INDEPENDENTS, DEMOCRATS STILL ALIGNED IN ANGER 

Cold Facts on Global Warming

hat is the contribution of anthropogenic carbon dioxide to global warming? This question has been the subject of many heated arguments, and a great deal of hysteria. In this article, we will consider a simple estimate based on well-accepted facts, that shows that the expected global temperature increase caused by doubling atmospheric carbon dioxide levels is bounded by an upper limit of 1.76±0.27 degrees Celsius. This result contrasts with the results of the IPCC's climate models, whose projections are shown to be unrealistically high. Even though global warming has become mostly an academic concern now that the climate has moved into a cooling phase [24], it's still important to understand what is and is not factual about the climate.

The Greenhouse Effect

Fig. 1. Theory of global warming.

There is general agreement that the Earth is naturally warmed to some extent by atmospheric gases, principally water vapor, in what is often called a "greenhouse effect". The Earth absorbs enough radiation from the sun to raise its temperature by 0.5 degrees per day, but is theoretically capable of emitting sufficient long-wave radiation to cool itself by 5 times this amount. The Earth maintains its energy balance in part by absorption of the outgoing longwave radiation in the atmosphere, which causes warming.

On this basis, it has been estimated that the current level of warming is on the order of 33 degrees C [1]. That is to say, in the absence of so-called greenhouse gases, the Earth would be 33 degrees cooler than it is today, or about 255 K (-0.4° F) [2]. Of these greenhouse gases, water is by far the most important. Although estimates of the contribution from water vapor vary widely, many sources place it between 90 and 95% of the warming effect, or about 30-31 of the 33 degrees [3, 25]. Carbon dioxide, although present in much lower concentrations than water, absorbs more infrared radiation than water on a per-molecule basis and contributes about 84% of the total non-water greenhouse gas equivalents [4], or about 4.2-8.4% of the total greenhouse gas effect.

Of course, this 33 degree increase in temperature is not caused simply by absorption of radiation by the gases themselves. Much of the 33 degree effect is caused by the Earth's adaptation to higher temperatures, which includes secondary effects such as increased water vapor, cloud formation, and changes in albedo or surface reflectivity caused by melting and aging of snow and ice. Accurately calculating the relative contribution of each of these components presents major difficulties.

The theory of global warming is shown in Fig. 1. Infrared radiation comes from two sources: the sun and the earth's surface. CO2 absorbs some of the infrared radiation and re-emits it in a random direction. If there is more CO2, the radiation is absorbed closer to the source. For radiation from the sun, this theory predicts that increased CO2 would cause cooling in the upper atmosphere and warming in the lower atmosphere. Thermometer measurements show that the lower atmosphere was warming between about 1906 and 1944 and between about 1976 and 1998, and either constant or cooling at other times. However, the validity of the temperature figures is hotly disputed on both sides because the issue is highly political.

Global Warming Potential (GWP)

Traditionally, greenhouse gas levels are presented as dimensionless numbers representing parts per billion (ppb) multiplied by a scaling factor (global warming potential or GWP) that allows their relative efficiency of producing global temperature increases to be compared. For carbon dioxide, this scaling factor is 1.0. The factors for methane and nitrous oxide are 21 and 310, respectively, while sulfur hexafluoride is 23,900 times more effective than carbon dioxide [5]. The GWP from carbon dioxide is primarily due to the position of its absorption bands in the critical longwave infrared region at 2, 3, 5, and 13-17 microns.

Methane, nitrous oxide, ozone, CFCs and other miscellaneous gases absorb radiation even more efficiently than carbon dioxide, but are also present at much lower concentrations. Their high GWP results from their molecular structure which makes them absorb strongly and at different wavelengths from water vapor and carbon dioxide. For example, although ozone is usually thought of as an absorber of ultraviolet radiation, it also absorbs longwave infrared at 9.6 microns. These gases account for another 1.3% of the natural greenhouse gas effect. The increase in the global energy balance caused by greenhouse gases is called "radiative forcing".

The GWP of a greenhouse gas is the ratio of the time-integrated radiative forcing from 1 kg of the gas in question compared to 1 kg of carbon dioxide. These GWP values are calculated over a 100 year time horizon and take into consideration not only the absorption of radiation at different wavelengths, but also the different atmospheric lifetimes of each gas and secondary effects such as effects on water vapor. For example, methane contributes indirectly to the production of tropospheric ozone and stratospheric water vapor. For some gases, the GWP is too complex to calculate because the gas participates in complex chemical reactions. Most researchers use the GWPs compiled by the World Meteorological Organization (WMO).

Even though most of the so-called greenhouse effect is caused by water vapor, about 1-2 degrees of our current empirically-measured temperature of roughly 288 K (59° F) can be attributed to carbon dioxide. Water vapor at least 99.99% of 'natural' origin, which is to say that no amount of deindustrialization could ever significantly change the amount of water vapor in the atmosphere. Thus, climatologists have concentrated mostly on carbon dioxide and methane. However, in the past few years, a few climatologists have started talking about anthropogenic increases in atmospheric water vapor [17]. This validates suspicions that, if environmentalists get their way with CO2, a campaign to force us to reduce water vapor could well be next.

Carbon Dioxide Levels

The Carbon Dioxide - Bicarbonate Equilibrium 
CO2 dissolves rapidly in water, and reacts with water to form carbonic acid, which rapidly ionizes to form bicarbonate and carbonate. Dissolved CO2 causes water to become slightly acidic; the current atmospheric levels of CO2 are sufficient, in the absence of other factors, to cause pure water to have a pH of 5.7, which is roughly the same pH as normal rain. However, the oceans contain many other pH buffers, including borate, phosphate, and silicate, which tend to counteract this effect, while acid rain increases it. The pH of sea water today is typically between 7.36 and 8.4, which is slightly basic.

Living cells contain the enzyme carbonic anhydrase, which greatly accelerates the reaction in both directions, helping cells to get rid of excess CO2. Bicarbonate is also sequestered by plants and animals to form calcium carbonate. The vast majority of the earth's carbon is locked in the form of limestone and other carbonate rocks.

Figures from the U.S. Department of Energy show that the pre-industrial baseline of carbon dioxide is 288,000 ppb. The total current carbon dioxide is 368,400 parts per billion, or 0.0368% of the atmosphere.

