May 24, 2004


Chris Forest

I saw this article on /. and was pleasantly surprised. Not because this is the right answer but because this is opens up the discussion on nuclear energy as a part of the mixture of solutions required to begin addressing global climate change.

I would also point out a recently published report on Nuclear Energy, http://web.mit.edu/nuclearpower/ that also has served to stir up the debate. The report does not attempt to weigh this option against others but does lay out the issues to address. To summmarize the Executive Summary: "Four critical problems must be overcome: Cost, Safety, Waste, and Proliferation." If there can be publicly accepted solutions to these, then nuclear energy has a future in this mix of energy choices, perhaps not a permanent one but certainly in the next 50 years.

Why is this a good thing? *If* we find that global warming becomes a much bigger issue than as it's presently understood, in my opinion, we *must* consider nuclear energy in the mix. Why? Because every option will be needed, not just a chosen few. The current mix of viable carbon-free energy options includes "increased efficiency, expanded use of renewables, carbon-sequestration, and increased use of nuclear power." My understanding is that without a major research initiative like the Manhattan Project or Moon Mission, these will remain the near-term (few decades) choices. Anyone of these alone will make little difference in putting us "on a path" to stabilization which will require zero net emissions to be in balance. The key here is being "on a path" which will require taking a rational first step. The unknown future technologies will have their environmental threats most likely and it seems that we've already had 60 years of learning about nuclear energy. So, it seems that not including it as an option doesn't make sense, if the climate problem ends up being worse than expected.

My view is that the visceral response of the Greens is not unexpected but in the nature of this forum, probably there are other gut reactions that tend to balance this out.

Here's the Slashdot link:


One issue that I did find surprising in the /. discussion was that one of the underlying premises (climate change is occuring and that humans are partially responsible) was barely touched. Several posts attempted to attack this but I would have to conclude that most /. readers no longer find this alarming. Please comment on this if you like.

All for now,
Chris Forest PhD
MIT Climatology Dept.

Adrian Spidle

Great post, Chris. After our discussion the other evening I'm really concerned for the welfare of my children and grandchildre.

CleArly nuclear power is the most feasible solution at this time. How can we move it forward?


Adrian Spidle

Great post Chris. I have to admit that you have convinced me that action needs to be taken to solve/ameliorate this problem.

How would you prioritize the cost/effectiveness of the various possible solutions you've outlined. Would nuclear power or carbon sequestration be #1?


Chris Forest

Thanks, Adrian.

Re: Nuclear energy and its return. I think the MIT report summarized it well.
"Four critical problems must be overcome: Cost, Safety, Waste, and Proliferation."

The key is public acceptance and this was shot down by the Three Mile Island and Chernobyl disasters or the mishandling of nuclear materials in Japan several years ago. Will the public's trust ever be restored? Will the risks of nuclear energy ever match those of other options? This is not my expertise so I'm only guessing but if we have a few more severe summers like in Europe last year, public acceptance of nuclear might return. Clearly, France has been "successful" so far with their program and the world only needs to open their eyes and look for such successes and thereby learn from the 50 years of practice. Another major roadblock, besides cost, is the licensing process which is highly politicized. If the right-wing wants to take this on, they'll have to have a clear proposal with handling the "four problems."

Re: Carbon sequestration
Several carbon sequestration projects exist at the moment though not at the scale of producing a zero-emissions power plant. The research community is very active here and there are several alternatives. Burying CO2 in large saline aquifers has been demonstrated in a few places (e.g., off Norway). The ability to fertilize plant-life in the ocean is also a highly publicized option.

If I had to guess, CO2 sequestration is more politically palatable in the near term and, correspondingly, is getting the funding. It also wins on the "public acceptance" side over nuclear but the risks are less well known.

