Engelskaflevering d. 01.09.95
"Green laws boost clean-up industry"
I
Have companies around the globe really become "house-proud", or is planet earth just in for a spring cleaning? It is hard to say - but one thing is for sure; the environmental sector is en-joying a boom. The market for pollution control technology is on a steep exponential growth curve, which seems to be interminable. Especially the European companies put down their names for an immense part of the expansion. But what is the precise nature of this sudden environmental con-cern? After all the deteriorating state of the environment is hardly a novel phenomenon, to say the least.
Just how vigorous this potential goldmine is going to be for the clean-up industry ac-tually depends on law and order, so to speak. That is to say that one of the main reasons for the turn up is new legislation. Recent EU-directives as to pollution may cause heavy demands on the purse of one company and consequently pour that money down the pockets of the clean technology indu-stry. Moreover the deadlines for plants to meet EU-directives are getting close, and everything se-ems to show that the laws will be enforced. Yet far from all companies have to meet with the raised finger of the law to start investing in their environmental responsibilities. Investments on a volunta-ry basis are often due to the fact that it makes good ecnomic sense or because it gives the corporate image a face-lifting.
Seen from a geoprahical point of view Germany and primarily eastern Europe form tremendously good breeding ground for the sale of clean-up equipment. As a result of opencast mi-ning of lignite coal in Poland, for example, a huge clean-up is left, which will amount to billions of dollars. However accidents also occur at sea, where a spate of oil tanker disasters are likely to fill out the order book at oil cleaning industries.
Nevertheless a stroke of bad luck is far from necessary in order to make firms under-stand their green obligations. The power of the consumers has been on the increase over the last few years, and the public environmental image means more to a firm than ever before. The average con-sumer going down to the grocer's for a few necessaries is starting to attach importance to something else than just the product itself. How is the detergent wrapped - is the paper bleached? Is this bottle reusable? Are these outdoor tomatoes? - and so on. Personally I don't think that you notice it, as you're walking alongside the shelves in the local supermarket - but you do pay more attention to ecological messages on the products than you did just 5-10 years ago. After all this is a topic very much in the public mind, so I guess it's quite natural to get involved one way or the other. I know from my own experiences that we have started to put down se-veral ecological products on the shopping list at home, when going to the grocer's. Products like: carrots, rye bread, milk, and cheese appear regularly on our shopping list and always in ecological form. But just recently another common purchase was substituted; red wine, French red wine to be exact, had to give way to a Spanish bottle instead. The day by day "revolution" on the dinner table was my mother's contribution to the prevention of the French nuclear tests. French products in gene-ral was banned on our shopping list - and still are. How far her exertions have got appreciable effect with monsieur Chirac is dubious - but many a little makes a mickle, as they say!
On a more global scale this environmental consciousness of the consumers was to be witnessed just a couple of months ago. The sinking of the drilling rig "Brent Spar" at open sea cau-sed an outcry all over Europe, and customers "rippled their muscles". Shell, the mastermind behind the sinking, was boycott by a vast number of both bulk buying companies and ordinary consumers which resulted in a more environmentally friendly solution at last. To my mind this way of carrying one's point is absolutely excellent. Henceforward I feel that the consumers should utilize "the power of their shopping list" far more frequently. As to "Brent Spar", we kept that one afloat and got it sent to the breakers pre-venting the environment from further molestation. Let's only hope that this will go for the French nuclear weapons as well - before it's too late! "Consumers, unite!"
III
COWIconsult
Parallelvej 15
2800 Lyngby
Denmark
The European
Att.: Michael Bond
Orbit House
5 New Fetter lane
London EC4A 1AP
U.K. 12 June 1994
Dear Sir
Thanks for your letter of 6 June. I regret that I unfortunately can not answer your question, since we are a consulting firm which is not directly involved in any environmental acitvities.
The environmental sector has truely enjoyed a boom during the past few years. Industry is begin-ning to take its green responsibility seriously, consequently we help the companies in finding out whether they can make profits from a green image or not. For instance we do calculations for com-panies so that they can see the financial consequences of any environmental investments.
That is why we can not be of any assistance to you regarding information on special projects. However we do enclose our latest annual report, where you will find the names of some Danish firms, which have been involved in either the cleaning of polluted soil in eastern Europe or the sale of equipment for monitoring oil spill from ship tanks in the North Sea. Perhaps you can obtain fur-ther details at the mentioned companies.
Moreover we refer to our office in London, 35 Bassinghall Street, London EC2V 5DB.
We wish you the best of luck on your articles.
Yours sincerely
COWIconsult
Marlene Eriksen
Marlene Eriksen
Information Manager
Encl
4
Sunday, October 14, 2012
Global Warming
Mission Plan
a. Analysis of the Problem
1. History of the Problem
Some scientist's have been concerned since 1896 about what might happen if there
were 5.5 billion tons carbon dioxide in our atmosphere. In 1961 a British scientist did an
experiment showing that the carbon in the air was absorbing some of the sun's radiation.
Afterward a Swedish scientist, Suante Arrhenius, found out if the radiation of the sun was
trapped in the carbon dioxide the temperature of the earth would increase by 1-2 degrees.
In 1988 James Hanson, a respected scientist, told the U.S. Congress "the greenhouse
effect is occurring now and it's changing global climate."(1989 Koral). After the 1900's
people started making factories and started using fossil fuels like coal, oil, and aluminum.
It was the industrial revolution and overpopulation of humans that was the cause of the
environmental problems that we have today.
2. Human Activity Causing the Problem
The reason our Earth is getting hotter is that human activities are emitting too
much carbon dioxide into the atmosphere. The radiation from the sun gets trapped in the
bag of carbon dioxide that surrounds our earth.
One main reason for the problem of global warming is the burning of fossil fuels.
Fossil fuels are coal, oil and natural gases. We use these fuels to run factories, power
plants, cars, trucks, buses, air conditioning and etc. The people of the earth are putting
5.5 billion tons of carbon, in the form of carbon dioxide in the air every year! Seventy
five percent of this is fossil fuels.
3. Impact Causing Global Change
For many years, scientists have been predicting that our disregard for Mother
Nature would make the climatic temperature of this Earth to increase greatly. There have
been arguments that the whole idea of Global Warming is a hoax, that the temperature
cycle is just experiencing an upward trend and will eventually come back down. Now,
however, we are starting to see the evidence of our behavior.
Remember the great heat wave in Chicago? That could have been a consequence
of global warming. Nearly a hundred people died, and the city's economy came to a
standstill. A much more tragic but less known heat wave smashed into India, causing
upward of 600 deaths.
Global Warming doesn't only increase temperatures in hot areas. It also decreases
temperatures in cold areas. An example of this has been the cold spell that struck the
midwest. In Montana, temperatures plummeted to 30 degrees below and stayed there.
The coldest weather ever recorded plagued our country's heart for over three weeks, and
still hasn't returned to normal. A related incident has been the blizzards of the east coast.
Some places in New York State got over twenty feet of snow.
On a Native Island, where native tribes live, if the sea level rises three fourths of a
meter then half of the island will sink. This will happen in many different islands around
the world and if the water keeps on rising as it is, then farming land near the seashores
will be flooded and the crops will be destroyed.
