Around the planet, difficult cultural norms exist for writing. Avoidance of direct discussion and attribution seem to be the norm for many nations. Over recent decades, the U.S. business world has adopted an emphasis on using more direct language with the active voice. When it comes to passive voices, a standard recommendation:

Use the passive voice sparingly. It may make the writing unclear by keeping the identity of the actor secret.

As to when you should use passive voice,

Usually use passive voice when you do not know the actor, you want to hide the identity of the actor, or the actor is not important to the meaning of the sentence.

With this in mind, I read the opening to Richard Tol’s letter to the Journal of Economic Perspectives providing a set of corrections to an earlier article that asserts, in essence, that economic modeling provides uncertainty as to whether climate change will have a net negative or positive impact in coming decades. The following is the abstract as well as opening paragraph for this five-page letter.

Correction and Update: The Economic Effects of Climate Change Article Citation Tol, Richard S J. 2014. “Correction and Update: The Economic Effects of Climate Change.” Journal of Economic Perspectives, 28(2): 221-26.DOI: 10.1257/jep.28.2.221 Abstract Gremlins intervened in the preparation of my paper “The Economic Effects of Climate Change” published in the Spring 2009 issue of this journal. In Table 1 of that paper, titled “Estimates of the Welfare Impact of Climate Change,” minus signs were dropped from the two impact estimates, one by Plambeck and Hope (1996) and one by Hope (2006). In Figure 1 of that paper, titled “Fourteen Estimates of the Global Economic Impact of Climate Change,” and in the various analyses that support that figure, the minus sign was dropped from only one of the two estimates. The corresponding Table 1 and Figure 1 presented here correct these errors. Figure 2 titled,”Twenty-One Estimates of the Global Economic Impact of Climate Change” adds two overlooked estimates from before the time of the original 2009 paper and five more recent ones.

“minus signs were dropped … minus sign was dropped”.

Who dropped those minus signs and “overlooked estimates”. Evidently, those unnamed and nefarious “gremlins” who “intervened” to undermine the quality of Professor Tol’s research and publications.

Using the passive voice makes one wonder whether editors, research assistants, technical glitches, or Professor Tol, himself, were the “gremlins” who “intervened”.

As to the substance of the correction, Tol first writes;

The parameters of the impact curves are not statistically significantly different from one another

In essence, this phrase says ‘okay, item corrected, but it has no substantive import’.

That “not statistically different”, as Professor Tol explains, is driven by the relative paucity of data sets which drive wide error bars and thus require extreme shifts for “statistically significant” change.

Let us remember that Richard Tol is perhaps the leading voice assessing that climate change’s economic impact could well (or even is likely to) be a net positive and that climate mitigation with an impact, therefore, could actually hurt the economy. With that in mind, this comes from later in the letter.

First, unlike the original curve (Tol 2009, Figure 1) in which there were net benefits of climate change associated with warming below about 2°C, in the corrected and updated curve (Figure 2), impacts are always negative

When it comes to the economic analysis of climate change impacts in the coming decades, Professor Tol writes, “impacts are always negative”.

Note, on the substance of this correction, please see And then there’s Physics. “What’s maybe more interesting, is that Tol updates the analysis by including 7 newer studies. … With the new studies included, there is essentially no positive benefit for future warming. This seems like quite a significant change …”



Professor Tol’s use of passive voice to introduce this article and to attribute (avoid attribution of) responsibility for the errors arrives within the context of Tol’s rather vitriolic engagement with those who have challenged his work. For a perspective on this, see Frank Ackerman’s The Tol Controversy: Beyond the bounds of acceptable debate. That discussion came to my attention two months ago amid a tussle between

Tol and Bob Ward, with some rather over the top tweets along the lines of

.@flimsin wins the award: A picture of Bob as the evil triplet of John & Ed [data point shifted from 4.9 to 4.8] pic.twitter.com/RniLoG9Jpf — Richard Tol (@RichardTol) March 5, 2014

academic duty implies that every accusation is followed by an audit. Sometimes an error is found, although rarely by Mr Ward.

Following this, Bob Ward added to his discussion with a two-part Errors in estimates of the aggregate economic impacts of climate change. Ward made this comment,

when I examined Tol’s paper in detail, I discovered that he had made a number of errors, wrongly plotting studies which had found net negative impacts as if they were positive benefits.

With that in mind, read the letter’s acknowledgment:

I am grateful to Bob Ward for finding a small error, to Mike Mastandrea for finding a bigger one, to Doug Arent for checking things again and again, to David Autor and Tim Taylor for their understanding, and to Ann Norman for superb editorial support. All remaining errors are, of course, mine and mine only.

Of course, unless additional “gremlins intervene …”

Note 1:

For those interested in delving into this realm more, here are two suggested (of innumerable potential) pieces:

paper came to my attention after I saw a notice from Adam Marcus that it was recently revised because of data errors. But after looking at the paper more carefully, I see a bunch of other problems that, to me, make the whole analysis close to useless as it stands. … Tol attributed the errors to “gremlins,” but I’m guessing that they happened when he was typing data into a file. … The short story that the problems with Tol’s analysis go beyond a simple miscoding of some data points. … my impression is that Tol’s 2009 paper, even with all errors aside, is far below the quality of usual empirical papers that get published in top economics journals.

Note 2: The issue of economic analysis of climate change risks and costs along with the benefits and costs for mitigation/adaptation investments is a difficult arena, with great complexity. Perhaps the most distressing element, however, is the systematic overestimation of costs and under assessments of benefit streams

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