Re: other options
The big issue for me would be increasing efficiency and primarily in the transportation sector through cars and trucks. In the short term, it's unlikely that transportation will be emissions-free and so the fuel-cell or hybrid options are certainly going to become more competitive and start penetrating the market. The new Ford Escape Hybrid will drive like a V6 and get 30-40 mpg. (40mpg is what Ford considers the upper bound on the FWD version and so perhaps 30mpg will be closer to the 4WD version) The Chevy Silverado is being configured as a hybrid as well and so this market could be a big fuel savings... if people start to buy them.

To me, the toughest issue is convincing people to take these issues into consideration when making everyday choices. While it might be a no-brainer decision given the possible win-win scenarios, that doesn't translate into positive results unless it's also an easy alternative. Try convincing the local car dealer to push the hybrid cars, when the profit margin on the standard cars is obviously higher. I'm sure we could list many other examples in which social pressures make such choices less desirable.

Chris Forest

Adrian Spidle

To me, the toughest issue is convincing people to take these issues into consideration when making everyday choices. While it might be a no-brainer decision given the possible win-win scenarios, that doesn't translate into positive results unless it's also an easy alternative...

Chris Forest




Chris Forest

I was trying to look at ethanol subisidies and found this example of how one rule regarding a benefit to farmers has become twisted and is affecting people's vehicle choices:


"By taking advantage of a loophole in the tax code, small business owners can deduct the full cost of a SUV from their taxes. The provision, which allows deductions up to $100,000 on any vehicle heavier than 6,000 pounds, was originally intended to benefit farmers, who employ pickups and other heavy vehicles on a regular basis. But most SUVs weigh more than 6,000 pounds, and now the provision is being used by lawyers, doctors, and other self-employed individuals to write off SUVs bought for personal use."

Adrian Spidle

"I was trying to look at ethanol subisidies and found this example of how one rule regarding a benefit to farmers has become twisted and is affecting people's vehicle choices: "

Chris, I assume you think SUVs are dangerous to the environment. Could you please answer a few questions, then:

1 - How much greenhouse gasses are in the atmosphere,

2 - How much are added by human activity,

3- How much would be saved if SUV drivers switched to VWs.



Chris Forest

From Adrian: "I assume you think SUVs are dangerous to the environment."

I think this misses the point that loopholes like the one above make it difficult to let the "market" sort out where people can choose to adjust their fuel consumption when they are only looking at the short-term costs and not the cumulative effect of a vehicle's lifetime. The CO2 molecule emitted today will take 60-80 years to be removed from the atmosphere. Do people know or understand this issue? I seemed to have struck a nerve in the "Day After Tomorrow" thread where I was told to "lighten up". Effectively, this means let's let the next generation deal with the world we give them. Do we like to clean up messes made by other people? The "Golden Rule" is to treat others as you'd want to be treated. Apparently this doesn't apply to the next generation.

"Could you please answer a few questions, then:"

Q1: How much greenhouse gasses are in the atmosphere,

see http://www.giss.nasa.gov/data/

Q2: How much are added by human activity,

CO2 has increased from 275ppm to present-day concentrations of 375ppm.

Q3: How much would be saved if SUV drivers switched to VWs.

Approx. 6% of current co2 emissions in the US is coming from "Light Duty Trucks." For argument's sake, let us suppose one half of those are SUVs and that switching to hybrids (or VWs) would yield 50% improvement in efficiency (one third less fuel consumption). This means we get a reduction of US emissions of 1% with no investment costs. There are too many factors to do a bote estimate but I'm guessing that gas prices would be unaffected by this and so it would be a zero-cost alternative that is doable today. For some, it might even be cheaper.

Is a 1% reduction a large amount? I'd say it's modest. It would be a small step in the right direction.


Kathy Sue Angel

There's a great essay debunking greenhouse gases at


The Greenhouse Gas Myth
by Reason McLucus

© 2004

originally published at Mediard.com

The debate over human impact on climate is distressing because of the lack of science on both sides of the debate. The scientists involved are behaving more like people involved in political debates than in scientific debates. The debate focuses on superficial issues like average temperature rather than on the amount of heat present. Debaters talk about the amount of carbon dioxide(CO2) in the atmosphere and ignore the possible impact of the heat generated by human activity and the alteration of the thermal characteristics of the physical environment.

