There is a relationship between how much CO2 is in the atmosphere and sea level. More CO2 means a warmer atmosphere and that means less long term (glacial) ice and that means more sea water. Also, a warmer planet means the ocean water is warmer, and thus it expands, and that also contributes to sea level rise.

However, there is something of a falsehood generated when we read estimates of sea level rise. The straight forward link between CO2 and sea level (via heating oceans and melting ice) leads to estimates that are very small for sea level rise. We see things like “1.8 mm per year” which would be a very small number that does not seem like much of a threat. This is a falsehood for several reasons. The variation in sea level linked to a given level of CO2 is potentially great, in the order of meters; one level of CO2 could produce a wide range of sea levels, with a range of variation way bigger than the total sea level rise with annual increments like 1.8 mm. Sea level rise of seemingly small amounts, i.e. several centimeters, produce lateral (transgressive) shifts in the sea of potentially much greater amounts. This transgression can be fast, or it can be longer term. We are still experiencing the transgression from the post-glacial sea level rise that slowed to nearly a halt thousands of years ago. Meanwhile, coastal storms can be much more likely to flood inland with higher seas. All this means that the time scale of effects varies from days (storms) to decades (barrier beach erosion) to centuries (erosion against more stable coastal areas made of consolidated sediment) to millennia (erosion of major glacial features) to time periods that transcend climate change (erosion of continental bedrock). The scale of past sea level change is enormous, larger than any possible future sea level rise, but the “worst case” scenarios for the future are both dramatic and not all that unlikely. All this comes from taking a paleo-perspective on sea level change. In short, when we paleo-people hear estimates of a few millimeters a year of sea level rise over a century’s time, we laugh. Nervously.

I’ve written up a much more extensive analysis of sea level rise from a paleo-perspective as part of the Daily Kos Climate Change SOS Blogathon. You must click here and read my post and make comments on it or the Daily Kos will totally fire me. What are you waiting for?

Meanwhile, here is the list of the other amazing and wonderful blog posts that make up this Blogathon so far. I’ll update it to include all the posts later:

Climate Change Blogathon at Daily Kos!

so far…

Comments

  1. #1 Physicalist
    August 23, 2012

    Arctic ice extent will hit record minimum in a matter of days. Most likely before we hit September.

    Ice area is already at record low. Ice volume will soon follow.

  2. #2 adelady
    city of wine and roses
    August 24, 2012

    Whoops!

    I can’t comment at Daily Kos just yet, but you got the name of the **Nullarbor** Plain wrong. (It’s easy to remember when you realise that it’s straight Latin for “no tree”.)

  3. […] Climate Change, Sea Level Rise, and The Biggest Blogathon Evah! [Greg Laden's Blog] (scienceblogs.com) […]

  4. #4 TOMS shoes
    http://toms2012.webeden.co.uk
    September 22, 2012

    “smarmy”

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