"If there is a moral to the story, it is that prolonged
scientific debate and confusion can sometimes result from a
failure to step back and look at all aspects of a problem.
And a second moral is that out-of-context technological
fixes aimed at a single aspect of a complex whole may prove
destructive. Much of the research on alternative fuels today
is premised on the belief that water vapor is a benign
emission. But if we have learned anything over the past
decade, it is that a life-giving element can become
destructive if it is removed from a balanced context. The
faith being placed in hydrogen and fuel cell technologies
(which emit nothing but water) may need more thorough study."
Original source URL:
http://natureinstitute.org/txt/mda/warm/warm.htm
The Nature Institute
20 May Hill Road, Ghent, New York 12075 Tel: (518) 672 0116
Water, Energy, and Global Warming
Michael D'Aleo and Stephen Edelglass
We have all learned, during this scientific era, to speak of causes and effects.
While this language may prove useful, it can also mislead, as when the public is
brought to focus upon El Niño as the "cause" of altered weather patterns around
the world. Yet El Niño is itself a seamless part of the global weather picture,
and is as much the result of ongoing changes as their cause. By itself it
explains nothing. An undue focus on causes and effects encourages us to fragment
the earth's natural cycles and lose sight of their integral unity.
We suspect that this affinity for well-defined (and preferably villainous!)
causes throws light on the current debates about global climate change. The
fixation upon a single atmospheric constituent -- carbon dioxide, which has the
advantage of now being widely viewed as a dangerous pollutant -- may have
encouraged us to ignore elements of the larger picture. Our intention here is to
fill out another part of that picture in a way that may prove startling: it
appears that perfectly "harmless" water vapor and the actual quantity of energy
produced with it may be at least as much the villains as carbon dioxide.
Some Questions
Perhaps nothing evokes fear of humanity's destructive impact on the environment
more than global warming. The past decade brought many news reports of unusual
weather and natural disasters. Commentators speculated that hurricanes,
droughts, hot spells, floods, and ice storms were due to global warming. But
while many people are concerned about the apocalyptic implications of warming,
very few, including the scientists reporting the data, are looking at the whole
complex of phenomena associated with the idea. Are carbon dioxide emissions
really the primary cause? Recently in the U.S. we have seen other "greenhouse"
gasses begin to receive more attention. Is global warming, as it is currently
envisioned, the main cause of climate destabilization, or might something else
be at least partly responsible?
In 1861 the English physicist, John Tyndall, suggested a relationship between
the earth's atmospheric levels of carbon dioxide and global temperature(1).
Tyndall theorized that increasing levels of carbon dioxide in the atmosphere
would trap more of the earth's thermal energy before it radiated into space.
That is, carbon dioxide would create an insulating layer around the earth,
causing atmospheric temperatures to rise.
Emissions of carbon dioxide come from natural sources such as volcanic activity,
forest fires, and animal and plant respiration. They also come from fossil fuel
combustion, industrial processes, and other human activities. At the same time,
various natural processes remove carbon dioxide from the atmosphere--for
example, the oceans absorb it, and plants require it for photosynthesis. So
carbon dioxide is essential for life. But a problem may arise when mankind
produces more carbon dioxide than these natural processes can accept. Since we
are doing that now, it is natural to wonder whether we are looking at the cause
of global warming.
But has there actually been warming over the past century, and if so, how much?
The problem underlying the current debate is that there are two conflicting sets
of data. Ground-based data consists of thermometer readings taken at weather
stations in various cities and rural areas throughout the world. Some of this
data is complete and meticulously maintained, while other portions appear less
rigorous. When averaged, it indicates a change of approximately 0.6 degrees C
since record-keeping began in the nineteenth century (2). Most of this increase
occurs in the second half of the twentieth century, with the greater part, 0.2
to 0.3 degrees, coming after 1975. While these figures may seem small, they are
potentially significant for climate change.
A second set of measurements, available only since 1980, derives from satellites
and balloons that scan the temperature of the lower atmosphere across the entire
surface of the planet. These measurements show an increase ranging from under
0.1 degree C to essentially zero (3). So while the first method indicates a
rather substantial change, the second suggests a fairly modest change. Much of
the wrangling focuses on which set of data is correct.