This situation is common in human political debates. Another common practice in political debates is looking at only those conditions which appear to validate the arguments of one side or the other rather than looking at all possibilities. Typically this process involves a linear view of relationships. Climate is highly chaotic and cannot be explained as the result of any linear process.

Those who warm of “global warming” claim that humans are increasing average temperatures by increasing the amount of the carbon dioxide in the atmosphere which they claim serves as a global thermostat even though it only constitutes about 0.035% of the atmosphere. Opponents claim if there is any such “warming” that it results solely from increases in the sun’s radiation output even though the earth’s billions of humans add terra calories of heat to the atmosphere daily and have modified the thermal characteristics of the earth’s surface..

The term “global warming” while useful as a political slogan has little scientific value. Average temperatures are as meaningless as the average family size which typically includes a fraction of a person. For example, temperature ranges between 60 and 90 F would have the same average temperature as a range between 50 and 100 F, but the former would be more conducive to biological activity than the latter.

Temperatures can be highly localized. The amount of shade present can affect temperatures as can structures which reflect light or protect an area from the wind. In winter low areas may have lower overnight temperatures than other areas. Areas near water may have higher temperatures. If temperature measurements aren’t taken from all types of areas the measurements may not reflect the actual global averages.

The impact of temperature depends more on the range of temperatures than on the average. For example, plants need temperatures within a particular range. Temperatures that are too cold, particularly below freezing, can cause plants to become inactive or even die. Temperatures that are too high can also inhibit growth or even cause fatal wilting.

Climate depends upon temperature distribution rather than average temperature. Climate in different regions can change with no change in average global temperature. For example, this past summer northwestern Europe suffered from high temperatures while the northeastern United States had cooler than normal temperatures.

The earth normally receives sufficient heat energy from the sun to preclude polar ice fields. The tilt of the earth prevents polar regions from receiving heat directly from the sun during part of the year allowing these regions to become extremely cold. The earth’s heat redistribution system moves some excess heat from tropical regions to polar regions. An increase in such heat movement, such as increased velocity for the Gulf Stream, can reduce ice cover. A decrease in heat movement, such as a blockage in the Gulf Stream’s return flow, could cause an increase in ice cover.

One sub debate involves the question of whether average temperatures were higher in the past than today. Such information cannot be obtained. Physical evidence and human accounts can show the extent to which conditions might have favored plant growth, for example, but not what the average temperature was. Favorable conditions would likely indicate a more moderate range of temperatures rather than temperatures too low or too high for plant growth. The “Medieval Warming Period” may not have been a period of higher average temperatures but a period of moderate weather instead of a period of frigid winters and hot summers.

Those who claim that CO2 plays a controlling role in atmospheric temperature fail to provide a scientific basis for this theory. The theory was originally proposed by Svante Arrhenius. His theory is based on earlier theories about the atom and its relationship with light that were subsequently disproved.

Mathematician Jean Baptiste Fourier proposed the theory that infrared radiation(IR)(which he called “dark heat”) was responsible for heating the atmosphere. Under his theory the atmosphere allowed the “light rays” from the sun to pass through and then absorbed the “dark rays” from the ground.

He and other 19th Century physicists believed that atoms were the smallest particles of matter. Atoms could not be further subdivided. An atom of one element could not be converted to the atom of another element( a process they termed “alchemy”).

Atoms were heated by absorption of radiation. Sadi Carnot considered and then rejected a theory in which a weightless fluid he called “caloric” carried heat. Various physicists speculated about the relative role played by carbonic acid(CO2) and “aqueous vapour”(water vapor)

Arrhenius defined the accepted theory of atmospheric heating in the article proposing his theory:

“It(heat absorption) is not exerted by the chief mass of the air, but in a high degree by aqueous vapour and carbonic acid, which are present in the air in small quantities. Further, this

absorption is not continuous over the whole spectrum, but nearly insensible in the light part of it, and chiefly limited to the long-waved part, where it manifests itself in very well-defined

absorption-bands, which fall off rapidly on both sides.” [Arrhenius article]

The debate over heating involved the question of whether CO2 or H2O were the primary molecules involved in heating. Arrhenius theorized that CO2 was most important and that changes in the amount of CO2 would produce corresponding changes in ground temperature. An increase in CO2 would increase temperature. A decrease would decrease temperature.