The ocean and biosphere possess a large buffering capacity, mainly because of carbon dioxide's large solubility in water. Because of this, it is safe to conclude that the anthropogenic component of atmospheric carbon dioxide concentration will continue to remain roughly proportional to the rate of carbon dioxide emissions for any conceivable rate of human emission. In other words, the carbon dioxide buffers are in dynamic equilibrium with atmospheric carbon dioxide and are not in any danger of being saturated, which would allow all the emitted carbon dioxide to go into the atmosphere. This means:

• The percentage of emitted carbon dioxide that ends up in the atmosphere can be treated as approximately constant. This percentage is about 50% [6]. However, the buffering capacity of the oceans is enormous. The oceans currently contain about 50 times as much CO2 as the atmosphere [20].
• The effects of carbon dioxide emissions are not cumulative. That is, lowering carbon dioxide would produce an almost instantaneous reduction (on a climatological scale) in any warming effect that it was producing.
• If fossil fuel use increases or decreases, atmospheric carbon dioxide will also increase or decrease proportionately.

Comment added 1/5/2008: 
This last point has been misinterpreted by some commentators. To clarify, this means that if we were to stop emitting carbon dioxide, the CO2 levels in the atmosphere would rapidly return to pre-industrial levels. Geologists tell us that the residence time of CO2 in the atmosphere is on the order of five to ten years [23]. In contrast, the IPCC says it is 50-200 years. Whatever the actual number, there is no question that emitting CO2 will cause it to accumulate over short periods. But other processes, such as sequestration, also work against it, causing the levels to decrease rapidly over time.

This fact is the very basis of the effort among global warming advocates to lower CO2 emissions. Indeed, if this were not true, there would be no possible benefit to reducing CO2 emissions, as CO2 levels would ratchet up indefinitely, whether by natural or artificial means, without limit.

Amplification and Dampening

Of course, climate, like weather, is complex, nonlinear, and perhaps even chaotic. Increased solar irradiation can lower the surface albedo (reflectivity), which could amplify any effect caused by changes in solar flux, making the relation between radiation and temperature greater than linear. A change in albedo can occur through several factors: (1) at the edges of snow/ice cover, where snow and ice cover bare ground or vegetation for only part of the year; (2) as ice cover ages, its reflectivity can change; and (3) dust and dirt can land on top of the ice, increasing absorption of light.

Increased temperatures also cause increased evaporation of sea water, which can cause warming because of water's greenhouse effect, and also can by creating additional clouds, which reflect more radiation into space. On the other hand, increased plant growth, especially in the oceans, would tend to extract carbon dioxide from the atmosphere, making the fraction of emitted carbon dioxide that stays in the atmosphere lower. Thus, higher emissions would probably cause a slightly smaller proportion of carbon dioxide to remain in the atmosphere than is currently the case, tending to make the relation less than linear.

Absorption of Infrared Radiation

Fig.2. Transmitted light is a logarithmic function of concentration. This curve is the familiar Beer's Law.

The arithmetic of absorption of infrared radiation also works to decrease the linearity. Absorption of light follows a logarithmic curve (Fig. 2) as the amount of absorbing substance increases. It is generally accepted that the concentration of carbon dioxide in the atmosphere is already high enough to absorb almost all the infrared radiation in the main carbon dioxide absorption bands over a distance of only a few km. Thus, even if the atmosphere were heavily laden with carbon dioxide, it would still only cause an incremental increase in the amount of infrared absorption over current levels.

This means that a situation like Venus could not happen here. The atmosphere of Venus is 90 times thicker than Earth's and is 96% carbon dioxide, making the atmospheric carbon dioxide concentration on Venus 300,000 times higher than on Earth. Even so, the high temperatures on Venus are only partially caused by carbon dioxide; a major contributor is the thick bank of clouds containing sulfuric acid [7]. Although these clouds give Venus a high reflectivity in the visible region, the Galileo probe showed that the clouds appear black at infrared wavelengths of 2.3 microns due to strong infrared absorption [8]. Thus, Venus's high temperature might be entirely explainable by direct absorption of incident light, rather than by any greenhouse effect. The infrared absorption lines by carbon dioxide are also broadened by the high pressure on Venus [9], making any comparison with Earth invalid.

Very little of the radiation from the sun at the wavelengths at which carbon dioxide absorbs reaches the surface of the Earth directly (see Fig. 3) [10]. Similarly, very little of the radiation at these wavelengths that originates at the surface makes it all the way to space. Most of the infrared at these wavelengths is produced by black body radiation from objects that have been heated up by absorbing radiation at shorter wavelengths. This means that even if the carbon dioxide levels increase, it will have little effect on the total amount of infrared radiation that is absorbed from the sun. The main effect would be to trap radiation originating at the surface at lower levels in the atmosphere than before, where it would be slightly more difficult for the heat to be re-radiated back into space. This is the principle on which most of the global warming predictions are based.

CO2 is more evenly distributed than water, so if CO2 caused warming it would have a proportionately greater effect in areas where there is little water vapor (such as deserts and in very cold regions), while in areas with a lot of water, the effect of CO2 may be insignificant (in terms of its effect on local temperature) compared to the effect of water vapor. This is one of many factors that mitigate against the idea of a "climate catastrophe." [16]

Fig.3. Absorption of ultraviolet, visible, and infrared radiation by various gases in the atmosphere. Most of the ultraviolet light (below 0.3 microns) is absorbed by ozone (O3) and oxygen (O2). Carbon dioxide has three large absorption bands in the infrared region at about 2.7, 4.3, and 15 microns. Water has several absorption bands in the infrared, and even has some absorption well into the microwave region. There is already sufficient CO2 in the atmosphere to absorb almost all of the radiation from the sun or from the surface of the earth in the principal CO2 absorption bands. (Data from ref. [1], page 93; original data are from Howard et al [21] and Goody [22]).

The net effect of all these processes is that doubling carbon dioxide would not double the amount of global warming. In fact, the effect of carbon dioxide is roughly logarithmic. Each time carbon dioxide (or some other greenhouse gas) is doubled, the increase in temperature is the same as the previous increase. The reason for this is that, eventually, all the longwave radiation that can be absorbed has already been absorbed. It would be analogous to closing more and more shades over the windows of your house on a sunny day -- it soon reaches the point where doubling the number of shades can't make it any darker.

Another way of looking at it is by thinking of adding blankets to your bed on a cold night: if you have no blankets, adding one will have a big effect. If you have a thousand blankets, adding another thousand will have an unmeasurably small effect.

The analogy with a greenhouse would be that the glass in the roof becomes slightly thicker. The effect of warming also depends on the conditions inside the greenhouse. If the greenhouse were full of ice at exactly -0.01 degrees Celsius, making the glass slightly thicker just might be enough to melt all the ice and flood the greenhouse. But if the greenhouse had some regions that were hot and some that were very cold (as the planet Earth does), it would have a very small overall effect.

