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US Geological Survey stunner: Sea-level rise in 2100 will likely “substantially exceed” IPCC projections, SW faces “permanent drying” by 2050

By Joe Romm  

"US Geological Survey stunner: Sea-level rise in 2100 will likely “substantially exceed” IPCC projections, SW faces “permanent drying” by 2050"


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A major new report warns that on our current emissions path, we face the severe risk of abrupt climate change impacts. The basic conclusions themselves are nothing new — see “Startling new sea level rise research: “Most likely” 0.8 to 2.0 meters by 2100” and “Australia faces the “permanent dry” — as do we.

But what is stunning is that these warnings come from the United States Geological Survey — the Bush Administration (!). This new science-based report, Abrupt Climate Change, is thus a sobering book-end to the fantasy-based talking points released by the Administration today on how the President has “Taken Constructive Steps To Confront Climate Change.”

This is a first-rate report from the USGS’s Climate Change Science Program. I highly recommend reading, Chapter 2, “Rapid Changes in Glaciers and Ice Sheets and their Impacts on Sea Level,” and Chapter 3, “Hydrological Variability and Change.” The chapters are much more readable than the IPCC reports, and the two together will make anyone an expert on what are perhaps the two most dangerous climate impacts that threaten this country.

The sea level rise conclusion, “based on an assessment of the published scientific literature” is:

Recent rapid changes at the edges of the Greenland and West Antarctic ice sheets show acceleration of flow and thinning, with the velocity of some glaciers increasing more than twofold. Glacier accelerations causing this imbalance have been related to enhanced surface meltwater production penetrating to the bed to lubricate glacier motion, and to ice-shelf removal, ice-front retreat, and glacier ungrounding that reduce resistance to flow. The present generation of models does not capture these processes. It is unclear whether this imbalance is a short-term natural adjustment or a response to recent climate change, but processes causing accelerations are enabled by warming, so these adjustments will very likely become more frequent in a warmer climate. The regions likely to experience future rapid changes in ice volume are those where ice is grounded well below sea level such as the West Antarctic Ice Sheet or large glaciers in Greenland like the Jakobshavn Isbrae that flow into the sea through a deep channel reaching far inland. Inclusion of these processes in models will likely lead to sea-level projections for the end of the 21st century that substantially exceed the projections presented in the IPCC AR4 report (0.28 ± 0.10 m to 0.42 ± 0.16 m rise).

Again, the recent post-IPCC literature has been quite consistent in warning of sea level rise of one meter or more by 2100. Beside the 2008 Science study noted above, a Science article from 2007 used empirical data from last century to project that sea levels could be up to 5 feet higher in 2100 and rising 6 inches a decade (see Inundated with Information on Sea Level Rise) and another 2007 study from Nature Geoscience came to the same conclusion (see “Sea levels may rise 5 feet by 2100“). But now we have the U.S. government acknowledging the inadequacy of the IPCC conclusion.

[Note: The UK Guardian's headline "Sea level rise could top 1.5m by 2099, experts warn," is quite a stretch. You won't find that in the study.]

A key drought conclusion is:

The serious hydrological changes and impacts known to have occurred in both historic and prehistoric times over North America reflect large-scale changes in the climate system that can develop in a matter of years and, in the case of the more severe past megadroughts, persist for decades. Such hydrological changes fit the definition of abrupt change because they occur faster than the time scales needed for human and natural systems to adapt, leading to substantial disruptions in those systems. In the Southwest, for example, the models project a permanent drying by the mid-21st century that reaches the level of aridity seen in historical droughts, and a quarter of the projections may reach this level of aridity much earlier.

What else is there to say but “The science is beyond dispute… Delay is no longer an option. Denial is no longer an acceptable response”?

Kudos to the USGS and US Climate Change Science Program for this must-read report.

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9 Responses to US Geological Survey stunner: Sea-level rise in 2100 will likely “substantially exceed” IPCC projections, SW faces “permanent drying” by 2050

  1. Bob Wallace says:

    Well, Merry Friggin’ Christmas to us. One and all….

  2. Bob Wright says:

    Good News: Add USGS to NOAA and NASA who tell it like it is.

    Bad News: Read the report.

  3. Modesty says:

    The Guardian headline doesn’t seem like THAT much of a stretch.

    “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.

  4. Joe says:


    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.

  5. paulm says:

    There is also the creep factor which should be taken in to account. i.e. from report to report whats the precentage change (increase) which seems to be introduced. Apply that to current and future projections.

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

  6. Modesty says:


    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.


    [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.]

  7. Modesty says:


    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.


  8. Forget sea level. Worry about the drought because when the drought reaches Iowa, your grocery store is going to have empty shelves. Notice that they said that it can happen faster than we will be able to adapt, meaning irrigate. If we were sure of what would happen and when, we could start laying pipe from the great lakes to the farms, but we don’t know that much.
    See the book: “The Long Summer” by Brian Fagan. Something
    like 2 dozen civilizations have already disappeared because of
    climate changes smaller than the one we have already caused.
    Starvation was the cause of death.
    See: “Collapse, How Societies Choose to Fail or Succeed” by Jared Diamond
    If agriculture collapses, so does civilization. If civilization collapses, 99.99% of all Americans die.
    Remember that George W. Bush’s political appointee probably did water down the report a lot. It spells disaster like has never been recorded in the past 2000 years of Western civilization.

  9. Alex says:


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

    Cash Surveys