Like California and other states, we are adding CO2 and changing the earth's
weather. Some places are getting too little water which causes a drought and other places
get too much water which causes a flood.
In California, there was an almost permanent drought during the eighties. This
was gone in the nick of time by the great rainstorms of 1995. We also experienced a
frightening cold spell in 1992.
The Road Ahead
With all these obvious scourges plaguing us now, it seems that things cannot get
any worse. However, the current droughts, floods, and storms are just the tip of the
iceberg. If the greenhouse effect continues unabated, then the inhabitants of Planet Earth
have some surprises in store.
Scientists estimate that the global temperature will rise between 5 and 9 degrees
by the middle of the 21st century, accompanied by a sea-level rise of one to four feet. Five
degrees may not seem like a drastic change, but in the last ice age at the beginning of the
Quaternary period, the average temperature was only five degrees colder than it is now.
Thus, our actions our warming the earth enough to break out of an ice age.
Once the temperature reaches a certain threshold, the polar ice caps will began to
melt. While those living in the Arctic may find that a welcome surprise, the implications
for the rest of the world are serious. Even a partial melting of the polar ice caps will cause
sea levels to rise so much as to completely wipe out most coastal cities. This includes
such cultural centers as San Francisco and New York. Those cities that survive will be
battered down by hurricanes much more severe than anything seen in history. Of course,
inland cities are not immune either. Rather than floods, they will face drought. So while
half the world is swimming to work, the other half will be crawling on their knees with a
scorching sun beating against their backs.
When drinkable water is a scarcity, it will become a commodity that represents
political power. The countries with water will be the countries with power. This means
there will be a political upheaval of global proportions. Life as our children know it will be
completely different, and not necessarily for the better. With most of America's lakes
dried up and its major trading ports under several feet of salt water, perhaps we won't be
the economical leader.
If we don't start trying to stop global warming from happening now, there will be
many more consequences. Another consequence will be that there will be high raises in
temperature, affecting human life by causing skin cancer, damaging the human immune,
and causing cataracts. Raises in temperature will also affect agricultural and aquatic life.
Also, many species will die off. And in the forests or maybe animals, there could be
medicines to cure some kind of disease. The way these cancers and diseases come to be
is because the sun deadly rays like UV rays, which mutate human cells.
b. Experimental Design
1. Restate Problem
Natural occurrences are not the only caused and influences of our atmosphere
changing. Human activities also cause the atmosphere to change. Fossil fuels burning is
producing a worldwide increase in the atmosphere concentration of carbon dioxide. If
atmospheric carbon dioxide continues to increase at the present rate, studies estimate that
the average surface temperature will rise 2 degrees Celsius by the middle of the next
century. This will be a climate change greater than any other ever experienced in history,
that we know of. The four main greenhouse gases are Carbon Dioxide (CO2),
Chlorofluorocarbons (CFCs), Methane (CH4), and Nitrous Oxide (N2O). With the
exception of CFCs, all these gases are found in nature. It is the recent explosion of the
human population that has caused an exponential increase in their atmospheric presence.
Although nature has provisions for removing carbon dioxide, it does not take into
account the human factor. The long, complicated carbon cycle can only keep up with
increasing human activity if the tree population increases proportionately. Due to modern
medicine and increased awareness of nutrition and health, the human race has managed to
extend its lifespan considerably, thereby releasing more CO2 into the atmosphere. This,
combined with an alarming rate of rainforest depletion and air pollution, leads to an
unmanageable amount of CO2 in the atmosphere. Since its sources are both natural and
human, carbon dioxide is the largest contributor to the greenhouse effect, at 50%.
As far as CFCs, our only excuse is that "it seemed a good idea at the time." When
they were first invented, they seemed to be the miracle chemical of the century. Because
of their low boiling point, CFCs could act as coolers in refrigerators, freezers, and air
conditioners. Also, they were used to make Styrofoam and as aerosol propellants. As it
turns out, they are as skilled at destruction as they are at refrigerating. Scientists
discovered in the 1970's that CFCs destroy ozone, starting an international ban on their
usage. Later, it was determined that CFCs contribute to global warming as well, making
them a dangerous double whammy. CFCs are no longer used in aerosol and Styrofoam,
however most refrigerators still contain freon, a CFC. Fortunately, the freon can be
recycled. Contributing to 25% of global warming, CFCs are still a major problem, but at
least the U.S. and the other powers have recognized it as such. Methane, also known as a
natural gas, contributes 15% to the greenhouse effect. It is caused by cows and rice
paddies. The major American demand for so much beef urges foreign farmers to clear
forests for pastures. This also causes an increase in carbon dioxide, as well as a cow
population so high that the methane-rich burps of the complex digestive system are a
major contributing factor to the greenhouse effect. Add to that the methane released from
natural sources, and you have a very large problem. The ten percent that is left comes
from nitrous oxide, a common pollutant. It, along with carbon dioxide, forms the major
part of car exhaust. Half a billion cars drive the streets of the world today, a number
expected to double by 2030. N2O is also released by the burning of fossil fuels. Finally,
it finds its way into the atmosphere from nitrogen fertilizers, which are used heavily by
today's modern farmers.
Overall there are many pollutants in our atmosphere, influenced by humans, and
by natural effects. In our opinion if any member of this country wants to live in a good
environment then they have to take charge and to make a difference even if you have to
become a vegetarian so there will not be CO2 from the animals.
2. Hypothesis
If we continue to pollute the air with methane gases and don't do anything about
it, then the average global temperature will rise and there will be many consequences.
Warming expands ocean water and may melt some glaciers. The sea level could rise one
foot in the next 35 years and two in the next 100. Hurricanes, tornadoes and other
extreme storms may become more frequent. Centers of large continents, such as the U.S.
Great Plains, may be drier even if the overall world rainfall increases somewhat. Heat
waves may be more common. Movement of just 1 percent of a future population of 6
billion people due to higher sea level, drought, or other climate change would produce 60
million migrants, many times the number of all refugees today. Impact mixed. Carbon
dioxide stimulates plant growth. However, heat increases demand for water. Growing
zones will shift if weather patterns change. Warming that expands the tropics will also
expand the range of tropical diseases such as malaria and other insect borne maladies.
Possible mass extinction may occur as conditions change faster than species can move or
adapt. Urban and agriculture development leaves few wilderness corridors for migration.
3. EOS Satellite
The Earth Observing System (EOS) Data and Information System (EOSDIS)
is NASA's Mission to Planet Earth's (MTPE) project to provide access to Earth Science
data. EOSDIS manages data from NASA's past and current Earth science research
satellites and field measurement programs, providing data archiving, distribution, and
information management services. During the EOS era--beginning with the launch of the
TRMM satellite in 1997 EOSDIS will command and control satellites and instruments,
and will generate useful products from orbital observations. EOSDIS will also generate
data sets made by assimilation of satellite and in situ observations into global climate
models.
