Spurious linkages between extreme temperatures and farmer suicides


KAMAL KUMAR MURARI, Assistant Professor, School of Habitat Studies, Tata Institute of Social Sciences, Mumbai.

MADHURA SWAMINATHAN, Professor, Economic Analysis Unit, Indian Statistical Institute, Bengaluru.

T. JAYARAMAN, Professor, School of Habitat Studies, Tata Institute of Social Sciences, Mumbai.

A recent paper, published by the PNAS (Proceedings of the National Academy of Sciences of the United States) and authored by Tamma A. Carleton, titled “Climate Change and Agricultural Suicides in India” claims that “temperature during India’s main agricultural growing season has a strong positive effect on annual suicide rates.” Using state-level data for 1967 to 2013, the author suggests that an increase in 1°C temperature in a single day can cause 70 suicides. It also claimed that the evidence leads to the conclusion that it is the damage to crops by extreme temperatures that leads to economic hardship and suicide.

Regrettably, the paper has received widespread uncritical coverage in the Indian media.

We consider these claims to be baseless. These claims are a consequence of the uncritical use of data, bad assumptions, flawed analysis and unacceptable neglect of the existing literature on global warming and Indian agriculture as well as farmer suicides. Taking the conclusions of the paper at face value would lead, we strongly believe, to dangerously incorrect policy measures. Such conclusions also divert from the study of the real challenges that global warming, and extreme temperatures in particular, poses for Indian agriculture.

The paper is marked by several serious errors. The paper:

  • Incorrectly uses suicide data

  • Wrongly identifies extreme temperatures for crop production,

  • Wrongly identifies only kharif as the relevant agricultural season in which to consider extreme temperatures, and

  • Wrongly identifies the relevant crops.

As a result, the meaning of the correlation that the author claims to find between extreme temperatures and suicides is unclear. The manner in which the paper analyses the link between extreme temperatures and crop production is wrong.

The signatories to this press note have themselves conducted a detailed study of the impact of extreme temperatures on crop production in Karnataka, one among several such studies conducted by other responsible Indian and foreign authors. No such study provides any corroborative evidence for the dramatic conclusions of this paper.

The authors of this press note have also submitted a formal comment on the paper to the PNAS, where the original paper is published.

Uncritical use of data

The paper uses state-level data on suicides, data that includes both urban and rural suicides. How can urban suicides be included in an analysis of agricultural suicides? The paper also sets aside the fact that the suicide data, taken from the National Crime Records Bureau, has separated farmer suicides from those of other occupational categories only after 1995 and the inconsistency in data prior to that year. Suicide data are gathered from police records so there is likely to be underreporting.

Bad Assumptions

The paper, in attempting to show that temperature increase affects agricultural yields does not directly examine physical yield but only considers their monetary value, based on 1960-65 prices. It is widely recognized in the climate change literature, that the impact of extreme temperatures on crops and their economic consequences should not be confused with each other. It is well-established practice to consider physical yield as the first direct impact of increased temperatures and lowered monetary income a consequence that is also affected by a host of other economic and policy factors.

Further, and more damagingly, the author does not analyse individual crops but only considers a basket of such crops including rice, wheat, sorghum, sugar, maize and millet. Cotton, closely associated to farmer suicides wherever it is grown, is a notable omission as are a host of other cash crops.

The author, surprisingly and wrongly, considers extreme temperatures only during the kharif season. She completely ignores the rabi season, despite clear evidence to the contrary from ICAR and other authoritative research from India and across the world. Rabi crops like wheat are in fact most sensitive to extreme temperatures as has been well-established by research. Despite the fact that the predominant wheat-growing season is rabi, the paper includes wheat in its analysis but does not include the impact of rabi temperatures.

The paper also considers temperatures above 20 degrees Celsius as extreme temperatures. This is flatly contradicted by what is known of the temperature dependence of crop production. In general, temperature ranges of 20 degrees to 29 degrees Celsius are known to be beneficial for crop growth. Every crop has a specific temperature threshold, ranging from 33°C to 38°C, above which a negative impact on yields is possible, and extreme temperatures in the literature refer to temperatures above these corresponding thresholds.

