Once more unto the bray

We are a little late to the party, but it is worth adding a few words now that our favourite amateur contrarian is at it again. As many already know, the Forum on Physics and Society (an un-peer-reviewed newsletter published by the otherwise quite sensible American Physical Society), rather surprisingly published a new paper by Monckton that tries again to show using rigorous arithmetic that IPCC is all wrong and that climate sensitivity is negligible. His latest sally, like his previous attempt, is full of the usual obfuscating sleight of hand, but to save people the time in working it out themselves, here are a few highlights.

As Deltoid quickly noticed the most egregious error is a completely arbitrary reduction (by 66%) of the radiative forcing due to CO₂. He amusingly justifies this with reference to tropical troposphere temperatures - neglecting of course that temperatures change in response to forcing and are not the forcing itself. And of course, he ignores the evidence that the temperature changes are in fact rather uncertain, and may well be much more in accord with the models than he thinks.

But back to his main error: Forcing due to CO₂ can be calculated very accurately using line-by-line radiative transfer codes (see Myhre et al 2001; Collins et al 2006). It is normally done for a few standard atmospheric profiles and those results weighted to produce a global mean estimate of 3.7 W/m² - given the variations in atmospheric composition (clouds, water vapour etc.) uncertainties are about 10% (or 0.4 W/m²) (the spatial pattern can be seen here). There is no way that it is appropriate to arbitrarily divide it by three.

There is a good analogy to gas mileage. The gallon of gasoline is equivalent to the forcing, the miles you can go on a gallon is the response (i.e. temperature), and thus the miles per gallon is analogous to the climate sensitivity. Thinking that forcing should be changed because of your perception of the temperature change is equivalent to deciding after the fact that you only put in third of a gallon because you ran out of gas earlier than you expected. The appropriate response would be to think about the miles per gallon - but you'd need to be sure that you measured the miles travelled accurately (a very big issue for the tropical troposphere).

But Monckton is not satisfied with just a factor of three reduction in sensitivity. So he makes another dodgy claim. Note that Monckton starts off using the IPCC definition of climate sensitivity as the forcing associated with a concentration of 2xCO₂ - this is the classical "Charney Sensitivity" and does not include feedbacks associated with carbon cycle, vegetation or ice-sheet change. Think of it this way - if humans raise CO₂ levels to 560 ppm from 280 ppm through our emissions, and then as the climate warms the carbon cycle starts adding even more CO₂ to the atmosphere, then the final CO₂ will be higher and the temperature will end up higher than standard sensitivity would predict, but you are no longer dealing with the sensitivity to 2xCO2. Thus the classical climate sensitivity does not include any carbon cycle feedback term. But Monckton puts one in anyway.

You might ask why he would do this. Why add another positive feedback to the mix when he is aiming to minimise the climate sensitivity? The answer lies in the backwards calculations he makes to derive the feedbacks. At this point, I was going to do a full analysis of that particular calculation - but I was scooped. So instead of repeating the work, I'll refer you there. The short answer is that by increasing the feedbacks incorrectly, he makes the 'no-feedback' temperature smaller (since he is deriving it from the reported climate sensitivities divided by the feedbacks). This reverses the causality since the 'no-feedback' value is actually independent of the feedbacks, and is much better constrained.

There are many more errors in his piece - for instance he accuses the IPCC of not defining radiative forcing in the Summary for Policy Makers and not fixing this despite requests. Umm… except that the definition is on the bottom of page 2. He bizarrely compares the net anthropogenic forcing to date with the value due to CO2 alone and then extrapolates that difference to come up with a meaningless 'total anthropogenic forcings Del F_2xCO2′. His derivations and discussions of the no-feedback sensitivity and feedbacks is extremely opaque (a much better description is given on the first couple of pages of Hansen et al, 1984)). His discussion of the forcings in that paper are wrong (it's 4.0 W/m2 for 2xCO₂ (p135), not 4.8 W/m2), and the no-feedback temperature change is 1.2 (Hansen et al, 1988, p9360), giving k=0.30 C/(W/m2) (not his incorrect 0.260 C/(W/m2) value). Etc… Needless to say, the multiple errors completely undermine the conclusions regarding climate sensitivity.