Svante Arrhenius (1859-1927) "On the Influence of Carbonic Acid in the Air upon the Temperature of the Ground" Philosophical Magazine 41, 237-276 (1896)http://webserver.lemoyne.edu/faculty/giunta/ARRHENIUS.HTML

If atoms were in fact single particles and absorbed light without reradiating it, the energy received by absorption of specific wavelengths of radiation would be likely to lead to the atom becoming hotter. Shortly after Arrhenius published his theory J.J. Thomson started a revolution in atomic theory by reporting his discovery that atoms were comprised of smaller charged particles. He subsequently stated that an atom of one element could be changed to an atom of another element(processes called fusion and fission).

Thomson believed that the charged particles were evenly distributed in the atom. Ernest Rutherford replaced that theory with a theory that electrons orbited a nucleus containing protons and neutrons like the planets orbit the sun.

Niels Bohr further refined this theory beginning with a idea that electrons existed within “shells”. Bohr also discovered that the absorption of specific wavelengths of light changed the internal energy state of the atom. Absorption caused electrons to shift to a high energy state. Emission of the same wavelength dropped the electrons back to the previous state. Theories about electrons changed in subsequent years, but not the theory about changes in energy state.

Arrhenius’ theory assumed that the continued absorption of IR would cause heating because the energy wouldn’t be released as radiation. The modern theory suggests that the emission of radiation would cause heating. Such a process is unlikely because individual molecules are unlikely to absorb significant amounts of energy per wave and thus would not release radiation with any significant amount of radiant energy. The initial radiation would carry more energy than the parts of waves absorbed by molecules and reemitted by individual CO2 molecules. The emission of the same wavelength of radiation from multiple sources creates destructive interference that neutralizes the radiation.

According to thermodynamic theory, each absorption and emission event would result in a very small amount of entrophy, the loss of useable energy. The greater the number on times radiation is absorbed and reemitted, the greater the entropy.

Any radiation emitted by CO2 molecules would only be absorbed by other CO2 molecules rather than by other molecules in the atmosphere. Thus CO2 radiation of IR wouldn’t affect the rest of the atmosphere.

Many of those who support the idea of CO2 as a greenhouse gas may not understand that IR is not a specific wavelength of light, but a very wide spectrum of light. The wavelength and wattage of IR emitted by various substances varies greatly according to the nature and temperature of the substance emitting the radiation. The absorption of radiation by specific chemicals involves specific wavelengths rather than a wide range. IR isn’t the only form of radiation emitted by matter. Engineers are currently working on cameras that detect radiation in the terra hertz range, sometimes called T-rays.

There are other serious problems with the claim that a minor atmospheric chemical can play a major role in regulating planetary temperature. CO2 comprises less than 0.04% of the atmosphere. Earth is generally a poor radiator of energy except for human artifacts.

The very small amount of CO2 means CO2 molecules would have to generate a substantial amount of extra heat to heat the rest of the atmosphere. CO2 has approximately the same specific heat as dry air. Thus each gram of CO2 would have to generate over 2,000 times the amount of heat necessary to heat a gram of CO2.

Water vapor can achieve this ratio because of water’s high specific heat(1.0 - dry air less than 0.25) and high heat of vaporization(540 calories per gram at the boiling point – about 580 at normal temperatures). Condensation of water vapor can release sufficient heat to raise the temperature of air with a mass of over 2,000 times the mass of the water.

