Comments 1 to 17:

1. joe - at 23:43 PM on 22 May, 2017

   Climate change, and its impacts on extreme weather and temperature swings, is projected to reduce global production of corn, wheat, rice and soybeans by 23 percent in the 2050s, according to a new analysis.

   What makes this study any more valid that the the numerous studies and predictions put forth by Paul Ehrlich and others with similar predictions

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2. John Hartz at 00:12 AM on 23 May, 2017

   Joe: The study that you are referring to is cited below. It should and will be judged on its own merits.

   Impact of Climate Change, Weather Extremes, and Price Risk on Global Food Supply by Mekbib G. Haile, Tesfamicheal Wossen, Kindie Tesfaye, and Joachim von Braun, Journal of Economics of Disasters and Climate Change, May 6, 2017

   Abstract
   We analyze the determinants of global crop production for maize, wheat, rice, and soybeans over the period 1961–2013. Using seasonal production data and price change and price volatility information at country level, as well as future climate data from 32 global circulation models, we project that climate change could reduce global crop production by 9% in the 2030s and by 23% in the 2050s. Climate change leads to 1–3% higher annual fluctuations of global crop production over the next four decades. We find strong, positive and statistically significant supply response to changing prices for all four crops. However, output price volatility, which signals risk to producers, reduces the supply of these key global agricultural staple crops—especially for wheat and maize. We find that climate change has significant adverse effects on production of the world’s key staple crops. Especially, weather extremes— in terms of shocks in both temperature and precipitation— during crop growing months have detrimental impacts on the production of the abovementioned food crops. Weather extremes also exacerbate the year-to-year fluctuations of food availability, and thus may further increase price volatility with its adverse impacts on production and poor consumers. Combating climate change using both mitigation and adaptation technologies is therefore crucial for global production and hence food security.

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3. joe - at 00:35 AM on 23 May, 2017

   John - yes the study should be judged based on its one merits - yet it is basically a rehash of numerous other studies that have been proved wrong, In fact, just the opposite has occurred based on advancements in real science.

   my question remains - What makes this study any more valid that all the other previous studies that have been proved wrong, such as Ehrlich frequent predictions.

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   Moderator Response:

   [Rob P] How can projections for future decades be proven wrong now? The study authors used global production data from 1961–2013 to reach their conclusion. 

   Your comment does seem to be sloganeering (a violation of the comments policy) but if you can provide some examples/details of the prior studies you claim are wrong a genuine discussion with others can ensue. 

   And please note that sloganeering may result in comments being deleted.

4. michael sweet at 03:20 AM on 23 May, 2017

   Joe,

   And yet we have sent men to the moon and built computers.  Since scientists have made many millions of predictions it is easy to find some that were incorrect.  As John says, you have to evaluate this prediction on the merits of the data they provide to support their claims.

   You have not even commented on the merits of the article, you just make this ad hominum claim that all scientific predictions are incorrect.  Your second post is sloganeering and against the comments policy.

   I will note that Ehrlich's claims were never scientific consensus.  This article is not consensus yet, but there are many dangers from warming (like sea level rise and extended drought) that are.

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5. John Hartz at 03:35 AM on 23 May, 2017

   Joe: You state: 

   John - yes the study should be judged based on its one merits - yet it is basically a rehash of numerous other studies that have been proved wrong,

   How did you arrive at your assertion that the paper Climate Change, Weather Extremes, and Price Risk on Global Food Supply is basically a rehash of numerous other studies that have been proved wrong?

   Please list the studies that you are referring to and provide links to them. Have you personally read all of the studies that you are referring to?  How do you know that these studies have been proved wrong?  Please document the source(s) of your conclusions. 

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6. joe - at 04:12 AM on 23 May, 2017

   I will repeat my question - What makes this study any different from the similar & previous studies and predictions.  Simply cloaking the predictions in "science" doenst make it any more valid.