Flawed analysis

As a consequence of the errors explained above, the results on the negative effect of temperature on crop yields are not tenable. Of the six crops pooled, rice is mainly a monsoon crop, wheat is a winter crop, and sugarcane is a 12 to 18 month crop. How can the July-September “growing season” temperature explain changes in the combined yields of these crops?

The author finds a strong positive coefficient of proportionality when aggregate State level deaths from suicide are related to the total heat exposure in the kharif growing season alone. The quality of data on suicides is in doubt, and the definitions of temperature threshold and growing season are incorrect. The author refers to robustness checks of her results but all these checks retain the erroneous assumptions listed above. Without further study, it is not clear how we interpret the observed coefficient that she claims to find.

We are astonished to find such a poor analysis based on incorrect understanding of data and wrong analysis should find its way into policy discourse on climate change and agriculture. There is much excellent literature being produced on this important subject. The dissemination of such important and scientifically valid research is hampered by the publication of flawed papers such as the one in question.


Historical Notes – Left stand on Nuclear Weapons and Pokhran tests


These notes are taken  from a Facebook post of 7th August, 2017.


No to nuclear weapons in the subcontinent, no to the dictates of the global nuclear powers, no to nuclear jingoism aligned with Hindutva!!

The exchange between Prerna Gupta and my friend
Govindarajan on my earlier post merits the following clarification:

See the original press statement of the Left Parties on 16 May 1998 (retreived from my old email archives and posted on my blog) at https://tjayaraman.wordpress.com/…/historical-notes-left-p…/.

In case this is not enough, you may also see the following Frontline report of a well-attended meeting in Delhi, organised by the Left Parties. See the resolution passed by the meeting cited in full in the article (I was also a speaker there, representing scientists, from institutions including within the DAE, against the tests), and see particularly the call for protests on Hiroshima Day of 1998.

For a report on the Chennai convention against nuclear weapons tests of Pokhran, rreferred to by Govindarajan Thupil see report at

The biggest mobilisation was predictably in West Bengal and of course protests were held elsewhere too. (I assure, the crowd in Kolkata was not mobilised by Mamata Didi). For reports see,

You may disagree with us politically, but let us just stay with the facts while we are about it.

As far as I can make out from Ms. Gupta’s post, she seems to have taken her quotations based on excerpts from Prisoner’s of the Nuclear Dream edited by M. V. Ramana and C. Rammanohar Reddy. The particular article in the book (by Krishna Ananth) in its attitude to the CPM stand on nuclear weapons is a classic example of the disinformation that ANTI-NUCLEAR ENERGY activists have propogated against the CPM. (Ms. Gupta may of course may have referred to actual issues of People’s Democracy, but I rather doubt it).

The quotations she provides are very likely correct – I am certainly not challenging them. And it certainly also represents an initial confusion in the CPM’s reponse. But she does not acknowledge that it does not represent the official position of the party, nor does she bother to track what the CPM did beyond these selective quotations. In fact in the essay, it is acknowledged that these quotations are not the official stand of the party and there is an extended quotation from Prakash Karat, that shows a clear condemnation of nuclear weapons.

(Of course, Ms. Gupta refers to the statement of the Peoples Democracy of 17 May. This was, I recall, issued before the full politburo met and the final decision was made clear).

However, the essay also deliberately misrepresents by not including the statement, putting official within quotation marks and relegating the Prakash Karat quotation to a footnote (that runs over the bottom of two pages!!). Based on this selective quotation mongering, the book also draws wholly unwarranted conclusions at the end of page 330.

Historical Notes — Left Parties’ Statement of 16 May, 1998 on the Pokhran test


Press Statement

The Left Parties — CPI(M), CPI, RSP and Forward Bloc — met on 16 May, 1998 and have issued the following joint statement.

