I'm not familiar with the information you mentioned. But apparent sea level may rise or fall at any particular location depending on whether that area is subsiding or lifting, that is, whether geological forces are pushing the land up higher or allowing it to sink lower. That happens often, can vary by location and can change over time. So while the total volume of water in the oceans may be increasing due to thermal expansion and melting ice sheets and glaciers, what actually happens to "sea level" as measured at any particular spot also takes into account the subsidence or lift experienced by that spot. That's why there's all sorts of evidence that can appear to be contradictory, but in reality it's complications caused by variations in subsidence and lift. Satellite measurements of sea level are made independently of subsidence or lift, so are more accurate indicators of the actual level of the water in the world's oceans. The problem is that satellite measurements only go back a couple of decades. Hence the study I cited where the scientists tried (successfully) to match up the satellite measurements with recent coastal sea level gauges (subject to but corrected for subsidence and lift). When you can match up the two (coastal gauges and satellite measurements), then you can try to use the much older and longer record of sea level gauges to compare rates of sea level change in the past with current rates of change.
Dear Dave Burton,
Before you say I am mistaken, please read the rest of the article! You merely quote from the article's Introduction, where the authors summarize PAST work in the area. If you had any scientific training, you might have known that.
"To reconcile the nearly factor of 2 difference in the tide gauge and altimeter global rates, reconstructions of global sea level from tide gauges have been made using empirical orthogonal functions (EOFs) obtained from satellite altimeter data..."
---this sentence you quoted ended with this reference to a paper, (Chambers et al. 2002). It is Chambers et al. in 2002 who used the satellite altimeter data.
Merrifield, Merrifield, and Mitchum, the authors of the 2009 paper I cited, used tidal gauges for both time periods, and verified that the tide gauges agreed with the satellite altimeter data. You might read through to the Methods, Results, and Summary and Discussion sections next time you look at a scientific study if you want to understand what they did, what they found, and what it means. You won't find that in the Introduction.
Dear Dave Burton (aka sealevelinfo ):
No, you are wrong. I was not comparing apples and oranges. The numbers, 1.7 mm/year for sea level rise before 1993 and 3.2 mm/year for sea level rise after 1993 are supported by the following study (see link below), which used ocean gauges for both time periods. The ocean gauges post 1990 in this case, agreed with the satellite measurements.
You might disclose that you are a member of NC-20, a group well-known for its interest in avoiding any restrictions on coastal development. I would trust the scientists who grew up professionally learning to objectively learn how the oceans work, rather than a computer software engineer like Mr. Burton who clearly has an interest in the debate turning out one way rather than the other (that would not be considered being objective).
Just watched the trailer for Shored Up. Could not find your five falsehoods. The claim that sea levels are rising faster today than in the past is supported by researchers who report that before 1993 the average rate of sea level rise was 1.7 mm per year, but since 1993 that rate has averaged 3.2 mm per year. Hard to argue with data like that.
Any suggestions on how to find out about screenings like the one at NCSU of Chasing Ice, or future screenings of Shored Up if we are fortunate enough that they happen here? I think there are better venues at NCMNS for showing a movie than their Thursday night Science Cafe. The Daily Planet is a cafe with several big display screens (but not huge) spread high up around the seating area, which has room for maybe 150 if you include the bar. The museum has a wonderful auditorium in their main building that would be a great place to show Shored Up and Chasing Ice. As to the museum's reluctance to host such showings, it sure does appear to be out of fear of political retribution, a very sad state of affairs in a democratic country.
Regarding the original story about the documentary film, having been to many Science Cafe presentations and discussions at the museum's Daily Planet cafe over the past year, it is too small a venue for showing a movie, and not an appropriate venue for a movie at all. There was a Science Cafe presentation and discussion about the sea level rise issue at the time the legislature was considering the bill, and Stan Riggs gave an excellent in-person summary of the state of the science of sea level rise and answered audience questions. That is the strength of the Science Cafe format, in-person presentations by qualified scientists that address the science and allow for audience participation. A documentary film could be shown on their large television screens, but it would be a much-less-than-ideal venue for such a viewing. I know nothing about the film in question, but will admit that issue advocacy may not be the most fruitful kind of presentation for a science museum. That said, I'd sorely like to see someone air the documentary "Chasing Ice" in Raleigh. It was shown last week in Durham and I missed it. I believe it would fall more in the category of science than of issue advocacy.
I read said bill. Interesting that it stipulates that that the CRC "...shall not define rates of sea level rise for regulatory purposes until July 1, 2016." So coastal development gets to go to town for another three years without giving any consideration to likely future rises in sea level that could threaten new or even existing development? Is that true?
Second, the statement in the bill, "...compare the determination of sea level based on historical calculations versus predictive models" in effect implies that CO2 increases and warming oceans either do not exist or of course will have no effect on sea level in the future. Historical calculations alone, by definition, ignore future changes to past conditions. Increasing atmospheric CO2 and warming oceans (evidence for both of which is unequivocal), strongly suggest that the future will not be like the past, and sea level rise predictions based solely on historical calculations would hardly be considered as sound science by any trained scientist.
Most of the energy imbalance created by increasing atmospheric CO2 concentrations is being absorbed by the oceans. As a result they are warming and expanding in volume. As surface waters and the atmosphere continue to warm, it is only reasonable to expect that more and more currently frozen water resting on land surfaces (think Greenland and Antarctica) will melt, contributing even more to the ocean's total volume. As that volume increases, sea levels will rise inevitably. The local exceptions will be in places where the land surface is rising as fast as or faster than sea level due to other geological forces at work (eg., rebound near areas where ice melt reduces the mass of water holding a land surface down, not a particularly likely circumstance in NC, but not out of the question).
It's pretty clear that the NC legislature and NC-20 were most interested in protecting development interests in coastal counties and skeptical of the work of climate scientists that could threaten the pace of such development. Very much like what was done to the Jordan Lake Rules, the legislature put off any considerations that might slow development due to environmental considerations. Heaven forbid we consider long-term consequences that might threaten short-term gains. The problem with that idealogy is that the long-term consequences might far outweigh the short-term gains, but we'll never know if we don't ask reasonable people (i.e., trained scientists) to examine the issue objectively. That is not what the legislature did this past session when they delayed the consideration of reasonable scientific judgement arrived at after extensive and objective research.
Make sure you're signed up so we can inbox you the latest.
Login to choose your subscriptions!
Indy Week • 201 W. Main St., Suite 101, Durham, NC 27701 • phone 919-286-1972 • fax 919-286-4274
RSS Feeds | Powered by Foundation