(updated 4/26/2009, 5:00 p.m. w/clarification on the role of cost-benefit analysis in the regulation of greenhouse gases by the EPA)

“No amount of experimentation can ever prove climate models right; a single experiment can prove climate models wrong.”
– adapted from Albert Einstein quote.

Two days ago, on April 17, the EPA ruled that greenhouse gases (especially carbon dioxide) endanger human health and welfare. There is now a 60 day public comment period for people to give their opinions on this ruling before the EPA takes the next step and actually implements regulations on greenhouse gas emissions.

To help out, I’ve whipped up some commonly asked questions and their answers (below) on global warming to help you better understand the issues involved. As you will see, the science of global warming is far from ‘settled’. It is only because of the political and financial ramifications of global warming that so many people (mainly politicians and those who have vested interests) are trying to convince you otherwise.

IS GLOBAL WARMING HAPPENING NOW?
There is no way to know if warming is ‘happening now’. Because natural climate fluctuations on a year-to-year basis are so large, we will only recognize warming (or cooling) several years down the road when it appears in the rearview mirror. The most important statistic to me is that global average temperatures stopped rising in 2001, as shown in the following chart of global tropospheric temperatures that John Christy and I derive from satellite measurements.

As you can see, we might have even entered a new cooling trend. The claim that the warming trend over the last 50 to 100 years is continuing right now, or that it is even ‘accelerating’ is pure speculation, based upon the assumption that what has happened in recent decades will continue into the future.

ISN’T IT WARMER NOW THAN IT HAS BEEN IN THOUSANDS OF YEARS?
Well, look at the following recently published proxy reconstruction of global temperatures over the last 2000 years. This graph is based upon 18 previously published temperature proxies, and so provides the most robust estimate available to date. It can be seen that significant warming and cooling periods of 50 to 100 years in duration seem to be the rule, rather than the exception. There were probably even warmer years during the Medieval Warm Period (MWP) than we have seen in recent years. Even the warmth of the ‘record’ warm El Nino year in 1998 (see temperature chart above) might well have been surpassed several times during major El Nino events that occurred during the MWP. Unfortunately, there is no way to know how warm individual years were a thousand years ago…the graph below is made up of thirty-year averages. I added the dotted line toward the end showing the modern thermometer record.

ISN’T DISAPPEARING SEA ICE IN THE ARCTIC PROOF OF MANMADE GLOBAL WARMING?
Warming, yes. Manmade, no. As can be seen in the following chart, it was just as warm in the Arctic (or nearly as warm) in the 1930s, with loss of sea ice and changing wildlife patterns reported in newspapers. The water levels in the Great Lakes reached record lows during this time, too…just as has happened again in recent years.

It should be remembered that we have had accurate satellite measurements of sea ice only since 1979, a period which has been entirely during the positive (warming) phase of the Pacific Decadal Oscillation (PDO, see graph below). The PDO is an index of weather patterns over the North Pacific Ocean that flips every 30 years or so. The coincidence that the satellite era started right after the “Great Climate Shift of 1977” has probably biased what we consider to be ‘normal’ for global climate. In fact, based upon the 2,000-year temperature graph shown previously, one might argue that there is no such thing as ‘normal’ climate.

ISN’T ARCTIC SEA CONTINUING TO MELT FASTER AND FASTER?
No. As can be seen in the graph below (updated here through April 21, 2009), 2007 was the year when summer ice melt resulted in a 30-year record low in sea ice coverage. In 2008, the ice recovered somewhat. And from looking at 2009, we might well see further recovery this summer. Based upon the PDO index (above) it could be we have entered a new cooling phase of the PDO, which might explain this sea ice recovery, as well as our recent return to colder, snowier winters in the Northern Hemisphere.

AREN’T THE POLAR BEARS DYING FROM DISAPPEARING SEA ICE?
Generally speaking, no. While 2 sub-populations of polar bears appear to be threatened by the recent reduction in Arctic sea ice, the other dozen or more sub-populations are either stable or growing. Polar bears survived previous periods of Arctic warmth, and they will survive this one, too.

Polar bears, especially the cubs, tug at our heartstrings because they are so cute, and so make wonderful ‘poster children’ for global warming. What is ironic is that the polar bear is the only predator that will actively track down and eat a human being. The following two photos were sent to me by someone in Alaska…a polar bear that was waiting for a man to return to his truck.


You can learn the truth about the polar bear issue from a polar bear researcher here.

WHAT ABOUT THE COLLAPSING ICE SHELVES IN ANTARCTICA?
Just as Greenland glaciers will continue to flow downhill and break off into the sea as snow keeps falling on Greenland, the Antarctic ice sheet also slowly flows toward the sea. But in Antarctica, this forms ice ‘shelves’ that can extend out over the ocean a considerable distance. These ice shelves ring the entire continent, and eventually they must break off and float away. It could be that ice shelf collapse events become more common when warmer ocean waters affect a portion of the continent, as has been the case in recent years. Maybe a period of more rapid ice shelf collapse also occurred during the Medieval Warm Period of 1,000 years ago…we just don’t know.

On a whole, Antarctica has not warmed. And because it is so cold there, even a few degrees of warming will not cause the ice sheet to melt anyway. In fact, as can be seen in the following graph, sea ice around Antarctica has increased over the same 30-year period of time that Arctic sea ice has decreased.

ISN’T CARBON DIOXIDE A DANGEROUS GAS?
Well if you breathe pure CO2, you will die — from a lack of oxygen, not because CO2 is poisonous. But if you breathe pure oxygen for very long, that will also kill you. Carbon dioxide is necessary for life on Earth; photosynthesis by plants on land and by plankton in the ocean depend upon it. And without those forms of life, all the animals (and we humans) would die as well. For something as essential as CO2, it verges on the bizarre for people like Al Gore to liken carbon dioxide to sewage.

