Chapter 18: Carbon Cycle Science in the Support of Decision-making
Overview/Main Issues
This chapter examines how scientific knowledge about carbon cycle dynamics is currently used, and can be more effectively used, to inform different types of decision making needs. The chapter is focused mainly on decision-making in agriculture, forestry and other land use (AFOLU); it does not consider decisions made in many other sectors and activities that affect the carbon cycle. The chapter would be strengthened by more coverage of ways that AFOLU components of the carbon cycle are integrated into broader considerations, such as models and analysis of national GHG mitigation policy that balance AFOLU measures with other types of mitigation measures.
Statement of Task Questions
- Are the goals, objectives and intended audience of the product clearly described in the document? Does the report meet its stated goals?
The chapter would best open with a clear statement about the decision domain it addresses (drawing from P740, lines 39-41), followed by a statement about the goals of this chapter (drawing on P741, lines 6-9). The reader should be informed that the discussion mainly concerns AFOLU. And it should be made clearer at the outset what attention is given to issues such as climate change impacts, vulnerability and adaptation, in addition to the focus on carbon fluxes, stocks, and emissions mitigation.
It would be helpful in the examples used to provide some sort of explicit framework that clarifies questions such as: What information, how is it presented, and to whom? Who are the decision makers? What aspects of the carbon cycle do these decisions affect (sinks, sources, stocks, flows)? What information do decision-makers get, need, act upon?
- Does the report accurately reflect the scientific literature? Are there any critical areas missing from the report?
Noted below are some particular areas where additional discussion would be helpful:
Full Carbon Cycle. The text does not devote sufficient attention to ways that AFOLU (the main focus of the chapter) is integrated into carbon-cycle decisions, particularly those concerning mitigation of CO2 emissions. For example:
- Section 18.2.1 (Science Support for Decision Making) reads as if only the natural sciences are relevant to the carbon cycle–not economics and other social sciences.
- Sections 18.3.1, 18.3.2 and 18.3.3 focus on data, models and accounting for the land use components of decision—even for decisions about land use that involve the energy sector and its emissions. The long list of tools (P748-749) ignores the integration of AFOLU into the overall carbon cycle, even for the decisions mentioned (e.g., P748, line 23)
- It is not sufficient to say that decision tools with cycle-wide coverage are dealt with in other reports (see P747, lines 12-20). The text should give the reader some insight into the ways that integrated assessment methods and models are used to explore the interaction of land use with other components of the carbon cycle. These issues could be addressed by adding text/references that point to the mention of integrated assessment models in Box 18.2.
Biofuels. The discussion of biofuels (P745)—a key U.S. national decision area—could do a much better job of explaining the interactions and feedbacks in biofuels development, and the multiple disciplines that are relevant to decision support. For example, this could include:
- more explicit mention of biofuels production effects on agriculture, grasslands and forestry, and influence on food prices;
- technology issues (e.g., cost of cellulosic ethanol; non-AFOLU fuels such as algae; use of direct air capture to produce synthetic hydrocarbon fuels)
- consideration of the fossil fuels used in biofuel conversion, and their emissions
- international trade in biofuel products (e.g., forest products, Brazilian ethanol) which are integrated into national models of energy and emissions (see comment above).
Also, given that this section (18.2.3) is on “Examples . . . for Decision Making”, the discussion could be cast in the context of decisions about U.S. ethanol policy.
Ozone Damage. Mention should be made of feedbacks of carbon emissions (i.e., the resulting air pollution and climate effects) on ozone damage to agriculture and natural vegetation. Detailed discussion is not needed, but the effect deserves to be mentioned.
Communication. Section 18.2.2 (Science of Communicating Science) is incomplete in that it fails to call attention to the challenge posed by intentional dissemination of misinformation about climate change and efforts to undermine the public’s trust in scientific institutions. Examples of appropriate references for such a discussion might include, for instance, Anderegg et al. (2010); Farrell (2016); Supran and Oreskes (2017). The authors might also want to consider that the challenge is not only understanding how the public interprets available science, but also understanding how carbon-cycle (and climate) science can be more accessible and relevant to individual and collective decision making. If it is not possible to deal with these important issues in this report, it might be worth considering dropping this “communication” section from the chapter altogether.
Culture. The discussion of knowledge co-production could be better linked to the discussions in Chapter 7 (Tribal Lands) about different forms of decision making, and different information and communication needs, in different communities. The chapter should also acknowledge the importance of factors such as cultural and economic diversity in decision making. An example is the South Florida Regional Climate Change Compact (P743, L26-38), which works because the counties “are tightly linked socially and economically”. This aspect of the chapter could be enhanced by links to the earlier chapters on Tribal Lands and on Social Science.
