Idle speculation about sea level rise

Over at Lucia’s Blackboard they’re having an interesting discussion about UHI, BEST and of all things, sea level rise. I pitched in with a comment, reproduced below.

I found a paper that maps U.S. lands vulnerable to sea level rise. It can be found here. It found 58,000 square kilometers lying below a 1.5 meter contour along the Atlantic and Gulf coasts. They had data difficulties that hampered their ability to make similar estimates for the West Coast.


So I wrote, “Tol & Yohe 2007 found that 0.24% of habitable land would be lost to 50cm of sea level rise. As that’s mid-range of IPCC AR5 estimates, let’s go with it until incoming data shows otherwise.

Seacoast property is in most parts of the world very desirable and more expensive in the developed world. In the U.S. and Europe and the richer parts of Asia, it will be insured and protected. Parts of Tokyo have subsided several meters due to aquifer depletion, yet they’re still there and doing okay.

In the developing world, the monetary value is less but the utility is still very high. Because of high levels of poverty, much of the coastal infrastructure is fairly easy to relocate.

The environmental changes to estuaries, tidal marshes, etc. in the developed world will be significant. South of the equator things like mangrove stands tend to offer a good measure of protection.

In the rich world we seem to be pre-paying for damages due to sea level rise, due to frightening stories about extreme weather allowing insurance companies to charge higher premiums without having the damages to pay out on.

My judgement call is that if sea level rise comes in at about half a meter this century we’re in pretty good shape.”

Predictions of sea level rise without contributions from the great ice sheets in Greenland and Antarctica are not frightening. We can handle them.

Recent work on the Greenland and Antarctic ice sheets show that both are gaining ice in the huge centers of the ice caps, while losing some at the edges. Neither will contribute much water to sea level rise this century.

There is still one bad possibility. That some unstable masses of ice on the Western Peninsula of Antarctica might drop into the ocean due to mechanical reasons, reasons that might be accelerated by warmer water undercutting the ice that is holding the mass up. Scientists now think that might affect us in about two hundred years and that when the process starts it will take about 50 to 100 years to complete.

So I still maintain that sea level rise this century is an eminently solvable problem, assuming it stays within the IPCC’s projected range of 26cm to 98cm.


3 responses to “Idle speculation about sea level rise

  1. I’m not sure if I mentioned it before: some climate models project faster sea level rise for lower emissions and less warming. It seems the ice sheets are preserved more efficiently in the higher humidity environment we would experience with more global warming.

    The higher humidity leads to more snowfall over Antarctica, where the critical ice mass is located.

    Interestingly, a higher CO2 concentration leads to a negative greenhouse effect over Antarctica. It seems Antarctica is so cold the CO2 helps increase outgoing long wave radiation.

    This leads to a very interesting issue: the largest adverse economic impact from global warming we can quantify is from sea level rise. The other effects are speculative, estimated using regional impacts we can say are rather inaccurate.

    So, the “fight against global warming” could lead to a dip in humanity’s revenue stream caused by a huge investment in very expensive renewables, followed by a negative revenue stream caused by MORE sea level rise caused by the lower snowfall rates over Antarctica and Greenland, followed by a POSITIVE starting 100 to 150 years from now as the lower emissions rates lead to lower concentrations and less overall warming.

    This of course requires we have nearly endless fossil fuel resources as assumed in RCP8.5.

    It’s a pity the steering at the IPCC is being done by rather incompetent individuals. I just sat through the full set of CMIP6 presentations they showed at the workshop in Croatia. They are making a huge effort to improve the models, but from what I gather the emissions pathways are an afterthought.

    To make matters worse I see incoming resistance from what appears to be cornucopians in high places who don’t like it if one discusses the link between fossil fuel limits and global warming. I’m getting comments erased when I bring up the issue.

  2. Tom the estuaries, just like the coral atolls, respond dynamically to changes in water level. If Americans had done nothing to alter coastlines over the past 3 centuries, much of the land allegedly at risk would not be inhabitable in the first place.
    The idea that we will not maintain, upgrade or improve our coastal infrastructure whether or not sea levels rise is preposterous.
    Only in a world run by ignorant fanatics would we not allow engineers to do what they have done successfully since prior to Roman times- build levees, jetties, canals, dikes, dredge harbors and channels, and move coastal communities.
    Today the world is hearing from Ms. Merkel of Germany about climate, demonstrating that climate is the universal excuse for failed government policies:

    “Merkel: We must hit climate target to avoid refugee waves
    Nov 3, 7:40 AM (ET)
    (AP) German Chancellor Angela Merkel delivers a speech during a reception of the…

    BERLIN (AP) — German Chancellor Angela Merkel says the world must do everything it can to meet an international goal to fight global warming, arguing that failing to do so could set off large new waves of refugees.

    The U.N. and experts say governments’ emissions-cutting pledges ahead of a global conference in Paris beginning this month aren’t yet enough to hit the target of keeping the rise in global temperatures below 2 degrees Celsius (3.6 degrees Fahrenheit) by the end of this century compared with pre-industrial times.

    Merkel said in a speech Tuesday “if we don’t manage this, that could be a reason for many, many refugee movements” around the world.

    Scientists say a temperature rise over 2 degrees Celsius could have profound, irreversible effects on the climate.

    So instead of dealing with the real facts: Corrupt dictatorships, theocracies and medieval religious terrorists. so Merkel would rather deal with an over hyped long future (if ever) problem than the reality of today.
    THAT is the underlying failure of the West.

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