As an aside, the term "greenhouse effect" is actually a misnomer. In greenhouses, most of the warming that is observed is not caused by carbon dioxide, or by absorption of infrared radiation by the glass as many people think, but by reduction in convection [11].

What does 'saturation' mean?

Many people seem to be confused about the "saturation" argument. It's easy to calculate, using the known extinction coefficients [10], that 99% of the radiation in the CO2 absorption bands is absorbed within only a few tens to hundreds of meters of the source. These coefficients are derived from measurements in modern, high-resolution spectrometers. But strong absorption is also found even with older, lower-resolution instruments. So what does this mean? Is the global warming theory false? Or should older measurements not be trusted? Here is what it means:

1. The "saturation" argument does not mean that global warming doesn't occur. What saturation tells us is that exponentially higher levels of CO2 would be needed to produce a linear increase in absorption, and hence temperature. This is basic physics. Beer's law has not been repealed. 
   
2. Some people have gotten the idea that water vapor, which is mainly present at lower altitudes, is somehow necessary for the CO2 to absorb infrared radiation, and that therefore at higher altitudes, CO2 is not anywhere near saturation. This is not true. The presence or absence of water vapor has no bearing on whether radiation is absorbed by CO2. That is because, for all practical purposes, the absorption bands of H2O and CO2 important for warming are different. (If they weren't, CO2 absorption would be so insignificant compared to water vapor that it wouldn't be a potential problem, and we wouldn't be having this discussion.) 
   
3. CO2 is very nearly homogeneous throughout the atmosphere, so its concentration (as a percentage of the total) is about the same at all altitudes. Although the pressure is lower at high altitudes, there is also a much greater volume. That is why the ozone layer, which is around 30-90 km in altitude, is still able to absorb almost all of the shortwave UV, even though its concentration is only 8-12 ppm. So the importance of low concentrations of gases should not be underestimated. But water vapor is a red herring: it has essentially no effect on what CO2 does. Where water vapor becomes important is in the earth's response to CO2. 
   
4. Some people also think that line broadening of the CO2 absorption lines by pressure, water vapor, or temperature provides an escape from the saturation dilemma. But in line broadening, the absorbance is peak is only smeared out; the total amount of energy absorbed is not affected. For the same reason, measurements with lower-resolution spectrometers, which slightly smear out the absorption lines, are still valid.

Saturation does not tell us whether CO2 can raise the atmospheric temperature, but it gives us a powerful clue about the shape of the curve of temperature vs. concentration.

Calculating the actual temperature increase

So, what is the actual increase? Interestingly enough, that is easy to estimate--and without resorting to complex computer models.

Because a linear increase in temperature requires an exponential increase in carbon dioxide (thanks to the physics of radiation absorption described above), we know that the next two-fold increase in CO2 will produce exactly the same temperature increase as the previous two-fold increase. Although we haven't had a two-fold increase yet, it is easy to calculate from the observed values what to expect.

Between 1900 and 2000, atmospheric CO2 increased from 295 to 365 ppm, while temperatures increased about 0.57 degrees C (using the value cited by Al Gore and others). It is simple to calculate the proportionality constant (call it 'k') between the observed increase in CO2 and the observed temperature increase:

This shows that doubling CO2 over its current values should increase the earth's temperature by about 1.85 degrees C. Doubling it again would raise the temperature another 1.85 degrees C. Since these numbers are based on actual measurements, not models, they include the effects of amplification, if we make the reasonable assumption that the same amplification mechanisms that occurred previously will also occur in a world that is two degrees warmer.

If we want to include other greenhouse gases, such as methane, in the calculation, we need to use the "effective" CO2 concentrations instead. These effective CO2 numbers are less solid than the CO2-only numbers, but the best estimates are that effective CO2 increased from 305 to about 450 ppm during the 20th century[12]. Using these numbers, k becomes 0.6823 and the predicted ΔT becomes 1.02 degrees.

These estimates assume that the correlation between global temperature and carbon dioxide is causal in nature. This remains to be proved. Therefore, the 1.02 and 1.85 degree estimates should also be regarded as upper limits.

Refinements to the estimate

Unfortunately, the above calculations slightly overestimate the degree of warming, because they allow the temperature to rise indefinitely. At very high CO2 levels, self-absorption would become a limiting factor. A more accurate calculation is shown below.

A reader named Ted Ladewski made an interesting suggestion: use the 255K zero-greenhouse gas data point, where there is zero CO2, as a data point, and fit the other points to a smooth curve. To maximize the accuracy of the estimate, we will only use global CO2 and temperature values between 1900 and 2000 [14], about which there is relatively little dispute, and ignore estimates of prehistoric values, which could be more affected by changes in solar flux and other factors. This gives a total of 102 data points. These points are shown in blue in the figure below.

Including the CO2 = 0 data point severely constrains the shape of the curve (and, interestingly, effectively rules out any sort of hockey stick-shaped curve). It is also clear that some sort of monotonically-increasing curve, and not a straight line, has to be used. The best fit was obtained with a hyperbola. If the 102 data points are fitted to a hyperbola, we obtain 288.92 ±0.27K (±1 SD) for 736 ppm CO2 (red line).

The present-day value is taken as the average of the global mean temperatures between 1980 and 2000, or 287.17K. If the above estimate is correct, this means that the temperature would increase by 1.76 ±0.27°C above the present-day value when CO2 levels double their present levels. This is very close to the 1.85°C calculated above.

Stated differently, doubling CO2 from its pre-industrial value would increase the temperature about 1.2 degrees Celsius. 
 
Fig. 4.

However, there is a problem with this method. The 255K data point is not just zero CO2, it is zero water vapor as well. In reality, there would always be some water vapor present, even if there were no CO2. This means that the actual temperature for zero CO2 would be higher than 255K, which would change the shape of the curve. For example, if the CO2=0 value was 271 (halfway between 255 and the current temperature), the prediction changes to 288.55K, or about a 1.39 degree increase for doubling of CO2. This can be seen in the blue curve (see enlarged graph below). The result is not much different than the 1.76, but the important point is that as the estimates become more realistic, the predicted temperature does not increase, but decreases slightly. 
 

Fig. 5.

Fitting other curves to these data points gives similar results. For example, Ted Ladewski suggested deriving an exponential curve from Beer's Law. Although there are obvious problems involved in applying Beer's Law quantitatively to a transparent medium as complex as the atmosphere (as he discusses in greater detail on his website,http://mysite.du.edu/~etuttle/weather/atmrad.htm#Spec), the equation he recommends is:

where AIo and k are constants, C is the CO2 concentration, and T is temperature. (This is also discussed in http://www.sjsu.edu/faculty/watkins/GWnonlinear.htm )

Fitting the data to this equation, as shown in the brown curve in the figure above, gives the much lower value of 287.62±0.07 K (±1 SD), or 0.46±0.08 °C increase above the 1980-2000 mean for a doubling of CO2 from current values.

