Skeptics should cast a much wider net

Professional provocateur John Horgan bravely took on a room full of skeptics a few days ago when he scolded them for what he thinks are their misplaced priorities. Horgan thinks that a lot of skeptics are taking on ‘soft’ targets – homeopathy, astrology, UFOS etc. and instead should be spending far more time on ‘hard’ targets. Horgan thinks that this kind of cherry-picking not only allows skeptics to keep on patting each others’ backs in echo chambers, but it detracts from other important issues that deserve skeptical scrutiny even more. To a large extent his argument is simply one of degree, since he clearly does not think homeopathy or UFOs don't deserve skeptical takedowns.

What are Horgan’s favorite ‘hard’ targets? One is war. He says that more skeptics should spend time debunking the idea that war is intrinsic rather than cultural. The other hard target is belief in highly speculative theories from physics like string theory, parallel universes and the idea that our universe may be a simulation created by aliens. I won’t go as far as he does to say that string theory is akin to astrology or homeopathy, and I also think that these theories have come under much harsher criticism than he thinks in the last decade or so: I am more concerned about the fact that popular science books expounding these theories are taken quite seriously by uninformed laymen. But the general idea that many informed skeptics should spend more time on talking about the shaky pillars of some of these speculations seems to be a reasonable one. The third target that Horgan addresses is the field of medical diagnosis. By now it’s quite clear that standard diagnostic tests like mammograms and PSA (prostate-specific antigen) testing are subject to such a high false positive rate that they may cause more harm than good (a very good book on these pitfalls that I read recently is Steven Hatch's “Snowball in a Blizzard”).

Many bloggers and self-proclaimed skeptics have responded to Horgan. The main criticism is simply that skeptics are far less monolithic and more diverse, both in degree and kind, than he thinks. The criticism also includes the admonition that the good is not the enemy of the great and one needs to work on both. I would also add that a target like homeopathy or even UFOs is not ‘easy’ in the sense of easily convincing its proponents. But generally speaking I think Horgan is not wrong. There are certainly some topics which would benefit from more scrutiny than what they currently get.

Skepticism has a long tradition in both eastern and western cultures, best exemplified for me by the Royal Society’s motto “Nullius in verba”, or “Nobody’s word is final”. Sadly, I think that motto points to another failing of skeptics; their tendency to steer away from politically controversial topics, either because they think the last word on such topics has already been said or because they think that saying anything about them would be dangerous. To Horgan’s list of topics that reasonable skeptics don’t criticize as much as they should, I would add climate change and the study of genetic factors underlying race and gender (Ironically, Horgan himself once wrote a post asking if research on such topics should be banned). To me it appears that many skeptics seem to think that even discussing these topics is taboo or unreasonable. Such a stance would be deeply antithetical to the skeptical spirit of free inquiry. No topic should be taboo or unreasonable as long as it contains facts to be explored and assessed.

There are several interesting aspects of each of the above topics that not only deserve attention but which can also be discussed in a reasonable and respectful manner without dealing in either/or fallacies or derailing your basic beliefs for that matter. For instance, to cite only a few examples, as writers like Steven Pinker and Diane Halpern have discussed, you can talk about biological aspects underlying gender differences without believing even an iota that one gender is ‘superior’ or ‘inferior’ to the other. Similarly, as biologists like Jerry Coyne and E O Wilson have pointed out, you can accept the existence of different races (or groups) and genetic differences underlying them without ever thinking that one race is superior or inferior to others. In fact, not only is it an elementary logical fallacy to equate ‘different’ with ‘inferior’ or ‘superior’, but it's not even clear what superior or inferior could even mean in these contexts. Halpern, Pinker, Coyne and Wilson are all proud upholders of the skeptical and liberal traditions who believe in clearly separating what is known from what is unknown. The same goes for climate change; you can clearly accept the basic reality of climate change while pointing out that certain details about the phenomenon might still be ill-understood. For instance, you don’t have to trash climate change as a whole in order to question the validity of computer models of climate. Or you can acknowledge good scientific knowledge of the atmosphere while acknowledging poor scientific knowledge of the biosphere.

Sadly, many skeptics not only shy away from discussing these topics, but they also have a tendency to vilify or ignore those on the other side who raise the kinds of interesting questions which I pointed out above. An unfortunate instance would be the time that an entire organization of scientists ended up slandering the anthropologist Napoleon Chagnon because he tried to reveal rigorously researched facts about the violent culture of the Yanomamo tribe that flew in the face of everyone’s comfortable leanings about violence and human nature. Another example would be the censure that the historian of science Alice Dreger had to go through when she brought up some inconvenient scientific questions about transgender people (this is documented well in her readable book). The reaction to physicist Freeman Dyson’s views on climate change would also be in the same category. 

The most startling fact is that Dyson, Chagnon and Dreger are all liberals who have long championed liberal causes and freedom of the individual. Dreger's case is especially troubling since she has been an unusually vociferous and dedicated supporter of LGBT rights for almost her entire career; it would thus seem that the very community which she loved and fought for turned against her. She and the others also happen to be champions of going where the scientific truth leads, believing that knowledge is always better than ignorance and that even inconvenient knowledge can be prevented from being misused through our shared humanity. The antidote to misuse of knowledge is not opposition to knowing the facts, not the least because the facts have an inconvenient way of making themselves known.

The reality of critical discourse on many of these topics is more nuanced than we think; for instance, as I pointed out a few years ago, there is no doubt that some climate change “deniers” are actually deniers with vested financial or political interests, but some are also genuine skeptics who are asking fine-grained questions about specific parts of the topic in honest faith. Dreger and Chagnon were raising questions based on perfectly reasonable research and theorizing. Dyson who agrees with the basic reality of climate change nevertheless questions poorly understood aspects of computer models, cloud formation and soil chemistry. Science is complicated, and scientific disagreement is often also complicated, gray rather than black and white, and irreducible to binary categorization. Just because you are skeptical of some of the pieces does not mean you don’t trust the big picture, and just because you trust the big picture does not mean you cannot be skeptical of the little pieces.

As history demonstrates, there will always be ideologues with racial, misogynistic or otherwise ulterior motives who will use even the barest quibbling about details to bolster their prejudiced views (creationists do this in the context of evolution all the time), but opposition to these ideologues should be clearly distinguished from opposition to the inquiry itself. Ironically, in casting these skeptics as kooks or paid shills, it’s the so-called skeptics who are being close minded and the so-called kooks who are being the real open-minded skeptics.

Skepticism is tough because it involves not only modifying entrenched beliefs but rewiring emotional and gut responses that have been reinforced by conformation bias, echo chambers and community kinship. To thrive, the skeptical community needs to be diverse and open to careful consideration of arguments on all sides as long as the arguments have a good dose of serious science in them; it needs to separate empty, bullheaded or purely bigoted opposition from genuine criticism and concerns, and needs to address the latter. It needs to be tough minded in respectfully taking on politically or socially controversial topics. Perhaps some of the findings of science regarding these topics would be unsavory to our sensibilities, but as moral beings with control over their fate, we have the power to decide how to use such findings. 

The ultimate word on skepticism could well belong to Francis Bacon, one of the founders of modern science who said, “All depends on keeping the eye fixed upon the facts of nature…for God forbid we should give out a dream of our own imagination for a pattern of the world". We should strive toward our dream but build it on a foundation of facts.

Environmentalism is not climate change; climate change is not environmentalism

Freeman Dyson has an Op-Ed in the Boston Globe about the ongoing climate change talks in Paris in which he makes a cogent point - that environmentalism does not equal climate change and focus on climate change should not distract us from other environmental problems which may be largely unrelated to global warming.