The instrument that we chose that monitors the impact of human activity is
HIRDLS. HIRDLS is an infrared limb-scanning radiometer designed to sound the upper
troposphere, stratosphere, and mesosphere to determine temperature; the concentrations
of O3, H2O, CH4, N2O, NO2, HNO3, N2O5, CFC11, CFC12, and aerosols; and the
locations of polar stratospheric clouds and cloud tops. The goals are to provide sounding
observations with horizontal and vertical resolution superior to that previously obtained;
to observe the lower stratosphere with improved sensitivity and accuracy; and to improve
understanding of atmospheric processes through data analysis, diagnostics, and use of
two- and three-dimensional models.
HIRDLS performs limb scans in the vertical at multiple azimuth angles, measuring
infrared emissions in 21 channels ranging from 6.12 to 17.76 um. Four channels measure
the emission by CO2. Taking advantage of the known mixing ratio of CO2, the
transmittance is calculated, and the equation of radiative transfer is inverted to determine
the vertical distribution of the Planck black body function, from which the temperature is
derived as a function of pressure. Once the temperature profile has been established, it is
used to determine the Planck function profile for the trace gas channels. The measured
radiance and the Planck function profile are then used to determine the transmittance of
each trace species and its mixing ratio distribution.
Winds and threatening tornados are determined from spacial variations of the
height of geopotential surfaces. These are determined at upper levels by integrating the
temperature profiles vertically from a known reference base. HIRDLS will improve
knowledge of data-sparse regions by measuring the height variations of the reference
surface provided by customary sources with the aid of a gyro package. This level, which
is near the base of the stratosphere can also be blended downward using nadir
temperature soundings to improve tropospheric analyses.
Bibliography
"Climate Change Brings Trouble". The Earth Care Annual 1993. Emmaus:
Rodale Press, 1993
"EOS" http://eos.nasa.gov/ Logon November 3, 1996
"Global Warming" http://users.aimnet.com/~hyatt/gw/gw.html Logon October 25,
1996
"Global Warming". Microsoft Encarta 95, Microsoft, 1994.
"HIRDL" http://eos.acd.ucar.edu/hirdls/home.html Logon November 1, 1996
Newton, David. Global Warming A Reference Handbook. Santa Barbara:
ABC-CLIO, 1993
Silver, Cheryl. One Earth, One Future, Our Changing Global Environment.
Washington D.C., National Academy Press, 1990
Woodwell, George. The Rising Tide Global Warming and World Sea Levels.
Washington D.C., Island Press, 1991
a. Analysis of the Problem
1. History of the Problem
Some scientist's have been concerned since 1896 about what might happen if there
were 5.5 billion tons carbon dioxide in our atmosphere. In 1961 a British scientist did an
experiment showing that the carbon in the air was absorbing some of the sun's radiation.
Afterward a Swedish scientist, Suante Arrhenius, found out if the radiation of the sun was
trapped in the carbon dioxide the temperature of the earth would increase by 1-2 degrees.
In 1988 James Hanson, a respected scientist, told the U.S. Congress "the greenhouse
effect is occurring now and it's changing global climate."(1989 Koral). After the 1900's
people started making factories and started using fossil fuels like coal, oil, and aluminum.
It was the industrial revolution and overpopulation of humans that was the cause of the
environmental problems that we have today.
2. Human Activity Causing the Problem
The reason our Earth is getting hotter is that human activities are emitting too
much carbon dioxide into the atmosphere. The radiation from the sun gets trapped in the
bag of carbon dioxide that surrounds our earth.
One main reason for the problem of global warming is the burning of fossil fuels.
Fossil fuels are coal, oil and natural gases. We use these fuels to run factories, power
plants, cars, trucks, buses, air conditioning and etc. The people of the earth are putting
5.5 billion tons of carbon, in the form of carbon dioxide in the air every year! Seventy
five percent of this is fossil fuels.
3. Impact Causing Global Change
For many years, scientists have been predicting that our disregard for Mother
Nature would make the climatic temperature of this Earth to increase greatly. There have
been arguments that the whole idea of Global Warming is a hoax, that the temperature
cycle is just experiencing an upward trend and will eventually come back down. Now,
however, we are starting to see the evidence of our behavior.
Remember the great heat wave in Chicago? That could have been a consequence
of global warming. Nearly a hundred people died, and the city's economy came to a
standstill. A much more tragic but less known heat wave smashed into India, causing
upward of 600 deaths.
Global Warming doesn't only increase temperatures in hot areas. It also decreases
temperatures in cold areas. An example of this has been the cold spell that struck the
midwest. In Montana, temperatures plummeted to 30 degrees below and stayed there.
The coldest weather ever recorded plagued our country's heart for over three weeks, and
still hasn't returned to normal. A related incident has been the blizzards of the east coast.
Some places in New York State got over twenty feet of snow.
On a Native Island, where native tribes live, if the sea level rises three fourths of a
meter then half of the island will sink. This will happen in many different islands around
the world and if the water keeps on rising as it is, then farming land near the seashores
will be flooded and the crops will be destroyed.
Like California and other states, we are adding CO2 and changing the earth's
weather. Some places are getting too little water which causes a drought and other places
get too much water which causes a flood.
In California, there was an almost permanent drought during the eighties. This
was gone in the nick of time by the great rainstorms of 1995. We also experienced a
frightening cold spell in 1992.
The Road Ahead
With all these obvious scourges plaguing us now, it seems that things cannot get
any worse. However, the current droughts, floods, and storms are just the tip of the
iceberg. If the greenhouse effect continues unabated, then the inhabitants of Planet Earth
have some surprises in store.
Scientists estimate that the global temperature will rise between 5 and 9 degrees
by the middle of the 21st century, accompanied by a sea-level rise of one to four feet. Five
degrees may not seem like a drastic change, but in the last ice age at the beginning of the
Quaternary period, the average temperature was only five degrees colder than it is now.
Thus, our actions our warming the earth enough to break out of an ice age.
Once the temperature reaches a certain threshold, the polar ice caps will began to
melt. While those living in the Arctic may find that a welcome surprise, the implications
for the rest of the world are serious. Even a partial melting of the polar ice caps will cause
sea levels to rise so much as to completely wipe out most coastal cities. This includes
such cultural centers as San Francisco and New York. Those cities that survive will be
battered down by hurricanes much more severe than anything seen in history. Of course,
inland cities are not immune either. Rather than floods, they will face drought. So while
half the world is swimming to work, the other half will be crawling on their knees with a
scorching sun beating against their backs.
When drinkable water is a scarcity, it will become a commodity that represents
political power. The countries with water will be the countries with power. This means
there will be a political upheaval of global proportions. Life as our children know it will be
completely different, and not necessarily for the better. With most of America's lakes
dried up and its major trading ports under several feet of salt water, perhaps we won't be
the economical leader.
If we don't start trying to stop global warming from happening now, there will be
many more consequences. Another consequence will be that there will be high raises in
temperature, affecting human life by causing skin cancer, damaging the human immune,
and causing cataracts. Raises in temperature will also affect agricultural and aquatic life.