BUT WE CAN’T KEEP PUMPING CO2 INTO THE ATMOSPHERE FOREVER, CAN WE?
No…and we won’t. But the amount of CO2 we put into the atmosphere is pretty trivial: As of 2009, there are only 38 or 39 molecules of CO2 for every 100,000 molecules of atmosphere, and it will take mankind’s CO2 emissions another five years to raise that total by 1 molecule, to 40 out of every 100,000 molecules. The following graph shows how much the CO2 content of the atmosphere has risen in the last 50 years at Mauna Loa, Hawaii. The graph has a vertical scale that only extends to 1% of the atmosphere, and as can be seen, the increase in CO2 is barely visible. This graph is not a trick…it looks different from what you are used to seeing because CO2 is usually plotted with a greatly magnified vertical scale to make the CO2 rise look more dramatic. Yes, we might double the CO2 concentration of the atmosphere by late in this century…but 2 times a very small number is still a very small number.

ISN’T CO2 THE ATMOSPHERE’S MAIN GREENHOUSE GAS?
No. Water vapor accounts for about 85% or 90% of the Earth’s natural greenhouse effect, clouds account for another 5% or 10%. CO2 represents only about 3%, methane even less. You will see quite a bit of variability in the above percentages because they can only be calculated based upon theory, and involve a variety of assumptions. I have greatest confidence in the 3% number for the CO2 portion, which we have verified with our own calculations: The direct effect of doubling of CO2 would only be a 1 deg. C warming of the surface (this is not disputed, see below), and when you compare that to the 33 deg. C of surface warming due to all greenhouse components of the atmosphere, you get 3%.

BUT DON’T THE COMPUTER CLIMATE MODELS PREDICT SERIOUS GLOBAL WARMING…EVEN FROM THE LITTLE BIT OF EXTRA CO2 IN THE ATMOSPHERE?
Yes, but most of the warming produced by climate models is NOT directly from the CO2, but from assumed changes in clouds and water vapor in response to the small CO2-induced warming tendency. And this is the models’ Achilles heel. While all of those models now change clouds with warming in ways that amplify that warming, some by a catastrophic amount, there is increasing evidence that clouds in the real climate system behave in just the opposite way (peer reviewed papers of ours here and here). This could result in a doubling of atmospheric CO2 causing less than 1 deg. F of warming by the end of this century.

BUT WE’VE ALREADY SEEN 1 DEGREE OF WARMING…SO, WHAT COULD HAVE CAUSED IT?
My latest research (as yet unpublished) suggests most of the warming we’ve experienced in the last 100 years is due to natural changes in cloud cover…possibly caused by the Pacific Decadal Oscillation mentioned above. Something climate modelers apparently don’t appreciate is that it would only take about a 1% change in global cloud cover to cause ‘global warming’. Curiously, climate modelers do not believe this happens. Exactly why they don’t, I haven’t been able to figure out. Probably because we’ve not had accurate enough long-term observations of global cloud cover to document any such changes. But just because such changes are too small for us to measure doesn’t mean they do not exist. Most of us who were trained as meteorologists find 1% changes in global cloud cover to be entirely plausible, probably the result of natural, chaotic changes in weather patterns coupled to small chaotic changes in ocean circulation.

HASN’T THE “FINGERPRINT” OF MANMADE WARMING ALREADY BEEN FOUND?
No. Climate modelers claim they can only explain global warming by including greenhouse gas increases in their models. But that claim is based upon 2 critical assumptions: (1) the climate system is very sensitive to increasing CO2, a consequence of their climate models not handling clouds properly, and (2) as mentioned above, a lack of accurate observations over a long enough period of time to document potential natural, and stronger, warming mechanisms…such as a slight decrease in global cloud cover letting more sunlight in.

Another “fingerprint” claim is that global warming has been stronger over land than ocean, as would be expected with more greenhouse gases. But warming of the oceans and land in response to fewer clouds would be indistinguishable from warming caused by more carbon dioxide. A decrease in oceanic cloudiness would warm the oceans, which would then send more humid airmasses over land. And since water vapor is our main greenhouse gas, the land will warm in response. The land warming would be then be stronger than the ocean warming because the heat capacity of land is less than that of the ocean. So, don’t be fooled when you hear claims that the “fingerprint” of manmade warming has been found…it hasn’t. In fact, there is no known human “fingerprint”.

HAVEN’T SEVERE WEATHER EVENTS LIKE HURRICANES BECOME MORE COMMON IN RECENT YEARS?
No, only storm damage has increased. This is because people keep building along coastlines and in other areas prone to severe weather. And the more stuff we build, the more targets there are for hurricanes and tornadoes to destroy. Some of the records you have heard about for strongest hurricane, etc., are mostly because our technological ability to measure these storms has improved so much in recent years. There is no way to know if some recent storms (e.g. Katrina when it was in the central Gulf of Mexico) were stronger than major hurricanes that occurred in the early 20th Century, before we had weather radar, high resolution satellite data, and instrumented planes to fly into them.

WHAT ABOUT OCEAN ACIDIFICATION FROM MORE CO2?
The chemistry of the ocean is still poorly understood from the standpoint of how it varies over time, and how it is controlled. There is a common view among oceanographers that extra atmospheric CO2 has caused the average pH of the ocean to be reduced from 8.18 to 8.10 since the start of the Industrial Revolution. But pH varies widely across the global oceans, and that estimated decrease is more of a ‘theoretically-calculated expectation’ than it is an actual observation. A minority view I have heard is that the buffering capacity of the ocean will prevent ocean acidification. In fact, recent evidence suggests that (just like plants on land) plankton in the ocean will grow faster and be more abundant with more CO2 in the atmosphere.