"The environmental movement is a great force for good in the world, an alliance of billions of people determined to protect birds and butterflies and preserve the natural habitats that allow endangered species to survive. The environmental movement is a cause fit to fight for. There are many human activities that threaten the ecology of the planet. The environmental movement has done a great job of educating the public and working to heal the damage we have done to nature. I am a tree-hugger, in love with frogs and forests.  

But I am horrified to see the environmental movement hijacked by a bunch of climate fanatics, who have captured the attention of the public with scare stories. As a result, the public and the politicians believe that climate change is our most important environmental problem. More urgent and more real problems, such as the over-fishing of the oceans and the destruction of wild-life habitat on land, are neglected, while the environmental activists waste their time and energy ranting about climate change. The Paris meeting is a sad story of good intentions gone awry."

I rather agree with him that for many people the term environmentalism has become largely synonymous with climate change. However the two are not the same, as becomes clear to me when I hear him mention overfishing which is a real problem largely unconnected with climate change. I have recently been reading about the state of the world's fish in Paul Greenberg's excellent book "Four Fish". Greenberg focuses on the history and future of the four fish that have largely dominated the Western world's diet - salmon, sea bass, cod and  tuna. 

The book talks about how most of these fish were overharvested and almost driven to extinction by humans building dams and poisoning rivers with industrial effluent. Neither of these two issues is directly connected with climate change, but how often do we see high-profile global meetings which press everyone to deal with dam-building and water pollution on a war footing, let alone meetings led by presidents and prime ministers? 

Overfishing also brings another aspect of the climate change problem into sharp perspective: The only reason certain places in the US, such as the Salmon River in New York, are now full of fish is because those fish have been carefully cultivated in captivity and then released in the wild. Without this human intervention the Salmon River would have stayed barren. Then there is the revolution in fish farming, also described in "Four Fish", which has brought expensive fish to the plates of literally millions of people who were previously deprived of it. The equivalent of fish farming in case of climate change is geoengineering. Geoengineering carries more risks but also more potential benefits than fish farming, and it too deserves serious consideration in a meeting on climate change. As far as I know, most of these high-profile meetings on the topic focus on prevention rather than mitigation in the form of geoengineering. As exemplified by solutions to overfishing, any serious discussion of climate change should at least involve discussions of geoengineering.

Politically the sad history of the climate change wars seems to have a simple explanation in my mind. Before 2004 or so when the effects of climate change were not known as well and anti-science Republicans dominated the government, conservative deniers largely ruled over the debate and the media. After 2004 or so, in part because of better data and in part because of relentless and wide publicity by people like Al Gore, the media started paying much more attention to the issue. I do not blame the left for going a little overboard with emphasizing the case for climate change at the beginning, when it was important to counter the right-wing extremism against the topic. But since then the world has been sold on the issue, and there is no longer a need to be overzealous about it. Unfortunately segments of the left have continued the crusade which they started in good faith at the beginning and now many of them have turned into hard liners on the issue, extending the theory beyond where the evidence might lead and denouncing almost any opponent as motivated by politically enabled bigotry. This has led to the silencing of reasonable critics along with irrational deniers (see my previous post for a discussion of the distinction between deniers and skeptics).

But whatever our feelings about the political rancor surrounding climate change, I do share Dyson's concerns that it might distract us from problems that are at least equally important. I think environmentalism has been one of the most important movements for the common good in history, too important to be pigeonholed into one category. Climate change is not environmentalism; environmentalism is not climate change.

The second aspect of the op-ed is Dyson's contention that the science of climate change is not settled. Many people have attacked him for this contention in the past and they will no doubt attack him now, but both in conversations with him as well as based on what he has written, I have found that most of his issues about the science are very general and not extreme at all. He says we don't understand a system as complex as the climate enough to make detailed accurate predictions, and he also says that much of the debate has unfortunately turned so political and rancorous that it has become hard for reasonable people to disagree even on the scientific details. These statements are both quite true and should ideally be uncontroversial. In addition I have discussed parallels between molecular modeling and climate modeling with him; in both cases we seem to see a healthy amount of uncertainty as well as an incomplete understanding of key components involved in the process: for instance water seems to be a common culprit; we have as fuzzy an understanding of water in cloud formation as around the surface of proteins and small organic molecules. 

I think climate change is a serious problem that deserves our attention. There is little doubt that we have injected unprecedented amounts of carbon dioxide into the atmosphere since the industrial revolution, and we would be naive to think that these have not impacted the climate at all. But the devil is in the details. It seems not just bad science but bad policy to me to hold high-profile meetings on the topic every year while neglecting other equally valid topics, all the time making detailed plans for mitigation (and not active intervention) in a system which is not understood well enough right now for detailed preemptive actions which will impact the lives of billions of people, especially in the developing world. 

To me it seems reasonable to think that climate change should be part of a larger portfolio we should invest in if we want to try to protect our future. As they say, it's always best to diversify your portfolio to hedge your bets against future risks.

Naomi Oreskes and false positives in climate change: Do we know enough?

Historian of science Naomi Oreskes who has long since been a campaigner against climate change and science denialists (her book "Merchants of Doubt" is a touchstone in this regard) has a New York Times Op-Ed titled "Playing Dumb on Climate Change" in which she essentially - to my eyes at least - asks that scientists slightly lower the standards of statistical significance when assessing the evidence for climate change.

It's not that Oreskes is saying that we should actually use sloppier standards for climate change analysis. Her argument is much more reasonable and specific but ultimately she still seems to embrace a kind of certainty that I do not think exists in the field. She starts by reminding us of the two common errors in any kind of statistical analysis: Type 1 and Type II. In my field I tend to use the more informative names 'false positives' and 'false negatives' so that's what I will stick with here. False positives arise when you are too generous and allow spurious data along with legitimate facts. False negatives arise when you are too curmudgeonly and disallow legitimate facts. In some sense false positives are better than false negatives since you would rather run the risk of getting some noise along with all the signal rather than missing some of the signal.

The risk of getting false negatives vs false positives is governed in part by the confidence limits you are using. A confidence limit of 95% means that your standards for accepting something as a signal are very high - it means that you are bound to reject some true signal, resulting in a false negative. When you reduce the confidence limits, say to 90%, then you are lowering the bar for marking something as a signal, leading potentially to some false positives creeping in along with the true signal.

The crux of Oreskes's argument is that until now climate scientists have largely used a very high confidence limit for accepting and rejecting evidence which in her opinion has led to some false negatives. She is right that the magic number of 95% is arbitrary and has no objective basis in natural law. But, and this is her crucial point, we now know enough about the climate to warranty using slightly lower confidence limits since any false positives emerging from this lowered limit can be identified as such and therefore rejected. Perhaps, she suggests, we could consider using a lower confidence limit like 90% for climate change studies.

I see where Oreskes is coming from and her general argument about being able to use lower confidence limits in light of increased knowledge about a field is valid, but I am simply not as convinced as she is that we will be able to identify false positives in climate data and reject them. First of all, 'climate data' is a humungous and staggeringly heterogenous mass of facts from fields ranging from oceanography to soil chemistry. While we may be more confident about some of these facts, we don't know enough about others (especially concerning the biosphere) to be as confident about them. That means that we won't even know which facts are more likely to be false positives than others. There are certainly some false positives that are in the 'known unknown' category but there are also many others which are in the 'unknown unknown' category, so how will we identify these if they show up?

The second problem is that, even though I mentioned before that sometimes accepting false positives is better than rejecting true positives, in case of climate change one must weigh this tradeoff against the enormous cost and resources needed to pursue false positives. So for instance, if a false positive data point concerns melting glaciers in some part of the world, actually taking action to address that data point would mean the expenditure of tens of millions or even billions of dollars. Sadly in case of climate change, pursuing Type I errors is not as simple as spending a few man hours and a few thousand dollars investigating blind alleys.