The picture becomes more interesting when a comparison is made between urban and
rural ground-based weather stations. Urban stations show a significantly greater
temperature increase. In fact, many rural stations show no change at all. This
has led scientists to speculate about the existence of a so-called "heat island
effect", which might affect our global temperature measurements. In the late
1990s, NASA completed a study of this effect in Atlanta, Georgia. The study
showed temperatures inside Atlanta up to 8 degrees F higher than the surrounding
countryside. The suggested explanation is that man-made materials such as
concrete and asphalt store more of the sun's heat energy than forests do (4). A
number of studies also found significant temperature differences between
downtown business districts and downtown treed parks. The treed parks were up to
7 degrees F cooler than adjacent business areas (5, 6).
Another interesting phenomenon is the suspected link between forest fires and
global warming. These fires may play a significant role in contributing to
global temperature changes. At least one study suggests that up to 40% of the
global greenhouse gas emissions may result from combustion due to forest fires
that occur around the world. The report notes that forest destruction further
reduces plant absorption of carbon dioxide (7).
The link between global temperature increases and increased levels of carbon
dioxide is actually quite complex and not without its share of uncertainty. By
analyzing gas bubbles trapped in ice core samples, one group of scientists found
that the levels of carbon dioxide in the atmosphere, previously thought to be
constant, actually varied significantly during the last 11,000 years prior to
the industrial age.
They also found that, during some earlier periods, the temperature increased
before the carbon dioxide levels began to rise, sometimes with as much as a
400-to-1000-year lag (8). While this does not imply there is no link between
global temperature and carbon dioxide levels, it does suggest that other
mechanisms may help determine global temperature variation over time.
Finally and perhaps most puzzling: scientists have noted that while many weather
stations worldwide have been reporting increases in average temperature, there
also appears to be a worldwide decrease in global rates of evaporation. This was
unexpected, since warm air can receive more moisture than cool air and thus,
warmer air favors evaporation. In 1998 two researchers suggested that perhaps
the decreasing evaporation rates at the stations were counterbalanced by higher
rates of evaporation in other landscapes (9). However, there are no observations
to support this suggestion.
Has some mechanism put more water into the atmosphere, thereby reducing the
global rates of evaporation?
Water Cycles and Their Alteration
Water is essential for life. There are cycles of water transformation from the
individual organism all the way up to the scale of the entire earth. As always,
a certain balance must be achieved to prevent what supports life from becoming
destructive. The farmer hopes for a balance of rain and sun for a good crop. Too
little rain and the crop withers; too much brings decay and rot.
Water also plays a significant role in the earth's thermal balance. The specific
heat of water (the amount of heat required to raise the temperature of one gram
of water by one degree centigrade) is higher than for almost any other material
(Table 1). The heat of vaporization of water -- the amount of energy needed to
convert water from a liquid state to a vapor state at its boiling point is over
2,200,000 J/kg (40,700 kJ/kgmol)! This same amount of energy is released to the
surroundings when high-temperature water vapor condenses to from liquid water.
Table 1. Specific heat at approx. 100°C (10).
[see original]
The adage, "A watched pot never boils" pays tribute to water's massive ability
to absorb heat. Nearly everyone has experienced the moderating effect of the
ocean and large lakes on the climate of nearby cities. These masses of water are
slow to warm in hot weather, and slow to cool in cold weather.
When a fossil fuel is burned, it produces not only carbon dioxide, but also
water vapor (steam). For example, water vapor issues from every running
automobile. On cold days this vapor is often visible as it cools and condenses
upon exiting the exhaust pipe. The tremendous capacity of steam to store or
release thermal energy is utilized by all fuel-based power generating plants
including nuclear plants.
Table 2 shows the proportional amounts of water and carbon dioxide resulting
from the combustion of some common fuels.
Table 2. Water/carbon dioxide product ratio for fuels per reacting unit (kgmol)
[see original]
That is, the thermal effect of the water vapor is more than ten times that of
the carbon dioxide. This difference would be even greater for fuels that produce
a higher percentage of water vapor, such as methane. Additionally, the thermal
resistance or insulating properties of water vapor and carbon dioxide are
essentially identical in value. So the insulating (greenhouse) effects that are
of concern for carbon dioxide are even more troubling when we consider water
vapor emissions.
It is worth noting that "cleaner burning fuels" such as natural gas, often
touted as solutions to global warming, actually emit higher percentages of water
relative to carbon dioxide. As presently conceived, a fuel cell utilizing pure
hydrogen as a fuel would emit only water or water vapor.
Cities and industrial areas, of course, are primary sources of water vapor
production via combustion. But they also channel water into the atmosphere by
other means. Cities present vast evaporative surfaces preventing the return of
water to underground aquifers. (The evaporation of water from hot asphalt after
a summer rainstorm is particularly noticeable.) Water from city surfaces is
channeled into storm sewers, where it is finally put into a holding pond or
river, from which further evaporation occurs. Additionally, ground water tables
are falling in many cities.