This process is particularly important at the dew point, the temperature at which the atmosphere is saturated with water vapor. At this temperature the air normally cannot cool further without the condensation of water vapor. The 540 calories per gram that water vapor must release to condense keeps the air from cooling. The high specific heat of water magnifies this affect.

The combustion of hydrogen in hydrocarbon fuels adds water vapor to the atmosphere. If rainfall doesn’t increase by the same amount as the water added to the atmosphere by human activity then the water vapor content of the air will increase. If this increase raises the dew point above freezing, it will impact the amount of ice/snow cover.

Although the small percentage of CO2 in the atmosphere would limit any warming impact, if there was an impact, once the amount of CO2 reached a sufficient level to absorb all IR in the specific wavelength no more warming could occur.

Arrhenius and other 19th Century scientists believed that earth needed to radiate as much, or nearly as much, energy back into space as it received from the sun – that is function as a “black body”. Some scientists confuse the rock and water portion of the planet with the planet itself. The gaseous envelop that surrounds the planet is just as much a part of the planet as is the rock and water portion. Solar radiation that reaches the earth’s surface must penetrate miles of relatively dense atmosphere to heat the “interior” of the planet.

A biologically active planet like earth must use a significant portion of the energy it receives from the sun to fuel biological life. Plants convert sunlight into the chemical bonds used to produce plant structure. Plants in turn provide energy to animals that eat portions of the plants. Solar energy is also used to “do work” by evaporating water and then moving water vapor from the oceans deep inland to provide water for biological life. Entropy occurs at each energy transition stage.

The rock and water portion of earth is actually a poor radiator. Water like other transparent substances is a poor radiator because it is a poor absorber. Water generally releases heat through evaporation rather than radiation. Plants, which cover much of the rock, are ineffective radiators. Much of the energy they absorb is used to “do work” by growing the plant rather than to produce heat. Plants tend to be crowded together and radiation is more likely to be intercepted by other plants or other parts of the same plant than to be radiated toward space. Plants tend to release excess heat through evaporation of water rather than radiation because evaporation cools the plant faster than radiation would.

Desert sands tend to be poor radiators because they reflect much of the radiation back into space rather than absorbing it all and heating up.

Many human artifacts are good radiators. Black asphalt pavement is a particularly good absorber and radiator of solar energy. Buildings also may absorb and radiate heat well. Reflective glass buildings reflect radiation back and significantly increase heating of the air if several are in close proximity.

Mechanical devices directly heat the air as well as produce radiation. Outdoor lights radiate visible light into space as well as IR. Human beings are themselves good radiators. A human will stand out like a beacon against a natural background when viewed through IR sensitive cameras.

The subject of climatic change needs some real science to replace the believe in atmospheric gases with magical powers. In addition to the issue of how changes in solar radiation affect global heating, science should examine issues such:

1. The amount of heat energy present on the planet rather than looking at superficial atmospheric temperature;.

2. How heat generated by humans affects the amount of heat energy present in the system and how human artifacts affect heating on the rock surface;

3. The role of conduction and convection in redistributing heat energy among different areas as well as moving heat upward through the atmosphere;

4. The role of water vapor in moving heat around on the earth’s surface and moving heat from the rock and water portion of the planet upward through the atmosphere.

Solar Radiation

Although the earth’s interior is hot, the sun is responsible for heating the surface and atmosphere. Changes in solar radiation received are likely to cause different temperatures, but this impact is likely to involve a complex equation. Changes in solar radiation may not cause the same percentage change in earth’s temperature.

For example, the polar ice feedback loops may magnify the impact of changing radiation levels on temperature. As radiation increases, the area covered by ice declines causing less reflection of solar radiation back into space resulting in increased heating. As heating increases more ice melts, etc. Conversely reduced radiation means less melting and increased ice cover causing more reflection of radiation back into space lowering temperatures and further reducing melting.

1. Heat Energy Present

Looking only at atmospheric temperatures cannot provide an accurate measure of the amount of heat energy present on the planet. For example, an area with lower air temperature may actually have more heat energy than an area of higher temperature if the air in the cooler area has a higher water content. Water vapor has more heat energy than dry air because of water’s high heat of vaporization and higher coefficient of heat than dry air.