Oreskes like many other thinkers in the field is well-meaning and her suggestions apply to fields where enough is known to confidently identify and weed out false positives, but in case of climate change we are straitjacketed by a problem that has tragically been the bane of the field since its inception: our lack of knowledge and general ignorance about a very complex, unpredictable system. Unless we bridge this gulf of ignorance significantly, a 90% confidence limit would be as arbitrary and dangerous as a 95% confidence limit.

The Uncertainty Principle for climate (and chemical) models

A recent issue of Nature had an interesting article on what seems to be a wholly paradoxical feature of models used in climate science; as the models are becoming increasingly realistic, they are also becoming less accurate and predictive because of growing uncertainties. I can only imagine this to be an excruciatingly painful fact for climate modelers who seem to be facing the equivalent of the Heisenberg uncertainty principle for their field. It's an especially worrisome time to deal with such issues since the modelers need to include their predictions in the next IPCC report on climate change which is due to be published next year.

A closer look at the models reveals that this behavior is not as paradoxical as it sounds, although it's still not clear how you would get around it. The article especially struck a chord with me I see similar problems bedeviling models used in chemical and biological research. In case of climate change, the fact is that earlier models were crude and did not account for many fine-grained factors that are now being included (such as the rate at which ice falls through clouds). In principle and even in practice there's a bewildering number of such factors (partly exemplified by the picture on top). Fortuitously, the crudeness of the models also prevented the uncertainties associated with these factors from being included in the modeling. The uncertainty remained hidden. Now that more real-world factors are being included, the uncertainties endemic in these factors reveal themselves and get tacked on to the models. You thus face an ironic tradeoff; as your models strive to mirror the real world better, they also become more uncertain. It's like swimming in quicksand; the harder you try to get out of it, the deeper you get sucked in.

This dilemma is not unheard of in the world of computational chemistry and biology. A lot of the models we currently use for predicting protein-drug interactions for instance are remarkably simple and yet accurate enough to be useful. Several reasons account for this unexpected accuracy; among them cancellation of errors (the Fermi principle), similarities of training sets to test sets and sometimes just plain luck. Error analysis is unfortunately not a priority in most of these studies, since the whole point is to publish correct results. Unless this culture changes our road to accurate prediction will be painfully slow.

But here's an example of how "more can be worse". For the last few weeks I have been using a very simple model to try to predict the diffusion of druglike molecules through cell membranes. This is an important problem in drug development since even your most stellar test-tube candidate will be worthless until it makes its way into cells. Cell membranes are hydrophobic while the water surrounding them is hydrophilic. The ease with which a potential drug transfers from the surrounding water into the membrane depends among other factors on its solvation energy, on how readily the drug can shed water molecules; the smaller the solvation energy, the easier it is for drugs to get across. This simple model which calculates the solvation energy seems to do unusually well in predicting the diffusion of drugs across real cell membranes, a process that's much more complex than just solvation-desolvation. 

One of the fundamental assumptions in the model is that the molecule exists in just one conformation in both water and the membrane. This assumption is fundamentally false since in reality, molecules are highly flexible creatures that interconvert between several conformations both in water and inside the membrane. To overcome this assumption, a recent paper explicitly calculated the conformations of the molecule in water and included this factor in the diffusion predictions. This was certainly more realistic. To their surprise, the authors found that making the calculation more realistic made the predictions worse. While the exact mix of factors responsible for this failure can be complicated to tease apart, what's likely happening is that the more realistic factors also bring more noise and uncertainty with them. This uncertainty piles up, errors which were likely canceling before no longer cancel, and the whole prediction becomes fuzzier and less useful.

I believe that this is what is partly happening in climate models. Including more real-life factors in the models does not mean that all those factors are well-understood. You are inevitably introducing some known unknowns. Ill-understood factors will introduce more uncertainty. Well-understood factors will introduce less uncertainty. Ultimately the accuracy of the models will depend on the interplay between these two kinds of factors, and currently it seems that the rate of inclusion of new factors is higher than the rate at which those factors can be accurately calculated.

The article goes on to note that in spite of this growing uncertainty the basic predictions of climate models are broadly consistent. However it also acknowledges the difficulty in explaining the growing uncertainty to a public which has become more skeptical of climate change since 2007 (when the last IPCC report was published). As a chemical modeler I can sympathize with the climate modelers. 

But the lesson to take away from this dilemma is that crude models sometimes work better than more realistic ones. Perhaps the climate modelers should remember George Box's quote that "all models are wrong, but some are useful". It is a worthy endeavor to try to make models more realistic, but it is even more important to make them useful.
Image source

Book review: Robert Laughlin's "Powering the Future"

In the tradition of physicists writing for the layman, Robert Laughlin has emerged as a writer who pens unusually insightful and thought-provoking books. In his "A Different Universe" he explored the consequences and limitations of reductionism-based physics for our world. In this book he takes an equally fresh look at the future of energy. The book is not meant to be a comprehensive survey of existing and upcoming technologies; instead it's more like an assortment of appetizers designed to stimulate our thinking. For those who want to know more, it offers an impressive bibliography and list of calculations which is almost as long as the book itself.

Laughlin's thinking is predicated on two main premises. The first is that carbon sources are going to eventually run out or become inaccessible (either because of availability or because of legislation). However we will still largely depend on carbon because of its extraordinarily fortuitous properties like high energy density, safety and ease of transportation. But even in this scenario, simple rules of economics will trump most other considerations for a variety of different energy sources. The second premise which I found very intriguing is that we need to uncouple our thinking on climate change from that on energy instead of letting concerns about the former dictate policy about the latter. The reason is that planetary-level changes in the environment are so vast and beyond the ability of humans to control that driving a few more hybrids or curbing carbon emissions will have little effect on millennial events like the freezing or flooding of major continents. It's worth noting here that Laughlin (who has been called a climate change skeptic lately) is not denying global warming or its consequences here; it's just that he thinks that it's sort of beside the point when it comes to thinking about future energy, which will be mainly dictated by economics and prices more than anything else. I found this to be a commonsense approach based on an appreciation of human nature.

With this background Laughlin takes a sweeping and eclectic look at several interesting technologies and energy sources including nuclear energy, biofuels, energy from trash, wind and solar power and energy stored beneath the sea. In each case Laughlin explores a variety of problems and promises associated with these sources.

Because of dwindling uranium resources, the truly useful form of nuclear energy for instance will come from fast breeder reactors which produce their own plutonium fuel. However these reactors are more susceptible to concerns about proliferation and theft. Laughlin thinks that a worldwide, tightly controlled system of providing fuel rods to nations would allow us to fruitfully deploy nuclear power. One of his startling predictions is the possibility that we may put up with occasional Chernobyl-like events if nuclear power truly becomes cheap and we don't have any other alternatives.

Laughlin also finds promises and pitfalls in solar energy. The basic problem with solar energy is its irregular availability and problems with storage. Backup power inevitably depends on fossil fuel sources which sort of defeats the purpose. Laughlin sees a bright future for molten salt tanks which can very efficiently store solar energy as heat and which can be used when the sun is not shining. These salts are simple eutectic mixtures of potassium and sodium nitrates with melting points that are conveniently lowered even more by the salts' decomposition products. Biofuels also get an interesting treatment in the book. One big advantage of biofuels is that they are both sources and sinks of carbon. Laughlin talks about some recent promising work with algae but cautions that meeting the sheer worldwide demand for energy with biofuels that don't divert resources away from food is very challenging. Further on there's a very intriguing chapter on energy stored under the sea. The sea provides a stupendous amount of land beneath it and could be used for energy storage through novel sources like high-density brine pools and compressed natural gas tanks. Finally, burning trash which has a lot of carbon might appear like a useful source of energy but as Laughlin explains, the actual energy in trash will provide only a fraction of our needs.