The Prime Minister Atal Behari Vajpayee has made a public  declaration that the BJP led government has decided to go ahead with making and induction of nuclear weapons. He has also claimed that India is now a nuclear weapons state. This major policy declaration is fraught with serious consequences. The Left parties are of the categorical opinion that making of nuclear bombs and weaponry at this juncture is unwarranted and contrary to the interests of the country. There is no direct\ nuclear threat posed by any country against India which necessitates such a step. The BJP-led government has taken this drastic decision on its own without even caring to discuss with the national political parties. The Prime Minister is now promising to call a meeting of opposition leaders on the eve of the budget session of Parliament after making the BJP’s own policy a fait accompli.

The contempt shown by the Vajpayee government in not taking the people of the country into confidence while hastening to write to President Clinton has been exposed by the entire text of the Prime Minister’s letter being published in the United States. This letter has sought to mollify the United States by citing the threat to India from China as the main factor. It is short- sighted and against India’s national interests to revive aconfrontation with China after the decade-long progress in normalisation and improvement of relations between the two countries. By adopting this unilateral policy, the Vajpayee governmenthas seriously harmed the improvement in relations with our neighbouring countries which was being built up over the years and carried forward by the previous United Front government. As a result of the reckless nuclear policy, there will be a harmful nuclear arms race between India and Pakistan with diversion of scarce resources for a costly and futile build up of nuclear weapons. This will not benefit the Indian people whohave more serious problems about their livelihood to deal with.

The BJP has rushed into this adventurist policy with the political motive of rousing feelings of chauvinism and jingoism in order to cover up its own political difficulties of running a rickety coalition and its failure to address the serious problems facing the country. While condemning the sanctions imposed by the USA and some other countries, the Left parties strongly oppose the other policy track adopted of further opening up and wooing foreign multinationals in all sectors of the economy. This anti-national policy will only add to the burdens suffered bythe people. The Left parties demand that the BJP-led governmentimmediately stop the talk of nuclear weaponisation. It must take steps to restore the process of improvement of relations with our neighbours and rely upon the sound policy India has been pursuing of working for nuclear disarmament while safeguarding India’s security interests by not signing any discriminatory treaties like the NPT and the CTBT.

The meeting was attended by Harkishan Singh Surjeet, A. B.Bardhan, D.D. Shastri, Sushil Bhattacharya, Abani Roy, PrakashKarat, J. Chittaranjan, S. Ramachandran Pillai and Devarajan.

Marx on Science


It is a remarkable fact that at Marx’s funeral, his life-long friend and comrade-in-arms Friedrich Engels chose to eulogise his friend’s commitment to revolution in terms of his passion for science. Engels noted, “Science was for Marx a historically dynamic, revolutionary force. However great the joy with which he welcomed a new discovery in some theoretical science whose practical application perhaps it was as yet quite impossible to envisage, he experienced quite another kind of joy when the discovery involved immediate revolutionary changes in industry, and in historical development in general. For example, he followed closely the development of the discoveries made in the field of electricity and recently those of Marcel Deprez.” But to note only this part of Engels’ speech, would be to limit Marx’s vision of science.

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What’s on your mind asks Facebook, but my problem is — whats on the mind of Leftword Books?

The Leftword Books site carries the blurb of a proposed book, as noted on the web page http://mayday.leftword.com/…/letter-to-our-leftword-commun…/ :

“Red October: the Russian Revolution and the Communist Horizon, ed. Vijay Prashad. The book collects essays that reflect not only on the Revolution, but on the Soviet Union and its fall, as well as on the necessity of the Communist Horizon for the present. Historians Irfan Habib and Amar Farooqui take up the task of bringing to life the Revolution and its impact on the anti-colonial struggles. Essays by BT Ranadive, Prakash Karat and Sitaram Yechury – written between 1987 and 1991 – explore in real time the collapse of the USSR and offer very honest and thoughtful criticisms of its tragic fall. Finally, Prabhat Patnaik, Jodi Dean, Prabir Purkayastha and Shahrzad Mojab close the volume with fine essays on the imperative of the Communist Horizon.”

