Talk:Economic analysis of climate change

Kaya identity

I see some issues with the Kaya identity. I tried accessing the original book, but was unable to, so I hope someone with access to the book can contribute.

Editorial

• why is the identity split out on two lines? (I tried to fix it and failed)
• While I appreciate that it is an identity, which explains why the identity symbol is used, I have seen the identity included in several sources with an equals symbol. Don't we need at least one reference using the identity symbol to avoid OR?
• The article Kaya identity expresses the identity using LaTeX and a different set of symbols. Unless someone articulates a good reason for a different presentation, the presentation should be the same.

Content

• This identity has four factors, but the identity in the IPCC has three. Which is the preferred version?
• The IPCC identity refers to GHG, while this page uses CO₂. I understand that CO₂ is sometimes used as a placeholder for GHG, but that doesn't mean we can be so cavalier. My guess is that the original talks about GHG or emissions, not CO₂ --SPhilbrick(Talk) 16:38, 23 April 2012 (UTC)

I have had no difficulty accessing the cited sources [1][2]. The publications are also available commercially [3][4]

These issues are explained in the cited sources. The use of the Kaya identity in this article exactly follows its use in the cited source (Stern, 2006). I checked Kaya identity. Indeed, it presents the identity using LaTeX, but its content is the same as here, apart from the use of an equals sign instead of an equivalent sign. The cited source uses an equivalent sign. I don't see this as a major issue, either sign appears acceptable.

You are incorrect about the cited source referring to GHGs (presumably individually or aggregated to CO2-eq) rather than to CO2 only. There is nothing "cavalier" about using the Kaya identity to express changes in CO2 rather than CO2-eq. The two uses (three components or four) depends on what analysis is being presented. Decomposing into four components allows carbon intensity per unit of energy use to be distinguished from energy intensity of GDP. This is entirely consistent with the use of the Kaya identity in the IPCC report [5]. Enescot (talk) 06:06, 11 September 2012 (UTC)

I quote from IPCC

The reason can be illustrated by using the Kaya identity, which decomposes the emissions as follows:

GHG = Population x GDP per person x Emissions per GDP

or: (graphic not reproduced)

where GHG stands for greenhouse gas emissions, GDP stands for economic output, and POP stands for population size.

Why do you claim it doesn't use GHG?--SPhilbrick(Talk) 16:09, 3 October 2013 (UTC)

I did not claim that the IPCC report only refers to the 4-component, CO2-only Kaya identity. The IPCC report refers both to the identity that is cited in the article and the identity which you have cited – see the link that I cited previously, or page 66 (PDF numbering) of this report. Enescot (talk) 08:38, 4 October 2013 (UTC)

Cost-benefit analysis

The section claims that the monetary metric is willingness to pay, as opposed to net present monetary values. The two are not, in general, close to each other. The notion of using "willingness to pay" is an interesting concept, but it is not the canonical use (if Cost–benefit analysis is accurate), so some justification, and a reference is needed. If one is found, then the claim that it is "standard" should be changed. More likely, it is simply a mistake to claim that the CBA should be using "willingness to pay".--SPhilbrick(Talk) 15:08, 5 May 2012 (UTC)

Seeing no objection, I will change the metric to the more usual net present value.--SPhilbrick(Talk) 00:40, 18 June 2012 (UTC)

It is not a mistake - I've added the appropriate references to a reliable source, and revised the section.

I'm not sure what your argument is. In CBA where WTP is used, usually everything is still aggregated into a monetary value, with risk accounted for using certainty equivalents, which is then discounted to produce present values.