Overall the book presents a very thought-provoking treatment of the nature and economics of possible future energy sources in a carbon-strapped world. In these discussions Laughlin wisely avoids taking sides, realizing how fraught with complexity and ambiguity future energy production is. Instead he simply offers his own eclectic thoughts on the pros and cons of energy-related topics which may (or may not) prove important in the future. Of the minor gripes I have with the volume is the lack of discussion of promising recent advances in solar cell design, thorium-based fuels and next generation nuclear reactor technology. Laughlin's focus is also sometimes a little odd and meandering; for instance at one point he spends an inordinate amount of time talking about interesting aspects of robotic technology that may make deep sea energy sequestration possible. But these gripes detract little from the volume which is not really supposed to be an exhaustive survey of alternative energy technologies.

Instead it offers us a very smart scientist's miscellaneous musings on energy dictated by commonsense assumptions based on the simple laws of demand and supply and of human nature. As responsible citizens we need to be informed on our energy choices which are almost certainly going to become more difficult and constrained in the future. Laughlin's book along with others will stimulate our thinking and help us pick our options and chart our direction.

The flame of life and death: My favorite (insufferable) chemical reaction

For me, the most astounding thing about science has always been the almost unimaginably far-reaching and profound influence that the most trite truths about the universe can have on our existence. We may think that we are in charge of our lives through our seemingly sure control of things like food, water, energy and material substances and we pride the ability of our species to stave off the worst ravages of the natural environment such as disease, starvation and environmental catastrophe. We have done such a good job of sequestering ourselves from the raw power of nature that it's all too easy to take our apparent triumph over the elements for granted. But the truth is that we are all without exception critically and pitifully beholden to a few numbers and a few laws of physics.

And a few simple chemical reactions. Which brings me to my favorite reaction for this month's blog carnival. It's a reaction so elementary that it will occupy barely a tenth of the space on a napkin or t-shirt and which could (and should) be productively explained to every human being on the planet. And it's a reaction so important that it both sustains life and very much has the potential to end it.

By now you might have guessed it. It's the humble combination of hydrocarbons with oxygen, known to all of us as combustion.

First the reaction itself which is bleedingly simple:

C_nH_2n+2 + (3n+1)/2 O₂ → (n+1) H₂O + n CO₂ + Energy

That's all there is to it. There, in one line, is a statement about our world that packs at least as much information into itself as all of humanity's accumulated wisdom and follies. A hydrocarbon with a general formula C_nH_2n+2 reacts with oxygen to produce carbon dioxide, water and energy. That's it. You want a pithy, multifaceted (or two-faced, take your pick) take on the human condition, there you have it. While serving as the fundamental energy source for life and all the glory of evolution, it's also one that drives wars, makes enemies out of friends, divides and builds ties between nations and will without a doubt be responsible for the rise, fall and future of human civilization. Faust himself could have appeared in Goethe's dream and begged him to use this reaction in his great work.

First, the hydrocarbon itself. Humanity launched itself onto a momentous trajectory when it learnt how to dig carbon out of the ground and use it as fuel. Since then we have been biding our time for better or worse. The laws of quantum mechanics could not have supplied us with a more appropriate substance. Carbon in stable hydrocarbons is in its most reduced state, which means that you can get a bigger bang out of your buck by oxidizing it compared to almost any other substance. What billions of controlled experiments over the years in oil and natural gas refineries and coal plants have proven is that you really can't do better than carbon when it comes to balancing energy density against availability, cost, ease of handling and transportation and safety. In its solid form you can burn it to stay warm and to produce electricity, in its liquid form you can pump it into an incredibly efficient and compact gas tank. For better or worse we are probably going to be stuck with carbon as a fuel (although the energy source can wildly differ).

The second component of the chemical equation is oxygen. Carbon is very fortunate in not requiring a pure source of oxygen to burn; if it burned, say, only in an environment with 70% or more oxygen that would have been the end of modern civilization as we know it. Air is good enough for combusting carbon. In fact the element can burn under a wide range of oxygen concentrations, which is a blessing because it means that we can safely burn it in a very controlled manner. Varying the amount of oxygen can also lead to different products and can minimize the amount of soot and toxic byproducts. The marriage of carbon and oxygen is a wonderfully tolerant and productive one and we have gained enormously from this union

The right side of the combustion equation is where our troubles begin. First off, water. It may seem like a trivial, harmless byproduct of the reaction but it's precisely its benign nature that allows us to use combustion so widely. Just imagine if the combustion of carbon had produced some godforsaken toxic substance in addition to carbon dioxide as a byproduct. Making energy from combustion would then have turned into a woefully expensive activity, with special facilities required to sequester the poisonous waste. This would likely have radically altered the global production and distribution of energy and human development would have been decidedly hampered. We may then have been forced to pick alternative sources of energy early on in our history, and the face of politics, economics and technology would consequently have been very different.

Moving on we come to what's almost ubiquitously regarded as a villain these days- carbon dioxide. If carbon dioxide were as harmless as water we would live in a very different world. Sadly it's not and its properties again underscore the profound influence that a few elementary facts of physics and chemistry can have on our fate. The one property of CO2 that causes us so much agony is the fact that it's opaque to long-wavelength infrared radiation and absorbs it, thus warming the surroundings. This is not a post to discuss global warming but it's obvious to anyone not living in a cave that the issue has divided the world like no other. We still don't know for sure what it will do, either by itself or because of the actions taken by human beings from merely perceiving its effects. But whatever it is, it will profoundly alter the landscape of human civilization for better or worse. We can all collectively curse the day that the laws of physics and chemistry decided to produce carbon dioxide as a product of combustion.

Finally we come to the piece de resistance. None of this would have mattered if it weren't for the most important thing combustion produces- energy (in fact we wouldn't have been around to give a fig). In this context combustion is exactly like nuclear fission; twentieth-century history would have been very different if all uranium did was break up into two pieces. Energy production from combustion is what drives life and human greed. We stay alive by eating carbon-rich compounds - especially glucose - which are then burned in a spectacularly controlled manner to provide us with energy. The energy liberated cannot be used directly for our actions and thoughts. Instead it is used to construct devilishly clever chemical packages of ATP (adenosine triphosphate) which then serves as the energy currency.

Our bodies (and those of other creatures) are staggeringly efficient at squeezing oxidation-derived energy out of compounds like glucose; for instance in the aerobic oxidation of glucose, a single glucose molecule can generate 32 molecules of ATP. Put another way, the oxidation of a gram of glucose yields about 4 kilocalories of energy. This may not seem like a lot until we realize that the detonation of a gram of TNT yields only about 1 kilocalorie (the reason the latter seems so violent is because all the energy is liberated almost instantaneously). Clearly it is the all-important energy term in the combustion equation that has made life on earth possible. We are generously contributing to this term these days by virtue of quarter pounders and supersizing but our abuse does not diminish its importance.

The same term of course is responsible for our energy triumphs and problems. Fossil fuel plants are nowhere as efficient in extracting energy from carbon-rich hydrocarbons as our bodies, but what matters is whether they are cheap enough. It's primarily the cost of digging, transporting, storing and burning carbon that has dictated the calculus of energy. Whatever climate change does, of one thing we can be sure; we will continue to pay the cheapest price for our fuel. Considering the many advantages of carbon, it doesn't seem like anything is going to substitute its extraordinarily fortuitous properties anytime soon. We will simply have to find some way to work around, over or through its abundance and advantages.