What is remarkable about this collection is that Com. BTR, and the past and current Gen. Secys. of the Party (the CPM), are to be represented by essays written between 1987 and 1991, while the present and the future vision of communism is to be represented by essays around the theme of “Communist Horizon”. It turns out that Communist Horizon is also the title of a book by Jodi Dean, listed among the authors, who is a political scientist from some liberal arts college in Eastern US. Unheard of as a Marxist authority or poltical leader (outside the narrow realms of US academia perhaps), it defeats me why the theme of her work forms part title of a volume that includes BTR, Irfan Saab, Prakash Karat and Sitaram Yechury.

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Trump and the Paris Agreement


The U.S. pullout has sparked a surge of commitment to the accord, but not a focus on its deep flaws

Published in the Hindu on June 9, 2017.


Make no mistake, U.S. President Donald Trump has just dealt a body blow to the Paris Agreement. In its refusal to acknowledge the significance of this threat to global security, his decision to pull the U.S. out of the climate accord has virtually no parallel since the beginning of the post-World War II era of multilateralism.

Ripple effect likely

The rejection of the Kyoto Protocol by the George W. Bush presidency, signed by the Clinton administration in 1997, a rejection driven by both Republican and Democrat legislators, caused an 18-year hiatus before a new agreement could be crafted.

The new hiatus may not last as long, but that is small comfort when the climate threat has advanced considerably since then. Mr. Trump’s move is likely to set off a domino effect of inaction among other known climate laggards, the U.K., Australia, Canada, Japan and Russia being some of the most prominent among these.

Despite the diplomatic rhetoric, the weakening or dismantling of their domestic institutional arrangements for climate action has already given cause for alarm, while the radical deceleration in climate research by one of its leaders, the U.S., will also have grave consequences.

What exacerbates the danger is the hype that has greeted the Paris agreement since its signing and the illusions this has promoted. The agreement leaves the solution of a global collective action problem to purely voluntary action, with binding commitments only to processes and not to the adequacy of efforts to enforce greenhouse gas emission reduction targets, especially by the developed nations.

More bizarrely, even as the accord sharply diluted any attempt to ensure equity for developing countries, it also promised to attempt to limit global temperature increase to not more than 1.5°C of pre-industrial levels. But drowning any articulation of these deep flaws, the Trump decision has now renewed a surge of commitment to an already weak agreement, an outcome that will worsen the prospects of holding global temperature increase to even the 2°C limit.

No talk of climate leadership by the European Union and China, or joint action by other national, regional and local governments worldwide, can obscure the dangers of non-participation by the U.S. Without one of the world’s largest emitters on board, global emissions cannot be limited to the global carbon budget appropriate to the 2°C goal. Any such attempt, even as the U.S. consumes global carbon space at its current pace, will turn the screws, ever more tightly, on the development options of India and a large section of the G-77.

More fundamentally, Mr. Trump’s decision has called the bluff on the real rationale of the agreement, articulated by the outgoing Secretary of State, John Kerry, a year after Paris at Marrakech. Acknowledging the inadequacy of the agreement’s mitigation goals, Mr. Kerry argued that it nevertheless sent a strong signal to business the world over, and would stimulate industry and markets to action. This rationale has been reiterated by many following the Trump decision. Billionaire businessman-politician Michael Bloomberg’s pledge to provide a fraction of his vast fortune as a contribution to climate action speaks of the hubris of global capital in the contemporary world, of seeing personal charity as the key to the security of the planet.

The long-term future of the world hangs today by the slender thread of faith in neo-liberal economic theory and the hope and a prayer that this will work. Surely something more tangible and substantial is needed.

India as a Climate Leader – Impossible Dreams of Superpower status



It is the perennial temptation of journalists — to fall for the rhetoric and dreams peddled by politicians instead of keeping their eyes, minds and keyboard action focused on the realities of the world around them. Hardly has the (metaphorical) ink dried on a short piece I had just written on the Trump decision (unfortunately it is likely to be published, so I cant post it yet), warning of its seriousness, that a piece predictably appears on how it is an opportunity for India.

All the usual mythology is duly present:
i) How US was the climate leader and piloted the Paris Agreement to completion (really, Neville Chamberlain seems positively realpolitik — the reality being that it was the leading climate laggard and everyone had to bend over backward to accomodate it — and then it has done a Kyoto ver 2.0 and walked out anyway, as Trump himself has acknowledged.)