But if water tables are falling, where has the water gone? You might assume that
levels have risen in surface bodies of water, but this has not been observed.
Apparently the water has gone into the atmosphere.
Cities are not the only sites of large-scale, human-caused water vapor emission.
Deforestation by burning releases tremendous amounts of water into the
atmosphere: the tree itself is 50% water; combustion of the remaining 50%
(carbohydrates and cellulose) produces more water; and destruction of the forest
canopy exposes the moist forest soil to evaporation by sun and wind. Anyone who
has walked in a dense forest will attest to the dampness of both the soil and
air compared to adjacent fields.
Given present rates of deforestation, the potential for regional climate
modification is considerable, quite apart from the production of greenhouse
gases such as carbon dioxide. Deforestation releases more water vapor than
carbon dioxide.
Water Emissions and Climate Modification
If we have been releasing more water into the atmosphere, might it be falling
out of the sky somewhere? There is little evidence for increased precipitation
on a global scale. The National Oceanic and Atmospheric Association reports a
small (one percent) increase in precipitation over land in the twentieth
century, while the same report notes a general increase in cloud cover over both
land and oceans in recent decades (2). For the most part, areas experiencing
long wet spells seem to be counterbalanced by other areas experiencing drought.
The fact that there seems to be little overall increase in precipitation despite
increasing human contributions of water vapor suggests that the atmosphere's
water content might be rising. However, this would not be a global effect. Water
vapor, unlike carbon dioxide, does not diffuse easily through the atmosphere and
is therefore concentrated near the earth's surface.
Further, the atmospheric water vapor content will be higher near the sources of
water vapor -- for example, near cities and areas undergoing deforestation --
rather than being evenly dispersed in the manner of carbon dioxide. Higher
atmospheric water vapor would be expected near cities on a continuing basis, as
a result of the combustion of fossil fuels. It would also be expected near
deforested areas on a short-term basis; once deforestation is complete, the
effect would cease.
All this has definite implications for climate modification. In the first place,
given the higher temperature of the products of combustion, the release of
energy when water vapor is condensed, and the insulating effects of water vapor,
we should expect an increase in the cities' average yearly temperature. As we
have seen, this "heat island effect" has already been reported, although the
link to water vapor and combustion processes has been widely missed.
All energy production ultimately manifests as thermal energy. A very general
calculation is therefore possible by taking the overall energy produced in the
U.S. in 1988 and assuming it to be evenly distributed on a per capita basis. For
example:
In 1988 the U.S. produced:
80 quads of energy (1 quad = 1 x 1015 BTUs) (11)
The population of the U.S. in 1988 was:
approx. 250 million people (12)
The resulting energy use per capita was:
80 x 1015 BTU/year / 250 million people = 320 million BTU/person-year
For a densely populated and commercial region such as Queens County, New York,
assuming equal usage per capita (1988 population of 1,951,598) (13), the human
energy production of the county per year would be:
320 million BTU/person-year x 1,951,598 people = 6.2 x 1014 BTU/year
Given that the solar energy input for this region of the U.S. is approximately
471,327 BTU/ft2-year (14), the solar energy input for the 109 square miles (13)
of Queens County is:
4.71 x 105 BTU/ft2-year x 2.8 x 107ft2/mile2 x 109 mile2
= 1.4 x 1015 BTU/year
Thus, the human energy production in Queens as a percentage of the solar energy
input turns out to be a rather astounding
(6.2 x 1014 BTU/year) / (1.4 x 1015 BTU/year) = 43%
Of course, most of this energy production releases water vapor, and our
calculation leaves aside the further, insulating and thermal properties of this
vapor. (You'll have noticed, for example, that a cloudy night is generally
warmer than a clear night, and that a hot desert cools off significantly at
night due to a lack of water in the air and immediate surroundings.)
A second expectation is that moisture-rich metropolitan air should produce rain
when it moves over cooler, rural areas. This is exactly what the NASA study of
Atlanta found (4).