Also, many species will die off. And in the forests or maybe animals, there could be
medicines to cure some kind of disease. The way these cancers and diseases come to be
is because the sun deadly rays like UV rays, which mutate human cells.
b. Experimental Design
1. Restate Problem
Natural occurrences are not the only caused and influences of our atmosphere
changing. Human activities also cause the atmosphere to change. Fossil fuels burning is
producing a worldwide increase in the atmosphere concentration of carbon dioxide. If
atmospheric carbon dioxide continues to increase at the present rate, studies estimate that
the average surface temperature will rise 2 degrees Celsius by the middle of the next
century. This will be a climate change greater than any other ever experienced in history,
that we know of. The four main greenhouse gases are Carbon Dioxide (CO2),
Chlorofluorocarbons (CFCs), Methane (CH4), and Nitrous Oxide (N2O). With the
exception of CFCs, all these gases are found in nature. It is the recent explosion of the
human population that has caused an exponential increase in their atmospheric presence.
Although nature has provisions for removing carbon dioxide, it does not take into
account the human factor. The long, complicated carbon cycle can only keep up with
increasing human activity if the tree population increases proportionately. Due to modern
medicine and increased awareness of nutrition and health, the human race has managed to
extend its lifespan considerably, thereby releasing more CO2 into the atmosphere. This,
combined with an alarming rate of rainforest depletion and air pollution, leads to an
unmanageable amount of CO2 in the atmosphere. Since its sources are both natural and
human, carbon dioxide is the largest contributor to the greenhouse effect, at 50%.
As far as CFCs, our only excuse is that "it seemed a good idea at the time." When
they were first invented, they seemed to be the miracle chemical of the century. Because
of their low boiling point, CFCs could act as coolers in refrigerators, freezers, and air
conditioners. Also, they were used to make Styrofoam and as aerosol propellants. As it
turns out, they are as skilled at destruction as they are at refrigerating. Scientists
discovered in the 1970's that CFCs destroy ozone, starting an international ban on their
usage. Later, it was determined that CFCs contribute to global warming as well, making
them a dangerous double whammy. CFCs are no longer used in aerosol and Styrofoam,
however most refrigerators still contain freon, a CFC. Fortunately, the freon can be
recycled. Contributing to 25% of global warming, CFCs are still a major problem, but at
least the U.S. and the other powers have recognized it as such. Methane, also known as a
natural gas, contributes 15% to the greenhouse effect. It is caused by cows and rice
paddies. The major American demand for so much beef urges foreign farmers to clear
forests for pastures. This also causes an increase in carbon dioxide, as well as a cow
population so high that the methane-rich burps of the complex digestive system are a
major contributing factor to the greenhouse effect. Add to that the methane released from
natural sources, and you have a very large problem. The ten percent that is left comes
from nitrous oxide, a common pollutant. It, along with carbon dioxide, forms the major
part of car exhaust. Half a billion cars drive the streets of the world today, a number
expected to double by 2030. N2O is also released by the burning of fossil fuels. Finally,
it finds its way into the atmosphere from nitrogen fertilizers, which are used heavily by
today's modern farmers.
Overall there are many pollutants in our atmosphere, influenced by humans, and
by natural effects. In our opinion if any member of this country wants to live in a good
environment then they have to take charge and to make a difference even if you have to
become a vegetarian so there will not be CO2 from the animals.
2. Hypothesis
If we continue to pollute the air with methane gases and don't do anything about
it, then the average global temperature will rise and there will be many consequences.
Warming expands ocean water and may melt some glaciers. The sea level could rise one
foot in the next 35 years and two in the next 100. Hurricanes, tornadoes and other
extreme storms may become more frequent. Centers of large continents, such as the U.S.
Great Plains, may be drier even if the overall world rainfall increases somewhat. Heat
waves may be more common. Movement of just 1 percent of a future population of 6
billion people due to higher sea level, drought, or other climate change would produce 60
million migrants, many times the number of all refugees today. Impact mixed. Carbon
dioxide stimulates plant growth. However, heat increases demand for water. Growing
zones will shift if weather patterns change. Warming that expands the tropics will also
expand the range of tropical diseases such as malaria and other insect borne maladies.
Possible mass extinction may occur as conditions change faster than species can move or
adapt. Urban and agriculture development leaves few wilderness corridors for migration.
3. EOS Satellite
The Earth Observing System (EOS) Data and Information System (EOSDIS)
is NASA's Mission to Planet Earth's (MTPE) project to provide access to Earth Science
data. EOSDIS manages data from NASA's past and current Earth science research
satellites and field measurement programs, providing data archiving, distribution, and
information management services. During the EOS era--beginning with the launch of the
TRMM satellite in 1997 EOSDIS will command and control satellites and instruments,
and will generate useful products from orbital observations. EOSDIS will also generate
data sets made by assimilation of satellite and in situ observations into global climate
models.
The instrument that we chose that monitors the impact of human activity is
HIRDLS. HIRDLS is an infrared limb-scanning radiometer designed to sound the upper
troposphere, stratosphere, and mesosphere to determine temperature; the concentrations
of O3, H2O, CH4, N2O, NO2, HNO3, N2O5, CFC11, CFC12, and aerosols; and the
locations of polar stratospheric clouds and cloud tops. The goals are to provide sounding
observations with horizontal and vertical resolution superior to that previously obtained;
to observe the lower stratosphere with improved sensitivity and accuracy; and to improve
understanding of atmospheric processes through data analysis, diagnostics, and use of
two- and three-dimensional models.
HIRDLS performs limb scans in the vertical at multiple azimuth angles, measuring
infrared emissions in 21 channels ranging from 6.12 to 17.76 um. Four channels measure
the emission by CO2. Taking advantage of the known mixing ratio of CO2, the
transmittance is calculated, and the equation of radiative transfer is inverted to determine
the vertical distribution of the Planck black body function, from which the temperature is
derived as a function of pressure. Once the temperature profile has been established, it is
used to determine the Planck function profile for the trace gas channels. The measured
radiance and the Planck function profile are then used to determine the transmittance of
each trace species and its mixing ratio distribution.
Winds and threatening tornados are determined from spacial variations of the
height of geopotential surfaces. These are determined at upper levels by integrating the
temperature profiles vertically from a known reference base. HIRDLS will improve
knowledge of data-sparse regions by measuring the height variations of the reference
surface provided by customary sources with the aid of a gyro package. This level, which
is near the base of the stratosphere can also be blended downward using nadir
temperature soundings to improve tropospheric analyses.
Bibliography
"Climate Change Brings Trouble". The Earth Care Annual 1993. Emmaus:
Rodale Press, 1993
"EOS" http://eos.nasa.gov/ Logon November 3, 1996
"Global Warming" http://users.aimnet.com/~hyatt/gw/gw.html Logon October 25,
1996
"Global Warming". Microsoft Encarta 95, Microsoft, 1994.
"HIRDL" http://eos.acd.ucar.edu/hirdls/home.html Logon November 1, 1996
Newton, David. Global Warming A Reference Handbook. Santa Barbara:
ABC-CLIO, 1993
Silver, Cheryl. One Earth, One Future, Our Changing Global Environment.
Washington D.C., National Academy Press, 1990
Woodwell, George. The Rising Tide Global Warming and World Sea Levels.