If we think about it then, the implications of combustion for our little planet and its denizens are overwhelming and sometimes it's hard to take it all in. At such times we only need to take a deep breath and remember the last words spoken by Kevin Spacey's character from "American Beauty":

"Sometimes I feel like I'm seeing it all at once, and it's too much, my heart fills up like a balloon that's about to burst... And then I remember to relax, and stop trying to hold on to it, and then it flows through me like rain and I can't feel anything but gratitude for every single moment of my stupid little life..."

That's right. Let's have it flow through us like rain. And watch it burn.

Image source

The details do matter

Consider a protein-ligand binding model. How easy is it to predict the best and worst binders in terms of affinity? Now, how hard is it to quantitatively rank these binders in terms of free energy of binding?

The former, while not an easy problem, has been solved in various ways multiple times for individual problems. In fact a new docking program is expected to at least achieve the minimal goal of ranking the most active ligands at the top and the least active at the bottom.

However, in spite of impressive advances, the latter problem is still regarded as a holy grail.

Now consider molecular dynamics simulations of proteins. Coarse-grained MD approximates atomistic details by subsuming them into a broader framework; for instance, "united atom" force fields will sometimes treat the hydrogen atoms attached to carbons implicitly without explicitly representing them. Coarse-grained MD has been indispensable for simulating large systems where explicit representation of fine details would be prohibitively time-consuming. But coarse grained MD would not always be able to shed light on cases where the fine details do matter, such as proton transfer in enzyme active sites and the general detailed modeling of enzymatic reactions.

Finally, consider solvation models in molecular simulations, a topic of perpetual development and high interest. Implicit models where the solvent and solute are considered as mean dielectrics and their interaction is modeled as a sum of electrostatic and non-electrostatic interactions are all the rage. They frequently work very well and I have myself used them numerous times. But consider cases where the detailed thermodynamics of individual water molecules in protein active sites need to be modeled. Implicit solvation can be of scant use in such circumstances. The use of implicit solvation often makes general predictions about qualitative differences between protein-ligand interactions possible, but it can mask the detailed reasons for those differences and indeed cannot even account for such differences many times.

Something similar seems to be happening for climate change. It is relatively easy to make general statements about extreme events occurring. It is generally true that putting all that buried CO2 back into the atmosphere as a high entropy substance is probably a bad idea, and that cutting emissions is probably a good idea. My problem is not so much about politicians suggesting such general solutions as it is about them sounding crystal clear about all the scientific details. It's much harder to predict the details about individual effects and 'rank' them in terms of their severity, nor is it easier to rank individual solutions to the problem in terms of relative impact. That is something that is an inherent limitation of the science at this point, and any good scientist worth his salt should acknowledge this. Nonetheless, the science has been declared 'settled' and politicians seem to suggest implementing concrete policies in spite of the coarse-grained nature of the problem. As I mentioned before, the fathers of empirical inquiry Newton, Bacon, Locke, Boyle and Hume would have been rather chagrined with this state of affairs.

It's even more disconcerting to realize that activists propose solar and wind power which could be useful in limited amounts but have by no means proven to be robust, as global high energy density solutions. On the other hand there is nuclear power, a proven existing technology that packs more energy than any other, is clean, decidedly CO2-free and highly efficient and deployable. Yet the same politicians who condemn fossil fuels and talk about climate change constantly fail to tout the one solution that could solve the problem they are trying to address. What can you say when someone ignores a solution to a problem that's staring them in the face?

Freeman Dyson, who has been duly and gratuitously vilified for his skepticism about climate models, said that he lost interest in climate change when the issue turned from scientific to political. One can understand why he said that. The exemplar of tentative scientific understanding was Niels Bohr, and Einstein's quip about him captures the perfect attitude we should all have about complex scientific issues, an attitude that is sadly lost on many climate modelers; Einstein said of Bohr that "He looks like someone who never behaves as if he is in possession of the truth, but one who is perpetually groping".

Gropers are especially encouraged to apply to The Academy.

Middle Ages March

As far as possible I try to avoid writing about the teaching of evolution and opposition to climate change in this country because of their overly politicized nature, but this piece in the NYT is one that no one can wisely ignore. It details a growing movement to conflate rejection of evolution with rejection of climate change that many people, and sadly especially conservatives, are spearheading. States are trying to introduce bills encouraging the teaching of “all sides” of scientific issues. Conservative politicians are advocating for students to know “all the facts”. But nobody is fooled by these thinly veiled promotions of ignorance. These developments should appear ominous to anyone since they indicate a resourceful war against science and all it stands for.

A couple of years ago, journalist Chris Mooney wrote "The Republican War on Science", a laundry list of instances of systematic negligence and subversion by the Bush administration when it came to scientific matters. When Obama became President, those of us like Mooney heaved a sigh of relief, since the new President seemed to have a genuine appreciation for science and its funding and strove to "restore science to its rightful place". Sadly, what we did not fully realize is that the War on Science is not really fought in the corridors of Washington but rather on the streets and churches of states all over the country. No Presidential mandate can quell the intensity with which the foot soldiers in these quarters fight the war.

The main goal of these foot soldiers is to seed doubts about the foundational nature of scientific facts in the minds of the gullible. They want to misrepresent the tentative nature of scientific understanding as equivalent to complete lack of understanding. They don't understand or willfully neglect the simple fact that some things in science are more certain than others, and many things are so well-understood so as to be virtually certain. But by pitching the very nature of science as some kind of loose, tentative theorizing disguised as facts, these eager evangelists are destroying the very fabric of scientific inquiry and indeed, one of the essential bedrocks on which modern civilization is founded. To me their ultimate objective seems clear; convince people that most if not all of science and not just climate change and evolution consists of "just theories". Once that basic groundwork has been established, they are free to play fast and loose with each and every aspect of science that bears on public policy, which in the modern world encompasses most important spheres of political and public activity.

The anti-science crowd is too clever to call for downright subversion of science and embrace of religious dogma. Consider Tim Moore, a politician from Kentucky who claims that his motivation is not religious but it is to oppose the “distortion of scientific knowledge”. Surely Moore is intelligent enough to understand the number of religious votes he would garner if his suggestions are implemented. Moore and others are too clever to directly call for an indictment of science. Hence they are resorting to the gradual mobilization of doubt. Start with eager young minds first. The relentless movement to include "intelligent" design in textbooks as a valid "alternative" to evolution is well-known. Now they are also calling for textbooks to teach "both sides" of climate change. The time will come when they would insist that every scientific topic with which they have an issue should be accompanied by its opposite in school textbooks, simply because scientists are engaging in healthy debate about that topic. Stem cells and alternative energy are two prominent issues that come to mind. Scientists are still not sure what kind of technologies would make solar and wind power a reality? Good! Make sure you include every bit of opposition to these technologies as part of your textbook lessons. Scientists are still trying to understand how exactly stem cells would make it possible to cure or contain life-threatening disorders? Fantastic! Make that a case for including every bit of opposition to stem cell research so that you could argue against it; the religious aspects could always be smuggled in later through the back door. Lively technical disagreements taking place in the pages of scientific journals would be held up as resounding evidence that the soul of science itself is an amorphous blob devoid of certain existence. This is nothing less than the rape and rabid hijacking of the normal scientific process to portray it as some kind of fundamental structural flaw in the whole enterprise.

If this kind of descent into ignorance is terrible for schools and students, it's not at all helped by declining standards of science and math education in this country and by global competition in science and technology. What may be even more tragic is that such efforts, which started during the Reagan era but were much milder back then, would form such an ungodly and impenetrable meld of science, conservative politics and religion that it may well become impossible to ever separate the three. Sadly, one consistently finds mainly Republicans being opposed to climate change and the teaching of evolution. Those few Republicans who do support either or both of these are already keeping their mouths shut for fear of being alienated from the party. At the same time, evangelical Christians are convincing their brothers and sisters to add climate change to their list of enemies which long includes evolution. Since the Reagan era conservatism has already become synonymous with evangelical religion. Now they are also trying to make the two synonymous with anti-scientism. The effect of all this would be to downright intimidate any person with conservative sentiments who dares to have respect for the scientific process. It would also mean an exponential decline in members of the conservative coalition with any appreciation of science; after all, if evolution and climate change deniers are going to be the main recruits to the movement, the probability that these people will have any appreciation for the scientific method would already be very low to begin with.

