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River, exert a strong in
N. Today, the North Brazil
Current (NBC) carries Amazon freshwater towards the Caribbean Sea. However,
the NBC retro
uence on the signal at 12
ects up to 70 % of the Amazon plume eastward between
July and December (Lentz 1995 ). In a way similar to cold episodes of the last 30 ka
(Wilson et al. 2011 ), we propose that
ection de
the NBC retro
ection was seasonally
ecting oceanward the
plume of Amazon freshwater. Such changes would explain the relative decrease in
Amazon material recorded around 119 ka BP at 12
ed or prolonged in duration at the end of the LIG, de
N (Fig. 2 d), despite increasing
Amazon River discharge. The enhanced NBC retro
ection simulated by the climate
model (Fig. 1 d) at 115 ka BP compared to 125 ka BP supports this hypothesis
(Wilson et al. 2011 ). Our experiments isolating the impact of river runoff show that
the 16 % increase in Amazon river discharge contributed to the plume of decreased
SSS in the tropical Atlantic (Fig. 1 e). As a result of the fresher North Atlantic, the
position of the North Atlantic Deep Water formation region is shifted southward
(Fig. 1 f), inducing a signi
cant (p < 0.05) 4 % decrease in deep water formation.
This change in North Atlantic salinity and circulation led to changes in sea-surface
temperatures (not shown), which may impact Northern hemisphere atmospheric
circulation and ice sheet inception at the end of the LIG.
In summary, our model-data comparison indicates substantial shifts in South
American hydrologic cycle and upper tropical Atlantic salinities that may impact
the THC and North Atlantic climate at the end of the LIG.
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