I got a couple of emails today saying that I should take a look at the most recently posted sea level graph from the University of Colorado shown below:
The reason for the interest is that it dropped the rate of change from 3.3 mm/yr to 3.2 mm/yr. as shown in the next graph. That’s hardly news, since it is well within the error band of +/- 0.4 mm/yr.
But I thought it might be interesting to go back and see what I could find in the UC sea level archive of graphs. I’ve presented all of the ones I’ve found below. I should note that in some years, UC may only release 2 graphs (as indicated by the release #) or up to 5 in one year like they did in 2005. For the sake of presentation simplicity, I’m only presenting the last graph to be released in any year.
I realize there has been a great deal of interest in the flattening of the 60 day smoothing line that started in 2007 and continues to the present. But the trend line will take awhile to reflect any appreciable change in the rate if it continues to flatten. The yearly rate of rise has been between 3.0 and 3.5 mm per year since 2004.
Many projections by various models predict the rise of sea level:
Note the trend of the observations line from 1950 to 2000, if you follow the linear trend, it will end up somewhere between 20 and 30 cm by the year 2100. The graph above is from Wikipedia’s “global warming art” which for some reason doesn’t show the observations back that far.
Here is a better graph, from New Zealand’s Ministry of the Environment, which shows more of the historical record, all the way back to 1870:
It seems sea level has been rising for awhile, and that the observation line in black, if you follow the linear trend, will also end up somewhere between 20 and 30 cm by the year 2100.
To put it all in perspective, some example images are useful.
Here is what 3 millmeters of sea level rise in 1 year looks like. This is a tiny fuel cell chip, just 3mm x 3mm in size:
I know that many people are concerned about sea level rise over the next century. In the rate of 3 mm per year continues, we’d be at 300 mm (30 centimeters) of rise in 100 years. Here is what 30.48 cm (12 inches) looks like:
And finally, here is what the tide gauge at Anchorage Alaska looks like:
Anchorage Alaska boasts the world’s second highest tides: varying over 40 feet (1219 cm), low to high tide. Ok, that is an extreme example, how about this one in France:
Mt. St. Michel on the north coast of France at low tide (left) and high tide (right).
The water surrounding this island is the Gulf of Sant-Malo.
The point I’m making is that in 100 years, for some places that extra foot won’t make much of a difference. Some low lying areas will be affected certainly, but even some of the lowest lying areas of the earth won’t see all that much impact from a third of a meter of sea level rise in 100 years. Probably the worst place to live is in a river delta which is almost at sea level anyway. Even so, 30 cm falls short of the lowest notch on this graph of 1 meter.
Bangladesh is another low lying river delta where it is not desirable to live, yet many do. Even so it appears much of it is 1 meter or more above sea level.
Florida is often talked about as being at risk. yes there are a few places there that might be touched by a 30 cm rise in sea level 100 years from now.
Looking at the whole world, at the rate we are going, I’d say it will take awhile.