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To: i-node who wrote (354046)11/5/2025 2:13:01 PM
From: Wharf Rat  Read Replies (1) | Respond to of 355466
 
RealClimate: Model-Observation Comparisons

Since we have been periodically posting updates since 2009 of climate model output comparisons to observations across a range of variables, we have now set up this page as a permanent placeholder for the most up-to-date comparisons. We include surface temperature projections from 1981, 1988, CMIP3, CMIP5, and CMIP6*, and MSU/AMSU satellite products from CMIP5 and CMIP6, SST and SSU from CMIP6, and we will update this on an annual basis, or as new observational products become available. For each comparison, we note the last update date, and where the comparison was first discussed.

This is a collation of opportunity. To be included, there needs to be a pre-existing public archive of the processed model output for the historical period and projections, and at least one regularly-updated observational data source. Lots of these archives have been produced, but they are not easily discoverable, if available publically at all. Please let us know of others that could be included as well by leaving a comment on the latest open thread. You can use these figures anywhere (with a citation and link back to RealClimate).

*Note that Hausfather et al. (2020) made a more complete assessment of surface temperature projections from models from 1970 through to CMIP3 ( discussed here).

Global mean surface temperature anomaliesHansen et al (1981)


Original discussion (figure originally courtesy of Geert Jan van Oldenborgh, Hansen et al. (1981)). Observations are the GISTEMP LOTI annual figures and 5 year mean. Last updated: 23 Jan 2025.

Hansen et al (1988)


Original discussion (2007), Last discussion (2018). Scenarios from Hansen et al. (1988). Observations are the GISTEMP LOTI annual figures. Trends from 1984: GISTEMP: 0.22ºC/dec, Scenarios A, B, C: 0.35, 0.29, 0.15ºC/dec respectively (all 95% CI ~±0.02 or 0.03). Last updated: 23 Jan 2025.

CMIP3 (circa 2004)


Last discussion (2015). Model spread is the 95% envelope of global mean surface temperature anomalies from all individual CMIP3 simulations (using the SRES A1B projection post-2000). Observations (GISTEMP) are the standard quasi-global estimates of anomalies with no adjustment for spatial coverage or the use of SST instead of SAT over the open ocean. Last updated: 23 Jan 2025.

CMIP5 (circa 2011)

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To: i-node who wrote (354046)11/5/2025 3:21:52 PM
From: combjelly  Read Replies (3) | Respond to of 355466
 
Can you show that the 25 year projections were vastly overstated? The ones I have seen have been far too conservative.