From so simple a beginning…

By now everyone and his grandmother must have heard about the hacked emails of the prestigious University of East Anglia Climate Research Unit (CRU). The emails were sent by leading climate change scientists to each other and seem to express doubts and uncertainty. More importantly they also seem to display some troubling signs of rather dishonest discourse, with scientists trying to hold dangerously unfavorable opinions of journal editors who seem to be open to publishing papers that don’t seem to agree with their views, and asking each other to delete emails which might signal doubt.

There is at least one example of bad science revealed in the emails. It seems that one set of data from tree ring proxies did not show the expected rise in temperatures for a particular period and showed a decline. What was done was that just for that period, a different set of data from another method which did show the rise was grafted on to this piece of data. John Tierney of the NYT has the two graphs on his blog. Does this change the general conclusion? Probably not. Is this bad science and enough to justify a flurry of indignant questions in the minds of outsiders? Certainly so. Good science would have meant revealing all the pieces of data including those which showed a decline.

What is remarkable (or perhaps not remarkable at all) is the vociferous political- not scientific- reaction that has erupted in blogs all over the internet. I would point readers to my fellow blogger Derek Lowe’s succinct summary of the matter. While I am not as skeptical about climate change as he is, it is disconcerting to see how much political, personal and social baggage the whole issue is carrying. Whenever a scientific issue starts carrying so much non-scientific baggage, one can be assured that we are in trouble.

The comments on most blogs range across the spectrum. There are the outright deniers who claim that the emails “disprove global warming”; they don’t, and I can’t see how any set of personal exchanges could say almost anything definitive about a system as complex as the climate. Phrases like “hide the decline” and “trick” have been taken out of their technical context to indicate subversion and deception. And then there are the proponents who want to act like nothing has happened. I like George Monbiot’s take on it where he says that even if the science of climate change has certainly not come crashing down, the public image of climate change has been dealt a serious blow, and denying this would simply mean burying your head in the sand. After all, we are supposed to be the good guys, the ones who are supposed to honestly admit to our limitations and failings, and we are not doing this. What ramifications this will have for the important Copenhagen climate summit this month is uncertain.

However, the very fact that we have to worry as much about the public image of climate science as the science itself plainly speaks to the degree of politicization of the issue. I think the liability of this entire matter has basically become infinite and I think scientists working in the field are facing an unprecedented dilemma which few scientists have ever faced. Here’s the problem; we are dealing with an extremely complex system and it is hardly surprising if the science of this system (which after all is only a hundred years or so old) keeps getting revised, reshuffled and reiterated even if the basics remain intact. That would be perfectly normal for a vast, multidisciplinary field like this. That is the way science works. One finds such revision and vigorous debate even in highly specific and recondite areas like the choice of atomic partial charges in the calculation of intermolecular energies. The climate is orders of magnitude more complicated. If the usual rules of scientific discourse were to be followed, making such debates and disagreements open would not be a problem.

But with an issue that is so exquisitely fraught with political and economic liabilities and where the stakes are so enormously high, I believe that the normal process of scientific debate, discourse and progress has broken down and is being bypassed. Scientists who would otherwise engage in lively debate and disagreements have become extremely loathe to make their doubts public. These scientists fear that they would essentially be condemned by both sides. The right wing extremists would seize upon any honest disclosure of debate as the kick that brings the entire edifice crumbling down. They would predictably try to discredit even reasonable conclusions drawn by climate change scientists. At the same time, left wing extremists would essentially disown such scientists and either declare them an anomaly or more predictably declare them to be political and corporate shills. A scientist who honestly voices his doubts would become a man without a country.

This is of course in addition to the ample scorn that establishment upholders like climate blogger Joe Romm would heap on them. Thus, if you are a scientist working in climate change today, it would be rather difficult for you to make even the normal process of science transparent. Plus, most scientists are genuinely scared that all the momentum they have built over the years would fizzle out if their right wing opponents pounce on their private doubts. Think about it. The Copenhagen summit is going to be held in a month. Scientists have faced enormous obstacles in convincing the public and governments about climate change. Your work has been crowned by grudging acknowledgement even by George W Bush and the Nobel Peace Prize for Al Gore. Would you be ready to throw away all this rightly hard-earned and hard-fought consensus for the sake of a few dissenting opinions? The simple laws of human nature dictate that you probably would not.

