3.5 The West Pacific Warm Pool as a Long-Distance Voyaging Nursery
49
Warm Pool long-distance voyaging nursery, appear to have made it possible for
Spice Islanders to advance from regional trading to long-distance maritime spice
and plume trading in the northern Indian Ocean – probably initially in coastal trading to the Malabar coast of India and via Mesopotamian and Arabian coasts to ports
in the Red Sea from where their spices could be taken overland to Syria and Egypt.
The evidence for the volcanic heating of the WPWP, which Lamb cites as following the last Ice Age flood and which he dates to between 7,000 and 5,000 years
ago, may have been associated with the development “around 5,000 years ago” of
“the modern ENSO recurrence and associated upwelling regimens” that Donders
et al. describe as causing environmental change in the WPWP and present-day teleconnected areas [16]. The increased amplitude of ENSO events between 5,000 and
3,000 years ago suggests the persistence after 5,000 BP of a significantly enlarged
Warm Pool and of high SSTs within it.
The increased amplitude of ENSO events on the cusp of major climate change
about 3,000 years ago is interesting. It may have supported some of what we shall
describe as “first-wave” voyaging activity taking place between 3,600 and 3,000
years ago: notably the west–east Lapita settlement of Island Melanesia and Western
Polynesia (which may have exploited El Niño reversals of winds and currents) and
the colonization of New Zealand. (The voyage south to New Zealand from the Spice
Islands following the East Australian Current was possibly supported by an El Niño
northerly.) But it is clear that while strong El Niño winds might have supported
faster long-distance current-driven voyaging, El Niño support was additional rather
than fundamental.
Local and regional maritime trading during the last Ice Age would have been
supported by the high SSTs of the WPWP. Such trading would, however, have
been limited by the greater chill factor associated with the colder and stronger Ice
Age winds and the reduced size of the WPWP. International long-distance maritime trading belongs to the warmer mid-Holocene, supported by higher SSTs in the
WPWP, probably in some instances by useful El Niño winds, by the doubled ocean
area of the Warm Pool and by additional volcanic heating of the Pool. The global
cold period between 1000 BC and 400 BC effectively removed the conditions that
had made long-distance maritime exploration, trading and migration feasible before
1000 BC. The same limitations recurred nearly two and a half thousand years later
during the Little Ice Age which ended prehistoric voyaging to New Zealand.
The WPWP can perhaps best be thought of as a dynamic phenomenon, its boundaries changing seasonally and, within a longer time frame, the size of the Pool
itself changing in response to global warming and cooling. Its defining temperature as one exceeding 28
◦ C makes possible its role in driving global atmospheric
circulation, for it is when SSTs exceed 28 ◦ C that vigorous atmospheric convection begins. Given the strength and warmth of its major outflowing currents, it is
hardly surprising that three of these currents could exert a powerful influence on
maritime activity in the region. But it would have been far from trivial for prehistoric mariners to take advantage of the warmth of the WPWP and the strength of
its currents. A long tradition of maritime trading, a cumulative acquisition of maritime expertise and technologies and the evolution of genetic cold resistance might
49
Warm Pool long-distance voyaging nursery, appear to have made it possible for
Spice Islanders to advance from regional trading to long-distance maritime spice
and plume trading in the northern Indian Ocean – probably initially in coastal trading to the Malabar coast of India and via Mesopotamian and Arabian coasts to ports
in the Red Sea from where their spices could be taken overland to Syria and Egypt.
The evidence for the volcanic heating of the WPWP, which Lamb cites as following the last Ice Age flood and which he dates to between 7,000 and 5,000 years
ago, may have been associated with the development “around 5,000 years ago” of
“the modern ENSO recurrence and associated upwelling regimens” that Donders
et al. describe as causing environmental change in the WPWP and present-day teleconnected areas [16]. The increased amplitude of ENSO events between 5,000 and
3,000 years ago suggests the persistence after 5,000 BP of a significantly enlarged
Warm Pool and of high SSTs within it.
The increased amplitude of ENSO events on the cusp of major climate change
about 3,000 years ago is interesting. It may have supported some of what we shall
describe as “first-wave” voyaging activity taking place between 3,600 and 3,000
years ago: notably the west–east Lapita settlement of Island Melanesia and Western
Polynesia (which may have exploited El Niño reversals of winds and currents) and
the colonization of New Zealand. (The voyage south to New Zealand from the Spice
Islands following the East Australian Current was possibly supported by an El Niño
northerly.) But it is clear that while strong El Niño winds might have supported
faster long-distance current-driven voyaging, El Niño support was additional rather
than fundamental.
Local and regional maritime trading during the last Ice Age would have been
supported by the high SSTs of the WPWP. Such trading would, however, have
been limited by the greater chill factor associated with the colder and stronger Ice
Age winds and the reduced size of the WPWP. International long-distance maritime trading belongs to the warmer mid-Holocene, supported by higher SSTs in the
WPWP, probably in some instances by useful El Niño winds, by the doubled ocean
area of the Warm Pool and by additional volcanic heating of the Pool. The global
cold period between 1000 BC and 400 BC effectively removed the conditions that
had made long-distance maritime exploration, trading and migration feasible before
1000 BC. The same limitations recurred nearly two and a half thousand years later
during the Little Ice Age which ended prehistoric voyaging to New Zealand.
The WPWP can perhaps best be thought of as a dynamic phenomenon, its boundaries changing seasonally and, within a longer time frame, the size of the Pool
itself changing in response to global warming and cooling. Its defining temperature as one exceeding 28
◦ C makes possible its role in driving global atmospheric
circulation, for it is when SSTs exceed 28 ◦ C that vigorous atmospheric convection begins. Given the strength and warmth of its major outflowing currents, it is
hardly surprising that three of these currents could exert a powerful influence on
maritime activity in the region. But it would have been far from trivial for prehistoric mariners to take advantage of the warmth of the WPWP and the strength of
its currents. A long tradition of maritime trading, a cumulative acquisition of maritime expertise and technologies and the evolution of genetic cold resistance might