Washington D.C., Island Press, 1991
Global Warming and Human Population
The relationship between humans and the state of the ecosystem is not only dependent upon how many people there are, but also upon what they do. When there were few people, the dominant factors controlling ecosystem state were the natural ones that have operated for millions of years. The human population has now grown so large that there are concerns that they have become a significant element in ecosystem dynamics. One of these concerns is the relationship between human activities and climate, particularly the recent observations and the predictions of global warming, beginning with the alarm sounded by W. Broecker (1975).
The relationships among humans, their activities and global temperature can be assessed by making the appropriate measurements and analyzing the data in a way that shows the connections and their magnitudes. Human population can be closely estimated and the consequences of their activities can be measured. For example, the volume of carbon dioxide, methane and nitrous oxide emissions is an indicator of human's energy and resource consumption. An examination of population size, atmospheric concentrations of these gases and global temperature relative to time and with respect to each other is presented here to demonstrate the relations among these factors.
POPULATION GROWTH
Many of us have seen linear graphs of human population showing the enormous growth in the last two centuries. However, significant changes in population dynamics are lost in the exponential growth and long time scales. If the data are replotted on a log-population by log-time scale, significant population dynamics emerge. First, it is apparent that population growth has occurred in three surges and second, that the time between surges has dramatically shortened (Deevey, 1960).
<Picture>Figure 1. Population (Log-population verses log-time since 1 million years ago). Time values on x-axis, ignoring minus sign, are powers of 10 years before and after 1975 (at 0). Vertical dashed-line at 1995. Filled circles for known values are to left of 1995 and open circles on and to right of 1995 are for projected values. (Data updated from Deevey, 1960).
----------
Deevey's 1960 graph has been brought up to date in Figure 1 to reflect what has been learned since then. The data have been plotted relative to 1975 with negative values before 1975 and positive values thereafter. The reason for this will become clear below. The values of the time scale, ignoring the minus signs, represent powers of 10 years.
It has been argued that a population crash occurred about 65,000 years ago (-4.8, Fig. 1), presumably due to the prolonged ice-ages during the preceding 120,000 years (Gibbons, 1993). Humans came close to perishing and Neanderthal became extinct. However, by 50,000 years ago (-4.6, Fig. 1), humans had generated population mini-explosions all around the planet. Deevey's data for population size since 500 years ago have been replaced with more recent estimates taken from The World Almanac, (1992 - 1995) including population projections out to 2025. A vertical dashed-line has been placed at 1995. Filled symbols for the known values are to the left of it and open symbols on and to the right of it are for values projected into the short-term future.
The first surge coincides with the beginning of the cultural revolution about 600,000 years ago, interrupted by the population crash 65,000 years ago. Population size rebounded 50,000 years ago and then growth slowed considerably. The second surge began with the agricultural revolution about 10,000 years ago and was followed by slow growth. Deevey argued that moving down the food chain was the underlying cause of this large and rapid spurt. The timing of the present surge matches the rise of the industrial-medical revolution 200 years ago.
A relation between innovation and population growth is embedded in the log-log plot. There was rapid growth at the start of each surge. Then, growth rate slowed as people adapted to the precipitating innovations. Each surge increased the population more than 10-fold. It appears that we are nearing the end of the present surge as recent growth rates have declined. After the initial spurt, subsequent innovations did not perpetuate growth rates. The only significant innovations were those that produced the next surge. However, accumulated innovations during the surges may have played a role in the eventual decline in population growth rates. Starting with high birth and death rates, death rate declines and longevity increases, but birth rates stay high. Some time later, birth rates decline so that eventually, net births minus deaths produces slow growth. The result is a spurt in population size. When referring to the industrial revolution, this phenomenon has been called the "demographic transition". It appears that this dynamic may have occurred twice before.
The decreases in time between surges suggests that, if past behavior is the best predictor of future behavior, we are due for another surge. It may have already begun, as indicated by the upturn in the projections at the right end of the curve in Figure 1. What might the basis for another surge be? One can think of several possibilities, including the "green revolution" and the "global economy". A dominant element in past surges has been innovations in energy use (e.g., fire, descending the food-chain, beasts of burden, fossil fuels, high-energy agriculture). Thus, the development of an abundant and cheap energy source would have a profound effect. Another 10-fold (or more) surge would produce a population of 60 to 125 billion.
GLOBAL TEMPERATURE AND GREENHOUSE GASES
<Picture>Figure 2. Greenhouse Gases and Mean Global Temperature (Greenhouse gas concentrations and mean global temperature verses time). Time scale same as in Fig. 1. Gas-concentration data have been normalized to the 0 to 1 scale on left: CO2 (squares) - 190 to 430 ppm; CH4 (triangles) - 600 to 2400 ppb; N2O (diamonds) - 280 to 340 ppb. Mean global temperature (circles) plotted relative to oC on right. Vertical dashed-line at 1995, horizontal dotted line at maximum CO2 concentration and global temperature over human history before 1990. Filled and open symbols same as in Fig. 1. Projections in short-term future are based upon continuation at current growth rates. (Data measured from graphs in Gribbin, 1990 and Khalil and Rasmussen, 1992).
----------
Mean-global-temperature (MGT) is related to the concentration of greenhouse gases (carbon dioxide, methane, nitrous oxide, water vapor and other trace gases) in the atmosphere. The most prevalent greenhouse gas is carbon dioxide (CO2). It has been shown that there is a strong relation between the atmospheric concentration of CO2 and MGT over the last 160,000 years (Gribbin, 1990). It has been suspected that the burning of fossil fuels and the clearing of land has reached such proportions that these activities have precipitated a significant increase in atmospheric CO2 concentration. The concentrations of greenhouse gases in the atmosphere have been directly measured since about 1960 and have been determined over the more distant past from air-bubbles trapped in old Antarctic, Greenland and Siberian ice and from deep-sea sediments. Mean-global-temperature has also been measured directly over the last few decades. Estimates of global temperature in the distant past have been deduced from a variety of sources. From these data, the relation among atmospheric greenhouse-gas concentrations, MGT and time is illustrated in Figure 2.
The time scale in Figure 2 is the same as that in Figure 1. Because CO2, methane (CH4) and nitrous oxide (N2O) concentrations have different scales, the data have been normalized on a 0 to 1 scale on the left. For CO2 (squares; Gribbin, 1990), 0 is equivalent to 190 parts per million (ppm) and 1 is equivalent to 430 ppm. For CH4 (triangles; R. Cicerone in Gribbin, 1990), the range is 600 to 2400 parts per billion (ppb). For N2O (diamonds; Khalil and Rasmussen, 1992), the scale is 280 to 340 ppb. Mean global temperature (circles; Gribbin, 1990) has been graphed relative to the degrees-centigrade scale on the right. The vertical dashed-line is the same as that in Figure 1. The horizontal dotted-line is the highest CO2 concentration and temperature in human history before 1990. Greenhouse-gas concentrations and MGT in the short-term future are based upon continuation at the current growth rates. This will be justified in another context below.
