Interruption of the Gulf Stream in 2014 caused the 2014-16 North Atlantic Cold Fresh Anomaly and reciprocal warming/ salinification of the North American coastal region

Abstract We present evidence that the previously reported 2014-2016 North Atlantic cold fresh anomaly (CFA) and warming/ salinification of the North American coastal region are reciprocal effects of an interruption of Gulf Stream (GS) mass transport near 45oW. In February-March 2014, sudden cooling and reduced salinity near the Milne seamounts (45oN, 40oW) was quantitatively reciprocated by warming and increased salinity near the Tail of the Grand Banks (TGB, 43oN 50oW), creating coincident dipoles of heat and salt anomaly. The magnitude of these changes is consistent with a temporary interruption of about 70-75% of GS heat and salt transport close to where it branches to form the North Atlantic Current (NAC) and Azores Current (AC) near 40-43oN 45oW. The negative heat and salt anomalies near 40°W subsequently migrated northeastwards to constitute the CFA (centred on 50oN 30oW) while the reciprocal positive anomalies near 50°W spread westwards and southwards into the North American coastal region. The quantitative reciprocity of heat and salt anomalies in the CFA and North American coastal region can thus be explained by an interruption of mass transport between the GS and NAC. Although there has been much speculation regarding the possibility that global warming might block transport of heat and salt in the GS (possibly leading to extreme climate changes) this is the first evidence that a short-lived interruption of GS transport has already occurred.