Monthly Archives: April 2014

David Rose has an article in the Sunday Mail yesterday, which I provided the research for. The top article is about the dispute between Bob Ward and Professor Richard Tol.

David Rose asked me to compare the WGII SPM with the chapters. I found a number of discrepancies, which are written up in the paper, and do much (in my view) to support Professor Tol’s claim that the report’s alarmist tone was largely groundless.

The IPCC have responded to the article. The statement takes issue with Tol, first, and then seems to address the discrepancies I have found… But doesn’t.

The Mail on Sunday also quotes some passages from the Working Group II Summary for Policymakers on migration and refugees, wars and conflicts, famine, and extreme weather, which it claims are “sexed up” from statements in the underlying report. In doing so it misleads the reader by distorting the carefully balanced language of the document.

Which document was written in ‘delicately balanced’ language — the SPM or the chapters? And how was this fragile balance ‘distorted’ by the article? The SPM’s language certainly wasn’t balanced. It was unequivocal in many cases. But the language in the chapters told a different story.

For instance, the Mail on Sunday quotes the Summary as saying climate change will ‘increase risks of violent conflicts’. In fact the Summary says that climate change can indirectly increase risks of violent conflicts by amplifying factors such as poverty and economic shocks.

Here is what the article said:

WGII SPM, Page 20:

Climate change can indirectly increase risks of violent conflicts in the form of civil war and inter-group violence by amplifying well-documented drivers of these conflicts such as poverty and economic shocks (medium confidence). Multiple lines of evidence relate climate variability to these forms of conflict.

The SPM links to WGII Chapters 12.5, 13.2, and 19.4.

SPM chapter 12 is concerned with “human security”. Section 12.5 is concerned with “Climate change and Armed Conflict”. I found the chapter to be quite sober, in contrast to the SPM. For e.g.

There is a specific research field that explores the relationship between large-scale disruptions in climate and the collapse of past empires. Relationships are explored using statistical analysis and data derived from archaeological and other historical records. For example, the timing of the collapse of the Khmer empire in the Mekong basin in the early 15th century corresponds to an unusually severe prolonged drought (Buckley et al., 2010). DeMenocal (2001) summarizes evidence that suggests that major changes in weather patterns coincided with the collapse of several previously powerful civilizations, including the Anasazi, the Akkadian, Classic Maya, Mochica, and Tiwanaku empires. Other historical reference points of the interaction of climate with society emerge from analysis of the little Ice Age. Some studies show that the Little Ice Age in the mid 17th century was associated with more cases of political upheaval and warfare than in any other period (Parker 2008, Zhang et al., 2011), including in Europe (Tol and Wagner 2010), China (Brook 2010), and the Ottoman empire (White 2011b). These studies all show that climate change can exacerbate major political changes given certain social conditions, including a predominance of subsistence producers, conflict over territory, and autocratic systems of government with limited power in peripheral regions. The precise causal pathways that link these changes in climate to changes in civilizations are not well understood due to data limitations. Therefore, it should be noted that these findings from historical antecedents are not directly transferrable to the contemporary globalized world. The literature urges caution in concluding that mean future changes in climate will lead to large-scale political collapse (Butzer 2012).

That is an unequivocal statement of caution. And the measured tone continues:

Most of the research on the connections between climate change and armed conflict focuses on the connections between climate variability and intrastate conflicts in the modern era. For the most, part this research examines rainfall or temperature variability as proxies for the kinds of longer-term chances that might occur due to climate change. Several studies examine the relationship between short-term warming and armed conflict (Burke et al., 2009; Buhaug 2010; Koubi et al., 2012; Theisen et al., 2012; O’Loughlin et al., 2012). Some of these find a weak relationship, some find no relationship, and collectively the research does not conclude that there is a strong positive relationship between warming and armed conflict (Theisen et al., 2013).

Still the chapter is advising that we should be careful about linking climate change to armed conflict.

The large majority of studies focuses on Africa and use satellite-enhanced rainfall data collected since 1980. A global study by Hsiang et al. (2011) considers changes in climate over multiple years, and finds that since 1950 and in countries that are affected by ENSO the risk of war within countries rises during an ENSO period. This study is supported by some studies that find associations between deviations in rainfall and civil war (Miguel et al., 2004; Hendrix and Glaser 2007; Hendrix and Salehyan 2012; Raleigh and Kniveton 2012), but contradicted by others that find no significant association between droughts and floods and civil war (Buhaug 2010; Buhaug and Theisen 2012; Koubi et al. 2012; Theisen et al. 2012; Slettebak 2012). There is high agreement that in the specific circumstances where other risk factors are extremely low (such as where per capita incomes are high, and states are effective and consistent), the impact of changes in climate on armed conflict is negligible (Bernauer et al., 2012; Koubi et al., 2012; Scheffran et al., 2012a; Theisen et al., 2013).