In a similar way, we can look at the amount of water released from fossil fuel
combustion. U.S. oil usage in 1999 was 19.39 million barrels per day, or 814
million gallons per day (15). The per capita usage is therefore 3.25
gallons/person-day. Given that 1.1 gallons of water are produced for each gallon
of octane (gasoline) combusted, the total amount of water produced in Queens
County would be (16).:
3.25 gallons/person x 1.1 gallons water/gallon octane x 1,951,598 people
= 7 million gallons of water/day
However, oil usage accounts for only about 1/3 of total fossil fuel consumption,
the rest being natural gas and coal. We will multiply the average per capita
consumption of oil by a factor of three to get an approximation of the total
water output per capita per day due to fossil fuel combustion. If this water
were equally distributed over the 109 square miles of the county, it would be
equivalent to an annual increase in rainfall of 3.9 inches per year. The average
annual rainfall for Queens County is 42.82 inches/year (17). Needless to say,
not all the additional rainfall would fall within the county, but these figures
suggest the relative significance of the added water.
Applying the same calculations to a rural area such as Herkimer County, New York
(with a population of 65,809 on an area of 1412 square miles), one sees only a
tiny fraction of the effects seen in urban areas (13). For example, human energy
production turns out to equal only 0.1% of solar input.
Reconciling the Data
The role of water vapor and energy consumption also helps to explain both sets
of temperature data mentioned earlier. Even though global levels of carbon
dioxide are fairly consistent worldwide, temperature variations are not. But
these temperature variations -- including the urban-rural disparity -- do
correlate well with energy consumption and local water vapor production.
Moreover, there appears to be a strong correlation between areas of
deforestation and temperature change, as our analysis suggests should be the
case. Temperature increases in the Amazon region and Siberia, where significant
deforestation is under way, seem to be unusually high (18). Now, one might note
that these regions are interior landmasses, and therefore distant from the
moderating thermal effects of the ocean. One might further hypothesize that
perhaps the entire earth is warming, but the oceans are moderating the warming
effect in coastal areas.
However, this seems unlikely. The interior areas of the United States such as
the Midwest Plains do not show warming, and these areas are not being
deforested; rather, farmland has replaced prairie grassland. The same could be
said for the interior grasslands of other continents. These areas show no
significant warming. This suggests that the moderating effect of the oceans may
not be sufficient to explain the data for continental interiors. The effects of
ongoing deforestation may be responsible.
Finally, the decrease in measured evaporation rates now also finds explanation.
While the decrease is puzzling when taken only in conjunction with a thesis of
global warming, it makes sense once we add human-related sources of water vapor
to natural evaporation. Furthermore, as expected, the atmospheric water vapor
content in North America (the one place where reliable data are available) has
been increasing during the two-decade period starting in 1973 (19).
On the view presented here, one would expect to see some correlation between
carbon dioxide levels and temperature change, since both water vapor and carbon
dioxide are major products of combustion. But water vapor's dominant role fits
better with the overall pattern of global data, helping to resolve the
contentious debate between those who see global warming and those who don't.
Local and regional warming are occurring, even if the global picture shows no
clear warming trend.
One additional note: the role of increased cloudiness and its albedo
(reflective) effect is not discussed here, and requires further study.
We Are Environmental Causes
In sum, atmospheric warming -- the warming for which we currently have the
clearest evidence -- is a local and regional phenomenon more than a global one,
and it appears to be due more to human-caused energy production and water
emissions than to carbon dioxide emissions.
This is not to take a position for or against global warming as such. Nor is it
to downplay the potentially grave significance of any large- scale alteration of
the natural environment. Nor again is it to dismiss the global significance of
local and regional warming. When a NASA study of the metropolitan Atlanta area
finds that the rainfall in rural areas southeast of the city, was the result of
Atlanta's "heat-island" effect, we can no longer deny mankind's effect on the
greater environment. The possibilities of even larger regional effects continue
to be studied by various researchers.
Even if the globally averaged temperature fluctuations reflect improper
measurements or natural periodic variations, it seems impossible to attribute
local and possibly regional temperature fluctuations to anything other than
man-made influences. We have yet to see a report that denies the existence of
the "heat-island" effect. There is also sufficient evidence to suggest that the
atmospheric levels of water vapor are rising and may be responsible for local
and regional changes in temperature and in weather patterns.
If there is a moral to the story, it is that prolonged scientific debate and
confusion can sometimes result from a failure to step back and look at all
aspects of a problem. And a second moral is that out-of-context technological
fixes aimed at a single aspect of a complex whole may prove destructive. Much of
the research on alternative fuels today is premised on the belief that water
vapor is a benign emission. But if we have learned anything over the past
decade, it is that a life-giving element can become destructive if it is removed
from a balanced context. The faith being placed in hydrogen and fuel cell
technologies (which emit nothing but water) may need more thorough study.