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Utopian Rhetoric on Global Warming


Book Review: Vijay Parshad (ed.), “Will the flower slip through the asphalt: Writers Respond to Capitalist Climate Change,” Leftword Books, New Delhi, 2017.

P:ublished in the Economic and Political Weekly, Vol 52, Issue No 20, 20 May, 2017.

Amidst the increasing outpouring of literature on global warming and what the world should do about it, there is very little that is written from the perspective of enquiring into the relationship between capital and global warming. This is obviously not the same as writing on the economic or socio-economic dimensions of the problem or even writing that is passed off under subject headings such as the “political economy of climate change” or “politics of climate change.” To write about capital and global warming is clearly to adopt a viewpoint that sees capitalism as the essence of the global political, social and economic order, evoking clearly a critical Marxist view of how capitalism structures the relationship between human society and Nature. Expectedly the literature from this viewpoint on global warming is very sparse. Which is why this book will undoubtedly arouse the expectations of many who come across the title.

This slim volume counts among its more well-known contributors Naomi Klein, John Bellamy Foster and Amitava Ghosh, alongside others from various parts of the world. The main contribution is the essay by Naomi Klein, with a number of short comments on this by the others, and an introduction by Vijay Parshad. Klein’s essay is in fact her Edward Said lecture of 2016, available widely on the internet. Apart from this none of the comments appear to convey anything novel or particularly insightful that has not been published before, a possibility that is in any case curtailed by the format of brief comments. The volume as a result is not particularly attractive to those who are fully engaged with the issue of global warming, nor, given the brevity of contributions, particularly useful to those who would like to know more of the subject under discussion. Whatever may have been the original intent, one is left with the uncomfortable feeling of a public relations exercise for Naomi Klein and her brand of “Left” rhetoric on the issue of global warming. It is this last point that should perhaps engage us more seriously.

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Remembering Vijayalakshmi


A heroic struggle of a scientist with cancer: B Vijayalakshmi
(by T R Govindarajan). From, “Daughters of Lilavati”, Rohini Godbole and Ram Ramaswamy (ed.), Indian Academy of Sciences, 2008.

Viji joined the Department of Theoretical Physics in 1974
after obtaining her Masters from Seethalakshmi Ramaswami
College, Tiruchirapalli. Hers was a conservative background,
and it was remarkable that she could overcome conventional
gender restrictions and consider research an option.
Our advisor was Professor P. M. Mathews, who was the
head of department at that time. Always smiling and friendly, Viji
discussed the graduate courses with me like any other student.
Once, while we were discussing our work, she expressed some discomfort
and I enquired about it. Looking straight at me as if to
gauge my reaction, she replied that she had been diagnosed with
widespread cancer of the stomach and the abdominal region. I
was shocked and speechless for a few moments. Later she told me
that her major aim was to make some substantial research contribution
and be recognised as a physicist and that her immediate
goal was to finish her research degree before anything happened to

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Environmentalism: Utopian and Scientific



While many nineteenth century thinkers, revolutionary leaders and working class movements had a vision of a just society, Karl Marx and his comrade, Friedrich Engels, writing more than a hundred and fifty years ago, underlined how the ideal of socialism could be realised only through a scientific study of the current economic order of society, namely capitalism, and its contradictions. And precisely in the study of these contradictions would the “necessity” of socialism, and the means of its realisation, be established (as surely as the contradictions of the pre-capitalist era had marked the “necessity” of the rise of capitalism), taking it beyond the mere utopian desires or dreams that had until then marked the vision of a society free from exploitation.

A great majority of working people across the world today recognize that any view of a better, more just and equitable society, must also include the vision of an environmentally viable and sustainable one. And more particularly, for the politically conscious working class, the contemporary view of a socialist future most definitely includes a balanced, non-exploitative relationship between human society and Nature. A hundred and fifty years on from the appearance in print of Marx’s Capital, his path-breaking study of capitalism and its contradictions, there can be no other way that humanity can face its environmental crisis, except by tracing the same kind of scientific path that led to a scientific view of socialism. And such a scientific view cannot but begin with the insights of Marx himself.

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