Our Water
Resources
Resources and Man
The Malthusian trap
The kinds of resources
– renewable resources
– Nonrenewable resources
– Potentially renewable resources
The nature of
exhaustibility
Food is the most
basic of all
our needs
SELFACTUALIZATION
ESTEEM
SOCIAL
SECURITY
PHYSIOLOGICAL
MASLOW’S HIERARCHY OF NEEDS
Thomas Malthus (1766-1834)
In “An Essay on the Principles of
Population”, published in 1798, Thomas
Malthus argued that while population
increases in geometric
progression, the
resources to sustain this
growth do not. Thus, if
population grows too
much faster than food
production, this growth
is checked by famine,
disease, and war.
Thomas Malthus
5000
4000
3000
The sustainable levels for
Isle Royale inhabitants
2000
50
40
30
20
10
0
1000
1900
1920
1940
1960
1980
2000
Wolf population
Moose population
This should ordinarily signal disaster. Take
the case of wolves and moose at Isle Royale
National Park, Lake Superior, for instance.
Relative to the 1820 level
 World’s population, a little over a billion at the time of Malthus,
has multiplied about six-fold since then.
 Measured in inflation-adjusted dollars, world’s total output, now
about $40 trillion, was about $700 billion at the time of Malthus.
 Clearly, economic growth has been more strongly exponential
than that of the demand (population growth) that created it.
45
Economy
30
Population
15
0
1800
1850
1900
1950
2000
Source: A. Maddison, Monitoring the World Economy 1820-1992 (OECD, Paris, 1995).
World Grain Output
2
3
6
3
4
2
2
1
0
0
World Population
Gross World Product
1
The growth in
world’s grain output
has been faster than
population but world
economy has
growth even faster.
Values relative to 1950
6
Gross World Product
World Grain Production
4
2
World Population
0
1950
1960
1970
1980
1990
2000
Adam Smith (1723-1790),
the British philosopher and economist,
argued, in his celebrated treatise An
Inquiry into the Nature and Causes of the
Wealth of Nations (1776),
that every individual in
pursuing his or her own
good is led, as if by an
invisible hand, to
achieve the best good
for all. Therefore any
interference with free
competition by the
government is almost
certain to be injurious.
First Green Revolution in this century
took place in developed countries
during 1950-70.
First Green Revolution
Second Green Revolution has
occurred in developing countries
since mid-1960s.
First Green Revolution
Second Green Revolution
2.0
400
1.5
300
1.0
200
0.5
1940
1960
1980
Per Capita Grain Availability (kg per year)
World Grain Production (billion tons per year)
Despite the tremendous strides in world grain production, per capita grain availability has remained
unchanged since the mid-1970s*.
100
2000
*Lester R. Brown: “Facing the Prospect of Food Scarcity” in STATE OF THE WORLD 1997 (Worldwatch Institute, 1997)
Currently,
the annual food production
world-wide, including grains,
poultry, seafood and meat,
is about 4 billion tons per year, or
about 4½ lbs per person per day.
But per capita food consumption
varies, worldwide,
from ~1500 lbs
per year in
America, to
~1000 lbs per year
in Mediterranean/
Middle East region, and
about 500 lbs per year in
India and South Asia.
15
Desert
Mean Annual Temperature (
o
C)
Grassland
30
Tropical Forest
Farmland
Deciduous Forest
(seasonal loss of leaves)
Being largely
Coniferous Forest
stenohumid
(green year-round)
as well as
stenothermal,
0
agricultural
Arctic and alpine
treeless areas
crops impose
0
100
200
300
400
a rather
Mean annual precipitation (cm)
restricted
range of climatic conditions. Farmland therefore tends
to be in short supply.
Most
of the
Earth
is
covered
by water
Land
(29%)
Oceans
(71%)
“...water, water, every where
nor any drop to drink!”
But the supply of land too is limited...
In use
Oceans
(71%)
Land
(29%)
Potential
farming
8%
Tropical
forests
Cultivated Grazed
11%
10%
14%
Forests,
semi-arid
6% Arid
Ice, snow, deserts,
mountains (51%)
and
barely
a fifth of it
is available for
farming related activities.