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7. John Hartz at 04:25 AM on 23 May, 2017

   Joe: Unless you can precisely define what you mean by "valid" and answer the questions that I have posed, your global assertions disguised as questions are nothing more than sloganeering which is prohibited by the SkS Comments Policy. If I weren't conversing with you, I would come down hard on you as a Moderator.  

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8. MA Rodger at 06:00 AM on 23 May, 2017

   joe,

   You ask what is different with the study-under-discussion (Haile et al 2017) that makes it valid when the pedictions of Paul Ehrlich and other doom-mongers of the past have proved to be invalid.

   I would assume your question is not uniquely aimed at Haile et al (2017) but that you would likely question the validity of many other papers in an identical manner. If this assumption is correct, could you set out the characteristics of this broader work that leads you to question its validity?

   Or, if this isn't correct, could you explain what it is specifically that makes you question the validity of Haile et al (2017)?

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9. joe - at 07:54 AM on 23 May, 2017

   Or, if this isn't correct, could you explain what it is specifically that makes you question the validity of Haile et al (2017)?

   What makes me question the validity of the Haile study - Its the similarity of conclusions with the Paul Ehrlich predictions, et al.  Simply put, numerous studies have predicted the same and/or similar results, yet all have been wrong to date.  

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10. joe - at 08:00 AM on 23 May, 2017

    [Rob P] How can projections for future decades be proven wrong now? The study authors used global production data from 1961–2013 to reach their conclusion.

    Your comment does seem to be sloganeering (a violation of the comments policy) but if you can provide some examples/details of the prior studies you claim are wrong a genuine discussion with others can ensue.

    And please note that sloganeering may result in comments being deleted.

     

    Rob - This study is simply a variation of the numerous paul elrich predictions which have been demostratively wrong - My point and question is why does this study have any greater predictive value when it only a rehash of the multiple prior studies.

    Its a fair and valid question

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    Moderator Response:

    [PS] This is still heading into "someone once made a bad prediction, therefore all predictions are wrong". Can you show that Haile et al are using the same methodology and assumptions that have proved erroneous in the past? This would be a useful contribution to the discussion which is otherwise a bit handwavy.

11. joe - at 09:42 AM on 23 May, 2017

    "someone once made a bad prediction, therefore all predictions are wrong". Can you show that Haile et al are using the same methodology and assumptions that have proved erroneous in the past? This would be a useful contribution to the discussion which is otherwise a bit handwavy.

    Rob - True - Haile is using a different methodology and assumptions, etc., yet the conclusions have a striking similarity to the Paul Ehrlich et al conclusions.  Why is a re-hash of those failed studies and predictions any more valid? 

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    Moderator Response:

    [PS] Different methodologies and assumptions means that it is not a rehash. You argument remains that because it produces predictions like Ehrlich, it must be wrong. This is a logical fallacy. Demonstrating problems with Hailes method or assumption would more constructive.

12. John Hartz at 10:41 AM on 23 May, 2017

    Joe: You state:

    Haile is using a different methodology and assumptions, etc., yet the conclusions have a striking similarity to the Paul Ehrlich et al conclusions. Why is a re-hash of those failed studies and predictions any more valid?

    If Haile uses a different methodology and assumptions than Erlich did, Haile's study cannot, by definition, be a rehash of Erlich's work.    

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13. nigelj at 12:15 PM on 23 May, 2017

    So according to "Joe" science gets some environmental things wrong, so all environmental things must be wrong. On that basis we might as well give up on all fields of science.

    Some people are just plain frustrating and childish.

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14. Tom Curtis at 13:33 PM on 23 May, 2017

    PS inline@11, Joe's argument is worse than that.  Haile et al make specific predictions about the impact of climate change in three crops.  They allow that "...some farming changes—such as improved irrigation or genetically modified crops, or more sustainable practices like increased organic production or tilling less—could help offset some climate-induced losses" (from article linked above).  Without specific quantification, it is consistent with Haile et al that those offsets could more than compensate for the climate related losses.  As such, Haile et al represents a prediction about a specific difficulty, without a claim that we will be ruined by it - let alone that it will lead to a catastrophe.  Consequently, when Joe says that Haile et al's conclusions "... have a striking similarity to the Paul Ehrlich et al conclusions", he is guilty of massive exaggeration. 

