The Evolution of Communicating the Uncertainty of Climate Change to Policymakers: A Study of IPCC Synthesis Reports

Abstract

The Intergovernmental Panel on Climate Change (IPCC) reports on climate change have served to alert both the public and policymakers about the scope of the predicted changes and the effects they would have on natural and economic systems. The first IPCC report was published in 1990, since which time a further four have been produced. The aim of this study was to conduct a content analysis of the IPCC Summaries for Policymakers in order to determine the degree of certainty associated with the statements they contain. For each of the reports we analyzed all statements containing expressions indicating the corresponding level of confidence. The aggregated results show a shift over time towards higher certainty levels, implying a “Call to action” (from 32.8% of statements in IPCC2 to 70.2% in IPCC5). With regard to the international agreements drawn up to tackle climate change, the growing level of confidence expressed in the IPCC Summaries for Policymakers reports might have been a relevant factor in the history of decision making.

Meta-Analysis of Mitochondrial DNA Control Region Diversity to Shed Light on Phylogenetic Relationship and Demographic History of African Sheep (Ovis aries) Breeds

“…Thus, they are neglected, breeding without directional selection and hence encouraging high levels of inbreeding, which could lead to a loss of genetic diversity. Although their performance is low, these breeds could be crucial in the future, especially when the world is faced with climate change challenges [ 3 ].…”

“…The African sheep population is estimated to be above 400 million heads. To enhance production, diversity and adaptation under the current climate change challenges [ 3 ] in recent decades, researchers have extensively studied the origin, history, phylogenetic relationships and diversity of domestic animals within species and among populations such as in sheep [ 4 , 5 , 6 , 7 ], goats [ 8 , 9 , 10 ], and cattle [ 11 ]. Information on the diversity and history of the species and/or breed provides the foundation on which conservation and breeding programs are made [ 12 ].…”

Communicating uncertainty using words and numbers

“…International organizations operating within consequential decision domains from food safety [110,111] to defense and security [112] (see also [87]) to climate science [113] (also see also [114]) have chosen to communicate uncertainty using standardized lexicons. These require senders to use a small, preselected, rank-ordered set of probability terms that are each assigned a numeric probability range.…”

Confidence levels and likelihood terms in IPCC reports: a survey of experts from different scientific disciplines

“…Indeed, a suggestion has been to only use confidence levels when evidence is robust and agreement is high (Mastrandrea and Mach 2011). Consequently, the use of high confidence levels has increased since the IPCC's first assessment report in 1990 (Janzwood 2020;Molina and Abadal 2021).…”