Unusable
Potential
grazing
Economic growth exacerbates
the demand for water, e.g.,
• with economic growth at 7-10% per year,
poultry consumption is rising at the rate of
15% per year in India, Indonesia and China the water demands of this nontraditional
industry are only likely to grow;
• we need about 250,000 gallons of water to
produce a ton of corn, 375,000 gallons to
produce a ton of wheat, 1,000,000 gallons to
produce a ton of rice, and 7,500,000 of water
to produce a ton of beef.
•to which we should also add industry’s needs.
U.S.A.
Public (6%)
Farming (41%)
China
Industry
(7%)
Public
(10%)
Industry
(11%)
PowerPlant (38%)
Farming (85%)
PowerPlant (2%)
this comparison of U.S. and China shows how
economic growth necessitates increased use of
Source: Worldwatch Institute
water for nonagricultural purposes.
How much
water do
we have?
The hydrological cycle
Ignoring such long-term effects as the
changes in atmospheric storage conditions,
run-off filling the ocean basins etc., hydrological
cycle is
merely
the recycling
of water
between
land and
oceans.
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/smry.rxml
How much water in the hydrosphere?
Conventional estimate assumes
a total groundwater storage of about
1,700 quadrillion gallons. This gives
the estimate of hydrosphere’s total
water content as 3.5x1020 gallons.
Underground water (0.5%)
Surface water (0.02%)
Atmospheric
moisture (0.001%)
Oceans (97%)
Ice (1.2%)
An alternate assumption is that pores in sediments contain
about 80,000 quadrillion gallons of groundwater (almost 50
times the conventional estimate). This yields an estimate of
about 4x1020 gallons of water in the
Ice (1%)
entire hydroshere.
Surface water (0.002%)
Atmosphere
(0.001%)
Groundwater (19%)
Groundwater (19%)
Oceans (80%)
As is evident from the comparison of water use in
the U.S. and China, economic growth necessitates
increasing use of water for power generation.
U.S.A.
Public (6%)
Farming (41%)
China
Industry
(7%)
Public
(10%)
Industry
(11%)
PowerPlant (38%)
Source: Worldwatch Institute
Farming (85%)
PowerPlant (2%)
Global mean temperature change
through the past century
Temperature Change (ºC)
0.6
0.3
0.0
- 0.3
5-year
running
average
- 0.6
Source: NOAA and NASA
1900
1950
2000
Sea level relative to 1951-70 (cm)
The global mean sea-level rise
through last century
8
4
0
-4
5-year
running
average
-8
-12
1900
1950
2000
Source: T.P. Barnett, in CLIMATE CHANGE (IPCC Working Group Report: Cambridge University Press, 1990)
DT (oC)
0
0
0.3
0.6
0.9
1.2
Depth (m)
100
200
300
The 1950-91 hydrographic data
off California coast show that
sea surface waters (0-100m) became
~0.8oC warmer in the 35-year period
between 1950-56 and 1985-91; which
400
Distance off California coast (km)
500
400
300
200
raised the sea level surface by 3.1+0.7 cm.
Note: Warming by 1oC the top 100
m of ocean with 15oC temperature
and 3.4% salinity should raise the
sea level by ~2.2 cm.
Source: D. Roemmich, SCIENCE: v. 257, p.
373-375 (July 17, 1992).
0
100
95
1985-91
90
1950-56
85
80
Steric height (dynamic cm)
500
100
Steric height (dynamic cm)
Sea surface off California has risen by
about 2 cm, on average,
between 1950 and 1991
100
95
19851991
90
85
80
500
19501956
400
300
200
100
Distance off California coast (km)
0
Dean Roemmich:
Ocean warming and sea
level rise along the
southwest U.S. coast
[Science: 257 ( 373-375),
1992]
The availability of water too is a limiting factor. An average human needs
about 300,000 gallons of water annually, including 250,000 gallons for
growing food. Indeed, nations with under 150,000 gallons of annual per
capita water supply face severe limits to their growth.