    Taking that into account, his argument form is really, "x predicted negative consequences in the future, that did not arise, therefore, any predictions of negative consequences in the future of any nature, and no matter how well supported are false".  It is likely, although we have no specific evidence of that, that he makes a specific exception for economic predictions of ruination premised on action to mitigate climate change.  That is, like many climate change deniers he may subscribe to the principle that a free market economy is so robust that it can generate growth regardless of adverse circumstances except for the adverse circumstances of any spefic policy they happen to disagree with. 

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    Moderator Response:

    [PS] Give him chance please.

15. chriskoz at 22:42 PM on 23 May, 2017

    NOAA SEA LEVEL RISE SCENARIOS recently published is a nice easy-to-read yet very comprehensive SLR summary and prediction until y2200.

    Jump staraight to page 22 - Figure 8 & Table 4 - to learn the precis of their projections. Only a bit higher than IPCC for RCP2.5 but more than twice higher for higher emission scenarios, esp. RCP8.5.

    But their 6 scenarios in table 4 have very sharply defined upper bounds. E.g.: middle range Intermediate scenario (1.0 m SLR by 2100) hasd only 17% hance of excceeding in RCP8.5 emissions. Extreme scenario (2.5 m) is very unlikely - only 0.1% chance of at least such SLR in RCP8.5. I feel like they underestimated the uncertainties in icesheet stability in that scenarion.

    Nonetheless higher SLR than IOPCC, even though somewhat conservative IMO. So, I don't understand the alarming and somewhat exaggerated news about it, like this one by Peter Hannam in smh. Peter quotes the SLR values 2.7 metres as "plausible". I don't even understand where that number came from as I cannot find it in the study in question. But I see the number 2.8m as the central estimate of Intermediate scenario by y2200 (table 5) which is the first such estimate AFAIK.

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16. John Hartz at 23:07 PM on 23 May, 2017

    Chriskoz:

    More "hot-off-the-press" news about SLR...

    Scientists say the pace of sea level rise has nearly tripled since 1990 by Chris Mooney, Energy & Environment, Washington Post, May 22, 2017

    PS - If you have not already done so, you may want to communicate your concerns about Peter Hannam's article directly to him.

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17. MA Rodger at 00:57 AM on 25 May, 2017

    In the discourse above, the paper Haile et al (2017) is discussed but the work it is being compared with, that of Paul Ehrlich has not been described.

    I note @8 I managed to provide a broken link to the Paul Ehrlich Wiki page.  His work was entirely unknown to me but the idea that the world is heading for an overpopulated and miserable future is not something that hasn't been projected by many others at various times. Yet I was surprised to find that Ehrlich's most famous work "The Population Bomb" (1968) is less a proper study and more an opinion piece with little substance running through its two-hundred pages of chat. (This PDF of its Chapter 1 describes his 'Population Bomb' in twenty-five tiresome pages.) His prediction of "massive famine" within a decade or two didn't fail due to him overestimating population growth (a growth he fails to set out clearly but which can be surmised from his discussion of the various growth rates). Rather, his decadal prediction failed due to increases in agricultural output. However, over a longer timespan, Ehrlich failed to spot the dramatic drop in the global population growth rate. The growth he describes would have yielded a world population of ~10bn for 2017, 25% greater than actually now exists.

    

    As of 2009 Ehrlich doesn't see any problem in predicting in 1968 that the wheels would fall off and humanity would be facing "massive famines" in (pessimistically) a decade or (optimistically) two. He just doubles down and asserts that his "basic message is even more important today than it was forty years ago."

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