Generally speaking, these are the kinds of issues that get spotted by peer-reviewers: are the citations correctly interpreted? is the mathematics correct? is the reasoning sound? do the conclusions follow? etc. In this case, there really wouldn't have been much left, and so it is fair to conclude that Monckton's piece only saw the light of day because it wasn't peer-reviewed, not because it was. Claims that the suggested edits from the editor of the newsletter constitute 'peer-review' are belied by the editor's obvious unfamiliarity with the key concepts of forcing and feedback - and the multitude of basic errors still remaining. The even more egregious claims that this paper provides "Mathematical proof that there is no 'climate crisis' " or is "a major, peer-reviewed paper in Physics and Society, a learned journal of the 10,000-strong American Physical Society" are just bunk (though amusing in their chutzpah).

The rational for the FPS publication of this note was to 'open up the debate' on climate change. The obvious ineptitude of this contribution underlines quite effectively how little debate there is on the fundamentals if this is the best counter-argument that can be offered.

Here is some talk by Freeman Dyson on the climate problem:

FREEMAN DYSON is professor of physics at the Institute for Advanced Study, in Princeton. His professional interests are in mathematics and astronomy. Among his many books are Disturbing the Universe, Infinite in All Directions Origins of Life, From Eros to Gaia, Imagined Worlds, and The Sun, the Genome, and the Internet. His most recent book, Many Colored Glass: Reflections on the Place of Life in the Universe (Page Barbour Lectures), is being published this month by University of Virgina Press.

Freeman Dyson’s Edge Bio Page

HERETICAL THOUGHTS ABOUT SCIENCE AND SOCIETY

1. The Need for Heretics

In the modern world, science and society often interact in a perverse way. We live in a technological society, and technology causes political problems. The politicians and the public expect science to provide answers to the problems. Scientific experts are paid and encouraged to provide answers. The public does not have much use for a scientist who says, “Sorry, but we don’t know”. The public prefers to listen to scientists who give confident answers to questions and make confident predictions of what will happen as a result of human activities. So it happens that the experts who talk publicly about politically contentious questions tend to speak more clearly than they think. They make confident predictions about the future, and end up believing their own predictions. Their predictions become dogmas which they do not question. The public is led to believe that the fashionable scientific dogmas are true, and it may sometimes happen that they are wrong. That is why heretics who question the dogmas are needed.

As a scientist I do not have much faith in predictions. Science is organized unpredictability. The best scientists like to arrange things in an experiment to be as unpredictable as possible, and then they do the experiment to see what will happen. You might say that if something is predictable then it is not science. When I make predictions, I am not speaking as a scientist. I am speaking as a story-teller, and my predictions are science-fiction rather than science. The predictions of science-fiction writers are notoriously inaccurate. Their purpose is to imagine what might happen rather than to describe what will happen. I will be telling stories that challenge the prevailing dogmas of today. The prevailing dogmas may be right, but they still need to be challenged. I am proud to be a heretic. The world always needs heretics to challenge the prevailing orthodoxies. Since I am heretic, I am accustomed to being in the minority. If I could persuade everyone to agree with me, I would not be a heretic.

We are lucky that we can be heretics today without any danger of being burned at the stake. But unfortunately I am an old heretic. Old heretics do not cut much ice. When you hear an old heretic talking, you can always say, “Too bad he has lost his marbles”, and pass on. What the world needs is young heretics. I am hoping that one or two of the people who read this piece may fill that role.

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2. Climate and Land Management

The main subject of this piece is the problem of climate change. This is a contentious subject, involving politics and economics as well as science. The science is inextricably mixed up with politics. Everyone agrees that the climate is changing, but there are violently diverging opinions about the causes of change, about the consequences of change, and about possible remedies. I am promoting a heretical opinion, the first of three heresies that I will discuss in this piece.

