A physics-based early warning signal indicates that the Atlantic Meridional Overturning Circulation (AMOC) is on a tipping course. The study shows that the AMOC, a key climate tipping element, could collapse due to freshwater input in the North Atlantic. Using the Community Earth System Model (CESM), researchers simulated an AMOC tipping event and identified a critical early warning signal: the minimum of the AMOC-induced freshwater transport at the southern boundary of the Atlantic. Reanalysis data suggest the current AMOC is on a path to tipping. This physics-based signal is more reliable than classical statistical indicators, which are sensitive to the analyzed time interval before tipping. The AMOC collapse leads to significant climate impacts, including cooling in the Northern Hemisphere, warming in the Southern Hemisphere, and changes in precipitation patterns, particularly in the Amazon rainforest. The study also highlights the importance of the freshwater transport at 34°S (FovS) as an indicator of AMOC stability. The FovS minimum occurs 25 years before the AMOC tipping event, providing a reliable early warning signal. The results suggest that the AMOC is on course to tipping, with the FovS minimum indicating the onset of a tipping point. The study emphasizes the need for continued monitoring of the AMOC and its freshwater transport to better understand and predict potential tipping events.A physics-based early warning signal indicates that the Atlantic Meridional Overturning Circulation (AMOC) is on a tipping course. The study shows that the AMOC, a key climate tipping element, could collapse due to freshwater input in the North Atlantic. Using the Community Earth System Model (CESM), researchers simulated an AMOC tipping event and identified a critical early warning signal: the minimum of the AMOC-induced freshwater transport at the southern boundary of the Atlantic. Reanalysis data suggest the current AMOC is on a path to tipping. This physics-based signal is more reliable than classical statistical indicators, which are sensitive to the analyzed time interval before tipping. The AMOC collapse leads to significant climate impacts, including cooling in the Northern Hemisphere, warming in the Southern Hemisphere, and changes in precipitation patterns, particularly in the Amazon rainforest. The study also highlights the importance of the freshwater transport at 34°S (FovS) as an indicator of AMOC stability. The FovS minimum occurs 25 years before the AMOC tipping event, providing a reliable early warning signal. The results suggest that the AMOC is on course to tipping, with the FovS minimum indicating the onset of a tipping point. The study emphasizes the need for continued monitoring of the AMOC and its freshwater transport to better understand and predict potential tipping events.