AREN’T SPECIES GOING EXTINCT EVERY DAY DUE TO GLOBAL WARMING?
Generally speaking, there is no way to know if any species are going extinct. We would have to inventory all of the life that exists on every acre of the Earth to determine this, and as it is, science is discovering new species all the time. And, as discussed above, even if warming is causing some species to become extinct, that warming is likely to be mostly natural anyway. As is the case with climate models, statistics about species extinctions are largely theoretical calculations, based upon dubious assumptions. And in science, it is always the long-held assumptions that end up misleading us.

SHOULDN’T WE BE GETTING OFF FOSSIL FUELS ANYWAY, NO MATTER WHAT THE SCIENCE SAYS?
We eventually will…but right now there are no energy technologies that can offer replacements on the massive scale of what humanity needs for energy on a daily basis. Solar, wind, biofuels, only nibble around the edges of the problem, and they bring their own disadvantages (e.g. environmental impacts of wind and solar, rising food prices from diverting corn production from food to fuel). Both government (using your tax dollars) and private industry (using part of the money you spend on goods and services) have been researching new energy technologies for decades. The free market is the best way to solve this problem because, whoever develops new cost-effective energy technologies stands to make a fortune.

You can not simply legislate new sources of energy into existence. And if you try, economies will be hurt – if not decimated. The world’s poor, those living on the edge of the economy, will be the first to suffer. Since energy is required for everything we do, an increase in energy prices translates directly into more expensive goods and services across the economy.

And given the global nature of trade and business, misguided energy policies at home will simply drive many companies to other countries…where they can pollute even more than they used to here in the U.S..

SOME FINAL REMARKS ABOUT SCIENCE
There is a time-honored tradition in science that has led to a general public distrust of scientists: extrapolation into the future. Even in the 1800’s this failing of science was recognized:

“There is something fascinating about science. One gets such wholesale returns of conjecture from such a trifling investment of fact.”
-Mark Twain, Life on the Mississippi (1883)

As an example, consider the record low water level in Lake Superior experienced in 1926, shown in the graph below:

Here is what an ‘expert’ from that time said about the record-low lake levels (try not to laugh too hard):

“Ultimate extinction of the American side of the falls at Niagara is mathematically certain unless water levels in the Great Lakes are raised.”
-Daily Mining Journal, May 27, 1926.

Now, that wild statement was probably true in a literal sense. Note that it coveyed a maximum amount of alarm without being factually false. And this is exactly the same kind of prose contained in the Policymakers Summary of the latest (2007) report from U.N. Intergovernmental Panel on Climate Change (IPCC), a document that purposely minimizes any scientific uncertainties about anthropogenic global warming, while at the same time maximizing alarm.

Ultimately, fears of manmade global warming, species extinction, and ocean acidification arise from scientists not fully understanding the checks and balances which exist in nature. Nature is not static, but causes its own, internally-generated changes – both in climate and in biological systems. The common view that nature is in some sort of “delicate” balance is a romantic or religious opinion, and it is a view even held by most scientists. But balances in nature are always readjusting, either to internal forces or external forces. Nature is dynamic, not static. Just because a state of balance might be observed at any point in history does not mean that balance is in any way “delicate”.

Why is it OK for the presence of trees on Earth to change ecosystems and the climate system, but not for the presence of humans? Yes, nature must adjust to the presence of humans, but animals and plants are always adjusting to the presence of other animals and plants, anyway. Conferring these rights to plants and animals, but not to ourselves, makes absolutely no sense.

And since there is abundant scientific evidence that nature prefers more CO2 in the atmosphere, we need to seriously consider the possibility that burning of fossil fuels is, on balance, a good thing for life on Earth.

THE EPA IS ABOUT TO CAUSE A REGULATORY TRAIN WRECK

The US Chamber of Commerce has just issued a concise statement of the consequences of the EPA’s endangerment ruling, and it is a good introduction to the policy implications of the ruling.

I am told by those in the know that, if the EPA’s endangerment finding stands, it can then be used to justify any action to control energy policy and economic activity. While the section of the Clean Air Act that is involved in this has in the past also addressed cost/benefit analysis, it appears that regulating greenhouse gas emissions will not involve cost-benefit analysis. The endangerment finding instead discusses a ‘precautionary’ approach, where the indirect and uncertain effects of the U.S. sources of greenhouse gases on climate are recognized, but are ignored in an effort to help the climate change situation, no matter how small or incremental that help might be.

New regulations on CO2 emissions for new cars and trucks based on the endangerment finding will follow quickly. Numerous lawsuits to apply those auto regulations to other sections in the Clean Air Act will spread like wildfire. Many of these lawsuits are already in the system.

Folks, this is nothing like fixing the stratospheric ozone problem by developing other refrigerants to replace Freon. CO2 is produced by nearly all sources of energy. CO2 is a part of nature; Freon was a manmade chemical. While replacements for Freon were already developed by the time Freon was banned, we have no large-scale replacements for fossil fuels we can switch to in the near future.

This issue is at least as important as our recent global financial crisis – probably more so in the long run. It has been said that regulating carbon dioxide emissions will make the United States the cleanest Third World country on Earth. And whoever controls carbon dioxide emissions will control the world.

Finally, you can expect that the threat of the EPA regulating CO2 will cause many politicians and pundits to advocate congressional cap-and-trade legislation as a more palatable alternative. But the choice will be like deciding whether you want to die quickly or slowly. Either one will be lethal.

Instructions for Submitting Comments to the EPA

One of the basic tenets of the IPCC view on global warming is that cloud feedbacks are positive. That is, clouds react to a warming influence by further amplifying the warming.

