Category Archives: climate change

Sea Level Data: Church & White, or Jevrejeva et al.?

Before the satellite era, the best data we have about sea level comes from tide gauges. They give local sea level, which is the difference between the height of the sea surface and the height of the land (it can move up and down too). It is possible — but very complicated — to combine data from tide gauges around the world in order to estimate how global mean sea level (GMSL) has changed over the past century-and-a-half or so.

The two best-known such estimates come from two different teams of researchers; one from Church & White (which I’ll refer to as “cw”), the other from Jevrejeva et al. (which I’ll refer to as “jev”). Let’s compare them. Here they are:

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Drowning in Sea Level Rise

It’s not likely that sea level rise will drown you personally. The sea is creeping up on us slowly, and yet — all too soon — it has already flooded streets even on sunny days, seeped into groundwater making it undrinkable, carried sewage from septic tanks onto lawns, even stranded an octupus in a parking garage (yes that really happened, on a calm sunny day even). It’s not just hurting coastal property values, it’s killing them.

But there’s one group that actually is drowning due to sea level rise: climate deniers.

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Dum Dum Dum Dum Dum

I’m sometimes puzzled by GWPF (the “Global Warming Policy Foundation”). Do they think their readers are gullible idiots, or is the GWPF itself that stupid?

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Sea Level Change on the U.S. East Coast, part 2

A tide gauge doesn’t measure the height of the sea surface; rather it measures the difference between the height of the sea and the that of the land. Thus is it sensitive to changes in sea surface height (SSH), and to vertical land movement (VLM) as well.

In the previous post I took sea level data from tide gauges on the east coast of the U.S., and computed a composite sea level record for each of four regions: New England, the northern mid-Atlantic, the southern mid-Atlantic, and Florida. Now that PSMSL (the Permanent Service for Mean Sea Level) has updated their database to include the latest complete year I recomputed my composites, using the data as is (not removing those periodic fluctuations I discussed previously, but yes removing the yearly cycle of the seasons by using anomaly values). And here are the regional time series, offset to make them easier to see:

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Sea Level on the U.S. East Coast

Lately I’ve been looking closely at sea level time series from the east coast of the U.S. Available stations are marked here with red dots:

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How Climate Deniers can “Hide the Incline”

Most of us have seen graphs of global temperature anomaly, like this one using data from NASA:

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Recent Sea Level Change

NOAA provides an excellent website for acquiring and examining sea level data from tide gauges. It includes maps with which one can select individual stations, but which also show the rate of sea level rise based on fitting a linear trend to all the available data. Here’s their map, zoomed in on the USA:

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