Accompanying this active propaganda against science is a slick publicity campaign that pits scientific issues as not really being scientific but being political dogfights between liberals and conservatives, and declares science and especially academic science to be a political liberal enterprise. It extols the folksy, down to earth demeanor of grass roots politicians and encourages derision towards "elitist", high-brow scientists educated at respectable schools along with the politicians of the Eastern Establishment who nurture them. The two-time election of George W Bush (ironically a failed member of the Eastern Establishment) demonstrated that many citizens of this country are indeed suckers for such stereotypes and are ready to fundamentally mistrust any educated intellectual or scientist. Whether we like it or not, conservatives have turned this confluence of mutually reinforcing strategies and stereotypes into a well-oiled PR machine that is set to pay its own way into hell.

Is there any silver lining at all to this precipitous slide into the Middle Ages? The article does talk about conservative Christians who seem to display a refreshing acceptance of both evolution and climate change. Their numbers are low, but their convictions seem strong. They think that earth and everything that it encompasses are God's creations and need to be taken care of. Atheists may vehemently disagree with this interpretation, but as E O Wilson says in his book ”Creation”, at least they can leave aside differences and try to find common ground for this most important of causes. No matter how powerful and influential the leaders of the war against science seem, they critically depend on the citizenry to make their voice known. They speak because their constituencies listen. They prey and thrive on the nods of their audience. Educate the audience, and the tables turn; now it’s they who decide whether the magician on stage lives or dies.

We don't know yet whether this citizenry can wake up to the wisdom of recognizing science as a value-neutral, apolitical, open-minded, independent and freedom-loving framework to improve their lives. But it is clear that to have any chance of rescuing this country from the divisive forces of ignorance which are gradually making their way from coast to coast, one must use every tactic at his or her disposal to drive home the importance of science and to try to reinforce its separation from politics and religion.

These days one regularly comes across opposite and polarized factions of "New Atheists" who are up in arms against "Accommodationists". The former faction believes that only a highly vocal effort to weed out religion from the masses can turn enough people toward science, even if it permanently alienates the hardest of the fundamentalists. The latter faction believes that a more moderate approach will work better. Both factions believe that fundamentalists will largely remain unmoved.

To me the arguments between them mainly seem to be based on degree, since many from the latter also call themselves atheists. I have never understood why the approach needs to be either/or. It is clear that insiders from the religious establishment still stand the best chance of convincing their own flock. These promising young insiders are going to be persuaded only when they are repeatedly convinced and in turn convince others that yes, they can safely practice their faith and still believe in science as a candle in the dark. Whether atheists like it or not, their support is crucial. People come in all kinds of shades, and the best bet for us to convince them about the value of science is to pitch it to them at all levels, in all forms and guises, vocally and mildly, through every possible channel. Human society is a complex organism, and it needs a complex mix of ideas to cause fundamental changes. Just like in my field of computational chemistry, when you don't know the composition of this mix, you simply try out all combinations.

It seems to be the least we can do to stop a straight downhill crash into dark ignorant oblivion.

Quo Vadis, natural science?

On Wednesday last week the town where I lived got 20 inches of snow in a twenty-four hour period. I got an unexpected, happy, day off work. Bizarrely, southern regions like DC and Baltimore got much more than northern ones; Baltimore got 40 inches, Philadelphia got about the same. Records were set in both places for the snowiest winters in recent history. People were left wondering and reeling at this capriciousness of the Norse Gods.

So what could be the reason for this sudden onslaught of severe weather? That's akin to asking what could be the reason for cancer suddenly emerging in someone's body or for a particular drug demonstrating a slew of side-effects. The reasons are non-obvious, often non-intuitive, complex, multifactorial and extremely hard to determine. And that is also what one should say if asked to elucidate reasons for a particularly snowy winter.

But human beings don't work that way. Immediately there sprung up a debate about whether global warming could be responsible for the increased snow. Engaging in the common and never-dying fallacy of equating weather with climate, climate change skeptics declared the cold to be a slap in the face of AGW proponents. On the other side, while most climate scientists are pointing out that single weather events have scant connection with global warming, some proponents are also saying that this is actually a good instance of the effects of global warming, that global warming does predict extreme weather events, that all this is simply part of the connected whole. More vapor in the air, El Nino and other events have been suggested as plausible candidates.

Now let's step back a little and think about this from the educated layperson's perspective. Less snow has been commonly predicted to be a consequence of global warming, but now the same explanation is being provided for lots of snow. The layman should be excused for being skeptical about a model that seems to equally explain diametrically opposite events. Of course, as we mentioned before, more or less snow neither "proves" nor "disproves" global warming. But to me this is yet another reminder of why I don't say much about the topic these days; the whole damn thing has gotten so overly politicized that each side feels compelled to say something non-scientific just to make the other side shut up.

However, from a scientific perspective too this issue illustrates the pitfalls that natural science faces in the twenty first century. When I discussed this issue with my father who is an economics professor the other day, he said "Welcome to the social sciences". Social scientists face such problems all the time. What happens when a model becomes so complex that it can explain virtually any observation you throw at it? (To begin with the model also become so complex that you stop truly understanding it; case in point- derivatives on Wall Street). Surely there seems to be a problem with a model that is invoked to explain both more precipitation and absence of precipitation. That would be akin to a molecular model that predicts the same reason for compounds with both high and low potencies against a protein target.

The hallmark of a judicious model is that it is not so spare as to be useless but also not so full of parameters and variables so as to fit almost any data point. A model that seems to explain everything (as sometimes seems to be the case with global warming) is a bad scientific model because in principle it's hard to see how it could be falsified (Popper again). In addition, you should always ask how many data points are enough to build confidence in a model; statisticians have struggled for decades with this sampling problem, and there is no straightforward general answer. Sadly, it's not climate scientists that have first raised such issues through their model-building. That dubious honor belongs to evolutionary biologists.

Evolutionary biology is notorious for advancing adaptationist explanations which can account for almost any observed trait. For instance, polar bears are white because they are supposed to camouflage well into their surroundings, but penguins are black because their skin should absorb enough sunlight to keep them warm. Now why does the first explanation not apply to the second case and vice versa? Well, in case of evolutionary biology the short answer that is given is "trade offs". Depending on the details of the problem (in this case the species, its body requirements, genetic makeup etc.), in the first case the ability to camouflage won out over the need to remain warm, and vice versa for the second one. But beyond a certain point it can be impossible to actually explain such trade offs since so much in evolution is a matter of contingency. And one can conveniently invoke trade-offs (Shazam!) as a magical whitewashing word for almost any trait. That's hardly an actual explanation.

Nevertheless, such ingenious explanations have often been advocated by evolutionary biologists. In a classic article, Stephen Jay Gould and Richard Lewontin shot down this relentless urge to wrap everything into an adaptionist program; their main point was that every trait is not the consequence of adaptation and natural selection and some traits can be simply carried along for the ride with others without possessing any evolutionary benefit. The main merit of the adaptationist explanations is their internal logic. However, internal logic by itself, no matter how tempting, does not make an explanation. In the absence of experimental data, such hypotheses about evolutionary adaptations are just that, good hypotheses waiting to be validated by good data. A professor of mine got so fed up with these ingenious evolutionary explanations for everything from homosexuality to sloths coming down from trees to bury their feces that he wrote a highly readable book about it. Again, it's not that these ideas are bad, but in the absence of causal evidence they can only remain respectable armchair speculation. So how then do we come up with explanations?