In my opinion, that is what seems to have happened with the scientists at the CRU. They have been so afraid of not only expressing their doubts (many of which as noted above would be valid given the science involved) but also entertaining other dissenting opinions that they have unfortunately picked the option of trying to silence open debate in a way that would be unacceptable in science in general. One can understand their motivation, but their actions still seem deplorable.

I think these emails point to a much more serious structural problem in the scientific enterprise of climate change. For good reasons and bad, whether to stand up to political hacks or ironically to defend good science, this enterprise has accumulated so much political baggage that it is now virtually impossible for it to compromise, to change, to maneuver even in the face of cogent reasons. The science of climate change has essentially bound itself into a straitjacket. My prediction is that important decisions about this science will in the future be mainly politically motivated. Public consensus not completely backed by good science will be the driving force for major decisions. The consequences of those decisions, just like the climate, are uncertain. We will have to wait and see.

But as usual, the casualty is ultimately science itself. What was good science and ineffective politics before is becoming effective politics and bad science. Whatever else happens, science never wins when it gets so overtly politicized. And hopefully about this there will be universal consensus.

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 an 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 tried to keep abreast of the basic facts of climate change and 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). I had penned my own personal biography of him a little while back. 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.

Source: Nobelprize.org

Venki Ramakrishnan has done it. He, Ada Yonath and Tom Steitz have won the Nobel Prize for chemistry for 2009 for their pioneering studies on the structure of the ribosome. The prize was predicted by many for many years and I myself have listed these names in my lists for a couple of years now; in fact I remember talking with a friend about Yonath and Ramakrishnan getting it as early as 2002. Ramakrishnan thus joins the ranks of Raman, Khorana and Chandrasekhar as the latest Indian science Nobel Laureate. Will his achievement inspire more students in India to study science? We sure hope so.

The importance of the work has been obvious for many years since the ribosome is one of the most central components of the machinery of life in all organisms. Every school student is taught about its function in acting as the giant player that holds the multicomponent assembly of translation- the process in which the code of letters in RNA is read to produce proteins- together. The ribosome is also an important target for antibiotics like tetracycline. The ribosome comes as close to being an assembly line for manufacturing proteins as something possibly can. It’s undoubtedly a highly well-deserved accolade. The prize comes close on the heels of the 2006 prize awarded to Roger Kornberg for his studies of transcription, the process preceding translation in which DNA is copied into RNA.

Venkatraman or “Venki” Ramakrishnan as he is known has resided for many years at the Medical Research Council’s (MRC) Laboratory of Molecular Biology, a hotbed of discovery which has produced many Nobel Prize winners including Watson and Crick, Perutz, Kendrew, Walker and Sanger (the only person to win the chemistry Nobel twice). Ramakrishnan who holds US citizenship received his undergraduate training in physics in India at Baroda and then worked in Ohio, San Diego and New Haven (Yale). After long stints at Brookhaven National Laboratory and the University of Utah he finally took up a position at the MRC. His conversion from physics in biology follows in the august footsteps of several physicists like Francis Crick and Walter Gilbert who made major contributions to molecular biology.

Will Ramakrishnan’s example inspire an Indian scientist who has worked in India to win the prize soon? We don’t know. The last and only time a bona fide Indian scientist won a science Nobel was Raman in 1930.

The solution of the ribosome structure by x-ray crystallography is a classic example of work that has a very high chance of getting a prize because of its fundamental importance. X-ray crystallography is a field which has been honored many times and as I mentioned before, if there’s any field where you really stand a good chance of winning a Nobel Prize, it’s x-ray crystallography on some important protein or biomolecule. In the past x-ray crystallography on hemoglobin, potassium ion channels, photosynthetic proteins, the “motor” that generates ATP and most recently, the machinery of genetic transcription, have all been honored by the Nobel Prize. It’s also the classic example of a field where the risks are as high as the rewards, since you may easily spend two decades or more working on a structure and in the end fail to solve it or worse, be scooped.

However, when this meticulous effort pays off the fruits are sweet indeed. In this case the three researchers have been working on the project for years and their knowledge has built up not overnight but incrementally through a series of meticulous and exhaustive experiments reported in top journals like Nature and Science. It’s an achievement that reflects as much stamina and the ability to overcome frustration as it does intelligence.