This makes all the difference in the world for forecasts of global warming because the existence of negative cloud feedbacks could limit manmade global warming to less than 0.5 deg. C by late in this century, while positive feedbacks could result in ten times that amount of warming: 5 deg. C.

What is peculiar about all of the IPCC climate models now producing positive cloud feedbacks is that it is well known in the climate business that the average effect of clouds on the climate system is one of cooling…not warming. In the presence of radiative heating by the sun, clouds provide a stronger solar shading effect than their greenhouse warming effect, leading to a net reduction in average global temperatures by about 5 deg. C.

Another way of looking at this is, as the sun warms the Earth, a point is reached where the clouds in effect say “OK, that’s enough sunlight. We’ve got the temperature we want now.”

So, isn’t it peculiar that clouds would be claimed to do just the opposite in response to the small radiative warming effect from more carbon dioxide in the atmosphere? I think it’s more than peculiar…it verges on being logically inconsistent.

I believe there has been a self-delusion of sorts in the climate research community regarding cloud feedbacks. As I have discussed elsewhere, the observation that specific years with warmer-than-average global temperatures have less cloud cover, thus letting more sunlight in (and so suggesting positive feedback) ignores the fact that the warmth was probably the result of less cloud cover – not the other way around.

Another observation that has led to confusion over cloud feedbacks is the fact that the tropics – the geographic region where the greatest amount of sunlight is absorbed – show a distribution of low and high clouds that lead to an approximate cancellation between the low clouds’ solar shading effect, and the high clouds’ greenhouse warming effect.

This apparent ‘zero feedback’ state suggests to some researchers that feedbacks in response to warming from more CO2 could go either way. Indeed, the original paper discussing the net cooling effect of clouds, contained in its abstract the following statement regarding this cancellation, “…which indicates the delicately balanced state of the tropics.”

(And where did THAT come from? Since when does a balance between two opposing forces constitute a ‘delicate’ balance? This published statement was an early foretaste of today’s religious obsession among scientists that nature is precariously balanced).

But what is ignored is the fact that the tropics can not be studied in isolation. The tropics are continuously exporting heat to higher latitudes. The higher latitudes, in contrast, are where the net effect of clouds is confidently known to be one of cooling. This equator-to-pole difference in the radiative effect of clouds then leads to an enhancement of the equator-to-pole temperature difference, which then helps drive the transport of heat from the tropics to high latitudes.

I know this sounds complicated…but that’s my point. One can’t look at clouds in just the tropics and make any deductions about the net effect of clouds on climate…even on just tropical climate…because the tropics are not a “closed system”.

From the standpoint of energy being moved from one region to another, only the whole Earth is a closed system. So, we are forced to return to the fact that the net effect of clouds is to cool the whole climate system.

Finally, I think another mistake that has been made when trying to determine the warming versus cooling influence of clouds is the way in which those effects have been defined. This has been done with satellite observations by comparing cloudy regions to surrounding clear regions. The difference between cloudy and clear regions has been assumed to be just due to the clouds.

The trouble with this assumption is that the clear regions have also been cooled by clouds. The air in the clear regions traveled there from somewhere else, where the air was also influenced by the cooling effects of clouds. This mistake in interpretation has probably led to an underestimate of the net radiative cooling effect of clouds.

Everyone agrees clouds are complicated beasts. So, one can expect that handling of clouds is probably the single biggest uncertainty in climate model predictions of global warming. Even the IPCC has admitted this in their latest (2007) report: “Cloud feedbacks are the primary source of inter-model differences in equilibrium climate sensitivity, with low cloud being the largest contributor”.

I know the IPCC would disagree, but I think what Robert Cess said 12 years ago remains true today:

“the [models] may be agreeing now simply because they’re all tending to do the same thing wrong. It’s not clear to me that we have clouds right by any stretch of the imagination.”

In a court of law, you would never be able to convict clouds as accomplices in the ‘crime’ of global warming. Indeed, the ‘balance of evidence’ suggests they have been acting to reduce the small amount of warming being caused by more greenhouse gases in the atmosphere.

Something that fascinates me about the science of global warming is that some climate ‘experts’ do not have any better understanding of the basic physical processes involved than the lay person does.

For instance, in a recent paper of mine that was rejected for publication in Geophysical Research Letters, the editor assigned only a single peer reviewer, who did not even understand what causes temperature to change. And yet, the reviewer was casting judgment on my analysis that showed that the cloud-altering behavior of the Pacific Decadal Oscillation over the last 100 years might explain most of what we now call climate change and global warming.

So, let’s review the basics of why the temperature of an object changes. In a few minutes, you will have a better understanding than even that (presumed) climate expert has. It doesn’t matter whether it is the Earth, or a pot of water on the stove, the fundamental concepts are the same. And if you think you already understand why a pot of water on the stove warms up, you might be in for a surprise.

Question: TRUE or FALSE? A pot of water on the stove warms because the stove is transmitting heat into the pot.

Answer: FALSE.

Well…it’s only half true. Let’s examine what happens when we place a pot of room temperature water on a hot stove. In the following figure I’ve illustrated the flows of heat with arrows.

Let’s say it is a gas stove, so that we can produce a small, constant flame under a pot of room temperature water, with no lid. Heat flows from the stove into the pot, and the water gradually warms.

After about 10 minutes, though, the water reaches a certain temperature and just stays there. But how can this be? How can the stove still be pumping heat into the pot, and yet the water has stopped warming? Obviously, what controls the temperature of the water is more than just the rate of heat input from the stove.

What we are missing is that the pot was losing heat to its surroundings at the same time it was gaining heat from the stove. As illustrated in the above figure, the temperature of the pot will only change if there is an imbalance between the rate of heat flow into the pot and the rate of heat flow out of the pot.