<Picture>Figure 3. Population and Global Warming (CO2 concentration and mean global temperature verses log-population) CO2 concentration (circles) and mean global temperature (squares) plotted relative to their absolute scales, ppm on the left and oC on the right, respectively. Vertical dashed line at 1995. (Data from Figs. 1 and 2)
----------
It is clear that the concentrations of all three gases have increased exponentially since 1950 (-1.4, Fig. 2) and that MGT has done so since 1975. Carbon dioxide concentration began to rise in conjunction with the use of fossil fuels after 1850. Although methane comes from a variety of sources, including plant decay, termites and bovine flatulence, CH4 concentration rises at the same time as CO2. This is probably due to its association with fossil-fuel production. Nitrous oxide concentration does not begin to rise until 1950. At this time, the use of human-made fertilizers and internal-combustion-engine exhaust increased dramatically. Ten thousand years ago (-4, Fig. 2), MGT increased substantially just as the agricultural revolution got started. Over the previous 200,000 years, the ecosystem was dominated by ice-ages. Projected MGT in 2025 (1.7, Fig. 2) is about 17oC, 1.5oC higher than in human history prior to 1990.
POPULATION AND GLOBAL TEMPERATURE
We have seen in Figures 1 and 2 that recent population, atmospheric greenhouse-gas concentrations and MGT have grown exponentially over about the same time-course. The relation of CO2 and MGT relative to population size can be observed by graphing these variables as above. Figure 3 shows this graph, where the log of population replaces log-time and CO2 concentration (circles) and MGT (squares) are plotted relative to their absolute scales, ppm on the left and oC on the right, respectively. The vertical dashed-line denotes 1995, as in Figures 1 and 2. When the population reached 4 billion in 1975, the converging relation between population and the other two variables becomes apparent.
The magnitude of the relations in Figures 2 and 3 can be determined by calculating the correlation coefficient between pairs of variables. Table 1 lists these coefficients for the population, greenhouse-gas concentration and MGT variables that we have been examining. The coefficients for the relations during the industrial revolution, 1800 through 1994, are above the diagonal of the table. The coefficients since 2000 years ago through 1994 are below the diagonal. Over the past 2000 years, there is a nearly perfect correlation between the concentration of greenhouse gases and population and between the greenhouse gases themselves. However, the correlations between both population and greenhouse-gas concentrations and MGT (bottom row) are not as strong. After 1800, the latter correlations increase to near perfection (rightmost column). The conclusion from the graphs and table is that there is a strong relationship among population size since 1800, greenhouse-gas concentrations and MGT.
TABLE 1. Correlation coefficients among population size, atmospheric greenhouse-gas concentrations and mean global temperature (1800 through 1994 above the top-left to bottom-right diagonal, n=10; 2000 years ago through 1994 below the diagonal, n=15).
Pop CO2 CH4 N2O Temp
----------
Pop .996 .984 .977 .916
CO2 .990 .994 .974 .942
CH4 .991 .992 .949 .945
N2O .959 .943 .942 .932
Temp .718 .716 .728 .829
GLOBAL WARMING AND CLIMATE
Determining that there is a strong relation between population size and global warming does not tell us what the underlying mechanisms are. However, documentation of the relationship between human activities and the release of greenhouse gases produces a strong inference that population size and global warming are closely related (Gribbin, 1990).
Forecasting the future is risky business. Growth rates for greenhouse-gas concentrations and MGT could decline from those at present due to unanticipated innovations or natural events. For example, volcanoes can spew enough ash into the atmosphere to block sunlight and temporarily reduce MGT slightly. However, short-term continued growth at current rates is probably an underestimate. Although population growth rate has slowed, the population is still growing. The dominating factor is that per-capita energy and resource consumption rates are increasing much faster than the population. This is not only due to anticipated increases in standards of living in underdeveloped countries, but also to future increases in the demand for energy in the developed countries (e.g., air conditioning) as summer temperatures rise. Since most of the energy will come from fossil fuels, at least for the next few decades, we can expect the atmospheric concentrations of greenhouse gases and MGT to rise in the short-term future at a faster rate than they have recently. As MGT rises, water vapor, another greenhouse component, will become a more and more significant factor due to increased evaporation.
Although a 1.5oC increase in MGT above where we were in 1990 (1990 to 2025 in Fig. 2) does not seem like much of a change, it is enough to precipitate major changes in climate. A 1.5oC drop in MGT from where we were in 1990, for example, would put the ecosystem on the verge of an ice-age. Already, there is a suspicion that, since 1975, the persistent El Nino is the first sign of the relation between global warming and climate (Kerr, 1994). As MGT increases further, we can expect more frequent and severe hurricanes and perpetual summertime droughts in many places, particularly in the US Midwest. Paradoxically, more intense winter storms will occur in some places and climatic conditions for agriculture will improve in some areas, such as in Russia (Gribbin, 1990; Bernard, 1993).
There has been considerable debate over the ecosystem's carrying capacity for humans. If we define that carrying capacity as the level that the ecosystem can support without changing state more than it has over the duration of human history, then Figures 2 and 3 indicate that we exceeded that capacity in 1975. This is the point in time where exponential growth began to push MGT along a path which has taken it outside the previous range. This does not necessarily mean that humans could not survive if MGT is about 2oC higher than it has ever been in their history. However, we will have to adapt to a radically different climate pattern and, if MGT goes any higher than that, there could be disastrous problems.
If MGT continues to increase beyond 2025 to 4oC above that in 1990, high-northern-latitude temperatures could be as much as 10oC higher than at the equator. The Arctic ice-cap would begin to melt and the permafrost under the tundra would start thawing out. As a consequence, a thick layer of rotting peat would contribute further to atmospheric CO2 and CH4 concentrations (Gribbin, 1990). With a number of human-made and natural positive-feedback elements in operation simultaneously, a threshold could be crossed (Meyers, 1995; Overpeck, 1996). Are these risks that we should be willing to take for the sake of short-term gains?
REFERENCES
Bernard, H. W. Jr., "Global Warming Unchecked", Indiana Univ. Press, Bloomington, 1993
Broecker, W., Science, 189:460, 1975
Deevey, E. S., Scientific American, 203:195, 1960
Gibbons, A. , Science, 262:27, 1993
Gribbin, J. , "Hothouse Earth", Grove Weidenfeld, New York, 1990
Kerr, R. A., Science, 266:544, 1994
Khalil, M. A. K. and R. A. Rasmussen, J. Geophys. Res., 97:4651, 1992
"The World Almanac", Pharos, New York, 1992 - 1995
Meyers, N. Science 269:358, 1995
Overpeck, J. T. Science, 271:1820, 1996
Post Script
After this document was written (about a 2 years ago), two books came out which provide much more detail relevant to some of these issues:
HOW MANY PEOPLE CAN THE EARTH SUPPORT? by Joel E. Cohen; Norton, 1995.
DIVIDED PLANET: THE ECOLOGY OF RICH AND POOR by Tom Athanasiou; Little Brown, 1996.
Both are superbly done and provide a much more comprehensive and up to date treatment of the population and economic topics included here.
