Environmental Engineering Reference
In-Depth Information
2
Science, Matter, and Energy
CASE STUDY
An Environmental Lesson
from Easter Island
the platforms and statues across wooden rails to vari-
ous locations on the island's coast.
In doing so, they used up the island's precious
trees faster than they were regenerated—an example
of the tragedy of the commons. By 1600, only a few
small trees were left. Without large trees, the islanders
could not build their traditional seagoing canoes for
hunting large porpoises and catching fish in deeper
offshore waters, and no one could escape the island
by boat.
Without the once-great forests to absorb and
slowly release water, springs and streams dried up, ex-
posed soils eroded, crop yields plum-
meted, and famine struck. There was
no firewood for cooking or keeping
warm. The hungry islanders ate all of
the island's seabirds and landbirds.
Then they began raising and eating
rats, descendants of hitchhikers on the
first canoes to reach Easter Island.
Both the population and the
civilization collapsed as rival clans
fought one another for dwindling
food supplies. Eventually, the
islanders began to hunt and eat
one another.
Dutch explorers reached the
island on Easter Day, 1722, per-
haps 1,000 years after the first
Polynesians had landed. They found
about 2,000 hungry Polynesians, liv-
ing in caves on grassland dotted with
shrubs.
Like Easter Island at its peak, the
earth is an isolated island in the vast-
ness of space with no other suitable
planet to migrate to. As on Easter Is-
land, our population and resource
consumption are growing exponen-
tially and our resources are finite.
Will the humans on Earth Island
re-create the tragedy of Easter Island
on a grander scale, or will we learn
how to live more sustainably on
this planet that is our only home?
Scientific knowledge about how the earth works and
sustains itself is a key to learning how to live more
sustainably, as discussed in this chapter.
Let me tell you a sad story that has an important les-
son for us.
Easter Island (Rapa Nui) is a small, isolated island
in the great expanse of the South Pacific. Polynesians
used double-hulled sea-going canoes to colonize this
island about 2,900 years ago. They brought along
their pigs, chickens, dogs, stowaway rats, taro roots,
yams, bananas, and sugarcane.
The settlers found an island par-
adise with fertile soil that supported
dense and diverse forests and lush
grasses. The Polynesians developed
a civilization based on two species
of the island's trees, giant palms and
basswoods (called hauhau). They
used the towering palm trees for
shelter, as tools, and to build large
canoes used for catching fish such as
porpoises. They felled the hauhau
trees and burned them to cook and
keep warm in the island's cool win-
ters. In addition, the Polynesians
made rope from these trees' fibers.
Forests were also cleared to plant
crops.
Life was good on Easter Island.
The islanders had many children,
with the population peaking at
somewhere between 6,000 and
20,000 by 1400. But then residents
began using the island's tree and soil
resources faster than they could be
renewed. As these resources became
inadequate to support the growing
population, the leaders of the is-
land's different clans began appeal-
ing to the gods by carving at least
300 huge divine images from large
stones (Figure 2-1). They directed
the people to cut large trees to make
huge platforms for the stone sculptures. They proba-
bly placed logs underneath to roll the platforms and
statues or had 50 to 500 people use thick ropes to drag
Figure 2-1
Natural capital degradation:
these massive stone figures on Easter
Island—some of them taller than the average
five-story building—are the remains of the
technology created by an ancient civilization
of Polynesians. Their civilization collapsed
because the people used up the trees (espe-
cially large palm trees) that were the basis of
their livelihood. At least 300 of these huge
stone statues once stood along the coast.