As the water started to warm on the stove, the pot became warmer than its surroundings, and so it also started to lose heat to its surroundings. This happens through three processes: (1) faster evaporation of the water, (2) air currents flowing past the pot and picking up heat and carrying it away, and (3) loss of infrared (heat) radiation of the warmer pot to its cooler surroundings.

As the water got warmer and warmer, those three heat loss processes accelerated. Finally, a temperature was reached where the rate of heat loss by the pot equaled the rate of heat gain from the stove. It is only at this point of energy balance that the temperature stops changing.

And, as I have illustrated in the following figure, it doesn’t matter whether it is a pot of water or the Earth, the basic concept is the same. An imbalance in the rate of energy flows in and out of the Earth, or the pot, will lead to a temperature change.

The main difference is the length of time involved for the temperature to respond to an imbalance: It takes only minutes for a few inches of water in a pot to come to a new equilibrium temperature. But it can take years for an energy imbalance of the Earth to cause hundreds or thousands of meters of ocean depth to fully respond with a temperature change.

Also note that warming can be caused either by (1) increasing the rate of energy gained, OR (2) decreasing the rate of energy lost. It is the second process that is involved in the theory of manmade global warming: Increasing atmospheric CO2 concentrations slightly reduce the rate at which infrared heat is lost by the Earth to outer space, leading to an energy imbalance. Warming then results, which stops after energy balance is once again restored as a warmer Earth radiates infrared energy at a greater rate to outer space.

In fact, the mechanism of heat loss by the Earth is simpler than that of a pot of water on the stove. Because there is no air in outer space to carry heat away from the Earth, there is only one heat loss mechanism, not three: Infrared radiation.

Of course, anything that can change the rate of energy input or output can cause climate change. For instance, natural fluctuations in atmospheric circulation patterns can alter global cloud cover by a small amount, thereby changing how much sunlight is allowed to reach the Earth’s surface. Or, circulation changes might result in small wind shear-induced changes in precipitation efficiency, thereby altering how much water vapor – our main greenhouse gas – is allowed to remain in the atmosphere. These natural fluctuations can cause warming or cooling.

And these are only two examples of the many potential kinds of natural climate change that the Intergovernmental Panel on Climate Change (IPCC) simply assumes do not exist.

The issue of global warming has so many facets that it has always been difficult to concisely state the objections we skeptics have to the theory (yes, ‘theory’) that our present warmth is caused by all of you consumers out there driving your SUVs and eating Big Macs. What follows is a demonstration of my main objection.

The claim that global warming is due to people is indeed a valid hypothesis. Human activity produces carbon dioxide, carbon dioxide in the atmosphere is increasing, and CO2 is indeed a greenhouse gas. Ergo….

But how often in science is it decided that the first hypothesis to come along will forever be the only one allowed? That is effectively what the United Nations Intergovernmental Panel on Climate Change (IPCC) has done.

Ever since the IPCC was formed twenty years ago, their intent has been to tie global warming to human greenhouse gas emissions. They have never seriously investigated potential natural sources of global warming…except to say they can’t think of any that are large enough to cause the warming.

They then run their climate models with tiny forcings, such as a tiny change in solar output, and then say, “See? Natural forcings can not explain warming…only increasing CO2 can!” This conclusion is then advertised with words like “this demonstrates that natural forcings can not explain global warming”.

As I keep emphasizing, though, this only shows how little we know about natural climate variability. The assumption that the climate system has always been in balance, with a constant temperature, until humans came along is just that: an assumption. There is no way to prove it because we do not have the global measurements needed to prove it.

AN EXAMPLE OF NATURAL GLOBAL WARMING

To demonstrate how easy it is for nature to cause global warming, I’ve run an enhanced version of the simple climate model described by Spencer & Braswell (2008), and assumed daily random changes in cloud cover, smoothed them with a 10-year averaging filter, and run the model over a 50 year period of time. I have also included the increasing global energy imbalance due to increasing carbon dioxide at the rate of 0.2 Watts per sq. meter per decade. A 30 meter deep ocean mixed layer absorbs or loses energy in response to the imbalances, and the resulting heating and cooling slowly diffuse to a second layer 300 meters deep. I’ve assumed zero net feedback, as suggested by some observational studies.

The following plot (Fig. 1) shows how much of a global radiative energy imbalance would be observed by satellites…if we had satellites that far back in time. The fluctuations seen here average about 1.4 Watts per sq. meter, which is similar to the 1.5 Watts per sq. meter that a recent reanalysis of Earth Radiation Budget Satellite data has shown (Wong. et al., 2006).

Fig. 1. Global average top-of-atmosphere radiative imbalance from increasing carbon dioxide and random cloud variations, the forcings from which drive the simple model’s temperature variations seen in Fig. 2.

By way of comparison, these variations are only 0.6% of the average amount of energy the Earth is continuously absorbing from the sun. So we are talking about small changes in global average cloud cover.

The temperature response of the global oceans to the CO2- and cloud-induced energy imbalances is shown in Fig. 2.

Fig. 2. Temperature response of the simple model to the random cloud and increasing CO2 forcing shown in Fig. 1.

As can be seen, realistic temperature variability is produced, and there are substantial warming and cooling trends that occur on time scales of 10 to 30 years or more. I picked this particular simulation (each one is different as the random numbers change) because it looks similar to the global-observed temperature variations since the 1940s…cooling for a couple of decades, then strong warming for 30 years, which then levels off.

In this particular simulation, 50% of the fifty year warming trend is due to the natural cloud variations, the other 50% is due to increasing CO2. If I remove the cloud variations, the temperature curve follows a trend line that looks like the one in Fig. 2, but with only half the slope.