Although extrapolating beyond the ends of the data, as is done here and as is done with climate models, is hazardous, it's clear that both of these curves are significantly lower than a straight linear estimate. The hyperbola is probably closest to the actual value, because it makes the fewest assumptions about the underlying physical processes. In any case, both estimates should be regarded as upper limits because, as mentioned above, they assume that CO2 is the root cause of the observed changes in temperature.

How long will it take to double CO2 levels?

Another issue that people are confused about is the rate of increase of carbon dioxide. Some people think that CO2 is rising dramatically. This is probably because of graphs like the one below.

 
Fig. 6.

However, in hard science journals, the graph above would be considered dishonest, because the y-axis starts at 290 instead of zero. This misleads the reader into thinking that CO2 levels have undergone a huge increase when in fact, CO2 levels have only increased by 23.7% since 1900. When the data are plotted honestly, with the y axis starting at zero, the true scope of the change becomes clear.

 
Fig. 7.

According to the US Department of Energy, about 14.8% of the total CO2 is man-made. The remainder is caused by natural forces, such as volcanoes and forest fires [25].

At the current rate of increase, CO2 will not double its current level until 2255.

 
Fig. 8.

Some climatologists, making assumptions about ever-increasing rates of carbon dioxide production, assert that the doubling will occur within a few decades instead of a few centuries. However, they are doing sociology, not climatology. They are assuming that fossil fuel consumption will increase drastically over current levels. This is very unlikely. The only honest way to estimate the change of CO2 levels is to make predictions based on what is happening now, not what might happen in some hypothetical future society; otherwise, we are merely inflating our predictions by indulging in speculation about future social trends.

Many people have used tricks like these to exaggerate the amount of global warming, and this has made it into a political issue. Most people would have great difficulty feeling an increase of 0.6 degrees Celsius. Any effects of such a small change would be slow and subtle. In general, if you are able to see or feel some change, that means it is almost certainly not caused by CO2-induced global warming.

Secondary effects

What about secondary effects, such as ice melting, changes in albedo, and so forth? Doesn't this increase the predicted temperature beyond the 1.39 to 1.76 degree estimate?

In short, no. Because these calculations are based on observed measurements, they automatically take into account all of the earth's responses. Whatever way the climate adapted to past CO2 increases, whether through melting, changes in albedo, or other effects, is already reflected in the measured temperature, and therefore it will also be reflected in the prediction. This is because the prediction is based on an extrapolation of past measurements that were taken after the earth adapted to the CO2 increase.

In order to get higher temperatures than those predicted above, it would be necessary to assume that a small increase in warming causes a large change in the amplification effect that had never occurred before. In other words, the "rules of the game" would have to drastically and abruptly change in a fundamentally new way--in response to an increase of only one or two degrees. Such changes do not occur in the real world--only in computer models. (If these so-called "tipping points" existed, random, day-to-day, and seasonal variability would have pushed us past them a long time ago.)

This is what makes the "empirical" method superior to all the computer models, as sophisticated as they may be. The empirical model just looks at what's happening and makes a reasonable extrapolation, with very few prior assumptions. The only drawback of the empirical method is that it can only predict an upper limit, because it does make one big assumption: that correlation implies causality. Therefore, although the actual warming cannot be greater than the predicted estimate, it could be considerably less.

Masking

Some climatologists may object to the foregoing analysis, pointing out that the effects of an increase in CO2 could be masked by sulfate aerosols or other factors. For example, the eruption of Mount Pinatubo in 1991 released large amounts of volcanic aerosols that may have been responsible for a brief global cooling [18]. However, later studies showed that water vapor feedback was necessary to account for this effect [19]. Applied to global warming, the reasoning is that human sulfate emissions might "mask" warming by cooling the atmosphere. In the future, they say, sulfate emissions might decrease while CO2 remains constant, and the true global warming would be revealed.

The problem here is that trying to account for sulfates drags us into the morass of modeling of social trends. It is much more reasonable to assume that, as industry shifts production to developing countries and people use more coal and high-sulfur oil to replace dwindling supplies, that sulfate emissions will greatly increase. Additionally, sulfates are only one factor. Many other factors, even including such things as cosmic rays, have been shown to have potential effects on climate. Some of these hypothetical effects would cause warming and some would cause cooling. We need to focus on what can be measured directly. The only issue is whether CO2 is a problem. To add or subtract these myriad hypothetical effects, and claim that the actual amount of warming that is occurring is different from the warming that can be observed, only serves to take climatology that much closer to metaphysics.

One reader pointed out a similar factor that is sometimes mentioned: the heat absorbing capacity of the oceans. Water has 4.13 times the heat capacity of air on a weight basis at 25°C (2.58 times on a molar basis). The oceans contain 273 times as much mass as the atmosphere, and the top few meters alone can store as much heat energy as the entire atmosphere. Thus, much of the extra heat is undoubtedly going into the oceans. But what does this really mean? If the oceans masked all the warming by absorbing the heat, we would have to multiply the time scale by about 1128 before we see the real warming. That means warming that we thought would occur over a 250-year time period would actually take 250×1128 = 282,000 years. By then, humans will almost certainly be getting their energy from some other source besides combustion of hydrocarbons. And then there is the earth's crust, which can absorb additional heat over a scale of billions of years.

Linear Climate Projections

An alternative way of calculating future temperature increases is to consider the fraction of warming that is caused by CO2. To do this, we cannot just use the fraction of radiation that is absorbed by CO2, because that does not take feedback processes into account.

As a first step, let us suppose that temperature increases linearly with greenhouse gas concentrations. From the above numbers, it is easy to calculate that a doubling of atmospheric carbon dioxide would produce an additional warming of (0.042 to 0.084) x 33 = 1.38 to 2.77 degrees centigrade. This is the temperature change one would expect that if CO2 doubles over its current levels.

It is important to realize that the original factor of 0.042 to 0.084 used in these calculations represents the incremental fraction of the total global warming, taken as a holistic phenomenon, initiated by carbon dioxide. This means that the calculation automatically includes the secondary and amplification effects caused by increased water vapor, changes in albedo, and so forth, caused by including the Earth's adaptation to the increment of carbon dioxide.

