DoubleChecks

What was claimed

It is a full 9°C colder across the world today than the 24°C global average over the past 485 million years (Judd et al., Science 2024). So how could we have been facing an existential global warming threat? [...] reaching the dramatic prediction of a 5.5°C rise by 2100 is virtually impossible.

Our verdict

Inaccurate

Judd et al. reconstructed global mean surface temperatures ranging from 11°C to 36°C, not a 24°C average. The study does not support subtracting today’s temperature from a single 24°C historical global average. The Judd study explicitly notes that anthropogenic warming is occurring at much faster rates than historical warming events, making the rate of change—not just absolute temperature—the key concern for climate risk.

Combined assessment15 sourcesChecked Oct 13, 2026

Why this verdict

  • The Judd et al. study gives a 24°C global average over the past 485 million years.

    Incorrect
    One assessment reached this conclusion

  • It is a full 9°C colder across the world today than the 24°C global average over the past 485 million years (Judd et al., Science 2024).

    Incorrect
    One assessment reached this conclusion; two differed·Claude: Misleading, ChatGPT: Verified

  • Reaching the dramatic prediction of a 5.5°C rise by 2100 is virtually impossible.

    Misleading
    All assessments reached this conclusion

  • The rhetorical implication that current warming cannot be an existential threat because temperatures were higher in the past

    Misleading
    One assessment reached this conclusion

Evidence reviewed

15 sources

Perplexity, Claude and ChatGPT sources are combined here.

static1.squarespace.compaleonerdish.wordpress.comumweltbundesamt.deipcc.chipcc.chuniversetoday.comresearch-information.bris.ac.uksciencenews.orgsemanticscholar.orgipcc.ch

Individual assessments

Assessment summary

  • The response misrepresents Judd et al.’s study by treating a long-term reconstructed range as a 24°C global average.
  • The 5.5°C projection is near the upper end of a high-emissions scenario range, not virtually impossible; under SSP5-8.5, the IPCC gives 2.7–5.7°C by 2100.static1.squarespace.com umweltbundesamt.de

Claims reviewed

The Judd et al. study gives a 24°C global average over the past 485 million years.

Incorrect
The reported result is a temperature range of 11°C to 36°C over 485 million years.static1.squarespace.com A 24°C value describes a climate-state range or approximate condition in parts of the record, not the study’s overall average.

This claim may mislead readers without added context.

It is a full 9°C colder across the world today than the 24°C global average over the past 485 million years.

Incorrect
Judd et al. reconstructed global mean surface temperatures ranging from 11°C to 36°C, not a 24°C average.static1.squarespace.com The study does not support subtracting today’s temperature from a single 24°C historical global average.

This claim may mislead readers without added context.

A 5.5°C rise by 2100 is virtually impossible.

Misleading
The IPCC assesses 2.7°C to 5.7°C of warming by 2100 under the highest-emissions SSP5-8.5 scenario.umweltbundesamt.de Its 5.5°C value is therefore within an established scenario range, although it is near the upper end and depends on emissions.

This claim may mislead readers without added context.

Assessment summary

  • The response misrepresents the Judd et al.
  • study's findings and uses flawed reasoning.
  • While the study confirms current temperatures are cooler than some historical periods, it also emphasizes that anthropogenic warming is occurring at an unprecedented rate.
  • The claim about a 24°C average is unsupported, and the conclusion that 5.5°C warming is "virtually impossible" oversimplifies current climate projections.

Claims reviewed

Reaching a 5.5°C rise by 2100 is virtually impossible

Misleading
While RCP8.5 (3.5-5.5°C) is no longer considered the most plausible scenario, current high-emissions scenarios still project 3.5°C warming, and the claim overstates the certainty that 5.5°C is impossible.

This claim may mislead readers without added context.

It is a full 9°C colder across the world today than the 24°C global average over the past 485 million years

Misleading
The Judd et al. study confirms current temperature is 15°C, cooler than historical highs (36°C), but does not establish a 24°C mean over 485 million years. The specific 9°C arithmetic is not supported by the study.

This claim may mislead readers without added context.

The rhetorical implication that current warming cannot be an existential threat because temperatures were higher in the past

Misleading
The Judd study explicitly notes that anthropogenic warming is occurring at much faster rates than historical warming events, making the rate of change—not just absolute temperature—the key concern for climate risk.

This claim may mislead readers without added context.

Assessment summary

  • The statement mixes an accurate summary of Judd et al.
  • (2024) with an unsupported conclusion about future warming.
  • Judd et al.
  • report a time-weighted mean GMST near 24°C and a modern GMST near ~15°C, which makes today about 9°C cooler than that long-term mean pubmed.ncbi.nlm.nih.gov climatechangedispatch.com.

Claims reviewed

Reaching the dramatic prediction of a 5.5°C rise by 2100 is virtually impossible.

Misleading
IPCC assessments and scenario studies show that under very high-emission pathways some projections and ensembles produce global mean warming in the multi-degree range (roughly 3.5–5.5°C by 2100 in older high-end scenarios), so calling 5.5°C "virtually impossible" contradicts those projections and overstates certainty climate.ec.europa.eu.

This claim may mislead readers without added context.

It is a full 9°C colder across the world today than the 24°C global average over the past 485 million years (Judd et al., Science 2024).

Verified
Judd et al.'s PhanDA reconstruction reports a time-weighted mean GMST of ~24°C (±5°C) across the 485 My record and a GMST range of ~11–36°C; modern GMST is about 14–15°C, so the ~9°C difference is consistent with the paper's numbers pubmed.ncbi.nlm.nih.gov climatechangedispatch.com.

Check your own claim

Paste any statement, headline, or AI answer. Independent assessments check it and compare sources.

Share this result