You state that "The section claims that the monetary metric is willingness to pay, as opposed to net present monetary values. The two are not, in general, close to each other." What are you comparing WTP-derived valuations with? Enescot (talk) 05:57, 11 September 2012 (UTC)

Citation style

As detailed in the Citation style tag, there should be a consistent style. There doesn't seem to be a predominant style, so I'm starting the discussion on what style to use. –Temporal User (Talk) 08:11, 3 May 2013 (UTC)

Over the last year, I have been gradually revising the citations in this article. I think the harvnb template works well, e.g., see effects of global warming. I find revising citations very tedious, so I've broken up the workload. Enescot (talk) 07:27, 19 May 2013 (UTC)

Impacts section

I'm thinking of revising economics of global warming#Impacts. In my opinion, the main problem with this section is that it does not discuss non-monetized impacts. A risk-based approach would account for the full range of climate change impacts. This is relevant to the article, since a broad understanding of climate change impacts is necessary when making policy decisions. There's already an article on the effects of global warming, so it's probably only necessary to present a brief summary of the most important risks and benefits of climate change.

The section's coverage of monetized impacts should be revised in view of more recent studies.

References:

• Jacoby, H.D. Informing Climate Policy Given Incommensurable Benefits Estimates
• Jones, R.N. (2004) Managing Climate Change Risks
• Stern, N. (2008), "The Economics of Climate Change", American Economic Review, vol. 98, no. 2, p. 23. Paper website at the American Economic Association.
• Yohe, G.W. (May 2010), Pages 19-22 in: Addressing Climate Change through a Risk Management Lens. In: Assessing the Benefits of Avoided Climate Change: Cost-Benefit Analysis and Beyond. (Gulledge, J., L. J. Richardson, L. Adkins, and S. Seidel (eds.)), Proceedings of Workshop on Assessing the Benefits of Avoided Climate Change, March 16–17, 2009, Arlington, Virginia, USA: Pew Center on Global Climate Change. Link to workshop.

Enescot (talk) 08:23, 5 August 2014 (UTC)

@Enescot: did you do that? EllenCT (talk) 06:35, 29 September 2014 (UTC)

Hi. I'm not sure I understand your question. What am I supposed to have done? Thanks. Enescot (talk) 07:23, 29 September 2014 (UTC)

@Enescot: revising the Impacts section, as you said you were thinking of at the beginning of this section? EllenCT (talk) 05:30, 1 November 2014 (UTC)

I'm currently working on a draft revision of economics of global warming#Impacts. Enescot (talk) 07:30, 1 November 2014 (UTC)

New Climate Economy Report

I noticed an IP user tried to add [6] and [7] but was reverted for "probable block evasion". I would like to know what editors think of those sources. EllenCT (talk) 06:33, 29 September 2014 (UTC)

The first is essentially self-published, and I doubt they are considered "experts" in all the relevant fields, which is what would be required for it to be a WP:RS. The second source from the NYT notes the first one, so the first may be significant, but not reliable. Unless The Global Commission on the Economy and Climate can be considered a reliable source in itself, which seems unlikely, its publication can only be used for proof of its (the publication's) existence. not for any proof of accuracy. I do believe that the NYT source alone could be used to source the statement that "A report has asserted that the costs of mitigation may be less than the costs caused by the effects." in the body; it's not definitive enough to support the statement in the lead. The IPCC reports have been considered reliable, even though there are few, if any, economic experts involved in writing the reports. — Arthur Rubin (talk) 21:17, 30 September 2014 (UTC)

Is there any evidence that the costs of mitigation are greater than the costs caused by the effects? There are plenty of high-quality sources on the question. E.g. [8] described at [9]. EllenCT (talk) 20:51, 1 October 2014 (UTC)

I'm afraid that's an error on my part; that wasn't what the added unreliable source said. The statement actually added was unsourced and tangential, to a lead which is already too long, per WP:LEAD. If a reliable source could be found, it could be added to the body. — Arthur Rubin (talk) 05:40, 3 October 2014 (UTC)

The best-cited MEDRS-class sources on the subject, [10], [11], [12], and [13], are all in agreement that the strictly financial benefits of transition to sustainable energy outweigh the costs, without regard to years of productive life lost, which is currently somewhere around 11 million per year primarily due to drought- and flood-related communicable tropical disease transmission rates. EllenCT (talk) 22:02, 3 October 2014 (UTC)