Bruce Calvert

Estimating the uncertainty of sea-ice area and sea-ice extent from satellite retrievals Abstract. The net Arctic sea-ice area (SIA) can be estimated from the sea-ice concentration (SIC) by passive microwave measurements from satellites. To be a truly useful metric, for example of the sen...

After reading the paper thoroughly, I particularly liked the section on uncertainty in sea ice estimates. I was not aware of the recent paper that estimated uncertainty using spatiotemporal correlations lengths of 300km and 5 days, although I did read some predecessor papers. doi.org/10.5194/tc-1...

SSP3: AIM implementation of Shared Socioeconomic Pathways This study quantifies the Shared Socioeconomic Pathways (SSPs) using AIM/CGE (Asia-Pacific Integrated Assessment/Computable General Equilibrium). SSP3…

... population projections are countered by assumptions of very limited aerosol policies. See figure 1 of the SSP3 paper: www.sciencedirect.com/science/arti...

Thanks for clarifying @climateofgavin.bsky.social & @michaelemann.bsky.social. For this particular criticism by Piekle, I suggest that a more direct response could be to point out that AIM projects the same 7.0 W/m^2 by 2100 for no policy scenarios under both SSP2 & SSP3. The above average...

Isn't the issue under disagreement the appropriateness of SSP3-7.0 rather than about climate science? Such as the appropriateness of the assumptions used by the AIM integrated assessment model to produce SSP3-7.0? Piekle mention population projections specifically.

... sailors of potential sea ice rather than be representative of sea ice conditions, but was treated as representative in HadISST2. An upcoming community science paper on 1.5°C of warming, which might be submitted in the next few weeks, will discuss this issue briefly.

A year ago, I was looking into the issue because I was curious about the reliability of HadISST2, which is used in most instrumental temperature datasets and ERA5. The presatellite Antarctic estimates are based on two atlases, one German and one Soviet. The German atlas was intended to warn...

Among other things, I liked the attempt to use multiple historic sea ice datasets and to acknowledge differences between HadISST2 and recent reconstructions. The large decrease in Antarctic sea ice in HadISST2 is largely due to misinterpreting a Nazi-era sea ice Atlas.

Economic Impacts of Climate Change in the United States: Integrating and Harmonizing Evidence from Recent Studies This paper synthesizes evidence on climate change impacts specific to U.S. populations. We develop an apples-to-apples comparison of econometric studies that empirically estimate the relationship betw...

It is disappointing to learn that recent work to update the U.S. social cost of carbon, by updating the 2022 GIVE model, has been removed from the EPA's website. @climateofgavin.bsky.social or @michaelemann.bsky.social should make the link available @realclimate.bsky.social. arxiv.org/abs/2509.00212

Read "Effects of Human-Caused Greenhouse Gas Emissions on U.S. Climate, Health, and Welfare" at NAP.edu Read chapter Front Matter: The scientific community has been studying the question of how human-caused emissions of greenhouse gases are affecting the cli...

On a related issue, it is disappointing that this work on the costs of #climatechange was not mentioned by the NAS did not mention this work in their recent report. It would have been very relevant. nap.nationalacademies.org/read/29239/c...

Economic Impacts of Climate Change in the United States: Integrating and Harmonizing Evidence from Recent Studies This paper synthesizes evidence on climate change impacts specific to U.S. populations. We develop an apples-to-apples comparison of econometric studies that empirically estimate the relationship betw...

It is disappointing to learn that recent work to update the U.S. social cost of carbon, by updating the 2022 GIVE model, has been removed from the EPA's website. @climateofgavin.bsky.social or @michaelemann.bsky.social should make the link available @realclimate.bsky.social. arxiv.org/abs/2509.00212

... If one were to include sensitivity tests over all possible uniform priors for monotonic transformations of ECS (e.g., ln(ECS), sqrt(ECS), ECS^3), then the resulting uncertainty range would be excessively large. Using a single broad well-justified prior could help avoid this arbitrariness.

Hi Cristi, I enjoyed reading your 2020 paper. It is true that the choice of prior wasn't a big issue in Sherwood et al. and the baseline specification did not use a problematic prior. Although the expansion of the ECS range based on prior sensitivity tests was a bit arbitrary...

Addressing misconceptions about Climate Sensitivity research: a Response to recent Criticisms - Climate Etc. by Nic Lewis The determination of equilibrium climate sensitivity (ECS)—the long-term warming response to doubled atmospheric CO2 concentrations—remains one of the most crucial yet challenging problem...