My first heresy says that all the fuss about global warming is grossly exaggerated. Here I am opposing the holy brotherhood of climate model experts and the crowd of deluded citizens who believe the numbers predicted by the computer models. Of course, they say, I have no degree in meteorology and I am therefore not qualified to speak. But I have studied the climate models and I know what they can do. The models solve the equations of fluid dynamics, and they do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry and the biology of fields and farms and forests. They do not begin to describe the real world that we live in. The real world is muddy and messy and full of things that we do not yet understand. It is much easier for a scientist to sit in an air-conditioned building and run computer models, than to put on winter clothes and measure what is really happening outside in the swamps and the clouds. That is why the climate model experts end up believing their own models.

There is no doubt that parts of the world are getting warmer, but the warming is not global. I am not saying that the warming does not cause problems. Obviously it does. Obviously we should be trying to understand it better. I am saying that the problems are grossly exaggerated. They take away money and attention from other problems that are more urgent and more important, such as poverty and infectious disease and public education and public health, and the preservation of living creatures on land and in the oceans, not to mention easy problems such as the timely construction of adequate dikes around the city of New Orleans.

I will discuss the global warming problem in detail because it is interesting, even though its importance is exaggerated. One of the main causes of warming is the increase of carbon dioxide in the atmosphere resulting from our burning of fossil fuels such as oil and coal and natural gas. To understand the movement of carbon through the atmosphere and biosphere, we need to measure a lot of numbers. I do not want to confuse you with a lot of numbers, so I will ask you to remember just one number. The number that I ask you to remember is one hundredth of an inch per year. Now I will explain what this number means. Consider the half of the land area of the earth that is not desert or ice-cap or city or road or parking-lot. This is the half of the land that is covered with soil and supports vegetation of one kind or another. Every year, it absorbs and converts into biomass a certain fraction of the carbon dioxide that we emit into the atmosphere. Biomass means living creatures, plants and microbes and animals, and the organic materials that are left behind when the creatures die and decay. We don’t know how big a fraction of our emissions is absorbed by the land, since we have not measured the increase or decrease of the biomass. The number that I ask you to remember is the increase in thickness, averaged over one half of the land area of the planet, of the biomass that would result if all the carbon that we are emitting by burning fossil fuels were absorbed. The average increase in thickness is one hundredth of an inch per year.

The point of this calculation is the very favorable rate of exchange between carbon in the atmosphere and carbon in the soil. To stop the carbon in the atmosphere from increasing, we only need to grow the biomass in the soil by a hundredth of an inch per year. Good topsoil contains about ten percent biomass, [Schlesinger, 1977], so a hundredth of an inch of biomass growth means about a tenth of an inch of topsoil. Changes in farming practices such as no-till farming, avoiding the use of the plow, cause biomass to grow at least as fast as this. If we plant crops without plowing the soil, more of the biomass goes into roots which stay in the soil, and less returns to the atmosphere. If we use genetic engineering to put more biomass into roots, we can probably achieve much more rapid growth of topsoil. I conclude from this calculation that the problem of carbon dioxide in the atmosphere is a problem of land management, not a problem of meteorology. No computer model of atmosphere and ocean can hope to predict the way we shall manage our land.

Here is another heretical thought. Instead of calculating world-wide averages of biomass growth, we may prefer to look at the problem locally. Consider a possible future, with China continuing to develop an industrial economy based largely on the burning of coal, and the United States deciding to absorb the resulting carbon dioxide by increasing the biomass in our topsoil. The quantity of biomass that can be accumulated in living plants and trees is limited, but there is no limit to the quantity that can be stored in topsoil. To grow topsoil on a massive scale may or may not be practical, depending on the economics of farming and forestry. It is at least a possibility to be seriously considered, that China could become rich by burning coal, while the United States could become environmentally virtuous by accumulating topsoil, with transport of carbon from mine in China to soil in America provided free of charge by the atmosphere, and the inventory of carbon in the atmosphere remaining constant. We should take such possibilities into account when we listen to predictions about climate change and fossil fuels. If biotechnology takes over the planet in the next fifty years, as computer technology has taken it over in the last fifty years, the rules of the climate game will be radically changed.