I have quoted nearly all of 12.5. It is immediately followed by Box 12-5. Climate and the Multiple Causes of Conflict in Darfur (page 16):

Climate variability or climate change are popularly reported to be significant causes of the mass killing in the Darfur region that began in 2003 (see Mazo, 2009). Five detailed studies dispute the identification of the Darfur conflict as being primarily caused by climate change (Kevane and Gray, 2008; Brown, 2010; Hagen and Kaiser, 2011; Sunga, 2011; Verhoeven, 2011).

All studies of this conflict agree that it is not possible to isolate any of these specific causes as being most influential (Kevane and Gray, 2008; Hagen and Kaiser, 2011; Sunga, 2011; Verhoeven, 2011). Most authors identify government practices as being far more influential drivers than climate variability, noting also that similar changes in climate did not stimulate conflicts of the same magnitude in neighboring regions, and that in the past people in Darfur were able to cope with climate variability in ways that avoided large scale violence.

I’m still not getting how the SPM got to its concern about “amplifying well-documented drivers of these [armed] conflicts such as poverty and economic shocks”.

But, on the other hand, the IPCC does identify in 12.5.2 much more clearly that climate change mitigation can cause conflict:

Research is beginning to show that climate change mitigation and adaptation actions can increase the risk of armed conflict, as well as compound vulnerabilities in certain populations (Bumpus and Liverman, 2008; Adger and Barnett, 2009; Webersik, 2010; Fairhead et al., 2012; Marino and Ribot, 2012; Steinbruner et al., 2012). This is based on robust evidence that violent political struggles occur over the distribution of benefits from natural resources (Peluso and Watts, 2001). Hence, in circumstances where property rights and conflict management
institutions are ineffective or illegitimate, efforts to mitigate or adapt to climate change that change the distribution of access to resources have the potential to create and aggravate conflict.

The attempts to create a link between climate change and conflict have been made for obvious reasons: it would help to sell the idea of the world descending to hell, and sell the climate change agenda to security agencies. But it is at best a contested claim that climate even has a trivial influence over conflict. The IPCC’s rebuttal that climate change can “amplify” the “well-documented drivers of conflicts such as poverty and economic shocks” is equally bogus. It appears to me to be a weaselly way of trying to sustain a link between climate change and conflict no matter what the evidence says, through truisms. But even if it were true that climate change could “amplify” “poverty” and “economic shock” we are no better informed about the degree of amplification for any given amount of global warming. And then there is the problem of identifying the extent to which conflicts have been “driven” by poverty and economic shocks, amplified or not. Moreover, if climate change is a problem which “amplifies” poverty, then the problem is still fundamentally poverty, not climate.

The IPCC’s rebuttal continues:

The Mail on Sunday says the Summary warns of negative impacts on crop yields, with warming responsible for lower yields of wheat, maize, soya and rice. In fact the Summary says that negative impacts of climate change on crop yields have been more common than positive impacts, with wheat and maize yields negatively affected in many regions and effects on rice and soybean yields smaller in major production regions.

The article says:

The SPM said:

Based on many studies covering a wide range of regions and crops, negative impacts of climate change on crop yields have been more common than positive impacts (high confidence). The smaller number of studies showing positive impacts relate mainly to highlatitude regions, though it is not yet clear whether the balance of impacts has been negative or positive in these regions (high confidence). Climate change has negatively affected wheat and maize yields for many regions and in the global aggregate (medium confidence). Effects on rice and soybean yield have been smaller in major production regions and globally, with a median change of zero across all available data, which are fewer for soy compared to the other crops. Observed impacts relate mainly to production aspects of food security rather than access or other components of food security. See Figure SPM.2C. Since AR4, several periods of rapid food and cereal price increases following climate extremes in key producing regions indicate a sensitivity of current markets to climate extremes among other factors (medium confidence).

The IPCC’s statement of the SPM line does nothing to address the problems identified by our article. The SPM is designed to give the reader the impression that crop yields and crop production have fallen. But neither are true. Over the years since AR4, the claim has come up time and time again. And we’ve been able to check claims against the UN’s own statistics.

The IPCC complains that the Mail on Sunday article has misled. But it’s a funny kind of world in which it is known that “negative impacts of climate change on crop yields have been more common than positive impacts”, and yet yields per acre and in total have increased. The IPCC’s WGII SPM was intended to mislead — to give the impression that yields were falling because of climate change.

