John’s Blog

We simply do not know how much sea level will rise in the next 30 – 100 years, the typical design life of buildings and infrastructure. Given the wide range of current projections, the common practice of planning for the average, or medium, rise is about the dumbest thing we could do.  As the US and other nations spend trillions to build infrastructure, this moronic tendency needs to be understood.

6 Sea Level Scenarios from NOAA 2017 (Technical Report NOS CO-OPS 083)

Projecting how high sea level will rise this century is dependent on two pieces of information that we do not have. First, the primary factor for the amount of land ice that will melt – primarily on Antarctica and Greenland –  the question of how warm the planet will get over the next eight centuries. For reference Earth is measurably warmer by 1.2 degrees Celsius (2.2 degrees Fahrenheit) compared to the “pre-industrial era.” The current debate, particularly leading up to the big climate negotiation in Glasgow in early November, is whether we can halt the warming at 1.5 or two degrees by reducing the amount of carbon dioxide in the atmosphere. On our current path of emissions and warming, we are headed to more than three degrees Celsius (5.4 degrees Fahrenheit).

#2. Even if we knew how much extra heat would be stored in the sea this century, the calculation of how that would melt the two major ice sheets is surprisingly vague. There are lots of models and projections, as illustrated by the wide ranging curves in the graphic above.

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