It’s a prize that is deserved in every way.

Update: As usual the chemistry blog world seems to be be divided over the prize with many despondently wishing that a more “pure” chemistry prize should have been awarded. However this prize is undoubtedly being awarded primarily for chemistry.

Firstly, as some commentators have pointed out, crystallography was only the most important aspect of the ribosome work. There were a lot of important chemical manipulations that had to be carried out in order to shed light on its structure and function.

Secondly, as Roger Kornberg pointed out in his interview (when similar concerns were voiced), the prize is being awarded for the determination of an essentially chemical structure, in principle no different from the myriad structures of natural and unnatural compounds that have been the domain of classical organic chemistry for decades.

Thirdly, the ribosome can be thought of as an enzyme that forms peptide bonds. To this end the structure resolution engaged knowing the precise locations of catalytic groups that are responsible for the all-important peptide bond formation reaction. Finding out the locations of these groups is no different from determining the catalytic parts of a more conventional enzyme.

Thus, the prize quite squarely falls in the domain of chemistry. It’s naturally chemistry as applied to a key biological problem, but I don’t doubt that the years ahead will see prizes given to chemistry as applied to the construction of organic molecules (palladium catalysis) or chemistry as applied to the synthesis of energy efficient materials (perhaps solar cells).

I understand that having a chemistry prize awarded in one’s own area of research is especially thrilling, but as a modified JFK quote would say, first and foremost “Wir sind Chemiker”. We are all chemists, irrespective of our sub-disciplines, and we should be all pleased that an application of our science has been awarded, an application that only underscores the vast and remarkably diverse purview of the discipline.

Source: Nobelprize.org

The 2009 Nobel Prize in Physiology or Medicine has been awarded to Elizabeth Blackburn (UCSF), Carol Greider (Johns Hopkins) and Jack Szostak (Harvard) for their discovery of the enzyme telomerase and its role in human health and disease.

This prize was highly predictable because the trio’s discovery is of obvious and fundamental importance to an understanding of living systems. DNA replication is a very high fidelity event where new nucleotides are added to the new DNA helix being synthesized with an error rate of only 1 in 10*9. Highly efficient repair enzymes act on damaged or wrongly structured DNA strands and repair them with impressive accuracy. And yet the process has some intrinsic problems. One of the most important problems concerns the shortening of one of the two newly synthesized strands of the double helix during every successive duplication. This is an inherent result of the manner in which the two strands are synthesized.

This shortening leads to shortened ends of chromosomes, termed telomeres. As our cells divide in every generation, there is progressive shortening of the chromosomal ends. Ultimately the chromosomal ends become too short for the chromosomes to remain functional and the cell puts into the motion the machinery of apoptosis or cell death which eliminates cells with these chromosomes. The three recipients of this year’s prize discovered an enzyme called telomerase that actually prevents the shortening of chromosomes by adding new nucleotides to the ends. Greider was actually Blackburn’s PhD. student at Berkeley when they did the pioneering work (not every PhD. student can claim that his or her PhD. thesis was recognized by a Nobel Prize). The group not only discovered the enzyme but actually demonstrated through a series of comprehensive experiments that mutant cells and mice lacking the enzymes had shortened life spans and other fatal defects, indicating the key role of the enzyme in preventing cell death. At the same time, they and other scientists also crucially discovered that certain kinds of cancers, brain tumors for instance, had high levels of telomerase. This high level meant that cancer cells repaired their chromosomes more efficiently than normal cells, thus accounting for their increased activities and life spans and their ability to outcompete normal cells for survival (As usual, what’s beneficial for normal cells unfortunately turns out to be even more beneficial for cancer cells; this need to address similar processes in both cells is part of what makes cancer such a hard disease to treat)

The work thus is a fine example of both pure and applied research. Most of the work’s implications lie in an increased understanding of the fundamental biochemical machinery governing living cells. However, with the observation that cancer cells express higher levels of telomerase the work also opens up possible chemotherapy that could target increased levels of telomerase in such cells using drugs. Conversely, boosting the level of the enzyme in normal cells could possibly contribute toward slowing down aging.