The only solutions that will truly decrease the destabilization of the
environment are those that work in conjunction with the entire natural process
found in any given ecosystem. A greater study and understanding of the complex
interactions found within natural ecosystems may indeed yield important details
in this regard and point to real solutions to these problems.
Michael D'Aleo (•••@••.•••), who is trained both as engineer and
educator, has spent a number of years working in industry, receiving several
patents along the way. His main interest has been to solve technical problems
artistically, based on processes found in the natural world. He currently
teaches physical science and mathematics at the Spring Hill Waldorf School in
Saratoga Springs, New York. He co-authored the recent book, Sensible Physics
Teaching, with Stephen Edelglass. D'Aleo is also a principal researcher at
SENSRI, a small organization in Saratoga Springs, New York, devoted to
phenomena-centered research.
Dr. Stephen Edelglass was for many years on the faculty of the Cooper Union for
the Advancement of Science and Art in New York City. He then taught high school
mathematics and physics at the Green Meadow Waldorf School in Spring Valley, New
York, until his death last year. In addition to Sensible Physics Teaching, he
co-authored The Marriage of Sense and Thought: Imaginative Participation in
Science. He was also a founder of SENSRI, a small organization in Saratoga
Springs, New York, devoted to phenomena-centered research.
References
1. Brown and Lemay, Chemistry, the Central Science (Englewood Cliffs N.J.:
Prentice-Hall, Inc, 1977), p. 302.
2. National Oceanic and Atmospheric Administration, "Global Warming Frequently
Asked Questions," Dec. 10, 1999.
http://www.ncdc.noaa.gov/ol/climate/globalwarming.html
3. Christy, John and Spencer, Roy, "Using Satellites to Monitor Global Climate
Change," 1999. http://www.atmos.uah.edu/essl/msu/background.html
4. Quattrochi, D. and Luvall, J., "Here Comes Urban Heat," Science @ NASA March
16, 2000. http://science.msfc.nasa.gov/headlines/y2000/essd16mar_1m.htm
5. Quattrochi, D. and Luvall, J., "NASA Studies Mother Nature's Air
Conditioners," ENN News Archive, May 15, 1997.
http://www.enn.com/enn-news-archive/1997/05/051597/05159718.asp
6. Zahoor, A., "Trees, Cities, and Global Warming Based on Effect of Trees in
Ameliorating Air Temperature in Urban Settings in Pakistan, ENN News Archive.
Doctoral dissertation in Range Resources at the Univ. of Idaho, 1997.
http://www.enn.com/enn-news-archive/1997/08/081997/08199713.asp
7. Graetz, D. "Fire's Role in Global Warming Studied," ENN News Archive, Sept.
27, 1999. http://www.enn.com/enn-news-archive/1999/09/092799/csirofire_5847.asp
8. Fisher, H., Whalen, M., Smith, J., Mastroianni, D., and Deck, B. "Ice Core
Records of Atmospheric CO2 around the Last Three Glacial Terminations," Science,
1999, 283:1712-1714.
9. Parlange, M. and Brutsaert, W., "Hydrological Cycle Explains the Evaporation
Paradox," Nature, Nov. 5, 1998.
10. Incropera, F. and DeWitt, D., Fundementals of Heat Transfer (New York: John
Wiley & Sons, 1981), Appendix A.
11. Borman, G. and Ragland, K., Combustion Engineering (New York: McGraw-Hill,
1998), pg. 8.
12. The World Almanac and Book of Facts (Mahwah, N.J.: Funk and Wagnalls, 1993),
pg. 361.
13. The World Almanac and Book of Facts (Mahwah, N.J.: Funk and Wagnalls, 1993),
pg. 415.
14. Watson, Donald, Designing and Building a Solar Home (Charlotte, Vt.: Garden
Way Publishing, 1977), pg. 12.
15. U.S. Department of Energy, EIA, Annual Energy Review.
http://www.eia.doe.gov/pub/energy/overview/aer1999/txt/aer0501.txt
16. Heywood, J.B., Internal Combustion Engine Fundamentals (New York: McGraw
Hill, 1988), p. 915.
17. The World Almanac and Book of Facts (Mahwah, N.J.: Funk and Wagnalls, 1993),
pg. 166.
18. Jones, et al., "Comparison Between Microwave Sounding Unit Temperature
Record and the Surface Temperature Record from 1979 to 1996: Real Differences or
Potential Discontinuities?", Journal of Geophysical Research 120:25, pp.
130-135.
19. American Geophysical Union, Water Vapor in the Climate System (Washington,
D.C., 1995). http://www.agu.org/sci_soc/mockler.html.
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