When I listen to the public debates about climate change, I am impressed by the enormous gaps in our knowledge, the sparseness of our observations and the superficiality of our theories. Many of the basic processes of planetary ecology are poorly understood. They must be better understood before we can reach an accurate diagnosis of the present condition of our planet. When we are trying to take care of a planet, just as when we are taking care of a human patient, diseases must be diagnosed before they can be cured. We need to observe and measure what is going on in the biosphere, rather than relying on computer models.

Everyone agrees that the increasing abundance of carbon dioxide in the atmosphere has two important consequences, first a change in the physics of radiation transport in the atmosphere, and second a change in the biology of plants on the ground and in the ocean. Opinions differ on the relative importance of the physical and biological effects, and on whether the effects, either separately or together, are beneficial or harmful. The physical effects are seen in changes of rainfall, cloudiness, wind-strength and temperature, which are customarily lumped together in the misleading phrase “global warming”. In humid air, the effect of carbon dioxide on radiation transport is unimportant because the transport of thermal radiation is already blocked by the much larger greenhouse effect of water vapor. The effect of carbon dioxide is important where the air is dry, and air is usually dry only where it is cold. Hot desert air may feel dry but often contains a lot of water vapor. The warming effect of carbon dioxide is strongest where air is cold and dry, mainly in the arctic rather than in the tropics, mainly in mountainous regions rather than in lowlands, mainly in winter rather than in summer, and mainly at night rather than in daytime. The warming is real, but it is mostly making cold places warmer rather than making hot places hotter. To represent this local warming by a global average is misleading.

The fundamental reason why carbon dioxide in the atmosphere is critically important to biology is that there is so little of it. A field of corn growing in full sunlight in the middle of the day uses up all the carbon dioxide within a meter of the ground in about five minutes. If the air were not constantly stirred by convection currents and winds, the corn would stop growing. About a tenth of all the carbon dioxide in the atmosphere is converted into biomass every summer and given back to the atmosphere every fall. That is why the effects of fossil-fuel burning cannot be separated from the effects of plant growth and decay. There are five reservoirs of carbon that are biologically accessible on a short time-scale, not counting the carbonate rocks and the deep ocean which are only accessible on a time-scale of thousands of years. The five accessible reservoirs are the atmosphere, the land plants, the topsoil in which land plants grow, the surface layer of the ocean in which ocean plants grow, and our proved reserves of fossil fuels. The atmosphere is the smallest reservoir and the fossil fuels are the largest, but all five reservoirs are of comparable size. They all interact strongly with one another. To understand any of them, it is necessary to understand all of them.

As an example of the way different reservoirs of carbon dioxide may interact with each other, consider the atmosphere and the topsoil. Greenhouse experiments show that many plants growing in an atmosphere enriched with carbon dioxide react by increasing their root-to-shoot ratio. This means that the plants put more of their growth into roots and less into stems and leaves. A change in this direction is to be expected, because the plants have to maintain a balance between the leaves collecting carbon from the air and the roots collecting mineral nutrients from the soil. The enriched atmosphere tilts the balance so that the plants need less leaf-area and more root-area. Now consider what happens to the roots and shoots when the growing season is over, when the leaves fall and the plants die. The new-grown biomass decays and is eaten by fungi or microbes. Some of it returns to the atmosphere and some of it is converted into topsoil. On the average, more of the above-ground growth will return to the atmosphere and more of the below-ground growth will become topsoil. So the plants with increased root-to-shoot ratio will cause an increased transfer of carbon from the atmosphere into topsoil. If the increase in atmospheric carbon dioxide due to fossil-fuel burning has caused an increase in the average root-to-shoot ratio of plants over large areas, then the possible effect on the top-soil reservoir will not be small. At present we have no way to measure or even to guess the size of this effect. The aggregate biomass of the topsoil of the planet is not a measurable quantity. But the fact that the topsoil is unmeasurable does not mean that it is unimportant.