The prize has been awarded for work that was done about twenty years ago. This is quite typical of the Nobel Prize. Since then Jack Szostak has turned his focus on to other exciting and unrelated research involving the origins of life. In this field too he has done pioneering work involving for instance, the synthesis of membranes that could mimic the proto-cells formed on the early earth. Blackburn also became famous in 2004 for a different reason; she was bumped off President Bush’s bioethics council for her opposition to a ban on stem cell research. Given the Bush administration’s consistent manipulation and suppression of cogent scientific data, Blackburn actually wore her rejection as a proud label. Catherine Brady has recently written a fine biography of Blackburn.

When on May 11, 1998 India tested nuclear explosives, there was considerable doubt about whether we had tested a bona fide thermonuclear or hydrogen bomb. Every country’s strategic nuclear deterrent has thermonuclear weapons, and to announce itself as a ‘true’ nuclear weapons power India had to demonstrate that we had the capability to build hydrogen bombs. However most outside sources did not believe we had tested a true thermonuclear.

Curiously we seem to have largely bluffed then about the yield, and now the debate seems to have been ignited again with a statement by P. Santhanam of the DAE who accepts that our purported thermonuclear might have fizzled out. Surprisingly, at the same time there seem to be statements from individuals as august as A P J Abdul Kalam who contends that the tests provided the “designed yield”.

Interestingly, Santhanam does not seem to offer any perspective about what the yield actually was. However, calculations and measurements done at the time seem to leave little doubt that the design fizzled out. It’s worth reviewing this analysis.

There seem to be three dominant sources which converge on a consensus that India’s purported thermonuclear test failed to work.

The first source is the Federation of Atomic Scientists, whose analysis indicated a yield of between 12-25 kT

The second source is nuclear specialist Robert Norris who analyzed data from sixty-two seismic stations and concluded a yield of 12 kT

The third source is the UK’s Atomic Weapons Establishment who compared the signals from the 1998 test to the 1974 ‘Smiling Buddha’ test. Comparing signal strength they arrived at a rather accurate estimate of 16 kT for the total yield.

Using an average estimate of 16 kT, we can apportion the energy between the three devices that India tested. Shakti 1 was supposed to be the thermonuclear. The second device (Shakti 2) was supposed to be a weaponization of the 1974 experiment and therefore we can be quite confident that we got the yield right and as announced- about 12 kT. Shakti 3 whose purpose was to generate interesting data released a relatively negligible 0.2 kT.

Simple subtraction leaves about 4kT for the ‘thermonuclear’ Shakti 2.

Now of course at the time, the Indian government talked about a yield of 45kT from Shakti 2. The design was supposed to be a classic Teller-Ulam kind of design in which a primary fission trigger ignites a secondary fusion package. However most experts now think that what happened was that the primary only partially detonated and delivered the 4kT, and with such a small yield the secondary simply failed to ignite. As painful as it sounds, this means that the device did not work at all as intended and was an embarrassing failure. Even the error estimates don’t leave too much room to wriggle.

However, what repurcussions this has for India’s nuclear deterrence is a different matter. I agree with some others that we should not have bluffed at the time. After all no country (except probably China) has really gotten it right the first time. Also, deterrence does not depend on the mere existence of hydrogen bombs but depends on a complex system of nuclear weapons and delivery systems. It’s worth recalling that many rather wise people in the US were pushing the development of better fission bombs when the whole debate about hydrogen bombs was going on in the late 40s.

Some have also argued that it’s better to have big thermonuclear weapons rather than ’small’ fission weapons so that countries won’t actually feel tempted to use the small bombs with their smaller yields. But this argument crucially rests on quantitative aspects. A Hiroshima style bomb with a yield of 20 kT is as good as a 1 megaton hydrogen bomb when employed strategically in sufficient quantities. Hydrogen bombs are certainly not essential for deterrence; in fact what’s really essential is an efficient triumvirate of delivery systems (submarines + bombers + missiles). That is what India should focus on instead of getting too hung up over hydrogen bombs and bigger bangs.

Note: The analysis is of course not my own. Apart from the websites I have referred to the excellent and authoritative The Nuclear Express by Thomas Reed and Danny Stillman, both of whom are veteran nuclear weapons specalists.