SEction 7.2.1 points out that

…Formal detection of impacts requires that observed changes be compared to a clearly specified baseline that characterizes behaviour in the absence of climate change…

And that

Attribution of any observed changes to climate trends are further complicated by the fact that models linking climate and agriculture must, implicitly or explicitly, make assumptions about farmer behaviour. […]In most cases, models implicitly assume that farming practices or technologies did not adjust in response to climate over the period of interest.

So in order to make the claim that “negative impacts of climate change on crop yields have been more common than positive impacts”, the IPCC — or the studies they have reviewed — have had to assume:

* That food producers are stupid.
* That a world without climate change would have been more fertile than the one we live in.

There is a very real possibility that the counterfactual scenario allows researchers to pass their premise off as a conclusion: if you assume that a world with climate change is less productive than a world without it, then, surprise surprise, when you compare a counterfactual statistic to a real world statistic, you get a result that reflects your assumptions. Either way, the world is still more productive than it ever has been, thanks in large part to the substances which are blamed for causing climate change. It would be difficult to imagine the following scenarios in a world without tractors, let alone fertiliser produced from natural gas:

Readers may want to investigate further why a lead author of the chapter in which these claims are made enjoyed so many citations:

Lobell, D. and M. B. Burke, 2008: Why are agricultural impacts of
climate change so uncertain? The importance of temperature relative to
precipitation. Environmental Research Letters, 3, 034007.
Lobell, D. B. and M. B. Burke, 2010: On the use of statistical models
to predict crop yield responses to climate change. Agricultural and
Forest Meteorology, 150, 1443-1452.
Lobell, D. B.and C. B. Field, 2007: Global scale climat-crop yield
relationships and the impacts of recent warming. Environmental
Research Letters, 2.
Lobell, D. B. and C. B. Field, 2012: California perennial crops in a
changing climate. Climatic Change, 109, 317-333
Lobell, D., Ortiz-Monasterio, J. 2007. Impacts of day versus night
temperatures on spring wheat yields. 2007. Agronomy Journal 99,
Lobell, D.B., Sibley, A. and Ortiz-Monasterio, J.I., 2012. Extreme
heat effects on wheat senescence in India. Nature Climate Change,
2(3): 186-189.
Lobell, D. B., U. L. C. Baldos and T. W. Hertel, 2013: Climate
adaptation as mitigation: the case of agricultural investments.
Environmental Research Letters, 8. doi10.1088/1748-9326/8/1/015012.
Lobell, D.B., Hammer, G.L., McLean, G., Messina, C., Roberts, M.J. and
Schlenker, W., 2013. The critical role of extreme heat for maize
production in the United States. Nature Climate Change, 3: 497-501
Lobell, D. B. , J. I. Ortiz-Monasterio, G. P. Asner, P. A. Matson, R.
L. Naylor and W. P. Falcon, 2005: Analysis of wheat yield and climatic
trends in Mexico. Field Crops Research, 94, 250-256.
Lobell, D.B., Schlenker, W. and Costa-Roberts, J., 2011. Climate
Trends and Global Crop Production Since 1980. Science, 333(6042):
Lobell, D.B., Banziger, M., Magorokosho, C. and Vivek, B., 2011.
Nonlinear heat effects on African maize as evidenced by historical
yield trials. Nature Clim. Change, 1(1): 42-45.
Lobell, D.B., M.B. Burke, C. Tebaldi, M.D. Mastrandrea, W.P. Falcon,
and R.L. Naylor, 2008: Prioritizing Climate Change Adaptation Needs
for Food Security in 2030. Science, 319, 607-610.

Ainsworth, E.A. and J.M. McGrath, 2010: Direct effects of rising
atmospheric carbon dioxide and ozone on crop yields. In: Climate
Change and Food Security: adapting agriculture to a warmer world.
[Lobell, D. and M. Burke(eds.)]. Springer, pp. 109-130.
Burke, M.B., D.B. Lobell, and L. Guarino, 2009: Shifts in African Crop
Climates by 2050, and the Implications for Crop Improvement and
Genetic Resources Conservation. Global Environmental Change, 19,
Hertel, T.W., M.B. Burke, and D.B. Lobell, 2010: The poverty
implications of climate-induced crop yield changes by 2030. Global
Environmental Change, 20, 577-585.

The IPCC is in no position to speak about misleading people about the possibility of reduced food yields.

Its rebuttal continues:

The references to the underlying report cited by the Mail on Sunday in contrast to the Summary for Policymakers also give a completely misleading and distorted impression of the report through selective quotation. For instance the reference to “environmental migrants” is a sentence describing just one paper assessed in a chapter that cites over 500 papers – one of five chapters on which the statement in the Summary for Policymakers is based.