Recent evidence (Mora et al.; SCIENCE 271:1105, 1996) indicates that the possibility of a "greenhouse runaway" on Earth is much more remote than indicated at the end of the previous version of this document. Therefore, the former apocalyptic ending has been changed. Although the data presented points to a catastrophic conclusion, this was (perhaps) an overstatement of the case.
The relationships among humans, their activities and global temperature can be assessed by making the appropriate measurements and analyzing the data in a way that shows the connections and their magnitudes. Human population can be closely estimated and the consequences of their activities can be measured. For example, the volume of carbon dioxide, methane and nitrous oxide emissions is an indicator of human's energy and resource consumption. An examination of population size, atmospheric concentrations of these gases and global temperature relative to time and with respect to each other is presented here to demonstrate the relations among these factors.
POPULATION GROWTH
Many of us have seen linear graphs of human population showing the enormous growth in the last two centuries. However, significant changes in population dynamics are lost in the exponential growth and long time scales. If the data are replotted on a log-population by log-time scale, significant population dynamics emerge. First, it is apparent that population growth has occurred in three surges and second, that the time between surges has dramatically shortened (Deevey, 1960).
<Picture>Figure 1. Population (Log-population verses log-time since 1 million years ago). Time values on x-axis, ignoring minus sign, are powers of 10 years before and after 1975 (at 0). Vertical dashed-line at 1995. Filled circles for known values are to left of 1995 and open circles on and to right of 1995 are for projected values. (Data updated from Deevey, 1960).
----------
Deevey's 1960 graph has been brought up to date in Figure 1 to reflect what has been learned since then. The data have been plotted relative to 1975 with negative values before 1975 and positive values thereafter. The reason for this will become clear below. The values of the time scale, ignoring the minus signs, represent powers of 10 years.
It has been argued that a population crash occurred about 65,000 years ago (-4.8, Fig. 1), presumably due to the prolonged ice-ages during the preceding 120,000 years (Gibbons, 1993). Humans came close to perishing and Neanderthal became extinct. However, by 50,000 years ago (-4.6, Fig. 1), humans had generated population mini-explosions all around the planet. Deevey's data for population size since 500 years ago have been replaced with more recent estimates taken from The World Almanac, (1992 - 1995) including population projections out to 2025. A vertical dashed-line has been placed at 1995. Filled symbols for the known values are to the left of it and open symbols on and to the right of it are for values projected into the short-term future.
The first surge coincides with the beginning of the cultural revolution about 600,000 years ago, interrupted by the population crash 65,000 years ago. Population size rebounded 50,000 years ago and then growth slowed considerably. The second surge began with the agricultural revolution about 10,000 years ago and was followed by slow growth. Deevey argued that moving down the food chain was the underlying cause of this large and rapid spurt. The timing of the present surge matches the rise of the industrial-medical revolution 200 years ago.
A relation between innovation and population growth is embedded in the log-log plot. There was rapid growth at the start of each surge. Then, growth rate slowed as people adapted to the precipitating innovations. Each surge increased the population more than 10-fold. It appears that we are nearing the end of the present surge as recent growth rates have declined. After the initial spurt, subsequent innovations did not perpetuate growth rates. The only significant innovations were those that produced the next surge. However, accumulated innovations during the surges may have played a role in the eventual decline in population growth rates. Starting with high birth and death rates, death rate declines and longevity increases, but birth rates stay high. Some time later, birth rates decline so that eventually, net births minus deaths produces slow growth. The result is a spurt in population size. When referring to the industrial revolution, this phenomenon has been called the "demographic transition". It appears that this dynamic may have occurred twice before.
The decreases in time between surges suggests that, if past behavior is the best predictor of future behavior, we are due for another surge. It may have already begun, as indicated by the upturn in the projections at the right end of the curve in Figure 1. What might the basis for another surge be? One can think of several possibilities, including the "green revolution" and the "global economy". A dominant element in past surges has been innovations in energy use (e.g., fire, descending the food-chain, beasts of burden, fossil fuels, high-energy agriculture). Thus, the development of an abundant and cheap energy source would have a profound effect. Another 10-fold (or more) surge would produce a population of 60 to 125 billion.
GLOBAL TEMPERATURE AND GREENHOUSE GASES
<Picture>Figure 2. Greenhouse Gases and Mean Global Temperature (Greenhouse gas concentrations and mean global temperature verses time). Time scale same as in Fig. 1. Gas-concentration data have been normalized to the 0 to 1 scale on left: CO2 (squares) - 190 to 430 ppm; CH4 (triangles) - 600 to 2400 ppb; N2O (diamonds) - 280 to 340 ppb. Mean global temperature (circles) plotted relative to oC on right. Vertical dashed-line at 1995, horizontal dotted line at maximum CO2 concentration and global temperature over human history before 1990. Filled and open symbols same as in Fig. 1. Projections in short-term future are based upon continuation at current growth rates. (Data measured from graphs in Gribbin, 1990 and Khalil and Rasmussen, 1992).
----------
Mean-global-temperature (MGT) is related to the concentration of greenhouse gases (carbon dioxide, methane, nitrous oxide, water vapor and other trace gases) in the atmosphere. The most prevalent greenhouse gas is carbon dioxide (CO2). It has been shown that there is a strong relation between the atmospheric concentration of CO2 and MGT over the last 160,000 years (Gribbin, 1990). It has been suspected that the burning of fossil fuels and the clearing of land has reached such proportions that these activities have precipitated a significant increase in atmospheric CO2 concentration. The concentrations of greenhouse gases in the atmosphere have been directly measured since about 1960 and have been determined over the more distant past from air-bubbles trapped in old Antarctic, Greenland and Siberian ice and from deep-sea sediments. Mean-global-temperature has also been measured directly over the last few decades. Estimates of global temperature in the distant past have been deduced from a variety of sources. From these data, the relation among atmospheric greenhouse-gas concentrations, MGT and time is illustrated in Figure 2.
The time scale in Figure 2 is the same as that in Figure 1. Because CO2, methane (CH4) and nitrous oxide (N2O) concentrations have different scales, the data have been normalized on a 0 to 1 scale on the left. For CO2 (squares; Gribbin, 1990), 0 is equivalent to 190 parts per million (ppm) and 1 is equivalent to 430 ppm. For CH4 (triangles; R. Cicerone in Gribbin, 1990), the range is 600 to 2400 parts per billion (ppb). For N2O (diamonds; Khalil and Rasmussen, 1992), the scale is 280 to 340 ppb. Mean global temperature (circles; Gribbin, 1990) has been graphed relative to the degrees-centigrade scale on the right. The vertical dashed-line is the same as that in Figure 1. The horizontal dotted-line is the highest CO2 concentration and temperature in human history before 1990. Greenhouse-gas concentrations and MGT in the short-term future are based upon continuation at the current growth rates. This will be justified in another context below.