The relative amount of solid, liquid and gaseous water on the planet needs to be examined. Water’s heat of fusion of 80 calories per gram means that liquid water contains significantly more heat than frozen water. Thus the melting of polar ice caps means the planet contains more heat energy.

Soil and water temperature increases will cause eventual increases in air temperatures depending on the process of heat transfer to the atmosphere.

2. Direct Human Impact on Temperature

Humans generate substantial amounts of heat. Human artifacts can also affect temperatures. Scientists have known about urban heat islands for years. Cities may have temperatures as much as 10 degrees F higher than the surrounding countryside.

Asphalt roads are good radiation absorbers that also radiate well. Roads and buildings also transfer heat energy directly to the air through conduction. Plants are good absorbers of radiation, but they convert radiation into the chemical bonds of organic molecules rather Replacing plants, especially trees with roads and buildings increases heating.

Another way in which humans can increase heating isn’t as obvious. Cold blooded animals in water absorb heat from solar radiation and the surrounding water. Thus a reduction in the ocean’s fish population could increase water temperature and eventually air temperature.Human induced changes in water composition may also impact temperature by changing the rate at which water transfers heat to atmosphere.

3. Conduction and Convection

Those who talk about global warming emphasize energy transfer through radiation, but conduction and convection play a more important role in redistributing heat energy including heating the air. Conversion of heat energy into radiation is fixed according to the temperature and radiative characteristics of the radiating substance.

Conduction is potentially much faster because it depends on the relative differences in temperatures of the substances exchanging heat energy as well as their heat coefficients. A human body will lose heat faster in cold water than in cold air because water has a higher coefficient of heat than air. Water must absorb more heat to change its temperature.

As water and rock heat up from absorption of solar radiation they immediately begin heating the air in thermal contact. That heated air then rises because air becomes lighter in weight as it warms. Cooler air falls to the surface and begins warming.

Even highly radiative surfaces like asphalt roadways transmit significant amounts of heat energy to air through conduction. The “heat waves” rising from such surfaces are caused by conductive heating of the air by the roadway. On a sunny day partially exposed sections of roadway will conduct sufficient heat energy to ice covered areas to cause melting and evaporation of some of that ice even when air temperatures are below freezing.

Movement of large air masses can transfer heat from hotter areas to colder areas. Movement of cold air masses can cause cooling of surfaces in areas that had been warmer by increasing conduction of heat to the air.

4. Role of Water in Moving Heat

The Gulf Stream and other ocean currents move heat from tropic areas to colder regions. Water vapor plays a major role in moving heat from the surface up through the atmosphere.

Traditional physics has taught that the primary forms of heat transfer are conduction, convection and radiation. Evaporation is a fourth method of heat transfer. Evaporation transfers substantial amounts of heat from bodies of water, biological life and water covered solids to the atmosphere. Plants evaporate water from their leaves to release excess heat. Animals release heat through exhaling water vapor. Humans and some other animals lose water through the skin which then evaporates into the air.

As water vapor moves upward through the atmosphere it takes that heat with it. The condensation of that vapor in the atmosphere to form clouds releases this heat. In warm areas, some of this heat energy is converted into electrical discharges including discharges above the clouds called by such names as “sprites” and “blue jets”.

Clouds have a mixed impact on earth’s temperature. They reflect solar radiation back into space to reduce heating of the surface. Clouds also prevent air from rising and thus hold heated air closer to the surface.

The amount of water vapor in the atmosphere determines the minimum air temperature. The dew point is the temperature at which the air is so saturated with water vapor that some of it must condense out of the air. At ground level the air temperature normally will not drop below the dew point. Thus if the water vapor content of the air increases so will the average minimum temperature. The impact is most important from late fall through early spring. An increase in the number of days in which the dew point is above freezing reduces freezing and increases melting of ice. Northern waterways may freeze over later and resume flow earlier.

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