If Sea Levels Rise While Your Head is Stuck in the Sand...Follow

I see what you did there.

The problem with historical sampling and graphs of CO2, is that prior to about 1952, we didn't posess accurate CO2 measuring equipment. There are a few isolated studies prior to 1952, going back all the way to 1800, but many scientists believe that data is faulty for a variety of reasons, including methodology, scientific understanding of the time, limited scope. limited sampling areas and other factors.

The other method of sampling historical Co2 levels is ice core sampling, which will get you close to a given epoch, but the further back you go, the more difficult it becomes to assign a specific date to a given ice layer. Some we can date fairly accuratly from embedded ash layers in the ice, or things of that nature, but for the most part we're talking hundred year spreads at a minimum. with absolutly no way to really know if the observed gas level in the core sample is really representative of what the Co2 conditions were at the time of freezing. We think we have a pretty good guess, but until we have a hundred years or so to observe ice samples where we know the exact date of creation, we don't really know, and even then there are a huge number of variables, such as re-melt, particulate impuraties in the ice offgassing and or reacting with the CO2 already there, etc.

There was much more vegitation on earth early on, (rain forests, pacific forests, etc.) and I would expect more CO2 in the atmosphere today than back then logically, but we really don't know, and presenting data on a graph like that that at best contains uncertanties, and at worst contains bad data is a problem.

That and the whole interesting phenominon of soot particles from coal burning potentially acting as a seed for snowflake formation and making winter snow worse in some areas than it would have been otherwise.

Also, on the OP, I'm still a little curious as to how this whole thing became a big deal. I'm a bit in the dark, but here's a nice quote I came across:



I'm not all up-to-date on this whole sea level rising thing. Regardless of who's right or wrong is the difference between 8" and 10.7" really that large that it necessitates a different planning strategy? To the layman it seems a little silly of a thing to bicker about. I suppose its the principle of the thing though?

The most accurate means of measuring CO2 levels on a year by year basis is tree ring samples, which can go back hundreds to thousands of years for very large, old trees and can be dated simply by counting. The reason that the methodology is questioned is because localized conditions can promote growth, or inhibit it. Yet, in these ancient trees, we have records of the atmosphere that precisely line up with known events that affected the entire world: Volcano blew up and caused shadows that made it a bad year for crops? Yep, that tree ring will be smaller.

One tree won't tell the whole story, but hundreds of trees around the world whose rings are matching up identically tell a much more complete story.

I guess flood planning is the only thing I was really familiar at all with, relatively speaking of course. I've seen the flood maps of our old town, and knew about some of the planning that went into what they would want to build in what flood zone and stuff. But that was all in 'feet above flood stage' for the most part. I mean 6' above flood stage and 10' above meant different things, but there wasn't the detail between say 11'3" and 11'6" or anything. Part of me is kind of impressed if they are really able to predict something that closely 100 or so years in advance, and have the ability to plan for the difference between those two measurements. Yay, science perhaps?

I suppose it does matter to engineers and planners. It also matters a lot to developers, since it directly affects the volume of coastal land they have to work with. Assuming that these numbers will end out affecting coastal building codes, it can be a big deal. Depending on the topology, the difference between a projected 1m worst case versus 15" can result in buildings having to be built a hundred feet or more back from the existing waterline. So yeah, it matters.


And of course, there's also the political angle and the whole "OMG! Global Warming!" versus "OMG! Global Warming Denial!". And let's face it, that's a hell of a lot more interesting and fun for most of us.



Having said that, I still have issues with the kinds of data in the quote you provided. IMO, it's still suffering from the same sorts of problems Kao spoke of. We have far more accurate measurements of (global) sea level change today than we did 50 years ago, or a century ago. So what's happening is that older measurements are going to tend to be extrapolated over time and area, versus recent data which is very precise. This is significant to something like global sea levels because it tends to soften out trends in the past, while making current ones very obvious. This creates exactly the sort of perception of radical change that said quote talks about.


To illustrate this, imagine you are riding in a car. Imagine also that your only perception of how fast you are going is based on information you are provided (no looking out windows in this case). The car is equipped with a speedometer and a computer which calculates average MPH for the trip. During the first hour of the trip, you are blindfolded and can't read any of the indicators. Then you are allowed to look at them (but nothing else). You note that the average speed for the trip reads 25MPH. Then you note that the current speed is 55MPH. Over the next 5 minutes, you watch these indicators and note that while the average measurement doesn't change, the speed keeps increasing and at the end of that 5 minutes, you are traveling 70MPH.

Would you conclude based on this information that the speed has increased steadily over time and will continue to increase until you crash? Or would you conclude that the speed at any 5 minute period of time varies, sometimes being faster and sometimes being slower? Obviously, the latter, right? You think that the current speed is an anomaly because you can see the exact speed at that time (and the odds of it staying the same as the average over the while trip is very close to zero). But it's your own perception and interpretation that is incorrect. In fact your speed has increased, then decreased, over and over the whole time. You just happened to first start watching the speedometer during a time when the car was traveling much faster than the average.


The point is that we can't say from looking at average increases over a long time during which we were not taking precise measurements what the actual pattern of that time period was. You *always* have to think about the methodology being used. We generate our historical data by taking the smallish bits that we know and then extrapolating across the whole that we don't know. This results in a smoothing of highs and lows just as an average MPH in a car will. You don't assume you traveled that speed the whole time, right? So why do that in this case? The odds of a relatively short period of any measurement we've taken matching an extrapolated average of the past is very very low. Certainly, if we then continue measuring in the present, we will see behavior which will appear to not match historical patterns. It's completely normal and (should be) expected. What's shocking to me is how many people who should know better appear willing to go along with (or even create) hysteria about this.


That's not to say that sea levels aren't rising at a faster rate. But it is to say that we should be skeptical of past data and doubly skeptical of comparing current data patterns to those in the past (which is exactly what you're doing when comparing relative rates of change as in this case). We should absolutely be cautious about making projections based on that sort of comparison. Because in the example I gave below, one might conclude that an hour later, their speed would be 200MPH or so. If they only looked at the data provided that is.

It's bad interpretation of data regardless of what he may believe or not believe. Surely, you can see that?

You'd be surprised what botanists can detect on a chemical level, even in old samples. P680 and P700 photosynthesis use a calculable amount of CO2 and the overall health of the plan can be directly extrapolated from that. We did an experiment back in Plant Physiology II with plans that were raised under happy conditions versus plants that were stressed and we could directly measure the amount of CO2 they were sucking in with a $10,000 gadget hooked up to their leaves. Fun times.

And that would just be one tree. Can you get such data on enough trees, over enough of the globe, over enough years to be able to accurately calculate global atmospheric C02 levels over a period of time? And what about selection bias? Is it possible that the only samples we have require specific conditions and/or specific types of trees? How many 200 year old trees do we have to test, and are they really representative of enough geographical areas for us to actually paint a global picture?

Again, you *must* consider carefully where the data you are using came from when doing good science. Factors that may not matter for one use may be of critical importance for another. Blindly using data you have without taking that into account will drive you to make poor analysis.

The wild fire expert guy says to expect more wild fires in the future. He cites increasing global temps as the reason. In the US, the west is particularly vulnerable.

The statistical analysis of dendrochronology is done with heuristics and uses thousands of samples globally. 200 year old trees are not the norm; they go for the thousand year methuselahs whenever they are available. Since the analysis is done with computers measuring the relative sizes of rings within the same trees rather than absolutes, the species of tree does not matter either.

And since the data is aggregate across thousands of trees, if there are local anomalies, they are blended into the average and a single tree's bad year won't affect the entire worldwide picture.