<Picture>Figure 3. Population and Global Warming (CO2 concentration and mean global temperature verses log-population) CO2 concentration (circles) and mean global temperature (squares) plotted relative to their absolute scales, ppm on the left and oC on the right, respectively. Vertical dashed line at 1995. (Data from Figs. 1 and 2)
----------
It is clear that the concentrations of all three gases have increased exponentially since 1950 (-1.4, Fig. 2) and that MGT has done so since 1975. Carbon dioxide concentration began to rise in conjunction with the use of fossil fuels after 1850. Although methane comes from a variety of sources, including plant decay, termites and bovine flatulence, CH4 concentration rises at the same time as CO2. This is probably due to its association with fossil-fuel production. Nitrous oxide concentration does not begin to rise until 1950. At this time, the use of human-made fertilizers and internal-combustion-engine exhaust increased dramatically. Ten thousand years ago (-4, Fig. 2), MGT increased substantially just as the agricultural revolution got started. Over the previous 200,000 years, the ecosystem was dominated by ice-ages. Projected MGT in 2025 (1.7, Fig. 2) is about 17oC, 1.5oC higher than in human history prior to 1990.
POPULATION AND GLOBAL TEMPERATURE
We have seen in Figures 1 and 2 that recent population, atmospheric greenhouse-gas concentrations and MGT have grown exponentially over about the same time-course. The relation of CO2 and MGT relative to population size can be observed by graphing these variables as above. Figure 3 shows this graph, where the log of population replaces log-time and CO2 concentration (circles) and MGT (squares) are plotted relative to their absolute scales, ppm on the left and oC on the right, respectively. The vertical dashed-line denotes 1995, as in Figures 1 and 2. When the population reached 4 billion in 1975, the converging relation between population and the other two variables becomes apparent.
The magnitude of the relations in Figures 2 and 3 can be determined by calculating the correlation coefficient between pairs of variables. Table 1 lists these coefficients for the population, greenhouse-gas concentration and MGT variables that we have been examining. The coefficients for the relations during the industrial revolution, 1800 through 1994, are above the diagonal of the table. The coefficients since 2000 years ago through 1994 are below the diagonal. Over the past 2000 years, there is a nearly perfect correlation between the concentration of greenhouse gases and population and between the greenhouse gases themselves. However, the correlations between both population and greenhouse-gas concentrations and MGT (bottom row) are not as strong. After 1800, the latter correlations increase to near perfection (rightmost column). The conclusion from the graphs and table is that there is a strong relationship among population size since 1800, greenhouse-gas concentrations and MGT.
TABLE 1. Correlation coefficients among population size, atmospheric greenhouse-gas concentrations and mean global temperature (1800 through 1994 above the top-left to bottom-right diagonal, n=10; 2000 years ago through 1994 below the diagonal, n=15).
Pop CO2 CH4 N2O Temp
----------
Pop .996 .984 .977 .916
CO2 .990 .994 .974 .942
CH4 .991 .992 .949 .945
N2O .959 .943 .942 .932
Temp .718 .716 .728 .829
GLOBAL WARMING AND CLIMATE
Determining that there is a strong relation between population size and global warming does not tell us what the underlying mechanisms are. However, documentation of the relationship between human activities and the release of greenhouse gases produces a strong inference that population size and global warming are closely related (Gribbin, 1990).
Forecasting the future is risky business. Growth rates for greenhouse-gas concentrations and MGT could decline from those at present due to unanticipated innovations or natural events. For example, volcanoes can spew enough ash into the atmosphere to block sunlight and temporarily reduce MGT slightly. However, short-term continued growth at current rates is probably an underestimate. Although population growth rate has slowed, the population is still growing. The dominating factor is that per-capita energy and resource consumption rates are increasing much faster than the population. This is not only due to anticipated increases in standards of living in underdeveloped countries, but also to future increases in the demand for energy in the developed countries (e.g., air conditioning) as summer temperatures rise. Since most of the energy will come from fossil fuels, at least for the next few decades, we can expect the atmospheric concentrations of greenhouse gases and MGT to rise in the short-term future at a faster rate than they have recently. As MGT rises, water vapor, another greenhouse component, will become a more and more significant factor due to increased evaporation.
Although a 1.5oC increase in MGT above where we were in 1990 (1990 to 2025 in Fig. 2) does not seem like much of a change, it is enough to precipitate major changes in climate. A 1.5oC drop in MGT from where we were in 1990, for example, would put the ecosystem on the verge of an ice-age. Already, there is a suspicion that, since 1975, the persistent El Nino is the first sign of the relation between global warming and climate (Kerr, 1994). As MGT increases further, we can expect more frequent and severe hurricanes and perpetual summertime droughts in many places, particularly in the US Midwest. Paradoxically, more intense winter storms will occur in some places and climatic conditions for agriculture will improve in some areas, such as in Russia (Gribbin, 1990; Bernard, 1993).
There has been considerable debate over the ecosystem's carrying capacity for humans. If we define that carrying capacity as the level that the ecosystem can support without changing state more than it has over the duration of human history, then Figures 2 and 3 indicate that we exceeded that capacity in 1975. This is the point in time where exponential growth began to push MGT along a path which has taken it outside the previous range. This does not necessarily mean that humans could not survive if MGT is about 2oC higher than it has ever been in their history. However, we will have to adapt to a radically different climate pattern and, if MGT goes any higher than that, there could be disastrous problems.
If MGT continues to increase beyond 2025 to 4oC above that in 1990, high-northern-latitude temperatures could be as much as 10oC higher than at the equator. The Arctic ice-cap would begin to melt and the permafrost under the tundra would start thawing out. As a consequence, a thick layer of rotting peat would contribute further to atmospheric CO2 and CH4 concentrations (Gribbin, 1990). With a number of human-made and natural positive-feedback elements in operation simultaneously, a threshold could be crossed (Meyers, 1995; Overpeck, 1996). Are these risks that we should be willing to take for the sake of short-term gains?
REFERENCES
Bernard, H. W. Jr., "Global Warming Unchecked", Indiana Univ. Press, Bloomington, 1993
Broecker, W., Science, 189:460, 1975
Deevey, E. S., Scientific American, 203:195, 1960
Gibbons, A. , Science, 262:27, 1993
Gribbin, J. , "Hothouse Earth", Grove Weidenfeld, New York, 1990
Kerr, R. A., Science, 266:544, 1994
Khalil, M. A. K. and R. A. Rasmussen, J. Geophys. Res., 97:4651, 1992
"The World Almanac", Pharos, New York, 1992 - 1995
Meyers, N. Science 269:358, 1995
Overpeck, J. T. Science, 271:1820, 1996
Post Script
After this document was written (about a 2 years ago), two books came out which provide much more detail relevant to some of these issues:
HOW MANY PEOPLE CAN THE EARTH SUPPORT? by Joel E. Cohen; Norton, 1995.
DIVIDED PLANET: THE ECOLOGY OF RICH AND POOR by Tom Athanasiou; Little Brown, 1996.
Both are superbly done and provide a much more comprehensive and up to date treatment of the population and economic topics included here.
Recent evidence (Mora et al.; SCIENCE 271:1105, 1996) indicates that the possibility of a "greenhouse runaway" on Earth is much more remote than indicated at the end of the previous version of this document. Therefore, the former apocalyptic ending has been changed. Although the data presented points to a catastrophic conclusion, this was (perhaps) an overstatement of the case.
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