The article said:

The SPM said:

Climate change over the 21st century is projected to increase displacement of people (medium evidence, high agreement). Displacement risk increases when populations that lack the resources for planned migration experience higher exposure to extreme weather events, in both rural and urban areas, particularly in developing countries with low income. Expanding opportunities for mobility can reduce vulnerability for such populations. Changes in migration patterns can be responses to both extreme weather events and longer-term climate variability and change, and migration can also be an effective adaptation strategy. There is low confidence in quantitative projections of changes in mobility, due to its complex, multi-causal nature.

It is worth recalling the UN’s previous prediction of 50 Million climate refugees. Wattsupwiththat had a fun and empirical post on the subject back in 2011 at

This is the ENTIRE section on migration from chapter 9. Migration

It is difficult to establish a causal relationship between environmental degradation and migration (see Section 12.4.1). Many authors argue that migration will increase during times of environmental stress (e.g. Afifi, 2011; Gray and Mueller, 2012; Kniveton et al., 2011; Brown and Crawford, 2008), and will lead to an increase in abandonment of settlements (McLeman, 2011). Climate variability has been associated with rural-urban migration (Mertz et al., 2011; Parnell and Walawege, 2011). Another body of literature argues that migration rates are no higher under conditions of environmental or climate stress (Black et al., 2011a and b; van der Geest, 2011; van der Geest and de Jeu, 2008; Tacoli, 2009; McLeman and Hunter, 2010; Gemenne, 2011; Foresight, 2011; Cohen, 2004; Brown, 2008). For Tacoli (2009) the current alarmist predictions of massive flows of so-called “environmental refugees” or “environmental migrants”, are not supported by past experiences of responses to droughts and extreme weather events and predictions for future migration flows are tentative at best. Analogies with past migration experiences are used frequently in such studies (McLeman and Hunter 2010). For example, in Ghana the causality of migration was established to be relatively clear in the case of sudden-onset environmental perturbations such as floods, whereas in case of slow-onset environmental deterioration, there was usually a set of overlapping causes – political and socioeconomic factors – which come into play (van der Geest, 2011). Similarly, a recent survey by Mertz et al. (2010) has argued that climate factors played a limited role in past adaptation options of Sahelian farmers. Given the multiple drivers of migration (Black et al., 2011a and b) and the complex interactions which mediate migratory decision-making by individual or households (Raleigh, 2008; McLeman and Smit, 2006; Kniveton et al., 2011; Black et al., 2011a and b), the projection of the effects of climate change on intra-rural and rural-to-urban migration remains a major challenge.

Chapter 12, section 12.4 (pg 15) states:

There is widespread agreement in the scientific and legal literature that the use of the term climate refugee is scientifically and legally problematic (Taccoli, 2009; Piguet, 2010; Black et al., 2011a; Gemenne, 2011; Jakobeit and Methmann 2012; Bettini, 2013; Piguet, 2013). McAdam calls the concept ‘erroneous as a matter of law and conceptually inaccurate’ (McAdam, 2011, p. 102). The reasons are threefold. First, most migration and climate studies point to the environment as triggers and not causes for migration decisions. Second, some studies focus on the negative geo-political implications of changing the Geneva Convention on refugees to include environmental migrants as well as the lack of global instruments to handle internal displaced peoples or international migrants (Martin, 2009; Cournil, 2011). Third, many small island countries are reluctant themselves to have their international migrants designated as being victims of climate change (McNamara and Gibson, 2009; Farbotko, 2010; Barnett and O’Neill, 2011; Farbotko and Lazrus, 2012).

There were not 500 studies cited by the IPCC WGII in relation to migration as a consequence of climate change. Worse, the chapters explicitly contradict the SPM in more than one chapter. And in fact, rather than depending on just one paper (out of 500), the article quotes from two different chapters’ own conclusions about the range of literature.

A simple keyword search shows many references to publications and statements in the report showing the opposite conclusion, and supporting the statement in the Summary that “Climate change can indirectly increase risks of violent conflicts in the form of civil war and inter-group violence…”

The implication here seems to be that there are lots of other papers, cited throughout the chapters, which support the SPM’s claims. If it’s true, it is the IPCC’s problem. I checked the SPM’s claims against the chapter references cited in the SPM. Moreover, if the evidence considered by the WGII is contradictory, the contradictory nature of the evidence should be reflected in the SPM. It wasn’t. We don’t need to think very deeply about why such an evaluation of the evidence was omitted.

The IPCC have misled people with the WGII SPM. And it has furthermore misled people about the criticism of the SPM.

More results from the research will be published soon.

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