Sadly, here's when fields like evolution and climate change run into fundamental roadblocks of the kind faced by social scientists; the sheer complexity of the system thwarts attempts at clean experiments. The big problem with fields like psychology, sociology and economics is that it is often difficult or even impossible to perform controlled experiments. Admittedly the situation here is worse than climate science, since the data itself is variable and represents a moving target (was the state of mind of your experimental subjects the same on Monday as on Tuesday?). Consider the hundreds of pop science books on neuroscience claiming that things like fMRI scans can "explain" emotions like hate and jealousy, and even spiritual and religious experiences. Other problems notwithstanding, how on earth do we not know that at the very least, like the perpetual observed-induced reality in quantum mechanics, we do not influence what we want to observe? But even in the apparently more rigorous discipline of climate science, models are the result of data conducted under less than ideal non-isolated laboratory conditions from thousands of places over dozens of years. Who can guarantee that at least some of this data won't even be contradictory, let alone that all of it would consistently be of the same standard? To be fair to climate scientists, they usually perform stringent checks on the validity of their models but no checks can help duplicate fine differences in experimental conditions spread over thousands of data points over long time frames.

Lest one think that only the "softer" sciences face these problems, witness the current debate about string theory. Skeptics say that about the only reason that the framework is so highly regarded is because it seems to be logically internally consistent, is mathematically elegant and seems to tantalizingly "feel right". All these qualities can be respectable, but I suspect that the pioneers of modern science in the eighteenth and nineteenth century would not have been happy with this state of affairs. From what I have read, there seem to be no hard experimental tests that could provide strong support for string theory.

That then is the dilemma the natural sciences find themselves in in my opinion, a dilemma that the social sciences have faced for centuries. In fact one can argue that the dilemma has been caused by the social sciences finally intersecting with the natural science as their integrated whole has become more and more complex and is now tackling extremely convoluted territory like the brain, the climate, the universe, human behavior, the economy, evolution and the mechanisms of drug action and disease. With this kind of complexity, scientists have been resigned to pick between two quite unsastisfactory choices; either no explanation at all, or an "explanation" based on models, internal logical consistency, "aesthetics" and elegance (case in point- string theory) and ingenious sounding armchair explanations. In many cases the underlying systems are simply so dense that scientists are forced to perform extensive parametrization and model building. There is probably an equation somewhere relating excessive parametrization to risk of model failure.

Nonetheless, in the absence of controlled experiments, there is not much that science can lean on at this point. But in fact one can argue that science actually proceeds in this way, by tentatively accepting hypotheses. As long as it's kept in mind that the hypotheses are only hypotheses, we can still have a wall to grasp as we grope around in the dark. If we start regarding the hypotheses as explanations and facts, we will leave the safety of that frail wall to grasp at imaginary will-o-wisps at our own peril.

The price of global warming science is eternal vigilance

John Tierney of the NYT weighs in on the hacked emails and accurately nails it

I’ve long thought that the biggest danger in climate research is the temptation for scientists to lose their skepticism and go along with the “consensus” about global warming. That’s partly because it’s easy for everyone to get caught up in “informational cascades”, and partly because there are so many psychic and financial rewards rewards for working on a problem that seems to be a crisis. We all like to think that our work is vitally useful in solving a major social problem — and the more major the problem seems, the more money society is liable to spend on it.

I’m not trying to suggest that climate change isn’t a real threat, or that scientists are deliberately hyping it. But when they look at evidence of the threat, they may be subject to the confirmation bias — seeing trends that accord with their preconceptions and desires. Given the huge stakes in this debate — the trillions of dollars that might be spent to reduce greenhouse emissions — it’s important to keep taking skeptical looks at the data. How open do you think climate scientists are to skeptical views, and to letting outsiders double-check their data and calculations?

We are all subject to the confirmation bias, and I can say from experience that we have to battle it in our research every single day as fallible human beings. But as Tierney says, when the stakes are so incredibly high, when governments and international budgets and debts and the fate of billions is going to be affected by what you say, you better fight the conformation bias ten times as much as usual.

Listen to Capt. Ramsey, son:

"Mr. Hunter, we have rules that are not open to interpretation, personal intuition, gut feelings, hairs on the back of your neck, little devils or angels sitting on your shoulders..."

A wrong kind of religion; Freeman Dyson, Superfreakonomics, and global warming

The greatest strength of science is that it tries to avoid dogma. Theories, explanations, hypotheses, everything is tentative, true only as long as the next piece of data does not invalidate it. This is how science progresses, by constantly checking and cross checking its own assumptions. The heart of this engine of scientific progress is constant skepticism and questioning. This skepticism and questioning can often be exasperating. You can enthusiastically propound your latest brainwave only to be met with hard-nosed opposition, deflating your long harbored fervor for your pet idea. Sometimes scientists can be vicious in seminars, questioning and cross questioning you as if you were a defendant in a court.

But you learn to live with this frustration. That's because in science, skepticism always means erring on the safer side. As long as skepticism does not descend into outright irrational cynicism, it is far better to be skeptical than to buy into a new idea. This is science's own way to ensure immunity to crackpot notions that can lead it astray. One of the important lessons you learn in graduate school is to make peace with your skeptics, to take them seriously, to be respectful to them in debate. This attitude keeps the flow of ideas open, giving everyone a chance to voice their opinion.

Yet the mainstay of science is also a readiness to test audacious new concepts. Sadly, whenever a paradigm of science reaches something like universal consensus, the opposite can happen. New ideas and criticism are met with so much skepticism that it borders on hostility. Bold conjectures are shot down mercilessly sometimes even without considering their possible merits. The universal consensus separates scientists into a majority who provide a vocal and even threatening wall of obduracy against new ideas. From what I have seen in recent times, this unfortunately seems to have happened to the science of global warming.

First, a disclaimer. I have always been firmly in the "Aye" camp when it comes to global warming. There is no doubt that the climate is warming due to greenhouse gases, especially CO2, and that human activities are most probably responsible for the majority of that warming. There is also very little doubt that this rate of warming has been unprecedented into the distant past. It is also true that if kept unchecked, these developments will cause dangerous and unpredictable changes in the composition of our planet and its biosphere. Yet it does not stop there. Understanding and accepting the details about climate change is one thing, proposing practical solutions for mitigating it is a whole different ball game. This ball game involves more economics than science, since any such measures will have to be adopted on a very large scale that would significantly affect the livelihood of hundreds of millions. We need vigorous discussion on solutions to climate change from all quarters, and the question is far from settled.

But even from a scientific perspective, there are a lot of details about climate change that can still be open to healthy debate. Thus, one would think that any skepticism about certain details of climate change would be met with the same kind of lively, animated argument that is the mainstay of science. Sadly, that does not seem to be happening. Probably the most recent prominent example of this occurred when the New York Times magazine ran a profile of the distinguished physicist Freeman Dyson. Dyson is a personal scientific hero of mine and I have read all of his books (except his recent very technical book on quantum mechanics). Climate change is not one of Dyson's main interests and has occupied very little of his writings, although more so recently. To me Dyson appears as a mildly interested climate change buff who has some opinions on some aspects of the science. He is by no means an expert on the subject, and he never claims to be one. However he has certain ideas, ideas which may be wrong, but which he thinks make sense (in his own words, "It is better to be wrong than to be vague"). For instance he is quite skeptical about computer models of climate change, a skepticism which I share based on my own experience with the uncertainty modeling even "simple" chemical systems. Dyson who is also well known as a "futurist" has proposed a very interesting possible solution to climate change; the breeding of special genetically engineered plants and trees with an increased capacity for capturing carbon. I think there is no reason why this possibility could not be looked into.

