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The tropical Pacific Ocean is a key regulator of Earth's climate, with teleconnections that influence remote locations all around the world. Here we use partially coupled climate model experiments to show that tropical Pacific cooling related to an abrupt Atlantic Meridional Overturning Circulation (AMOC) slowdown can strengthen the AMOC by ∼25%. This tropical‐extratropical teleconnection occurs initially via atmospheric Rossby waves propagating from the tropical Pacific to the North Atlantic which alter surface climate conditions locally. These changes facilitate ocean heat loss from the subpolar gyre, favoring enhanced oceanic convection. The AMOC strengthening is subsequently enhanced by anomalous northward salt advection in the Atlantic, with a potential contribution from oceanic wave adjustment triggered by increased Southern Ocean westerly winds. These results highlight the influence of the tropical Pacific on the AMOC on multidecadal timescales and suggest that cold phases of tropical Pacific decadal variability could drive temporary strengthening of the AMOC. Plain Language Summary Changes in the tropical Pacific sea surface temperature can exert significant remote weather and climate impacts via physical mechanisms known as teleconnections. In this study, we report unexplored teleconnections to the Atlantic basin which act in a timescale of decades. In particular we found that a mean cooling in the tropical Pacific could act to accelerate a large‐scale ocean circulation in the Atlantic basin known as the Atlantic Meridional Overturning Circulation (AMOC). This occurs via atmospheric and oceanic waves which propagate to the North Atlantic and alter local conditions, favoring the acceleration of the AMOC. Key Points Tropical Pacific cooling can drive a strengthening of the Atlantic Meridional Overturning Circulation (AMOC) The Pacific–North Atlantic teleconnection occurs via both atmospheric and oceanic planetary waveguides Pacific–AMOC teleconnections can be induced on a multidecadal time‐scale

How much and fast the Earth is warming in response to increasing greenhouse gas concentrations is one of the fundamental questions in climate science. Here we investigate the role that different modes of climate variability play in modulating the temperature response. We show evidence for a robust statistical relationship between global warming rate variations and Atlantic Multidecadal Variability (AMV) across multiple observational datasets since 1850. The correlation between AMV and the global warming rate is maximized—with a correlation coefficient of about − 0.8—at ~ 10 to 20 years lead-time. In contrast, such a relation between global warming rate and the Interdecadal Pacific Oscillation (IPO) is far less coherent, showing negative correlation before the 1920s and positive correlation after that. Similar statistical relationships between global warming rate variations and the AMV/IPO can also be seen in the majority of the models from the Phase 5 of Coupled Models Inter-comparison Project. Further, a targeted model experiment is conducted to demonstrate the dominant control of the AMV on the unforced fraction of the global warming rate (compared to the IPO).

The growing awareness about the need to anticipate the future of land systems focuses on how well we understand the interactions between society and environmental processes within a complexity framework. A major barrier to understanding is insufficient attention given to long (multidecadal) temporal perspectives on complex system behavior that can provide insights through both analog and evolutionary approaches. Analogs are useful in generating typologies of generic system behavior, whereas evolutionary assessments provide insight into site-specific system properties. Four dimensions of these properties: (1) trends and trajectories, (2) frequencies, thresholds and alternate steady states, (3) slow and fast processes, and (4) legacies and contingencies, are discussed. Compilations and analyses of past information and data from instruments and observations, palaeoenvironmental archives, and human and environmental history are now the subject of major international effort. The embedding of empirical information over multidecadal timescales in attempts to define and model sustainable and adaptive management of land systems is now not only possible, but also necessary.

We investigate the asymmetric modulation of the Atlantic Multidecadal Oscillation (AMO) on El Niño-Southern Oscillation (ENSO) amplitude using long-term observational and reanalysis datasets. Results show that the modulation of the AMO on ENSO amplitude exhibits significant asymmetry in both eastern Pacific (EP) and central Pacific (CP) types and El Niño (El) and La Niña (La) events. Both CP-La and EP-El events are significantly strengthened during the negative AMO phase, while EP-La and CP-El events show no remarkable changes under different AMO phases. Using ocean mixed layer heat budget, we show that the thermocline feedback and net surface heat flux are crucial for the strengthening of CP-La, while zonal advective feedback and thermocline feedback favor the intensification of EP-El during the negative AMO phase. Further analyses reveal that during the negative AMO phase there are relatively colder sea-surface temperatures (SSTs) in the western equatorial Pacific with weakened trade wind, while warmer SSTs occur in the eastern equatorial Pacific with strengthened trade wind, leading to a weakening of zonal SST gradient. As a result, the thermocline deepens (shallows) with the negative (positive) Ekman pumping velocity (EPV) in the eastern (central) equatorial Pacific. These conditions collectively favor the strengthening of CP-La and EP-El events. During the negative AMO phase, the relatively dry background and the zonal winds over the tropical Pacific can lead to significant dry advection toward the central tropical Pacific, which enlarges the local sea-air humidity difference and promotes the release of latent heat flux from the ocean to strengthen CP-La.

By performing a new adaptive time series decomposition on the composite average of multiple ice core records obtained from the Arctic and Greenland, we extracted a robust quasi-oscillatory signal with a period of ~70 years throughout the preceding millennium, and showed that it is strongly connected to the Atlantic Multidecadal Oscillation (AMO). In the same decomposition there exists the Greenland signature of the Little Ice Age and Medieval Warm Period. Throughout the warm and cold periods the AMO properties remained robust. It implies that the evolution of the AMO has its own coherent mechanism and was little affected by these large climatic excursions.