You are correct that the lower values are mostly due to other changes, including fixing coding errors, radiative forcing disagreements, the pattern effect, and the inclusion of paleoclimate data. The ECS prior is only a minor issue. Here is a link to Lewis' arguments:
judithcurry.com/2025/08/13/a...

Thanks for sharing. I'm not sure if the argument of zero probability assignments of Jeffrey's prior is of practical relevance in the case of ECS estimates. I like the cauchy prior suggestion by Annan and Hargreaves as it avoids the most problematic issues with the uniform ECS prior.

I'm suggesting to not use the problematic uniform prior over ECS. This prior also has the concerning property that the ECS estimates become unboundedly large as the upper bound of the prior increases. Uniform priors over ln(ECS) or process evidence, or Jeffrey's prior, would be less problematic.

I find the graph amusing as well. Although, to be fair to Lewis, since 2014 there have been changes to the underlying temperature datasets, such as infilling polar regions and high rates of warming since 2014, that would have resulted in increased ECS estimates even without methodological changes.

I think it makes complete sense to evaluate each technical issue separately and on its merits. In the case of the criticisms of the use of a uniform prior over ECS, that is an issue where I think Lewis' arguments have merit.

Maybe there are other issues with Lewis' methodology, but I think his criticisms of uniform ECS priors have merit. I would argue that Lewis' method isn't fancy enough and throws out information, resulting in less ability to exclude low ECS values. Time series analysis would be better.

@kenrice.bsky.social you are correct that there are more issues than just the choice of prior that cause Lewis' results. Are there better methods? Absolutely! The simple energy balance framework throws out a lot of information and it would be better to use a time series approach.

prior over ln(ECS). The outlier/problematic approach here is the use of a uniform prior over ECS. @kenrice.bsky.social and @andrewdessler.com perhaps you are being overreliant on intuition in this case? Lewis' suggestion to avoid overreliance on the arbitrary ECS definition seems reasonable.

... distributions are often approximately multivariate normal, so would have uniform Jeffrey's priors. But the likelihood distribution for ECS is far from multivariate normal. Reasonable alternatives to using a Jeffrey's prior would be to use a uniform prior over process evidence or a uniform ...

... prior that does not depend on this arbitrariness in the ECS definition. An approach that would be invariant to monotonic transformations of ECS would be Jeffrey's prior, which is what Lewis advocates.
The intuition of uniform priors as objective is usually reasonable since likelihood ...

Our definition of ECS is somewhat arbitrary. An alien civilization on a different planet might use a different metric for GHGs. Even if they had the same planet, there is no reason to belive that they would use ECS compared to alternatives such as ln(ECS). Therefore, it would be better to use a ...

Estimating Macrofiscal Effects of Climate Shocks from Billions of Geospatial Weather Observations (July 2025) - The literature studying the macroeconomics of weather has focused on temperature and precipitation annual averages, while microstudies have focused more on extreme weather measures. We c...

Interesting paper on the economic impacts of #climatechange, including the impact of #extremeweather. It's impressive to see such a rigorous methodology and robustness checks. www.aeaweb.org/articles?id=...

Estimating Macrofiscal Effects of Climate Shocks from Billions of Geospatial Weather Observations (July 2025) - The literature studying the macroeconomics of weather has focused on temperature and precipitation annual averages, while microstudies have focused more on extreme weather measures. We c...

Interesting paper on the economic impacts of #climatechange, including the impact of #extremeweather. It's impressive to see such a rigorous methodology and robustness checks. www.aeaweb.org/articles?id=...

Why base policy around temperature targets in the first place? Wouldn't policy based round Pigouvian taxes and estimates of the social cost of carbon be more appropriate to balance tradeoffs?

Congrats. It's crazy to see so few lead authors from the U.S.

Chinese global temperature datasets are relatively new. There is ChinaMST developed by Sun Yat-sen university (essd.copernicus.org/articles/14/... ) and CMA-GMST developed by the Chinese Meteorological Agency (link.springer.com/article/10.1... ). Will US fall behind China due to research defunding?

Thumbnail could also benefit from showing confidence intervals of uncertainty.

The thumbnail image and related publication are a bit disappointing. Why only these 4 temperature datasets? There are others available (e.g., COBE-STEMP3, China-MST3, ERA5, DCENT, my datasets). For the key thumbnail of your 527 page document, you would think someone would check for other datasets...