How we have mischaracterized climate risk

by J. Curry, Feb 19, 2022 in ClimateEtc.


“The current thinking and approaches guiding this conceptualization and description have been shown to lack scientific rigour, the consequence being that climate change risk and uncertainties are poorly presented. The climate change field needs to strengthen its risk science basis, to improve the current situation.” – Norwegian risk scientist Terje Aven

For decision-makers, climate change is a problem in risk assessment and management.  Climate change is a risk because it may affect prosperity and security in a negative way, and because its consequences are uncertain.

Global climate change policy has been dominated by a specific strategy of risk management – the Precautionary Principle as a justification for setting specific targets for the elimination of manmade emissions of carbon dioxide.  In the early 1980s, the United Nations Environmental Program (UNEP) became bullish on the idea that fossil fuels would produce dangerous climate change. The prospect of eliminating fossil fuels was congruent with UNEP’s broader interests in environmental quality and world governance. At Villach in 1985 at the beginning of the climate treaty movement, the policy movement to eliminate fossil fuels became detached from any moorings in the science – the rhetoric of precaution argued that we should act anyway to eliminate fossil fuels, just in case. This perspective became codified by the 1992 UN Framework Convention on Climate Change (UNFCCC) Treaty in 1992, the Kyoto Protocol in 1997 and the 2015 Paris Climate Agreement.

Instead of framing the IPCC assessments around risk assessment, the IPCC reports narrowly framed its assessments to support the UNFCCC policies, focusing on dangerous climate change associated with fossil fuel emissions.  The torquing of climate science and the manufacture of a consensus around dangerous human-caused climate change not only oversimplified the scientific and social challenges, but led to the adoption of a “predict then act” strategy to manage and control, supporting decisions about elimination of fossil fuel emissions that were begun in the 1980’s.  The congruence of the IPCC assessments and UNFCCC policies enforces the belief that climate change is a simple or tame problem, with science trumping all practical questions and conflicting values and purposes.

Evaluation of the Homogenization Adjustments Applied to European Temperature Records in the Global Historical Climatology Network Dataset

by P. O’Neill et al., Feb 24, 2022 in MPDI


The widely used Global Historical Climatology Network (GHCN) monthly temperature dataset is available in two formats—non-homogenized and homogenized. Since 2011, this homogenized dataset has been updated almost daily by applying the “Pairwise Homogenization Algorithm” (PHA) to the non-homogenized datasets. Previous studies found that the PHA can perform well at correcting synthetic time series when certain artificial biases are introduced. However, its performance with real world data has been less well studied. Therefore, the homogenized GHCN datasets (Version 3 and 4) were downloaded almost daily over a 10-year period (2011–2021) yielding 3689 different updates to the datasets. The different breakpoints identified were analyzed for a set of stations from 24 European countries for which station history metadata were available. A remarkable inconsistency in the identified breakpoints (and hence adjustments applied) was revealed. Of the adjustments applied for GHCN Version 4, 64% (61% for Version 3) were identified on less than 25% of runs, while only 16% of the adjustments (21% for Version 3) were identified consistently for more than 75% of the runs. The consistency of PHA adjustments improved when the breakpoints corresponded to documented station history metadata events. However, only 19% of the breakpoints (18% for Version 3) were associated with a documented event within 1 year, and 67% (69% for Version 3) were not associated with any documented event. Therefore, while the PHA remains a useful tool in the community’s homogenization toolbox, many of the PHA adjustments applied to the homogenized GHCN dataset may have been spurious. Using station metadata to assess the reliability of PHA adjustments might potentially help to identify some of these spurious adjustments. View Full-Text
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