate Research)

Keywords:Future climate change, Earth system models, Interior ocean changes, Detection of anthropogenic signals

Nearly two centuries of anthropogenic perturbations later, significant changes in our Earth system have been observed, particularly evident from surface measurements. Ocean heat accumulation in the upper 2000 m has also reached unprecedented highs since observational records began. Using simulations from CMIP6, we show that signals of other environmental changes such as salinity, oxygen and pH are projected to be detectable, often earlier in the interior than the surface, with spatially complex patterns. Pronounced acidification signals are detectable earliest in the deep water formation regions. Circulation changes as inferred from temperature and salinity would emerge earliest in the interior tropical Atlantic due to its stable preindustrial condition. Temperature and salinity changes in the subsurface tropical and subtropical North Atlantic are shown to be early indicators for a slowdown of the Atlantic Meridional Overturning Circulation strength. Even under mitigated scenarios, committed interior changes would continue to propagate into the interior over this century. Given the ocean inertia, our result highlights the importance of extending analysis of anthropogenically-induced signals beyond surface and into the ocean interior, particularly when assessing tipping points elements of the Earth system. Our study calls for establishment of long-term interior monitoring systems in the Tropical Atlantic, Southern Ocean and North Atlantic in order to elucidate how spatially heterogeneous anthropogenic signals propagate into the interior and impact marine ecosystems and biogeochemistry.