Mass of the present hydrosphere
Considering all sediments*
Conventional estimates
Total mass Share of the
Total mass Share of the
(trillion tons) hydrosphere (trillion tons) hydrosphere
Oceans
Pore water in the
sediments
Ice-caps, glaciers
Rivers, lakes
Atmospheric
moisture
1,370,000 80%
Total hydrosphere
1,720,313 100%
330,000 18.8%
20,000 1.2%
300 0.02%
13 0.0008%
1,370,000 97%
7,000 0.5%
20,000 1.4%
300 0.02%
13 0.0009%
1,397,313 100%
*Karl K. Turekian: GLOBAL ENVIRONMENTAL CHANGE (Prentice Hall, 1996)
Seafood is an important source of
animal protein worldwide,
nonetheless.
World fish harvest:
Annual fish harvest (million tons)
Note that Indian Ocean has the least yield.
Area
Volume
(106 km2) (106 km3)
Pacific Ocean 165.2
707.6
Atlantic Ocean
82.4
323.6
Indian Ocean
73.4
291.0
Primary production (gC/m2/yr)
World fish production*
Oceanic
50
Coastal
100
Upwelling 300
Average
number of
trophic
Ocean area
steps
2
(km )
325x106 (90%)
36x106 (9.9%)
36x104 (0.1%)
* J.H. Ryther: Science, 166 (1969): 72-76
5
3
15
Net transfer
efficiency
Total
fish production
(tons/yr)
0.0001
0.033
1.1
1.63x106 (<1%)
120 x106 (~50%)
120x106 (~50%)
Even the
maximum
possible
yield from
world’s
oceans
can hardly
suffice.
Annual fish harvests
of the leading
nations.
Seafood is already a major source of animal
protein in the Asian diet.
That Climate Thing
• Global warming and its
consequences
• The anthropogenic
contributions
U.S. 20th Century Natural Disaster Fatality-Frequency Plots*
Cummulative Number of Events per Year
10
Floods
Tornadoes
Hurricanes
Earthquakes
Floods
3
Tornadoes
1
Hurricanes
0.3
0.1
Earthquakes
0.03
0.01
1
3
10
30
100
300
1,000
3,000
10,000
Number of Fatalities per Event
* S.P. Nishenko and C.C. Barton: “Scaling Laws for Natural Disaster Fatalities” in REDUCTION AND PREDICTABILITY
OF NATURAL DISASTERS (Eds: Rundle, Turcotte and Klein) (Addison-Wesley, 1996)
Disasters*
by type: 1971-96
High wind: 21%
Man-made
disasters: 34%
Total: 8,219,000
Flood: 19%
Other natural
disasters: 21%
Volcanoes: 1%
Earthquake: 8%
Landslides: 3%
Drought & Famine: 6%
* International Federation of Red Cross and Red Crescent Societies (The Economist, Sept 6, 1997)
Global mean temperature
change through last century
Temperature Change ( oC)
0.6
0.3
1950-60 Mean level
0.0
- 0.3
5-year running
average
- 0.6
1900
1950
Source: Thomas Karl and C. Bruce Baker: GLOBAL WARMING UPDATE (NCDC-NOAA, 1994)
2000
Sea level relative to 1951-70 (cm)
The global mean sea-level
rise through last century
8
4
Mean 1951-1970 level
0
-4
5-year running
average
-8
-12
1900
1950
2000
Source: T.P. Barnett, in CLIMATE CHANGE (IPCC Working Group Report: Cambridge University Press, 1990)
Winter conditions in Eastern Europe through
the past millenium, based on manuscript
records*
0.8
Little Ice Age
o
D T ( C)
0.4
0
-0.4
-0.8
800
1000
1200
1400
* J. Imbrie & K.P. Imbrie: ICE AGES (Enslow Publishers, 1979)
1600
1800
2000
DT (oC)
0
0
0.3
0.6
0.9
1.2
Depth (m)
100
200
300
The 1950-91 hydrographic data
off California coast show that
the sea surface waters (0-100m)
became ~0.8oC warmer in the 35-year
period between 1950-56 and 1985-91;
which
400
Distance off California coast (km)
500
400
300
200
raised the sea level surface by 3.1+0.7 cm.
