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3 The Oceanographic Context
maritime history. We argue that the Spice Islanders’ evolution of genetic cold resistance and famine resistance was generated by the combined selective pressures of
limited local and regional maritime trading over the long period of the Ice Age followed by the change to more challenging long-distance voyaging in the Holocene.
Long-distance voyaging brought increased risks of hypothermia because the longer
distances attempted meant longer periods of exposure to cold.
In this chapter we explore the changing oceanographic conditions within the
WPWP from the Ice Age to the Holocene. Understanding these changing conditions is important for understanding how a maritime history encompassing 30,000
years of seasonally constrained limited trading in the Ice Age could have been so
remarkably transformed by the possibilities presented by the global warmth of the
Holocene and by the expansion of the WPWP made possible by this warmth.
3.2 The Oceanographic Functions of the West Pacific Warm Pool
The WPWP, also known as the Indo-Pacific Warm Pool (IPWP), has five major
functions:
(i) It has the role of equalizing heat in the world’s oceans and especially in the
Indian and Pacific Oceans. In association with the meteorological phenomenon
we know as the El Niño Southern Oscillation (ENSO), in warm climate periods
it appears to have a role in dispersing heat from the planet.
(ii) It has a role in equalizing sea surface salinity in the Indian and Pacific
Oceans and
(iii) a role in equalizing sea levels in these oceans.
All three functions are performed through the gathering and concentration of
warm ocean waters in the WPWP in response to the west-flowing equatorial
currents of the Pacific and through the dispersal of very warm waters from the
WPWP into the Indian and Pacific Oceans.
(iv) The WPWP also has a globally significant role in driving atmospheric circulation. Indeed it is a primary component of the global coupled ocean–atmosphere
system [4].
(v) It has an additional role with global implications, that of supporting or moderating ENSO events. This role appears to date back about 5,000 years. Donders
et al. [5] speak of a mid-Holocene intensification of ENSO:
The proxy data consistently indicate that a state change occurred at ∼5 ka cal BP
towards active ENSO cyclicity in the equatorial Pacific. Furthermore, from around
3 ka cal BP the ENSO-teleconnected regions are characterized by an increased impact
of ENSO, comparable to the present-day high-amplitude fluctuations of ENSO.
The authors suggest that WPWP heat charging “is a possible explanation for the
late-Holocene increase in ENSO amplitude”.
The high SSTs and the size of the WPWP (estimated to be today comparable
in area to the United States) go some way to explaining the significant role of the
3 The Oceanographic Context
maritime history. We argue that the Spice Islanders’ evolution of genetic cold resistance and famine resistance was generated by the combined selective pressures of
limited local and regional maritime trading over the long period of the Ice Age followed by the change to more challenging long-distance voyaging in the Holocene.
Long-distance voyaging brought increased risks of hypothermia because the longer
distances attempted meant longer periods of exposure to cold.
In this chapter we explore the changing oceanographic conditions within the
WPWP from the Ice Age to the Holocene. Understanding these changing conditions is important for understanding how a maritime history encompassing 30,000
years of seasonally constrained limited trading in the Ice Age could have been so
remarkably transformed by the possibilities presented by the global warmth of the
Holocene and by the expansion of the WPWP made possible by this warmth.
3.2 The Oceanographic Functions of the West Pacific Warm Pool
The WPWP, also known as the Indo-Pacific Warm Pool (IPWP), has five major
functions:
(i) It has the role of equalizing heat in the world’s oceans and especially in the
Indian and Pacific Oceans. In association with the meteorological phenomenon
we know as the El Niño Southern Oscillation (ENSO), in warm climate periods
it appears to have a role in dispersing heat from the planet.
(ii) It has a role in equalizing sea surface salinity in the Indian and Pacific
Oceans and
(iii) a role in equalizing sea levels in these oceans.
All three functions are performed through the gathering and concentration of
warm ocean waters in the WPWP in response to the west-flowing equatorial
currents of the Pacific and through the dispersal of very warm waters from the
WPWP into the Indian and Pacific Oceans.
(iv) The WPWP also has a globally significant role in driving atmospheric circulation. Indeed it is a primary component of the global coupled ocean–atmosphere
system [4].
(v) It has an additional role with global implications, that of supporting or moderating ENSO events. This role appears to date back about 5,000 years. Donders
et al. [5] speak of a mid-Holocene intensification of ENSO:
The proxy data consistently indicate that a state change occurred at ∼5 ka cal BP
towards active ENSO cyclicity in the equatorial Pacific. Furthermore, from around
3 ka cal BP the ENSO-teleconnected regions are characterized by an increased impact
of ENSO, comparable to the present-day high-amplitude fluctuations of ENSO.
The authors suggest that WPWP heat charging “is a possible explanation for the
late-Holocene increase in ENSO amplitude”.
The high SSTs and the size of the WPWP (estimated to be today comparable
in area to the United States) go some way to explaining the significant role of the