I asked NOAA public relations about this, and the answer I got back (awhile ago) was:
The statement in the press release was made on the basis of the following statements in the text:So by "continued to rise" NOAA apparently meant 'continued to have a positive trend.' That's kinda different. Yes, I understand you can't make conclusions about AGW or sea level based on a few year's worth of data, but you need to be precise too or you look like you're pushing inconvenient details under the rug. Anyway, NOAA continued:
* "The global rate of sea level change computed over the years 1993-2010 (cited references) is 3.1 +/- 0.4 mm yr-1"
* "Over this brief time period and in areas more than 200 km from the nearest coast where comparisons can be made with Argo and GRACE, the mean rate of total sea level rise is 1.5 ± 0.9 mm yr–1 (note that the uncertainties from here to the end of this section are 95% confidence levels). This rate cannot be compared with the global average over the entire altimeter time period cited above since at least 10 years of data are required to determine a reliable rate (Nerem et al. 1999). This rate is, however, in agreement (Fig. 3.29) with the sum (1.6 ± 0.6 mm yr–1) of the rates of the upper (depths < 700 m) ocean steric (0.5 ± 0.5 mm yr–1) and ocean mass components (1.1 ± 0.6 mm yr–1)."
Also, the graphic depicts monthly results, so while there is variation from month to month, the overall trend, if looking on a yearly basis, still looks to be upward. But it is true that that is not explicit in the graphic.
Maybe they're worried about giving anti-AGW people any ammunition, but really they're supposed to be a science organization first and would it really have made a difference if they said "despite its long-term upward trend, sea level has remained the same over the last few years, though scientists expect it to eventually resume its upward trend" or something to that effect?Anyway, now that I look at the sea level graph again from the University of Colorado (see figure) I think my question was nitpicking, because it's really only in the last 15 months or so that the 60-day smoothing trend is down, and that's not unusual at all (look at 2007-2008, or 1998-2000, or 1994-1997). I didn't ask a good question, and, as usual, Goddard was just trying to manufacture doubt.
13 comments:
The trend for the last 20yrs
3.2mm/yr
320mm/100yrs
32cm/100yrs
13in/100yrs
Yep Charles. Now let's compare your personal trend for the last ~60 years to what's likely for the next 60. No reason to think it'll change, right?
David,
Going back and reading your July 01, 2011 post you criticized Steven Goddard for referring to NOAA as either "Clowns, Or Criminals"
In a comment on a August 08, 2011
http://www.blogger.com/comment.g?blogID=28837843&postID=7867809292367111190
you said "Watts is a clown, an obvious clown, and if you believe anything he writes then you too are a clown."
What is the difference?
Goddard was stating a fact. There is nothing wrong that the fact may cause doubt. A fact is a fact and doubt is a hallmark of science.
Steve,
There is every reason to think that sea level rise will change in the next 60 years but I don't know in which direction.
In the last 20,000 or so years sea level has risen 130 or so meters.
130,000mm/20,000yrs
That works out to about 25 inches a century. It's currently rising at about 1/2 the 20,000 years average.
bloom,
co2 effects are logarithmic as the sensitive radiation bands saturate so one shouldn't expect co2 driven sea level rise to accelerate. what about other forcings? I have no idea.
The trend for the last 20yrs
3.2mm/yr
This is not true. You can use The Google and see their older charts have less steep trends.
HTH.
And what Steve said.
Best,
D
charlesH,
"What about other forcings? I have no idea."
That the problem. Nobody really knows what the forcings are or what direction they will take. Personally I think that they have to be negative in both directions. If not the earth's temperature couldn't have remained fairly stable for as long as it has. If you want to see planets with unstable feedbacks I suggest you look at Mars. It has had significant surface water in the past. Those days are long gone.
Dano,
Regarding the comment by charlesH regarding sea level rise.
"This is not true. You can use The Google and see their older charts have less steep trends."
I disagree. Sea level rise is relatively stable. He is a graph from the glorious Wikipedia dating back to about 1880."
http://en.wikipedia.org/wiki/Sea_level_rise
A few points:
Prior to about 1990 they used tidal gauge records. I simply don't believe that they can be considered as accurate as the satellite data.
Look at the individual years and see the annual variability. It's VERY significant and as a result it impacts the 3 year trend as well. Overall however the trend is pretty steady.
"And what Steve said."
Back at you Dano. Since the 130 year record shows that sea level rise has been all over the place consistently why would anybody expect it to be the same 60 years from now?
Now I've got a question for you:
Since sea level has averaged twice as much as it is currently averaging, why is the current rate such a cause for concern?
You can see the CU graphs back thru time on The Google. You can see, e.g., that a graph from 2005 had a rate of +2.7 mm/yr. These aren't tide gauges.
If you wish to believe that SLR is not increasing, good for you.
Thanks!
Best,
D
Charles, CO2's absorption bands are nowhere near saturation. See
http://www.realclimate.org/?comments_popup=370#comment-20982
Croq: that 130 m rise in 20,000 yrs is almost all glacial isostatic adjustment, I believe. Univ of Colorado now corrects for GIA and estimates its current value is -0.3 mm/yr. The remaining 2.9 mm/yr is the warming component.
David,
I think you are completely wrong. the glacial isostatic adjustment would LOWER sea level rise not increase it. Long term sea level estimates are not easy to calculate but over a period of 20,000 years there is every indication that sea level has risen by 400 feet. If anything continental rebound would result in a lower rate of sea level increase not a higher rate.
Yes, you're right: GIA lowers sea level. (Univ of Colorado says by 0.3 mm/yr)
http://sealevel.colorado.edu/content/what-glacial-isostatic-adjustment-gia-and-why-do-you-correct-it
But that 400 ft rise in 20,000 yrs you're talking about is from melting of the last ice age or meltwater pulses:
http://www.giss.nasa.gov/research/briefs/gornitz_09/
That page says the current rise in sea level is the highest rate in 5000 yrs.
David,
You are correct that the 400 foot rise in sea level happened after the maximum of the most recent sea level rise but I'm not convinced that we are not still in the most recent ice age. Think about it. We have an entire continent covered with ice and significant portions of three others (especially North America) covered with ice year round.
You are also correct that the sea level rise had probably been slower in the last 5,000 years (I think it's been more like 7,000-8,000 years) but you also have to realize that the measurements they use to determine sea level rise in the distant past are estimates and need to be treated as such.
We are currently measuring sea level changes using satellites by the millimeter per year and have been for 30 or so years. Prior to that we measured sea level changes using tidal gauges that were less accurate and that dates back to about 1880 or so. As stated above, prior to that we rely on estimates using sedimentary rock deposits and coral. You have to realize that prior to 1880 we could have had decades or centuries of either accelerated rising sea level or a drop of sea level without it showing up in the record. We do not have anywhere near the accuracy of long-term sea level history to state that "the current rise in sea level is the highest rate in 5000 yrs."
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