19.3 Sketching a Chronology for Long-Distance Voyaging
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long-distance return voyages. If an El Niño supported a journey to the east, with its
cessation the restored winds and currents would carry the voyager home. If a journey
to the west was undertaken at the first hint of an El Niño, the anticipated west/east
reversal of the trade winds and currents would eventually ensure a safe return. It
seems likely that exploiting the safety net inherent in an El Niño as an “oscillation”
was a stimulus for long-distance voyaging in the southern Pacific – tempting navigators to make longer voyagers for exploration, trading and migration, exploiting
an El Niño, than they could otherwise attempt. This suggests the possibility for calibrating a chronology for long-distance migrations and significant voyaging activity
from the analysis of climate data. Our aim is to correlate the exploits of these navigators with timings for significant El Niño events recorded in the low Nile proxy
data.
It is worth commenting here on the characteristic differences between the history of maritime activity in tropical Polynesia and the maritime history of the Spice
Islands where exploration, migration and trading followed major West Pacific Warm
Pool currents. We have shown the West Pacific Warm Pool to be a dynamic oceanographic phenomenon, its outflowing currents creating powerful and consistent paths
for transoceanic voyaging. ENSO events might also be thought of as oceanographic
phenomena, alternately driving and reversing the trade winds and currents in the
southern Pacific, alternately constraining and supporting long-distance exploration,
migration and trading in tropical Polynesia. But although ENSO events possess
oceanographic force (they involve Kelvin and Rossby waves crossing the full width
of the Pacific), in general they have an irregular and short-lived impact both on the
islands of tropical Polynesia and on the rims of the continents enclosing the Pacific.
The strength of ENSO events varies greatly. They might be thought of as irregular
climate-modulators. Yet, at their strongest they brought drought and starvation in
their wake, so that not only did strong El Niño events generate the oceanographic
conditions that made long-distance migration in the southern Pacific more feasible,
but they were also responsible for inducing the demographic stress that triggered
migration.
The consistent use by Spice Island mariners of West Pacific Warm Pool currents
as major ocean paths over millennia was possible because the currents were consistent, responding to the Coriolis effect, to the effectively invariable rotation of the
planet. Thus regular trading via the Cinnamon Route was possible in the Indian
Ocean. The character of the maritime activity in the two regions was essentially different: current-driven and based in the Spice Islands or wind-driven with a tropical
Polynesian base. It seems likely that in tropical Polynesia a significant proportion of
long-distance maritime activity, and especially migration, may have been driven by
irregular widely spaced intense ENSO events. If this was the case, the simplest way
to establish a chronology for tropical Polynesia may be by considering the irregular
patterns of extreme ENSO events.
This approach can be thought of as complementing the strong personal focus of
most traditional histories which highlight the courage and skill of individual navigators who explored new territories or led oceanic migrations. Given the precision
of El Niño low Nile flood proxy data it should be possible, where it is feasible to
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long-distance return voyages. If an El Niño supported a journey to the east, with its
cessation the restored winds and currents would carry the voyager home. If a journey
to the west was undertaken at the first hint of an El Niño, the anticipated west/east
reversal of the trade winds and currents would eventually ensure a safe return. It
seems likely that exploiting the safety net inherent in an El Niño as an “oscillation”
was a stimulus for long-distance voyaging in the southern Pacific – tempting navigators to make longer voyagers for exploration, trading and migration, exploiting
an El Niño, than they could otherwise attempt. This suggests the possibility for calibrating a chronology for long-distance migrations and significant voyaging activity
from the analysis of climate data. Our aim is to correlate the exploits of these navigators with timings for significant El Niño events recorded in the low Nile proxy
data.
It is worth commenting here on the characteristic differences between the history of maritime activity in tropical Polynesia and the maritime history of the Spice
Islands where exploration, migration and trading followed major West Pacific Warm
Pool currents. We have shown the West Pacific Warm Pool to be a dynamic oceanographic phenomenon, its outflowing currents creating powerful and consistent paths
for transoceanic voyaging. ENSO events might also be thought of as oceanographic
phenomena, alternately driving and reversing the trade winds and currents in the
southern Pacific, alternately constraining and supporting long-distance exploration,
migration and trading in tropical Polynesia. But although ENSO events possess
oceanographic force (they involve Kelvin and Rossby waves crossing the full width
of the Pacific), in general they have an irregular and short-lived impact both on the
islands of tropical Polynesia and on the rims of the continents enclosing the Pacific.
The strength of ENSO events varies greatly. They might be thought of as irregular
climate-modulators. Yet, at their strongest they brought drought and starvation in
their wake, so that not only did strong El Niño events generate the oceanographic
conditions that made long-distance migration in the southern Pacific more feasible,
but they were also responsible for inducing the demographic stress that triggered
migration.
The consistent use by Spice Island mariners of West Pacific Warm Pool currents
as major ocean paths over millennia was possible because the currents were consistent, responding to the Coriolis effect, to the effectively invariable rotation of the
planet. Thus regular trading via the Cinnamon Route was possible in the Indian
Ocean. The character of the maritime activity in the two regions was essentially different: current-driven and based in the Spice Islands or wind-driven with a tropical
Polynesian base. It seems likely that in tropical Polynesia a significant proportion of
long-distance maritime activity, and especially migration, may have been driven by
irregular widely spaced intense ENSO events. If this was the case, the simplest way
to establish a chronology for tropical Polynesia may be by considering the irregular
patterns of extreme ENSO events.
This approach can be thought of as complementing the strong personal focus of
most traditional histories which highlight the courage and skill of individual navigators who explored new territories or led oceanic migrations. Given the precision
of El Niño low Nile flood proxy data it should be possible, where it is feasible to