Fig. 9. Estimated greenhouse gas-induced global warming plotted against greenhouse gas concentrations expressed as a percentage of current-day values. The black curve is a linear extrapolation calculated from the DOE estimates of total current greenhouse gases. The sharp jump at the right is the data point from one computer model that predicts a nine degree increase from doubling current levels of carbon dioxide. Marked, unphysical deviations from linearity resulting in thermal runaway (red curve) are required to fit this data point with the two known points. Such a strong nonlinear effect is difficult to reconcile with our current understanding of climate.

However, our results are based on the assumption that the increase in temperature is linearly proportional to the greenhouse gas levels. This is not true. The relationship is not linear, but logarithmic. If we plot temperature vs. gas concentration (expressed as a percentage of current-day levels), we obtain a convex curve, something like the blue curve in Fig. 9. Thus, the 1.4-2.7 degrees obtained from our linear estimate is an upper bound, and depending on the exact shape of the blue curve, could be a large overestimate of the warming effect.

It goes without saying that the results from this method depend on the accuracy of the 5% estimate (from ref. [3]) and the validity of extrapolating the existing curve by an additional increment. The exact number is very difficult to pin down.

Note added 1/5/2008: 
Some authors [15] suggest that the percentage of warming attributable to CO2 is not 5%, but is closer to 26%. It is easy to show why the 26% estimate (and estimates similar to it) are almost certainly wrong. We know that the total warming from greenhouse gases is 33K. If 26% of this was from CO2, then doubling CO2 would raise temperatures by 0.26*33 or 8.6K. Since the 26% estimate is based on total radiation absorbed, and not the amount of warming, we would have to add secondary feedback effects to this figure. This would double or even triple the value, giving us a predicted temperature increase of up to 25° C, or a predicted global average temperature of 40°C (104°F). Balmy!

Whether the exact number is 5% or 9%, because our estimate is based on the percentage of warming, not percentage of radiation absorbed, that is attributable to CO2, feedbacks in the estimate here are automatically taken into account. However, because of the large uncertainty about the actual value, the estimate from Fig. 4 (which derives an estimate from extrapolation of current trends) is probably more accurate.

However, we can also check the plausibility of the IPCC's result by asking the following question: What number would result if we calculated backwards from the IPCC estimates?

Using the same assumption of linearity, if a 9 degree increase resulted from the above-mentioned increase of greenhouse gas levels, the current greenhouse gas level (which is by definition 100%) would be equivalent to a greenhouse gas-induced temperature increase of at least 107 degrees C. This means the for the 9 degree figure to be correct, the current global temperature would have to be at least 255 + 107 - 273 = 89 degrees centigrade, or 192° Fahrenheit! A model that predicts a current-day temperature well above the highest-ever observed temperature is clearly in need of serious tweaking. Even a 5 degree projection predicts current-day temperatures of 41°C (106°F). These results clearly cannot be reconciled with observations.

In order for the 9 degree estimate to make sense from a physical standpoint, we are forced to draw an exponential curve through the graph above (shown in red) through the three points instead of a straight line. However, this curve creates an even worse result: it predicts a thermal runaway. A thermal runaway is a reaction that suddenly switches from a smooth curve and goes wildly out of control. For the the nine-degree climate model to fit the observations, the curve that we must draw predicts that a 10 or 20% increase in greenhouse gases above their current levels would cause an infinite increase in temperature! Of course, some other factor (such as explosion of the Earth in a supernova-type explosion) would undoubtedly kick in to save us before an infinite temperature could be reached. But even so, it can be seen that an above-linear increase in temperature with increasing gas concentration is not only unphysical, but inconsistent with observations.

Although the estimates of global warming made by the IPCC and the predictions of "environmental catastrophe" made by environmental groups have gradually creeping back down as climate models gradually improve, environmentalists still worry that temperatures could increase by as much as 3 to 5 degrees over the next century.

However, even a 5 degree increase in temperature over the next century would constitute a significant departure from the previous rates of increase. It is clear from Fig. 9 that this too would be a marked deviation from the curve. Such strong nonlinear effects, especially when they are in the wrong direction from a physical standpoint, are difficult to reconcile with our current understanding of climate.

Conclusion

Although carbon dioxide is capable of raising the Earth's overall temperature, the IPCC's predictions of catastrophic temperature increases produced by carbon dioxide have been challenged by many scientists. In particular, the importance of water vapor is frequently overlooked by environmental activists and by the media. The above discussion shows that the large temperature increases predicted by many computer models are unphysical and inconsistent with results obtained by basic measurements. Skepticism is warranted when considering computer-generated projections of global warming that cannot even predict existing observations.

References and Notes

[1]. Peixoto, J.P. and Oort, A.H., Physics of Climate Springer, 1992, p. 118.
[2]. Thomas, G.E. and Stamnes, K. Radiative Transfer in the Atmosphere and Ocean. Cambridge University Press, 1999, p. 441.
[3] Most credible sources place the number at 95%. 
95% = Michaels, P.J. and Balling, R.C., The Satanic Gases. Cato Institute, 2000 p.25. 
90-95% = http://www.globalwarming.org/node/62 
90% = http://www.ncpa.org/press/transcript/globalwm/global2.html Norman J. Macdonald Carbon dioxide is about 5 percent, water vapor 90. 
Here is a paper that gives a different figure: http://www.atmo.arizona.edu/students/courselinks/spring04/atmo451b/pdf/RadiationBudget.pdf" 
S.M. Freidenreich and V. Ramaswamy, Solar Radiation Absorption by Carbon Dioxide, Overlap with Water, and a Parameterization for General Circulation Models. Journal of Geophysical Research 98(1993):7255-7264 
[4]. U.S. Climate Action Report 2000, US Environmental Protection Agency, page 38.
[5]. Houghton, J.T. et al, eds. Climate Change 1995: The Science of Climate Change (IPCC report), 1996, Cambridge University Press. http://www.ipcc.ch/pub/sarsum1.htm
[6]. Peixoto, J.P. and Oort, A.H., Physics of Climate. Springer, 1992, p. 436.
[7]. http://www.aas.org/publications/baas/v33n3/dps2001/354.htm
[8]. http://www2.jpl.nasa.gov/galileo/slides/slide3.html
[9]. Ma, Q., and R.H. Tipping, J. Chem. Phys., 96, 8655-8663, 1992.
[10]. [note added Feb 15, 2007] This can be easily calculated from the absorption of gaseous carbon dioxide. See Phys. Rev. 41, 291 - 303 (1932) P. E. Martin and E. F. Barker "The Infrared Absorption Spectrum of Carbon Dioxide". 

Thomas and Stamnes (ref. 2, page 91) that shows 0% transmittance at 22 km and below for the 15 micron CO2 band. This section discusses the "opaque region" and also gives a very clear discussion of line broadening, which is an additional point that many people are unfamiliar with. 

