12.6 Warm Wet Periods and the Destruction of Archaeological Evidence
201
Zealand in the Little Ice Age in a time of extreme resource depletion might be seen
as an extreme example of adaptive response, reflecting initial high populations and
extreme demographic stress.
12.5 Climate-Driven Demography in New Zealand
New Zealand has a larger land area than all the other Pacific islands together. A far
longer time depth is needed in New Zealand than in tropical Polynesia for a population to outgrow resources and so for the conditions for a climate-driven demographic
catastrophe to be met. As our argument against a late first settlement implies, with a
population growth rate appropriate to New Zealand’s settled hunter/gatherer mode,
a very long time would have been needed for populations to have reached levels
high enough for them to reach or breach ceilings of sustainability and so become
vulnerable to adverse climatic conditions.
The first occasion in which this could have happened was probably during the
50-year-long warm wet erosion period from AD 950 to AD 1000, by our estimate,
about 2,400 years after a first settlement which we date in Chapter 20 to about 1400
BC, a date supported by demographic analysis in Chapter 15. We shall present evidence in the next chapters to establish that, in some areas by the beginning of the
Medieval Climatic Optimum, and in all areas throughout the Little Ice Age, the vulnerability of populations in New Zealand to adverse climatic conditions resulted
in severe and in some areas continuous population decline. We argue that the conditions leading to this population decline explain the extraordinary proliferation of
Maori pa during the Little Ice Age. For there is implicit evidence in the 7,000 pa built
then of the starvation and ensuing conflict over land and resources that followed the
loss of biota during intense cold periods in the Little Ice Age.
In New Zealand the pattern of climate-driven demography appears to be more
complex than in Europe and to find a more extreme and longer-lasting expression.
Both in the Medieval Climatic Optimum and in the Little Ice Age two kinds of contrary adverse climatic factors were operating in New Zealand. Warmth, normally
favourable to the growth of fish stocks, forest foods and horticultural crops – as was
the case in northern Europe in the Medieval Climatic Optimum – can be accompanied in New Zealand by heavy rainfall leading to floods and erosion and by gales
destroying forests with loss of forest biota.
12.6 Warm Wet Periods and the Destruction of Archaeological
Evidence
Patrick Grant [13] defines eight “warm wet erosion periods” for New Zealand in
the last 1,600 years and claims that all led to major disturbances of the landscape
and destruction of biota. With permission, we have reproduced Grant’s diagram
(Fig. 12.1) showing both warm erosion periods and cold periods.
201
Zealand in the Little Ice Age in a time of extreme resource depletion might be seen
as an extreme example of adaptive response, reflecting initial high populations and
extreme demographic stress.
12.5 Climate-Driven Demography in New Zealand
New Zealand has a larger land area than all the other Pacific islands together. A far
longer time depth is needed in New Zealand than in tropical Polynesia for a population to outgrow resources and so for the conditions for a climate-driven demographic
catastrophe to be met. As our argument against a late first settlement implies, with a
population growth rate appropriate to New Zealand’s settled hunter/gatherer mode,
a very long time would have been needed for populations to have reached levels
high enough for them to reach or breach ceilings of sustainability and so become
vulnerable to adverse climatic conditions.
The first occasion in which this could have happened was probably during the
50-year-long warm wet erosion period from AD 950 to AD 1000, by our estimate,
about 2,400 years after a first settlement which we date in Chapter 20 to about 1400
BC, a date supported by demographic analysis in Chapter 15. We shall present evidence in the next chapters to establish that, in some areas by the beginning of the
Medieval Climatic Optimum, and in all areas throughout the Little Ice Age, the vulnerability of populations in New Zealand to adverse climatic conditions resulted
in severe and in some areas continuous population decline. We argue that the conditions leading to this population decline explain the extraordinary proliferation of
Maori pa during the Little Ice Age. For there is implicit evidence in the 7,000 pa built
then of the starvation and ensuing conflict over land and resources that followed the
loss of biota during intense cold periods in the Little Ice Age.
In New Zealand the pattern of climate-driven demography appears to be more
complex than in Europe and to find a more extreme and longer-lasting expression.
Both in the Medieval Climatic Optimum and in the Little Ice Age two kinds of contrary adverse climatic factors were operating in New Zealand. Warmth, normally
favourable to the growth of fish stocks, forest foods and horticultural crops – as was
the case in northern Europe in the Medieval Climatic Optimum – can be accompanied in New Zealand by heavy rainfall leading to floods and erosion and by gales
destroying forests with loss of forest biota.
12.6 Warm Wet Periods and the Destruction of Archaeological
Evidence
Patrick Grant [13] defines eight “warm wet erosion periods” for New Zealand in
the last 1,600 years and claims that all led to major disturbances of the landscape
and destruction of biota. With permission, we have reproduced Grant’s diagram
(Fig. 12.1) showing both warm erosion periods and cold periods.