the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Temperature Trends, Climate Attribution and the Nonstationarity Question
Abstract. The standard trend model for measuring climate warming assumes error terms are mean-reverting and stationary. But the climate econometrics literature has argued that if anthropogenic forcing is a dominant driver of climate, temperature trends must have nonstationary (unit root) error terms, which may be considered a “fingerprint” for anthropogenic forcing. Herein we explain this paradox and apply some tools from time series econometrics to resolve it. We formalize a previously proposed hypothesis for why past results have been unclear, namely that temperatures contain both a nonstationary forcing component and a stationary “weather noise” component that may bias unit root tests towards over-rejection. Our analysis yields a diagnostic method for assessing whether this problem matters in practice. We apply unit root tests to observed and modeled temperature series at surface and tropospheric layers. We find observed temperatures are stationary around a trend after allowing for a single structural break in trend, with no evidence of testing bias due to weather noise. Unit root tests applied to model-generated temperatures also indicate trend stationarity however we find evidence of testing bias due to weather noise. This implies that time series models for climate attribution need to deal carefully with the requirements for establishing cointegration. We discuss the implications for understanding the relationship between greenhouse gas forcing and atmospheric temperatures over time.
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RC1: 'Comment on esd-2023-11', Anonymous Referee #1, 30 Jun 2023
The comment was uploaded in the form of a supplement: https://esd.copernicus.org/preprints/esd-2023-11/esd-2023-11-RC1-supplement.pdf
- AC1: 'Reply on RC1', Ross McKitrick, 15 Aug 2023
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RC2: 'Comment on esd-2023-11', Anonymous Referee #2, 03 Jul 2023
The paper titled "Temperature Trends, Climate Attribution and the Nonstationarity Question" works about an interesting item considering the modeling of temperature natural data to test global changes and possible responsability. I am not a mathematician or statistician and in the base of my knowledge I can only make some comments about the absence of exploratory analysis concerning the treated data.
The authors only analyse the data in their time sequence to verify the presence of a trend (or verify stationariety). However a lot of information could be derived from a classical explorative analysis considering for example the shape of the frequency histogram (unimodal, bimodal, skewness???). Which type of probability model the data tends to follow? Normal, lognormal or what? Which type of link is possible to derive between this model and the developing of the data in the sequence? This information is fundamental to understand something about the dynamics goverining the investigate system and to intercept critical point (tipping points?) in the sequence See for example the papers in Front Physiol, 2013, doi: 10.3389/fphys.2013.00001, A fractal approach to dynamic inference and distribution analysis by van Rooij et al. or Nature 2009 by Scheffer et al., Early-warning signals for critical transitions, or Nature Sustainability, 2023, Earlier collapse of Anthropocene ecosystems driven by multiple faster and noisier drivers by Willcock et al.
In my opinion the matter is not exploted in all its aspects, as reqeuired by the argument, and the role of autocorrelation not sufficiently investigated in the light of recent references (some of them cited before, but also papers by Vasilis Dakos would be considered).
Citation: https://doi.org/10.5194/esd-2023-11-RC2 - AC2: 'Reply on RC2', Ross McKitrick, 15 Aug 2023
Status: closed
-
RC1: 'Comment on esd-2023-11', Anonymous Referee #1, 30 Jun 2023
The comment was uploaded in the form of a supplement: https://esd.copernicus.org/preprints/esd-2023-11/esd-2023-11-RC1-supplement.pdf
- AC1: 'Reply on RC1', Ross McKitrick, 15 Aug 2023
-
RC2: 'Comment on esd-2023-11', Anonymous Referee #2, 03 Jul 2023
The paper titled "Temperature Trends, Climate Attribution and the Nonstationarity Question" works about an interesting item considering the modeling of temperature natural data to test global changes and possible responsability. I am not a mathematician or statistician and in the base of my knowledge I can only make some comments about the absence of exploratory analysis concerning the treated data.
The authors only analyse the data in their time sequence to verify the presence of a trend (or verify stationariety). However a lot of information could be derived from a classical explorative analysis considering for example the shape of the frequency histogram (unimodal, bimodal, skewness???). Which type of probability model the data tends to follow? Normal, lognormal or what? Which type of link is possible to derive between this model and the developing of the data in the sequence? This information is fundamental to understand something about the dynamics goverining the investigate system and to intercept critical point (tipping points?) in the sequence See for example the papers in Front Physiol, 2013, doi: 10.3389/fphys.2013.00001, A fractal approach to dynamic inference and distribution analysis by van Rooij et al. or Nature 2009 by Scheffer et al., Early-warning signals for critical transitions, or Nature Sustainability, 2023, Earlier collapse of Anthropocene ecosystems driven by multiple faster and noisier drivers by Willcock et al.
In my opinion the matter is not exploted in all its aspects, as reqeuired by the argument, and the role of autocorrelation not sufficiently investigated in the light of recent references (some of them cited before, but also papers by Vasilis Dakos would be considered).
Citation: https://doi.org/10.5194/esd-2023-11-RC2 - AC2: 'Reply on RC2', Ross McKitrick, 15 Aug 2023
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