Schneider, Kucerovsky, and Brannen (Appl. Opt. 28:5, 1998) give an absorption coefficient at 9.90 ± 1.49 cm-1 atm-1 for low concentrations of CO2 in a 1-atm nitrogen atmosphere at 4.2 microns. This works out to 376 absorbance units per km for 380 ppm CO2, which is about as close to 100% absorption as you can get. Heinz Hug, a global warming skeptic, measured a similar value (0.03 absorbance units/10 cm for 357 ppm at 15μm) ( http://www.john-daly.com/artifact.htm). 

[11]. Peixoto, J.P. and Oort, A.H., Physics of Climate. Springer, 1992, p. 30.
[12]. The Satanic Gases, p.36.
[13]. Carbon dioxide is written here as CO2 instead of CO₂ because using subscripts messes up the line spacing in HTML. The Unicode character x2082 (2 or 2), which normally solves this problem, doesn't display properly in IE.
[14]. The temperature data for these calculations were obtained from http://lwf.ncdc.noaa.gov/oa/climate/research/anomalies/anomalies.html 
[15]. www.realclimate.org
[16]. One reader pointed out that the Arctic region has dew points above freezing during a significant portion of the year. The average desert atmosphere also has a much higher water content than many people think. 
[17]. However, some climatologists have tried to invoke anthropogenic increases in atmospheric water vapor: see Santer et al., "Identification of human-induced changes in atmospheric moisture content" (Proc Natl Acad Sci U S A. 2007 Sep 25;104(39):15248-53). Using a computer model, the authors concluded that human activity is increasing water vapor. 
[18]. Radiative Climate Forcing by the Mount Pinatubo Eruption. Minnis P, Harrison EF, Stowe LL, Gibson GG, Denn FM, Doelling DR, Smith WL Jr. Science. 1993 Mar 5;259(5100):1411-1415. 
[19]. Global cooling after the eruption of Mount Pinatubo: a test of climate feedback by water vapor. Soden BJ, Wetherald RT, Stenchikov GL, Robock A. Science. 2002 Apr 26;296(5568):727-30. 
[20]. http://www.aip.org/history/climate/oceans.htm This is a pro-global warming website.
[21]. Howare, J.N., Burch, D.L., Williams, D (1955). Near-infrared transmission through synthetic atmospheres. Geophys. Res. Papers No. 40, Geophys, Res. Dir., Air Force Cambridge Research Center, 244 pp.
[22]. Goody, R.M. (1964). Atmospheric Radiation: I. Theoretical Basis. Clarendon, Oxford, 436 pp. 
[23]. National Academy of Sciences, Climate Research Board (1979). Carbon dioxide and climate: a scientific assessment. National Academy of Sciences, 72pp.; cited in Ref. 1, p. 434.
[24]. See also: Steven Goddard, Divergence Between GISS and UAH since 1980 and 
Oceans are cooling according to NASA (non-technical newspaper article). 
[25]. Current Greenhouse Gas Concentrations (updated October, 2000) Carbon Dioxide Information Analysis Center, U.S. Department of Energy Oak Ridge, Tennessee 

Note This article is updated frequently. See here for information about copying or re-posting this document. 
This article is also available in PDF format . 
Thanks to many readers for pointing out mistakes and making constructive suggestions.

Copenhagen, Denmark-Global Warming Summit aka Climate Change Summit

The Lie: The former vice president said new research showed that the Arctic could be completely ice-free in five years, but the scientist his estimate was based on denies the timeline.

In his presentation, Gore told the conference: "These figures are fresh. Some of the models suggest to Dr. Maslowski that there is a 75 percent chance that the entire north polar ice cap, during the summer months, could be completely ice-free within five to seven years."

The Truth: However, Dr. Maslowski, the climatologist whose work Gore misquoted, dumped Arctic ice water on Al Gore’s 100 Million dollar conman’s head.

"It's unclear to me how this figure was arrived at," Dr. Maslowski rebutted. "I would never try to estimate likelihood at anything as exact as this."

Gore too cowardly to take back his own lie in person had his office later admit that per the already proven dishonest Al Gore’s recollection, the 75 percent figure was one used by Dr. Maslowski as a "ballpark figure" several years ago in a conversation with Gore.

The press paints Al Gore’s dishonesty as an, “embarrassing error,” instead of calling it what it is, “a lie!” Gore’s lie hammers another nail in the coffin of the dishonest scientist of East Anglia's Climate Research Unit, who manipulated data to strengthen their argument that human activities were causing global warming.

Global Warming Is A Lie, The Earth Is Cooling

Al Gore

FOR IMMEDIATE RELEASE

# # #

Http://www.articlesbase.com/nutrition-articles/tips-to-lower-cholesterol-and-your-medical-bills-1483451.html 


Http://www.articlesbase.com/education-articles/reading-activities-for-you-and-your-child-1493

As delegates in Copenhagen wrap up the greatest fraud perpetrated worldwide in the modern era, there is only one thing you need to know. It is all a lie.

It was a lie from the first moment a scientist like James Hansen told Congress on June 23, 1988 that the planet was going to be roasted by greenhouse gases in the atmosphere and it was a lie when Al Gore wrote Earth in the Balance and there were still more lies in his Oscar-winning documentary, An Inconvenient Truth.

A British court banned the documentary from being shown in their schools unless a long list of disclaimers was read to the students before his lies were inflicted on them. American students were not so fortunate. Indeed, as I have said many times before, global warming has been a form of child abuse, causing needless anxiety and fear for countless children on whom it was inflicted.

But how could such a lie be perpetrated on such a vast stage and for so long? My answer to you is "the Soviet Union." From its inception in 1917 when the czarist monarchy was overthrown and Marxist theory, Communism, was imposed on Russia, whole generations were forced to suffer under this huge lie that the state would provide everything for everybody.

It is such a popular lie that it has been resurrected in Venezuela, Bolivia, and Ecuador. It returned the Sandinistas to power in Nicaragua. In the last century, millions died under the Communist banner, but that lie never seems to die.

Little wonder then that, when Hugo Chávez, Venezuela's communist dictator addressed the conference, Andrew Bolt of Australia's Herald-Sun reported that he received "a rousing round of applause." He was followed by Zimbabwe's despicable president, Robert Mugabe, who decried "these capitalist gods of carbon burp and belch their dangerous emissions."

A conference that celebrates such communist blather betrays its true intent. No American President should participate in such a naked display of contempt for capitalism.