Now if this were the entire story, all one would expect at most would be experts in climate change respectfully debating and refuting Dyson's ideas strictly on a factual basis. But surprisingly, that's not what you got after the Times profile. There were ad hominem attacks calling him a "crackpot", "global warming denier", "pompous twit" and "faker". Now anyone who knows the first thing about Dyson would know that the man does not have a political agenda and he has always been, if anything, utterly honest about his views. Yet his opponents spared no pains in painting him with a broad denialist brush and even discrediting his other admirable work in physics to debunk his climate change views. What disturbed me immensely was not that they were attacking his facts- that is after all how science works and is perfectly reasonable- but they were attacking his character, his sanity and his general credibility. The respected climate blogger Joe Romm rained down on Dyson like a ton of bricks, and his criticism of Dyson was full of condescension and efforts to discredit Dyson's other achievements. My problem was not with Romm's expertise or his debunking of facts, but with his tone; note for instance how Romm calls Dyson a crackpot right in the title. One got the feeling that Romm wanted to portray Dyson as a senile old man who was off his rocker. Other bloggers too seized upon Romm-style condescension and dismissed Dyson as a crank. Since then Dyson has expressed regret over the way his views on global warming were overemphasized by the journalist who wrote the piece. But the fact is that it was this piece which made Freeman Dyson notorious as some great global warming contrarian, when the truth was much simpler. In a Charlie Rose interview, Dyson talked about how global warming occupies very little of his time, and his writings clearly demonstrate this. Yet his views on the topic were blown out of proportion. Sadly, such vociferous, almost violent reactions to even reasonable critics of climate change seems to be becoming commonplace. If this is how the science of global warming is looking like, then it's not a very favourable outlook for the future .

If Dyson has been Exhibit A in the list of examples of zealous reactions to unbiased critics of climate change, then the recent book "Superfreakonomics" by economists Steven Levitt and Stephen Dubner (authors of the popular "Freakonomics") would surely be Exhibit B. There is one chapter among six in their book about global warming. And yet almost every negative review on Amazon focuses on this chapter. The authors are bombarded with accusations of misrepresentation, political agendas and outright lies. Joe Romm again penned a rather propagandish and sensationalist sounding critique of the authors' arguments. Others duly followed. In response the authors wrote a couple of posts on their New York Times blog to answer these critics. One of the posts was written by Nathan Myhrvold, previously Chief Technology officer of Microsoft and now the head of a Seattle-based think tank called Intellectual Ventures. Myhrvold is one of the prominent players in the book. Just note the calm, rational, response that he pens and compare it to one of Joe Romm's posts filled with condescending personal epithets. If this is really a scientific debate, then Myhrvold surely seems to be behaving like the objective scientist in this case.

So are the statements made by Levitt and Dubner as explosive as Romm and others would make us believe? I promptly bought the book and read it, and read the chapter on climate change twice to make sure. The picture that emerged in front of me was quite different from the one that I had been exposed to until then. Firstly, the authors' style is quite matter of fact and not sensationalist or contrarian sounding at all. Secondly, they never deny climate change anywhere. Thirdly, they make the very important general point that complex problems like climate change are not beyond easy, cheap solutions and that people sometimes don't readily think of these; they cite hand washing to drastically reduce infections and seat belts to reduce fatal car crashes as two simple and cheap innovations that saved countless lives. But on to Chapter 5 on warming.

Now let me say upfront that at least some of Levitt and Dubner's research is sloppy. They unnecessarily focus on the so-called "global cooling" events of the 70s, events that by no means refute global warming. They also seem to cherry pick the words of Ken Caldeira, a leading expert on climate change. But most of their chapter is devoted to possible cheap, easy solutions to climate change. To tell this story, they focus on Nathan Myhrvold and his team at Intellectual Ventures who have come up with two extremely innovative and interesting solutions to tackle the problem. The innovations are based on the injection of sulfate aerosols in the upper atmosphere. This rationale is based on a singular event, the eruption of Mount Pinatubo in the Phillipines in 1990 which sent millions of tons of sulfates and sulfur dioxide into the atmosphere and circulated them around the planet. Sulfate aerosols serve to reflect sunlight and tend to cause cooling. Remarkably, global temperatures fell by a slight amount for a few years after that. The phenomenon was carefully and exhaustively documented. It was a key contributor to the development of ideas which fall under the rubric of "geoengineering". These ideas involve artificially modulating the atmosphere to offset the warming effects of CO2. Geoengineering is controversial and hotly debated, but it is supported by several very well known scientists, and nobody has come up with a good reason why it would not work. In the light of the seriousness of global warming, it deserves to be investigated. With this in mind, Myhrvold and his team came up with a rather crazy sounding idea; to send up a large hose connected to motors and helium balloons which would pump sulfates and sulfur dioxide into the stratosphere. Coupled with this they came up with an even crazier sounding idea; to thwart hurricanes by erecting large, balloon like structures on coastlines which would essentially suck the hot air out of the hurricanes. With their power source gone, the hurricanes would possibly quieten down.

Are these ideas audacious? Yes. Would they work? Maybe, and maybe not. Are they testable? Absolutely, at least on a prototypical, experimental basis. Throughout the history of science, science has never been fundamentally hostile to crazy ideas if they could be tested. Most importantly, the authors propose these ideas because the analysis indicates them to be much cheaper than long-term measures designed to reduce carbon emissions. Solutions to climate change need to be as cheap as they need to be scientifically viable.

So let's get this straight; the authors are not denying global warming and in fact in their own words, they are proposing a possible solution that could be cheap and relatively simple. And they are proposing this solution only to temporarily act as a gag on global warming, so that long-term measures could then be researched at relative leisure. In fact they are not even claiming that such a scheme would work, only that it deserves research attention. Exactly what part of this argument screams "global warming denial"? One would imagine that opponents of these ideas would pen objective, rational objections based on hard data and facts. And yet almost none of the vociferous critics of Levitt and Dubner seem to have engaged in such an exercise (except a few). Most exercises seem to be of the "Oh my God! Levitt and Dubner are global warming deniers!!" kind. Science simply does not progress in this manner. All we need to do here is to debate the merit of a particular set of ideas. Sure, they could turn out to be bad ideas, but we will never know until we test them. The late Nobel laureate Linus Pauling said it best; "If you want to have a good idea, first have lots of ideas, then throw the bad ones away". Especially a problem as big as climate change needs ideas flying in from all quarters, some conservative, some radical. And as the authors indicate, cheap and simple ideas ought to be especially welcome. Yet the reception to Superfreakonomics to me looked like the authors were being castigated and resented for having ideas. The last thing scientific progress needs is a vocal majority that thwarts ideas from others and encourages them to shut up.

Freeman Dyson once said that global warming sometimes looks like a province of "the secular religion of environmentalism" and sadly there seems to be some truth to this statement. It is definitely the wrong kind of religion. As I mentioned before, almost any paradigm that reaches almost universal consensus runs the risk of getting forged into a religion. At such a point it is even more important to respect critics and give them a voice. Otherwise, going by the almost violent reaction against both Dyson and the authors of Superfreakonomics, I fear that global warming science will descend to the status of biological studies of race. Any research that has to do with race is so politically sensitive and fraught with liabilities and racist overtones that even reasonable scientists who feel that there is actually something beneficial to be gained from the study of race (and there certainly is; nobody would deny that certain diseases are more common to certain ethnic minorities) feel extremely afraid to speak up, let alone apply for funding.

We cannot let such a thing happen with the extremely important issue of climate change. Scientific progress itself would be in a very sad state if critics of climate change with no axe to grind are so vilified and resented that they feel inclined to shut up. Such a situation would trample the very core principles of science underfoot.