Note: Warming by 1oC the top 100
m of ocean with 15oC temperature
and 3.4% salinity should raise the
sea level by ~2.2 cm.
Source: D. Roemmich, SCIENCE: v. 257, p.
373-375 (July 17, 1992).
0
100
95
1985-91
90
1950-56
85
80
Steric height (dynamic cm)
500
100
Global warming will hurt the
poor nations most!
20%
0%
- 20%
- 40%
- 60%
Change in average national crop yield by the
year 2,060 compared to yield corresponding to no change in climate
(based on the ocean-atmosphere coupling model) - SCIENCE NEWS, Aug 1992
Evaporation
60,000 km3
Evaporation
320,000 km3
Precipitation
285,000 km3
Precipitation
95,000 km3
Run-off
35,000 km3
Ocean Storage
1,370,000,000 km3
The Hydrological Cycle
diversions (billion m 3/yr)
Flow of Colorado River below all major dams and
Colorado River
40
United States
30
Mexico
20
10
1900
1920
1940
1960
1980
2000
Sandra Postel: Forging a Sustainable Water Strategy (STATE OF THE WORLD 1996: Worldwatch Institute , 1996)
80
Stream Flow into Aral Sea (billion m
3
/year)
Drying of the Aral Sea
Aral Sea
60
40
20
0
1940
1960
1980
2000
Sandra Postel: Forging a Sustainable Water Strategy (STATE OF THE WORLD 1996: Worldwatch Institute , 1996)
A century of human induced sea level rise*
Removable volume
(in 1012 m3)
North America
High plains
Southwest
California
Africa and Asia
Sahara
Sahel (soil water)
Arabia
Aral (Sea: 1960)
Aral (groundwater)
Caspian (Sea)
Caspian (groundwater)
Worldwide
Deforestation
Wetland reduction
Dams
Total
Extraction rate
(in 1010 m3/yr)
Sea-level rise Estimated sea-level
rate (mm/yr) change to date (mm)
4.0
3.0
10.0
1.20
1.00
1.30
0.03
0.03
0.04
1.10
0.92
1.20
600.0
0.1
500.0
1.1
2.2
56.0
220.0
1.00
0.34
1.60
2.70
3.70
0.77
0.47
0.03
0.01
0.04
0.08
0.10
0.02
0.01
0.56
0.28
0.89
2.20
3.10
1.30
0.78
3.3
8.6
-1.9
4.90
0.20
-
0.14
0.01
-
3.40
1.30
-5.20
1406.7
19.20
0.54
11.80
* Walter Newman and Rhodes Fairbridge: The Management of Sea-level Rise (NATURE, v. 320, p. 319-328, 1986).
Dork Sahagian, Frank Schwartz and David Jacobs: Direct Anthropogenic Contributions to Sea-level Rise in the
Twentieth Century (NATURE: v. 367, p. 54-57, 1994).
The 1900-94 trends reveal a general
tendency towards greater precipitation
(a) at higher latitudes and (b) on land
Change in
precipitation
(1900-94)
20%
0%
-20%
Thomas Karl, Neville Nicholls & Jonathan Gregory:
THE COMING CLIMATE, Scientific American, May 1997
Comparing the 1900-94 precipitation
change with (a) latitude and (b) land
area
Precipitation Change (%, 1900-94)
Latitude
- 10
0
10
20
0
1
2
40oN
0o
40oS
-1
Land, as % of Global Surface Area
Evaporation
60,000 km3
Evaporation
320,000 km3
Precipitation
95,000 km3
Precipitation
285,000 km3
Run-off
35,000 km3
Ocean Storage
1,370,000,000 km3
The Hydrological Cycle
In summary,
 Human ingenuity has defied the
“Malthusian Trap”, that the power of
population exceeds that of the earth.
 This has resulted in modifying the most
basic of nature’s processes - the
hydrological cycle.
 Perhaps technology defies the Gandhian
dictum, that “nature has enough for our
need, but not for our greed”.