Wednesday, November 09, 2011
Sea Level Tics Up
Skeptics/Deniers ("skepniers?") who live and die by every little tic in the graphs can explain away this one: the 60-day moving average in sea level is up. Just a short-term fluctuation in the overall cooling trend, I guess.... Seriously though, the recent "pothole" looks to have been due to the 2010 El Nino and La Nina.
No problem David. It's called natural variability.
ReplyDeleteNow maybe you can explain why we are told that the current rate of 3.2 mm per year, according to your chart going back 20 years, is caused by man when it's about half the 20,000 year average?
Was the last 20,000 years natural variability? If so why doesn't a rate half that qualify as natural variability? I mean 20 years, compared to 20,000 years seems like a tic to me.
One more thing. My understanding is that El Nino causes a temporary drop in sea level and La Nina a temporary increase in sea level. Since El Nino is warmer water shouldn’t it be the other way around?
That's really just astonishingly dull, TC. Are you really that stupid?
ReplyDeleteRe your non-stupid ENSO question, I believe the direct signal gets removed, although you could look that up.
Regardless, as is discussed in the updated portion of the second page David linked to, the recent big chunk taken out of sea level by La Nina was due to a lot of water getting moved onto land in a very short period. Of course after a while the extra water drained off and SLR could returne to its inexorable upward course.
Missed part of that last bit: If you understood what ENSO actually does, that the direct (thermal) effect of El Nino is a drop and La Nina a rise wouldn't be a mystery. To be fair, it's a little counter-intuitive.
ReplyDeleteThanks for the kind words Steve
ReplyDeleteSo what part of my post did you find dull and stupid? Was it the part where I said sea level change could be natural variability or maybe where I pointed out that current sea level rise is half the average for the last 20,000 years? Perhaps it was my request to find out if David thinks that 20,000 years of sea level rise is natural variability why shouldn't we think that 20 years of sea level rise could be caused by natural variability.
I'm not sure I agree with the claim "Regardless, as is discussed in the updated portion of the second page David linked to, the recent big chunk taken out of sea level by La Nina was due to a lot of water getting moved onto land in a very short period. Of course after a while the extra water drained off and SLR could returne to its inexorable upward course."
The image displayed on the JPL / NASA page only shows part of the earth. A fuller image is much less definitive.
http://www.jpl.nasa.gov/images/earth/grace/earth20110823b-full.jpg
When you take into consideration the distortion of the map the nearer you aproach the poles and the fact that most of the planet I'm not convinced it is but if so, who cares? As I stated earlier the drop in sea level can be explained away as natural variability as can any short term upward spike. Rainfall variability can certainly be natural. Sea level has been rising for almost 20,000 years before mankind started significantly adding CO2 into the atmosphere and for most of it at a faster rate then has been occuring for the last 20 years.
TC: Even things that vary naturally have a cause (though the cause might be chaos). Sea level has risen a lot in the last 20,000 years, but not much in the last 8,000 years:
ReplyDeletehttp://en.wikipedia.org/wiki/File:Post-Glacial_Sea_Level.png
And essentially nothing in the last 2,000 before the current rise:
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch5s5-5-2-4.html
But the offensive part of your comment is the suggestion that somehow it never occurred to scientists that the current rise might be "natural" or that they haven't looked for, and accounted for, natural factors.