Understanding sea level

Predictions on sea level change range from negligible and nothing to worry about to potentially catastrophic for many major population areas.

We are currently in an interglacial period. In the last interglacial period about 125,000 years ago sea levels rose to several metres higher than they are now, and that was without the degree of fossil fuel emissions we have now.

Even with natural variations there is cause for concern. If emissions trigger a massive icecap melt it could be calamitous with current low altitude population densities.

National Geographic: Why the New Sea Level Alarm Can’t Be Ignored

The physics of ice predicts that sea level will rise twice as much by the end of the century as previously estimated.

There are days when even a born optimist starts to waver in his conviction. The release of a new study projecting that sea level could rise between five and six feet by 2100—when many children born today will still be alive and have been forced to move inland—made Thursday one of those days.

Some 125,000 years ago, for instance, Earth was in an interglacial period, like the one we’re in now, a warm interlude between 100,000-year-long ice ages. The temperature then was about the same as it is today, a degree or two warmer at most. But the best evidence indicates sea level was at least 20 feet higher—which in itself is disconcerting, suggesting as it does that we might be poised on the brink of something big.

20 feet is about 6 metres.

The Thwaites glacier in West Antarctica is far more massive than the Jakobshavn glacier. According to another alarming study published last year, it has already become unmoored from the 2,000-foot high submarine ridge that holds it in place. If it begins to retreat down the long slope toward the center of the ice sheet, the cliffs it would produce would be far taller than the Jakobshavn one—and probably not stable.

“Then, rather than break-wait-wait-wait-break, it might switch to break-wait-break or just break-break-break,” Alley says.

That’s what Deconto and Pollard’s model suggests could start happening to the West Antarctic Ice Sheet by the second half of this century, if we don’t curb our carbon emissions: Just break-break-break.  And by 2100, when sea level had risen five or six feet, the breaking would have only just begun.

So there are real risks. We just don’t know how big the risks are – and we may not know until it’s too late, maybe not for us but for our children and grand children.

Sea level measurements and predictions are very complex.

NASA has set up a website on Understanding Sea level

NASA keeps track of sea level change and its causes from space. Find out more about how NASA satellite observations help our understanding of this complex topic.

Learn more about how models forecast the future of sea level, and how different components contributing to sea level change are predicted to evolve over time.

That looks like an excellent resource on sea levels.

Leave a comment

16 Comments

  1. Alan Wilkinson

     /  11th April 2016

    The first step in predicting the future is to understand the present and that means looking at current and recent rates of sea level rise. Beyond that models are only “what if”, “could” and “maybe” possibilities until they can be shown to match reality by predicting the present and testable near future. Most climate models have a very poor track record in doing the latter, including those modelling glaciers which can be sensitive to local factors not global.

    Moral: facts heavily outweigh speculation concealed as an unproven model.

    Reply
    • Gezza

       /  11th April 2016

      Re models that’s my understanding too. From what I gather they’ve got better matching past to recent present but they’re still not reliable indicators of the future, the evidence for sea level rise is inconsistent.

      Reply
  2. The physics of ice predicts that sea level will rise twice as much by the end of the century as previously estimated.

    Yay, yet another trained monkey has found work in media. The physics of ice predicts nothing without environmental constraints like temperature and pressure.

    IMO a blatant non-sequitur like that indicates that the article is pure propaganda.

    Reply
  3. Brown

     /  11th April 2016

    Sadly NASA is just a political tool for this alarmist stuff. How far they have fallen.

    Reply
  4. Alan Wilkinson

     /  11th April 2016

    Deborah Hill Cone is one of the few Herald columnists worth reading – so long as she doesn’t write about business or economics. Today she notes some children have been so traumatised by climate change scaremongering they don’t think they have a right to exist.

    Thanks Lefties.

    http://m.nzherald.co.nz/lifestyle/news/article.cfm?c_id=6&objectid=11620126

    Reply
    • Gezza

       /  11th April 2016

      I found that a bit hard to believe and wonder what they said that led her to that conclusion.

      Reply
      • Alan Wilkinson

         /  11th April 2016

        I would guess that they have been told the planet is doomed because of overpopulation and all the bad things humans are doing to it. From the sound of it they visited Parliament and play acted political debates so perhaps that’s where these feelings came out.

        Read any of the MSM comment threads on climate change and you see this doomsday opinion is prevalent in the Left and environmental memes.

        Reply
        • Gezza

           /  11th April 2016

          Yeah, it’s a difficult situation when you have to rely on experts when you have no idea how to evaluate who’s right and I guess this is taught in schools. I can picture the kids actually doing a better job of political debates than the usual denizens of the chamber actually.

          Reply
    • Alan Wilkinson

       /  11th April 2016

      What, only one downtick? Come on, Lefties, you know you hate humanity. Come out and vote against it.

      Reply
  5. Pantsdownbrown

     /  11th April 2016

    Nothing a tax couldn’t fix.

    Reply
  6. Pantsdownbrown

     /  11th April 2016

    I posted this some ago regarding pacific atolls and rising sea levels.

    http://www.stuff.co.nz/environment/9963480/Pacific-atolls-resilient-to-rising-seas-study

    Reply
  7. Jollo

     /  11th April 2016

    Alan do you also think Nasa faked the moon landing too?afterall that conspiracy takes far less effort than orchestrating tens of thousands of independent scientists across the globe.

    Or are you just one of these intellectually dishonest conspiracy theorists who just picks those that align with your political ideology?

    Reply
    • Alan Wilkinson

       /  12th April 2016

      Who said tens of thousands of scientists are orchestrated? There is a core group of fanatics but many others with a wide variety of views and contributions. The vast majority have nothing to do with these modellers and their crusading predictions.

      That said, they all know their bread is buttered on the side labelled climate change and if they want research funds that side had better land upwards even if with only a perfunctory genuflection.

      Reply
  8. Maggy Wassilieff

     /  12th April 2016

    Here’s a site where you can see the actual sea-level rise information from tide gauges.
    Nothing to be alarmed about…we are still tracking along at less than 1.5mm/yr

    http://notrickszone.com/2016/04/11/broken-altimetry-225-tide-gauges-show-sea-level-rising-only-1-48-mm-per-year-less-than-half-the-satellite-claimed-rate/#sthash.cadAUebt.dpbs

    Reply

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: