Lapointe and 8 co-authors reported in mid-2020 that global warming due to anthropogenic factors can be amplified or dampened by natural climate oscillations, especially those involving sea-surface temperatures (SSTs) in the North Atlantic which vary on a multidecadal scale (Atlantic multidecadal variability, AMV). Because the instrumental record of AMV is short, long-term behavior of AMV is unknown, but climatic teleconnections to regions beyond the North Atlantic offer the prospect of reconstructing AMV from high-resolution records elsewhere.
Annually resolved titanium from an annually laminated sedimentary record from Ellesmere Island, Canada, shows that the record is strongly influenced by AMV via atmospheric circulation anomalies. Significant correlations between this High-Arctic proxy and other highly resolved Atlantic SST proxies demonstrate that it shares the multidecadal variability seen in the Atlantic. The authors' record provides a reconstruction of AMV for the past ∼3 millennia at an unprecedented time resolution, indicating North Atlantic SSTs were coldest from ∼1400–1800 CE, while current SSTs are the warmest in the past ∼2,900 years.
The authors concluded that Atlantic multidecadal sea surface temperature variability (AMV) strongly influences the Northern Hemisphere’s climate, including the Arctic. Here using a well-dated annually laminated lake sediment core, the authors show that the AMV exerts a strong influence on High-Arctic climate during the instrumental period (past ∼150 y) through atmospheric teleconnection. This highly resolved climate archive is then used to produce the first AMV reconstruction spanning the last ∼3 millennia at unprecedented temporal resolution. The authors' terrestrial record is significantly correlated to several sea surface temperature proxies in the Atlantic, highlighting the reliability of this record as an annual tracer of the AMV. The results show that the current warmth in sea-surface temperature is unseen in the context of the past ∼3 millennia.
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