The assumed (neutral) feedback corresponds to a net surface warming of about 1 deg. C for a doubling of carbon dioxide. Since we’ve already experienced that amount of warming in the last 100 years, this would mean that global warming would now be ended for about the next 50 years….which is about how long it will take to reach CO2 doubling in the atmosphere.

If feedbacks end up being negative, though, then extra CO2 will have caused even less warming, which means that there is even more room for natural cloud variability to explain the warming experienced in the last 50 to 100 years. More about that possibility later.

The first objection to what I have just presented would probably be, “How do we know that natural cloud changes like that even exist?” Well, previous satellite studies (e.g. Wong et al.) have shown that similar fluctuations in the Earth’s radiative energy balance exist. All I’m claiming is that they existed in nature before we had satellites to measure them, which seems like an entirely reasonable assumption.

The second objection to what I have presented would probably be, “But you have not assumed positive feedback, and climate models show that the climate system has positive feedback!”

This issue is, of course, what I spend most of my time working on. And, as I have been harping on ad nauseum, the illusion of a sensitive climate system has arisen also because previous investigations have ignored natural, internally-generated cloud fluctuations, which cause a bias in their estimates of feedback toward positive feedback (Spencer & Braswell, 2008).

Our new mega-paper, almost ready for submission to JGR, introduces a new method to separate the effects of cloud forcing from cloud feedback. It leads to a diagnosis of strongly negative feedback in our most recent 7.5 year record of satellite data. (BTW, the negative feedback is only in the reflected solar part – probably due to low clouds. The infrared feedback was positive, probably due to positive water vapor feedback). The method also works pretty well at diagnosing the feedbacks in the IPCC climate models.

Oh, and guess what happens if we use the old traditional method of estimating feedback from the model data shown in Figs. 1 and 2 by plotting yearly averages of each against each other? You get a ‘false positive’…stronger positive feedback than even any of the IPCC climate models exhibit…even though neutral feedback was assumed in the model simulation.

Natural climate variability is the 800 pound gorilla in the room that the IPCC has been ignoring.

I get an amazing number of e-mails from engineers who point out that the climate system can not be dominated by positive feedback, because that would mean the climate is unstable, in which case it would have careened out of control long ago.

So, I have to keep explaining to them that climate researchers have ‘redefined’ positive feedback. We borrowed the concept from electric circuit theory, which was elucidated back in the 1940s. And, yes, all of you engineers are right…in your terms, the climate system IS dominated by negative feedback. The Earth DOES lose extra energy to outer space when it warms, which then stabilizes the climate system against perturbations.

But in the climate research world, the dividing line between ‘positive’ and ‘negative’ feedback is not whether extra energy is gained or lost with warming, but whether the increase is greater (or not) than the ‘temperature-only’ increase in infrared energy loss with warming.

That temperature-only response is what you feel when you turn up the stove, or make a fire bigger — hotter objects give off more radiant energy. Positive feedback in the climate system is defined as any indirect change in response to the warming (for instance, fewer low clouds) which then reduces the energy loss below the temperature-only response. This causes more warming to occur before energy equilibrium is once more restored.

In the absence of feedbacks, this temperature-only response is estimated to be about 3.3 Watts per sq. meter per degree C at the effective radiating temperature of the Earth, which is about 255 Kelvin (-18 deg. C).

Of course, what this also means is that if positive feedbacks exceeded that 3.3 Watts, then we really DO have an unstable climate system. So, in some sense, the climate system is always 3.3 Watts in positive feedback away from oblivion.

If positive feedbacks decrease the response from 3.3 to 1 Watt, then warming from a doubling of atmospheric CO2 would be almost 4 deg. C. That’s a lot of warming.

But if negative feedbacks dominate, and they increase that 3.3 Watts to, say, 3.7 Watts then there would only be 1 deg. C of warming with doubling of CO2.

Or, if (like our latest research suggests), the loss of radiant energy is as large as 6 Watts per degree of warming, then manmade global warming becomes only 0.6 deg. C.

Obviously, the feedbacks operating in the real climate system is the most important question in global warming research. But, unfortunately, there is relatively little research going on in this area. Everyone is too busy playing with computerized climate models.

But you engineers are indeed correct: When we climate researchers talk about positive feedback, what we are really talking about (in electrical engineering terms) is weak negative feedback.

…my April Fools Day post was NOT real, folks. Please stop sending me e-mails.

As regular readers here are already aware, I am increasingly convinced that the greatest mistake that the IPCC and mainstream climate researchers have made is their assumption that cloud cover on the Earth remains the same on climate time scales, say over 30 years or longer. The issue is critical because clouds determine how much solar energy is absorbed by the Earth, which then largely determines average global temperatures.

Assuming that cloud cover remains the same is part of the climate modelers’ worldview in which nature was in balance before humans came along and upset that balance.

But there is no way to support this worldview with data…it is a matter of faith. It takes only a 1% change in global average cloud cover to cause substantial climate change, either warming or cooling. It has only been since 2000 that have we had sufficiently stable satellite data (from NASA’s Terra and Aqua satellites) to determine whether there are any long-term, natural changes in global cloudiness, and unfortunately eight years of data is not much in the context of climate change.

Even our latest, state-of-the-art radiation budget instruments on those same satellites are still not sufficient to measure whether an imbalance in the Earth’s radiative budget exists to better than about 1% (about 4 Watts per sq. meter). That’s five times the ‘manmade imbalance’ that has been theorized to exist today from anthropogenic greenhouse gas emissions.

But there’s an interesting consequence of this assumption that the climate system has always been in balance: The assumption ends up leading to a tautology – a process of circular reasoning – regarding the role of mankind in climate change. Let me explain.