A really Big Lie told often enough acquires the verisimilitude of truth. Global warming, however, was dependent on a different kind of truth, one subject to vigorous review and challenge; it is scientific truth and no matter how many lies were told by the global warming scientists, there were others who stood their ground and challenged them.

By itself, the Big Lie cannot exist solely in a political framework like the United Nations or any one of the nations, including our own, that wasted billions based on it. It has to have the support of the media, both our own and those around the world.

Journalists are not scientists and they are subject to what scientists tell them unless they do some fairly easy investigation of their own. They didn't! Instead, journalists at influential newspapers like The New York Times repeated and amplified every global warming lie and they continue to this day.

The true science, not the stuff conjured up on computer models, always refuted the global warming theory. That's because it was widely known to honest climatologists, meteorologists, and others. It was always known that carbon dioxide (CO2) was a miniscule part of the Earth's atmosphere, barely 0.038 percent. Of that amount, man-made CO2 emissions constitute less than 0.00022 percent! Some will argue these figures, but they always remain within these very tiny parameters.

Carbon dioxide has nothing to do with global warming or as it is now called, climate change.

Nor has the Earth been rapidly warming. The last warming cycle began around 1850 as a respond to a Little Ice Age that began in 1300. The Earth warmed about one degree Fahrenheit. By 1998, it began to cool again!

So, when President Obama shows up in Copenhagen to attend the liar's competition called the United Nations Climate Change Conference or COP-15, anything and everything that is said about global warming, fossil fuels, CO2, et cetera, will be a lie.

Al Gore has been at the conference and managed to stumble around like a punch-drunk boxer saying really stupid things like the Arctic will completely melt away any day now or that the center of the Earth is millions of degrees hot. But Gore is a stranger to the truth because, as you may recall, he's a politician who served in Congress and as Vice President.

If George W. Bush is remembered for anything, it will be that he saved the nation from a "President Gore."

At the heart of the Big Lie is, of course, MONEY! There are millions to be made selling bogus "carbon credits" for the use of energy. That's what the administration's "Cap-and-Trade" scam is all about.

Billions were wasted on "climate research" over the past twenty years and now they are being wasted on "clean energy" research which we're told is needed to replace "dirty" fuels like coal, oil and natural gas. It too is all a lie.

Solar and wind power can never and will never replace or even rival the power that so-called fossil fuels provide. Combined, solar and wind provide barely one percent of all the electricity used daily in the nation. Biofuels are another bad idea.

Listen, if you can, to what's going on in Copenhagen and remember, they are lying.

FamilySecurityMatters.org Contributing Editor Alan Caruba writes a weekly column, “Warning Signs”, posted on the Internet site of The National Anxiety Center. His book, “Right Answers: Separating Fact from Fantasy”, is published by Merrill Press.

Eight Reasons to End the Scam

Concern over “global warming” is overblown and misdirected. What follows are eight reasons why we should pull the plug on this scam before it destroys billions of dollars of wealth and millions of jobs.

1. Most scientists do not believe human activities threaten to disrupt the Earth’s climate. More than 17,000 scientists have signed a petition circulated by the Oregon Institute of Science and Medicine saying, in part, “there is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth’s climate.” (Go to www.oism.org for the complete petition and names of signers.) Surveys of climatologists show similar skepticism.

2. Our most reliable sources of temperature data show no global warming trend. Satellite readings of temperatures in the lower troposphere (an area scientists predict would immediately reflect any global warming) show no warming since readings began 23 years ago. These readings are accurate to within 0.01ºC, and are consistent with data from weather balloons. Only land-based temperature stations show a warming trend, and these stations do not cover the entire globe, are often contaminated by heat generated by nearby urban development, and are subject to human error.

3. Global climate computer models are too crude to predict future climate changes. All predictions of global warming are based on computer models, not historical data. In order to get their models to produce predictions that are close to their designers’ expectations, modelers resort to “flux adjustments” that can be 25 times larger than the effect of doubling carbon dioxide concentrations, the supposed trigger for global warming. Richard A. Kerr, a writer for Science, says “climate modelers have been ‘cheating’ for so long it’s almost become respectable.”

4. The IPCC did not prove that human activities are causing global warming. Alarmists frequently quote the executive summaries of reports from the Intergovernmental Panel on Climate Change (IPCC), a United Nations organization, to support their predictions. But here is what the IPCC’s latest report, Climate Change 2001, actually says about predicting the future climate: “The Earth’s atmosphere-ocean dynamics is chaotic: its evolution is sensitive to small perturbations in initial conditions. This sensitivity limits our ability to predict the detailed evolution of weather; inevitable errors and uncertainties in the starting conditions of a weather forecast amplify through the forecast. As well as uncertainty in initial conditions, such predictions are also degraded by errors and uncertainties in our ability to represent accurately the significant climate processes.”

5. A modest amount of global warming, should it occur, would be beneficial to the natural world and to human civilization. Temperatures during the Medieval Warm Period (roughly 800 to 1200 AD), which allowed the Vikings to settle presently inhospitable Greenland, were higher than even the worst-case scenario reported by the IPCC. The period from about 5000-3000 BC, known as the “climatic optimum,” was even warmer and marked “a time when mankind began to build its first civilizations,” observe James Plummer and Frances B. Smith in a study for Consumer Alert. “There is good reason to believe that a warmer climate would have a similar effect on the health and welfare of our own far more advanced and adaptable civilization today.”

6. Efforts to quickly reduce human greenhouse gas emissions would be costly and would not stop Earth’s climate from changing. Reducing U.S. carbon dioxide emissions to 7 percent below 1990’s levels by the year 2012--the target set by the Kyoto Protocol--would require higher energy taxes and regulations causing the nation to lose 2.4 million jobs and $300 billion in annual economic output. Average household income nationwide would fall by $2,700, and state tax revenues would decline by $93.1 billion due to less taxable earned income and sales, and lower property values. Full implementation of the Kyoto Protocol by all participating nations would reduce global temperature in the year 2100 by a mere 0.14 degrees Celsius.

7. Efforts by state governments to reduce greenhouse gas emissions are even more expensive and threaten to bust state budgets. After raising their spending with reckless abandon during the 1990s, states now face a cumulative projected deficit of more than $90 billion. Incredibly, most states nevertheless persist in backing unnecessary and expensive greenhouse gas reduction programs. New Jersey, for example, collects $358 million a year in utility taxes to fund greenhouse gas reduction programs. Such programs will have no impact on global greenhouse gas emissions. All they do is destroy jobs and waste money.