- Are the findings documented in a consistent, transparent and credible way?
Because this chapter does not present new learning from research or empirical results, it does not lend itself well to findings akin to those of other chapters. Presumably however, the authors were required
to come up with at least 4 or 5 key findings, and as a result, some of these findings seem forced or weak. Some specific notes below.
Key Finding 1 (Co-produced Knowledge). This finding should be edited to provide a more coherent message. (e.g., More relevant than what?) It is not the case that all information relevant to decisions must be co-produced by the scientific community and stakeholders. The language in P743, lines 20-21 is more helpful: “continued communication among different shareholder communities and the scientific community . . .” Perhaps also state that collaboration can help ensure the science is relevant to decision-maker needs. The confidence statement seems odd, given that the “finding” is just a sensible proposition, not a finding based on empirical evidence of decisions made with and without co-production of the science inputs.
Key Finding 2 (Integrating Human Knowledge). The obvious point that human drivers are the main reason for study of the carbon cycle does not merit elevation to a key finding.
Key Finding 3 (Attribution, Accounting & Projection). The point is also obvious and does not seem to merit elevation to a key finding. Without information on carbon-cycle fluxes and their origin, there is no carbon-cycle science, much less science to support decision making.
Key Finding 4 (Strong Links among Research). Reasonable, but it is not clear what “medium likelihood” means in this context.
Key Finding 5 (Improved Understanding). This finding should take account of the problem of intentional programs of misinformation (see above). Also, the evidence base refers to improving communications, whereas the finding involves understanding the public: these two different parts of the problem are not clearly explained.
- Are the report’s Key messages and graphics clear and appropriate? Specifically, to they reflect supporting evidence, include an assessment of likelihood, and communicate effectively?
Messages and graphics are generally clear. The terminology in Figure 18.2 (Mode 1 and Postnormal) needs explanation, either in the text at P741 line 31 or in the caption.
- Are the Research needs identified in the report appropriate?
Yes, but many “needs” are listed with no sense of priority. Some rough ranking in importance would be useful. Additional effort is needed to provide guidance on research related to decision making. The main references to research needs are in short phrases in Boxes 18.2 and 18.3. The authors’ view of research tasks should be elaborated in the text, with discussion of how the work would contribute to particular decision-making challenges.
- What other significant improvements, if any, might be made in the document?
The chapter would be improved by illustrating the use of carbon-cycle data and analysis for support of one or more specific decisions at the national level.
It would be useful for the text to give more attention to issues that are particularly important in informing decision making; for instance, discussion of the “fat” upper tail of climate response and threatened damage, and the implied urgency for action.
Line-Specific Comments
P739, Line 36
This should state “different from, although complementary to.”
P740, Line 13-15
To say “optimal is most effective” is a tautology. Rewording is suggested.
P740, Line 5-12
The point being made in this paragraph is not clear. How is it that definitions enable eliminating gaps between science and decision making? What are the gaps? And why are the Management and Technology Drivers in Figure 18.1 mostly about agriculture, when something more general is called for? Why is renewable energy or nuclear energy not mentioned (and energy transition)?
P741, Line 12
Explain what, in particular, has changed over the last decade. Is it the items on P752, lines 32-40?
P741, Line 13
Explain what is meant by “traditional science supply paradigm.”
P741, Line 23
Does this mean communication with economics and the other social sciences, as well as among natural sciences? If so, specify.
P742, Line 22
Add a phrase to explain “attitudinal inoculation.”
P743, Line 14-15
There is repetition of a citation.
P743, Line 4-18
For this section, need to add an example of a decision where NACP was involved or relevant.
P748, Line 12-13
It is not true that a robust process to develop projections is “relatively new”. The work goes back a quarter century or more in the climate arena alone. If the authors believe this statement, the text should define “robust” and “new”.
P755, Line 2-3
Fluxes not useful for decision making? Why not? This statement is inconsistent with the finding.
P755, Line 20-21
Statement about emissions estimates is not true.
P755, Line 12
Statement implies that carbon accounting is not done for forestry, agriculture, and fossil fuels, which is not true.
P757, Line 2-3
A good deal is known about this. What is needed is an understanding of how portions of the public are misled and what can be done to persuade those individuals and groups to trust scientists and scientific institutions.
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