As we demonstrated in our 2008 J. Climate paper, chaotic fluctuations in cloud cover can give the illusion of positive feedback – that is, of a sensitive climate system. Climate researchers who have previously tried to determine how sensitive the climate system is from satellite data have ignored the biasing effect that natural, chaotic cloud fluctuations have on their estimates of feedback. And as a result, they have overestimated climate sensitivity. (As I have mentioned before, this can also be explained as getting cause and effect mixed up when observing cloud and temperature variations.)

This, in turn, has influenced how the climate modelers build their climate models. All of the IPCC climate models now produce a sensitive climate system, which amplifies the small amount of warming from the extra carbon dioxide in the atmosphere by a sufficient amount to explain most, if not all, of the warming we have seen in the last 50 years.

So, if the climate system is sensitive, then there is no need for a natural explanation for global warming (such as clouds) because increasing CO2 concentrations are sufficient to explain the warming.

But do you see what has happened here? By ignoring natural, chaotic fluctuations in clouds, researchers have come to the (mistaken) conclusion that there is no need to look for clouds as a cause of climate change. They ended up concluding only what they had assumed to begin with!

But I will admit that circular reasoning has one advantage: It always results in a self-consistent explanation.

So, when you hear that climate researchers have determined that the only way they can explain warming in the last 50 years is with human influences, you need to be very wary. The reason they can explain the warming only when they include humanity’s greenhouse gas emissions is because we do not have sufficiently accurate global observations to say otherwise.

So, since they don’t have the data to determine whether there are natural sources of climate change, they simply ASSUME it does not happen. This makes the theory of manmade global warming to large extent a matter of faith. From talking to a few of them, I think that many of these researchers are not even aware they have made this implicit assumption.

And the truth is there is no unique human fingerprint of global warming to identify our present warmth as manmade, either. For instance, a slight natural decrease in cloud cover would let more sunlight in and cause the oceans to warm, thus causing an increase in water vapor (our main greenhouse gas), which would then look like manmade warming. Even the greater warming over land than the ocean we have experienced can be explained by warming oceans…because warmer oceans send more humid airmasses over land, which then causes a naturally-enhanced greenhouse effect over land. (This finding was published here.)

I find that meteorologists (by training) are perfectly comfortable with the idea of natural cloud fluctuations causing climate change. But climate modelers tend to look down on meteorologists, who as a group are generally distrustful of climate models.

I would argue that, until climate modelers begin to appreciate the complexities of weather – especially of clouds — as much as meteorologists do, then their efforts to predict climate change with computer programs will be as futile as tilting at windmills.

…hot off the press…N. Hemisphere & tropics really cooled off last month.

YR MON GLOBE   NH   SH   TROPICS
2009   1   0.304   0.443   0.165   -0.036
2009   2   0.347   0.678   0.016   0.051
2009   3   0.208   0.313   0.104   -0.150

1979-2009 Graph

(corrected 2 April 2 p.m. CDT for error in discussion of Kirchoffs Law…kudos to Ben Herman, U. Arizona)

One of the points that Dr. Richard Lindzen made during his keynote speech at the 2nd International Conference on Climate Change, held in New York City March 8-10 this year, is that we global warming skeptics need to be careful about what aspects of the theory of manmade global warming we dispute.

And I fully agree.

In an e-mail I just responded to this evening, I once again found myself defending the existence of the Earth’s “greenhouse effect”. I’m talking about the Earth’s natural greenhouse effect, not mankind’s small enhancement of it. And it’s amazing how many scientists, let alone lay people, dispute its existence.

I’ll admit I used to question it, too. So, many years ago Danny Braswell and I built our own radiative transfer model to demonstrate for ourselves that the underlying physics were sound.

To briefly review: because water vapor, clouds, carbon dioxide, and methane in the atmosphere absorb and emit infrared radiation, the atmosphere stays warmer in the lower atmosphere and cooler in the upper atmosphere than it would otherwise be without the greenhouse effect.

Even though the physical process involved in this is radiative, the greenhouse blanket around the Earth is somewhat analogous to a real blanket, which we all know tends to hold heat in where it is being generated, and reduce its flow toward the colder surroundings. A blanket – real or greenhouse — doesn’t actually create the separation between hot and cold…it just reduces the rate at which energy is lost by the hot, and gained by the cold.

In the case of the Earth, most sunlight is absorbed at the surface, which then heats and moistens the air above it. This solar heating causes the lower atmosphere to warm, and the greenhouse effect of the water vapor thus generated helps keep the lower atmosphere warm by reducing its rate of cooling. (Long before radiation can make the surface too warm, though, convective air currents kick in…e.g. thunderstorms…and transport much of the excess heat from the lower to the upper atmosphere. As a result, the lower atmosphere never gets as warm as the greenhouse effect ‘wants’ to make it.)

So where do the objections to the “greenhouse effect” come in?

IT’S NOT A REAL GREENHOUSE
The processes involved in the atmospheric greenhouse effect are not the same as what happens in a real greenhouse. Yes, we all know that, but the misnomer has stuck, and it is not going away anytime soon. A real greenhouse physically traps warm air, preventing convective air currents from carrying warm air out of the greenhouse, which would then be replaced by cooler air coming into the greenhouse. In contrast, the infrared atmospheric greenhouse effect instead slows the rate at which the atmosphere cools radiatively, not convectively.

IT VIOLATES THE SECOND LAW OF THERMODYNAMICS
A second objection has to do with the Second Law of Thermodynamics. It is claimed that since the greenhouse effect depends partly upon cooler upper layers of the atmosphere emitting infrared radiation toward the warmer, lower layers of the atmosphere, that this violates the 2nd Law, which (roughly speaking) says that energy must flow from warmer objects to cooler objects, not the other way around.

