Climate change means worst droughts, rapidly change in glaciers and their effects on sea level.

————————-
Thanks,
Alex
Cash Surveys

I see your point.

The Guardian kind of made a use/mention error in interpreting the relevant passage, and I turned this quasi-error into a real one.

Your point was valid, and I was wrong.

Thanks.

1. If the Guardian had been reporting on Rahmstorf’s study, I think it would have been reasonable for them to use the headline: “..could reach 1.4 m…” Public interest is naturally focused on how high the sea level could rise, ie on the upper value of any range. They wouldn’t be claiming that Rahmstorf said it WOULD reach 1.4, just that it COULD, which he did.

2. Here, however, the Guardian is not reporting on Rahmstorf’s study. It’s reporting on the results of the USGS report which contextualizes the former. The USGS report says that if so and so, then because of such and thus, Rahmstorf’s “estimate” will likely need to be revised upwards. The Guardian presumably interprets this as the high value needing to be revised upwards, which I think would justify this headline “…could top 1.4 m…” (Or do you object to that step?) The stretch is thus going from 1.4 to 1.5, which, yes, is a stretch. Just not as much of one as a reader might infer from your “You won’t find that in the study” comment.

3. The headline may be the result of a mistake rather than a stretch on the part of the Guardian, though, as they, currently, have the pre-revision Rahmstorf range as 0.4-1.5 instead of 0.5-1.4.

4. The sentences used by the Guardian are in Chapter 1. Introduction: Abrupt Changes in the Earth’s Climate System, not some obscure, unimportant (?) part in the “middle”.

5. You’ve made me reassess my claim that you would be justified in claiming they were saying that the sea level rise could top 1.5 m. I’ll stick with 1.4.

Thanks.

[JR: And yet not a word of this in the executive summary on the study's many conclusion. So absent specifically saying they meant to say his upper estimate was low, one can only guess. Maybe worth a mention somewhere in the story -- if you could get a confirming quote from anybody -- but not the headline.]

Basically its going to be much worse and occur much sooner than what ever the current figures say.

If the study wanted to say that, it would have. Rahmstorf used a range. Given the kind of analysis he did, this conclusion was remarkably close to the latest 0.8 to 2.0 meter range. I suspect Rahmstorf would agree the new range is more accurate. But to take the sentences that you quoted from the middle of the report and then extrapolate from the high-end and make that the headline of the story is a bit much.

“Rahmstorf (2007) used the relation between 20thcentury sea level rise and global mean surface temperature increase to predict a sea level rise of 0.5 to 1.4 m above the 1990 level by the end of the 21st century, considerably higher than the projections by the IPCC AR4 (Meehl et al., 2007). Insofar as the contribution to 20th century sea level rise from melting land ice is thought to have been dominated by glaciers and ice caps (Bindoff et al., 2007), the Rahmstorf (2007) projection does not include the possible contribution to sea level rise from ice sheets.

Recent observations of startling changes at the margins of the Greenland and Antarctic ice sheets indicate that dynamic responses to warming may play a much greater role in the future mass balance of ice sheets than considered in current numerical projections of sea level rise. Ice-sheet models used as the basis for the IPCC AR4 numerical projections did not include the physical processes that may be governing these dynamical responses, but if they prove to be significant to the long-term mass balance of the ice sheets, sea level projections will likely need to be revised upwards substantially.

By implicitly excluding the potential contribution from ice sheets, the Rahmstorf (2007) estimate will also likely need to be revised upwards if dynamical processes cause future ice-sheet mass balance to become more negative.”

If someone told you that, I think you’d be justified in claiming they were saying that sea level rise could top 1.5 m by the end of the century.

Bad News: Read the report.