At present we do not know whether the topsoil of the United States is increasing or decreasing. Over the rest of the world, because of large-scale deforestation and erosion, the topsoil reservoir is probably decreasing. We do not know whether intelligent land-management could increase the growth of the topsoil reservoir by four billion tons of carbon per year, the amount needed to stop the increase of carbon dioxide in the atmosphere. All that we can say for sure is that this is a theoretical possibility and ought to be seriously explored.

3. Oceans and Ice-ages

Another problem that has to be taken seriously is a slow rise of sea level which could become catastrophic if it continues to accelerate. We have accurate measurements of sea level going back two hundred years. We observe a steady rise from 1800 to the present, with an acceleration during the last fifty years. It is widely believed that the recent acceleration is due to human activities, since it coincides in time with the rapid increase of carbon dioxide in the atmosphere. But the rise from 1800 to 1900 was probably not due to human activities. The scale of industrial activities in the nineteenth century was not large enough to have had measurable global effects. So a large part of the observed rise in sea level must have other causes. One possible cause is a slow readjustment of the shape of the earth to the disappearance of the northern ice-sheets at the end of the ice age twelve thousand years ago. Another possible cause is the large-scale melting of glaciers, which also began long before human influences on climate became significant. Once again, we have an environmental danger whose magnitude cannot be predicted until we know more about its causes, [Munk, 2002].

The most alarming possible cause of sea-level rise is a rapid disintegration of the West Antarctic ice-sheet, which is the part of Antarctica where the bottom of the ice is far below sea level. Warming seas around the edge of Antarctica might erode the ice-cap from below and cause it to collapse into the ocean. If the whole of West Antarctica disintegrated rapidly, sea-level would rise by five meters, with disastrous effects on billions of people. However, recent measurements of the ice-cap show that it is not losing volume fast enough to make a significant contribution to the presently observed sea-level rise. It appears that the warming seas around Antarctica are causing an increase in snowfall over the ice-cap, and the increased snowfall on top roughly cancels out the decrease of ice volume caused by erosion at the edges. The same changes, increased melting of ice at the edges and increased snowfall adding ice on top, are also observed in Greenland. In addition, there is an increase in snowfall over the East Antarctic Ice-cap, which is much larger and colder and is in no danger of melting. This is another situation where we do not know how much of the environmental change is due to human activities and how much to long-term natural processes over which we have no control.

Another environmental danger that is even more poorly understood is the possible coming of a new ice-age. A new ice-age would mean the burial of half of North America and half of Europe under massive ice-sheets. We know that there is a natural cycle that has been operating for the last eight hundred thousand years. The length of the cycle is a hundred thousand years. In each hundred-thousand year period, there is an ice-age that lasts about ninety thousand years and a warm interglacial period that lasts about ten thousand years. We are at present in a warm period that began twelve thousand years ago, so the onset of the next ice-age is overdue. If human activities were not disturbing the climate, a new ice-age might already have begun. We do not know how to answer the most important question: do our human activities in general, and our burning of fossil fuels in particular, make the onset of the next ice-age more likely or less likely?

There are good arguments on both sides of this question. On the one side, we know that the level of carbon dioxide in the atmosphere was much lower during past ice-ages than during warm periods, so it is reasonable to expect that an artificially high level of carbon dioxide might stop an ice-age from beginning. On the other side, the oceanographer Wallace Broecker [Broecker, 1997] has argued that the present warm climate in Europe depends on a circulation of ocean water, with the Gulf Stream flowing north on the surface and bringing warmth to Europe, and with a counter-current of cold water flowing south in the deep ocean. So a new ice-age could begin whenever the cold deep counter-current is interrupted. The counter-current could be interrupted when the surface water in the Arctic becomes less salty and fails to sink, and the water could become less salty when the warming climate increases the Arctic rainfall. Thus Broecker argues that a warm climate in the Arctic may paradoxically cause an ice-age to begin. Since we are confronted with two plausible arguments leading to opposite conclusions, the only rational response is to admit our ignorance. Until the causes of ice-ages are understood, we cannot know whether the increase of carbon-dioxide in the atmosphere is increasing or decreasing the danger.

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