There are different ways to illustrate why this is not a valid objection. First of all, the 2nd Law applies to the behavior of whole systems, not to every part within a system, and to all forms of energy involved in the system…not just its temperature. And in the atmosphere, temperature is only one component to the energy content of an air parcel.

Secondly, the idea that a cooler atmospheric layer can emit infrared energy toward a warmer atmospheric layer below it seems unphysical to many people. I suppose this is because we would not expect a cold piece of metal to transfer heat into a warm piece of metal. But the processes involved in conductive heat transfer are not the same as in radiative heat transfer. A hot star out in space will still receive, and absorb, radiant energy from a cooler nearby star…even though the NET flow of energy will be in the opposite direction.

In other words, a photon being emitted by the cooler star doesn’t stick its finger out to see how warm the surroundings are before it decides to leave.

Furthermore, we should not confuse a reduced rate of cooling with heating. Imagine you have a jar of boiling hot water right next to a jar of warm water sitting on the counter. The boiling hot jar will cool rapidly, while the warm jar will cool more slowly. Eventually, both jars will achieve the same temperature, just as the 2nd Law predicts.

But what if the boiling hot jar was by all by itself? Then, it would have cooled even faster. Does that mean that the presence of the warm jar was sending energy into the hot jar? No, it was just reducing the rate of cooling of the hot jar. The climate system is like the hot jar having an internal heating mechanism (the sun warming the surface), but its ability to cool is reduced by its surroundings (the atmosphere), which tends to insulate it.

Another way the objection is voiced is that a layer of the atmosphere that absorbs infrared energy at a certain rate must then also emit it at the same rate, so how can that layer “trap” any energy to warm? This misconception comes from a misunderstanding of Kirchoffs Law, which only says that the infrared opacity of a layer makes that layer’s ability to absorb and emit IR the same. The actual rate of infrared absorption by a layer depends upon that opacity AND the temperatures of the emitting layers above and below, but the rate of emission depends upon the the same opacity and the temperature of the layer itself. Therefore, the rate of infrared flows in and out of the layer do not have to be equal, and if they are not equal, the layer will either warm or cool radiatively.

THE ATMOSPHERE IS ALREADY OPAQUE TO THE TRANSFER OF INFRARED ENERGY

Some claim that since the atmosphere is already quite opaque to the transfer of infrared energy, adding a little more CO2 won’t do anything to warm the lower atmosphere and surface. While there is a grain of truth to this, it must be remembered that the Earth’s surface does not radiatively cool directly to outer space, but to the layer of air above it, which in turn cools to the next layer of air above it, etc.

Think of it like several blankets covering your body on a cold night. Your body does not lose energy directly to the cold air outside of the blankets, but to the first blanket, which then transfers heat to the second blanket, etc.

Finally, the most vivid evidence that infrared radiation can cool something below the temperature of its surroundings – in seeming contradiction to the 2nd Law — is what happens on a clear calm night. The Earth’s surface cools by losing infrared radiation, which then chills the air in contact with it. This nighttime cooling causes a thin layer of cold air to build up near the surface…even though it is colder than the ground below the surface, or the air immediately above it.

There is no way for cooler air aloft coming down to the surface to be causing this effect because when air descends from any altitude, it will always be warmer (not colder) than its surroundings, due to adiabatic compression.

Therefore, we have a cold air layer sandwiched in between two warmer layers, becoming colder still as night progresses. Is this a violation of the Second Law of Thermodynamics? No, because the entire depth of the atmosphere – as a system — is indeed losing infrared energy as a whole to the cold depths of outer space.

The same thing happens to the top of your car when the sun sets…it cools by infrared radiation to a temperature cooler than the air, and as a result is often the first place you will see dew form.

THE GREENHOUSE EFFECT WORKS…FOR NOW
The greenhouse effect is supported by laboratory measurements of the radiative absorption properties of different gases, which when put into a radiative transfer model that conserves energy, and combined with convective overturning of the atmosphere in response to solar heating, results in a vertical temperature profile that looks very much like the one we observe in nature.

So, until someone comes along with another quantitative model that uses different physics to get as good a simulation of the vertical temperature profile of the atmosphere, I consider objections to the existence of the ‘greenhouse effect’ to be little more than hand waving.

(OK, folks, this has gotten out of hand. I’m still getting e-mails asking what my source was for the information below. Note…I posted this on April Fools Day, and I dropped a pretty obvious hint in the last line, but some of you still think this was real. It’s not.)

In an unprecedented about-face, Al Gore last night recanted his claim that mankind is causing global warming. The announcement was made late Tuesday night from his Nashville home through his press secretary. Mr. Gore has remained unavailable for comment. In part, the announcement reads:

“While I will continue to support the development and rapid deployment of alternative energy technologies, I believe that the science can no longer support the view that catastrophic global warming is probable. This decision has required considerable soul searching on my part. But this is the nature of science, and scientific progress. I have no regrets over the path I have chosen.”

The announcement says that Mr. Gore will be publicly renouncing his portion of the Nobel Peace Prize, which was awarded to him in 2007 for his tireless efforts to raise global awareness of the climate crisis. In fact, he will no longer be referring to the fight against a ‘climate crisis’, but instead the fight will continue against a “global energy crisis”.

“The need for inexpensive and readily available energy is the most important issue facing the world’s poor”, the statement reads, “and I will be advocating free market approaches to the leaders of Third World countries in order to allow their citizens to enter and contribute to the 21st Century global economy.”

There is also the hint that he is considering returning his Academy Award for best documentary, although he hopes that a new movie category (best movie, science fiction) will be created to accommodate his highly acclaimed motion picture on global warming, An Inconvenient Truth.