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CLOCKS
About
the WORLDCLOCKS
I am currently working on a series
of JavaScript counters that show, among other things, the estimated
world population, which is increasing, and the amount of the world's
arable land, which is decreasing. This work builds on a script
written by Kevin McCann, now of Bellanet,
for the International Development
Research Centre in Ottawa, Canada.
How
are the numbers calculated?
World population data are extrapolated from statistics obtained
from the United Nations Population Division. The clock indicates
an increase of about three people a second by tracking both births
and deaths.
Data
on productive land are extrapolated from statistics produced by
the United Nations Food and Agriculture Organization. The clock
shows that one hectare is lost every 7.67 seconds. Productive
land is made up of arable land, pasture land, and forest.
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World
Population
From now until the middle of the 21st century, in only fifty years,
the world's population will increase by 50% from 6 billion at
the end of 1999 to close to 9 billion in 2050.
October
12, 1999 has been chosen as the official date marking the advent
of a planet with 6 billion inhabitants. This historic milestone
serves as a reminder that the rate of population growth has varied
widely down the centuries. Two thousand years ago, only about
300 million people lived on Earth. The world population grew rather
slowly, taking 1,500 years to double. From 1750 onward, however,
the rate began to accelerate, doubling to 1.7 billion in a mere
150 years. A decline in the mortality rate, coupled with scientific
and technical progress, was responsible for this spectacular growth.
Population
growth has continued to accelerate since the turn of the century.
In 1950, the world had 2.5 billion inhabitants; on the eve of
the third millenium there are 6 billion, with most of the new
births occurring in developing countries.
The
world's population continues to increase. Nevertheless,
we are living at the end of the fastest growth period of human
demographics. Between 1995 and 2000, the growth rate was
78 million people per year; less than predicted a few years ago
but the equivalent of a new China in 15 years nonetheless.
The
growth rate is slowing down. Between 2015 and 2020 the annual
growth rate will decrease to 64 million and then to 30 million
by 2045-2050. In 2050, the Earth will be inhabited by 8.9
billion humans. A much slower growth rate is predicted after
this time even though the possibility remains that the world's
population will continue to grow to one day reach 10 billion.
In
2050, Africa and Asia will be home to 20 and 60% of the
world's population respectively. Developed nations will
have twice as many elderly people as youth and the population
of many in between will be in decline.
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Productive
Land
The world's productive land is a constantly changing resource.
Climatic variations, natural disasters, and human intervention
are ceaselessly at work changing the boundaries of productive
land -- arable land, pasture land, and forest.
Arable
land covers 3% of the world's surface. Despite the fact that this
land is continually being lost to urbanization, the total area
under cultivation is rising because of deforestation. Demand for
agricultural land continues to increase in line with population
growth, resulting in the clearing of marginal land, such as hillsides.
The exploitation of marginal land is partly responsible for the
erosion of the fertile soil layer, increased drought, the loss
of essential soil nutrients, and salt contamination -- all reasons
for abandoning the land.
Land
used for pasture occupies twice the area of land now under the
plow. Although livestock raising produces less protein per hectare
than grain, especially in developing countries, it enables farmers
to take advantage of marginal land that is less suitable for growing
grain.
The
loss of productive land can be attributed largely to the destruction
of forests. The cultivation of land once forested, however, has
not stopped the steady decrease in arable land or pasture land.
Finally,
the land that produces our food, provides us with firewood and
construction lumber, purifies the atmosphere, maintains precipitation
levels, and slows down erosion is continually decreasing. It is
estimated that one hectare of productive land is lost every 7.67
seconds.
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About
the JavaScript
Behind the clocks is a JavaScript. The original script ran
under Netscape 2.0, although there were occaisional problems which
can be attributed to Netscape. The new version should function
just as reliably, but CSS formatting will not work on pre-4.0
browsers.
Recent
changes
·
Replaced looping function with setTimeout function.
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Clocks calculate based on UTC, not local time.
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CSS now formats form elements where clocks reside.
Changes
in progress
·
Make clock portable, to be displayed on other sites, while keeping
script on original site.
·
A DHTML version of the clock.
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