8. The best strategy to pursue is “no regrets.” The alternative to demands for immediate action to “stop global warming” is not to do nothing. The best strategy is to invest in atmospheric research now and in reducing emissions sometime in the future if the science becomes more compelling. In the meantime, investments should be made to reduce emissions only when such investments make economic sense in their own right.

This strategy is called “no regrets,” and it is roughly what the Bush administration has been doing. The U.S. spends more on global warming research each year than the entire rest of the world combined, and American businesses are leading the way in demonstrating new technologies for reducing and sequestering greenhouse gas emissions.

Time for Common Sense

The global warming scare has enabled environmental advocacy groups to raise billions of dollars in contributions and government grants. It has given politicians (from Al Gore down) opportunities to pose as prophets of doom and slayers of evil corporations. And it has given bureaucrats at all levels of government, from the United Nations to city councils, powers that threaten our jobs and individual liberty.

It is time for common sense to return to the debate over protecting the environment. An excellent first step would be to end the “global warming” scam.

Snow Falls on Beach in Southern France

                                  (AP Photo/Lionel Cironneau) 
                                  Saturday, Dec. 19, 2009 

Sure hope we get some global warming agreements passed soon, before all the snow melts off this beach in southeastern France.

Jan. 2 (Bloomberg) -- The U.S. East Coast faces the coldest night of the season as frigid air spills south and threatens agriculture in Georgia, Alabama and the orange crop in Florida.

Freeze warnings were posted by the National Weather Service as far south as the Orlando area, which may be as many as 20 degrees below normal tonight, the National Weather Service said. The advisory alerts growers that subfreezing temperatures are imminent and may kill crops or other sensitive vegetation.

Tampa and others cities in the central part of the state are under a freeze warning from 1 a.m. to 9 a.m. local time tomorrow. Temperatures may fall below 32 degrees Fahrenheit (zero Celsius) for more than three consecutive hours, theNational Weather Service in Tampa said on its Web site.

“This is a pretty significant cold snap,” Matt Keefe, a meteorologist withAccuWeather.com Inc. in State College, Pennsylvania, said in a telephone interview. “This could really put a hurting on the citrus crop.” He said the jet stream, which normally keeps the coldest air north of the Hudson Bay in Canada, is centered over parts of Alabama and Mississippi. “The cold temperatures could last for a good part of the week,” he said.

Jacksonville, Florida, may see a record low tonight, Keefe said. The Miami area will see temperatures 12 degrees to 13 degrees below normal for this time of year, Keefe said.

Tonight will be the coldest and offer the greatest danger of crop damage, Keefe said. The next chance for freezing will come next week.

The U.S. Department of Agriculture last month estimated Florida’s orange crop will be 0.7 percent smaller than earlier forecast because adverse weather reduced fruit size.

In New York, overnight lows may be 22 degrees, with wind chills dropping the experience to single digits. Philadelphia may see a low of 20 degrees, Keefe said. Washington may slip to 19 degrees, he said.

A FREEZING cold front swept over much of northern China on Sunday with snowstorms snarling traffic and air travel, while some of the coldest temperatures in decades were forecast for coming days.

Gale-force winds sweeping down from Siberia could result in temperatures as low as minus 16 degrees in the capital today, the Beijing meteorological station said.

Such temperatures are believed to be the coldest in the capital in 40 years.

Yesterday, major highways in Beijing and Tianjin, as well as in the surrounding provinces and regions of Hebei, Shanxi and Inner Mongolia were closed due to the heavy snowfall.

Beijing Capital Airport said 120 departures had been postponed and 86 flights cancelled from late Saturday until mid-morning yesterday because of heavy snow and poor visibility.

Freezing temperatures have also hit Britain, which is bracing itself for one of the coldest winters for a century.

Parts of Scotland have been under snow for nearly three weeks and temperatures are expected to drop to minus 16 degrees.

Meteorologists predicted the freezing snap will last until at least mid-January, with snow, ice and severe frosts dominating.

And the likelihood is that the second half of the month will be even colder.

On New Year's Day 10 extreme weather warnings were in place, with heavy snow expected in northern England and Scotland.

The continued freezing temperatures did not signal bad news for everyone, however. CairnGorm Mountain said it has had its best Christmas holiday season in 14 years.

More than 15,000 skiers have used the resort since the start of December, compared with 2000 last year.

The cold weather comes despite the Met Office's long-range forecast, published in October, of a mild winter. That followed its earlier inaccurate prediction of a "barbecue summer", which was marked by heavy rainfall and the wettest July for almost 100 years.

Paul Michaelwaite, forecaster for NetWeather.tv, said: "It is looking like this winter could be in the top 20 cold winters in the last 100 years.''

A fleet of gritters in Perth, central Scotland, was grounded because of the cold, leaving roads untreated in temperatures of minus 10 degrees.

Perth and Kinross Council said the gritters were unable to leave the depot after the extreme weather led to difficulties in refuelling.

Perth resident Ian Thomson said: "I've heard of the rail companies blaming the wrong kind of snow and leaves on the line for disruption, but for the council to say it was too cold to get the gritters out is just ridiculous."

These days it feels like Mother Nature is a disc jockey playing cheesy music at a wedding dance with the record stuck on "Limbo," as in: "How low can you go?"

Answer: Near-record low.

Thermometers across Iowa dipped into the negative double digits. And this intense cold probably isn't going anywhere until next weekend.

Temperatures stayed below zero for much of Saturday. Des Moines was at minus-1 by 3 p.m.

A wind chill advisory was set to expire at noon today for much of eastern Iowa, including Marengo, Iowa City, Tipton, Clinton, Muscatine, Bettendorf, Davenport, Sigourney, Washington, Wapello, Fairfield, Mount Pleasant and Burlington.

The area will see temperatures below zero with a wind chill 20 to 30 below zero. Frostbite can occur in less than 30 minutes in such conditions.

Des Moines bottomed out at 17 below zero, two degrees above the record low on Jan. 2 in the capital. The National Weather Service station in Johnston recorded 22 degrees below zero.

Spencer and Sheldon recorded the coldest temperatures in the state with minus-33 degrees. Estherville came in at 28 below zero, Fort Dodge at negative 26. Sioux City and Orange City both reported minus-22 degrees. At least 16 more cities across the state reported lows in the negative double digits.

"We're a solid 30 degrees below normal," said Jeff Johnson, a meteorologist with the National Weather Service.

Des Moines is expected to have highs in the single digits above zero through Monday, while temperatures are expected to hover between zero and 10 degrees elsewhere in Iowa.

Despite bitter cold temperatures, this week should be relatively snow-free. A dusting is forecast for Wednesday or Thursday, but accumulations should be minimal compared to the heavy pileups last month, Johnson said.