I posted this on Quack's in the (perhaps vain) hope that the discussion will focus more on philosophy of science and on hypothesizing explanations than on political screed. Please find one of the myriad West Mall threads if you wish to talk about politics. The trends for atmospheric CO2 (direct 20c and 21c measurements as well as ice core sampling indirectly to measure past values) tend to correlate well with the trends for our best estimates for recent and ancient global mean temperatures. It would seem reasonable to me that some combination of (1) CO2 levels influence temperatures, (2) temperatures influence CO2 levels, (3) some other factor(s) acts on both temperatures and CO2 levels is true. The current scientific vogue, not without its skeptics, is that (1) above is the driving causal relationship. The hypothesized reason relates to absorption spectra for CO2(g) and their relative maxima in bands emitted from earth's surface features compared to levels averaged through the overall incident radiation from extraterrestrial sources. Hence incoming energy transmits (more) effectively, while outgoing is (more) scattered, partially back at us. Tests for hypothesized explanations can be devised observationally or experimentally. As earth is a system too massive and complex to replicate or control experimentally, tests for our theories are apparently best conducted observationally. Any experiment purporting to simulate a controlled change to only one variable with regard to earth's entire collective thermodynamic state will certainly meet my extreme skepticism, to say the least. Experiments short of such control are merely contributory to plausibility as a factor but can never demonstrate causality. Designing an observational study to separate causality from other forms of correlation really amounts to probing for effects absent their purported cause, and vice versa. Exhaustive data in which A inevitably precedes or coicides with B in a fixed pattern is strong circumstantial evidence for a causal relationship. Significant data showing A without B shows that A doesn't always cause B, while B absent A demonstrates that at least one other factor can cause B were A never to occur. Most of the data I have seen for sea level measurements (a number of interest as catastrophic rises in sea levels are one of the feared consequences of GW and hence GHGs) show some fine noise, but a linear trend upward throughout the 20th century, conspicuously without an interruption in the middle of the century. Best estimates for mean global temperature seem to reach a period of relative maximum circa 1940 which is not restored again until circa 1980. In other words, decades pass without warming, but sea levels maintain their steady upward march. Only a fool would argue that heat does not melt ice and water (including freshly melted) run down to the sea, but a vast collection of empiric data suggests that no powerful causal relationship exists between temperature changes of the magnitude we are studying and sea levels as we are able to measure them. Turning our attention to the relationship between CO2 levels and temperature, we are left with the same question: how did CO2 in the atmosphere rise so steadily for so many years without even maintaining the same temperatures? How did it take until almost 1980 to get back the warmth of the 1940s in the face of ever more GHGs? Sea level can be affected profoundly by other factors, but for the 20th century, it mirrors CO2 levels better in a sense than either value relates to temperatures. Let me say that I still do not have a well-formulated answer to exactly what interplay exists between CO2, temperatures, and sea level. How much is rotational velocity of the earth involved? Specific bands of extraterrestrial radiation or overall incident energy density? Complex consequences of (not always apparent) tectonic forces? Anthropogenic changes, possibly in ways we do not currently suspect? Anyway, I have rambled long enough.
A lot of my own research into the subject had shown that while warming is real, it is a way more complicated process than just "CO2 makes the earth hot." It is funny that you bring up 1980, since that is when Mt. St. Helens erupted. Mt. St. Helens threw more green houses gases, the majority of which were CO2, up into the air than mankind had created in his entire "industrial" existance. The last mini ice age was caused by volcanic activity, just to show how a volcano can either heat or cool an earth depending on its compisition. My opinion is that it is too soon to be running to the hills over global warming. In fact, we could stop emitting all CO2, become a carbonless society, and the temps could keep rising. If the earth is going to heat up, there is nothing we can do about it. The earth has had life sustaining climate for millions of year, yes we only reference back to the last 40,000 years. Not a very telling or broad sample, IMHO.
I will save my opinion for the highest bidder. When I was in school we were warned about an Ice Age . It would be nice to get the real deal from people but it won,t happen it is , I believe, all about politics now and not fact.
I see your point, but... As it was explained to me by my geology teacher, we have been pumping out that much CO2 for only a couple hundred years, while volcanoes have been doing it for hundreds of thousands of years (anything earlier than that has been fully absorbed by the ocean or plant life). We will eventually catch up, though...
I'm unclear as to why it matters. We're outpacing volcanoes by anywhere from 30 to 150:1 in terms of CO2 output each year, so they're nearly negligible. Man is the one changing the atmosphere right now, and with that we can expect climate changes.
After reviewing all the possible causes of ice melting/sea level rising, soot appears to be the largest contributer to the glacial melting we see rather than CO2.
all I know is that in the 70's everyone thought another ice age was coming soon...so one could surmise that we don't really know a whole lot, or we were really wrong
The earth has been around (not trying to get into theological discussion, mind you) for 4 billion years. If the life of earth was a 24 hour day, man came in at 2 seconds until midnight. There is no way that we can develop patterns of climate change with such a small sample. Plus, we don't have anything similar in our solar system, so we don't have a control sample, either. Humans are adaptive by nature and as soon as technology permits, we will make the appropriate discoveries necessary to better the planet.
"After reviewing all the possible causes of ice melting/sea level rising, soot appears to be the largest contributer to the glacial melting we see rather than CO2." Do you have a reference for this statement, or are you basing it on your own research?
If you want to read what scientists say about global warming read the report from the National Academy of Science: The Link or you can rely on Rush Limbaugh, James Dobson, and other self-acknowledged experts on climate change.
The farthest back those graphs go is 150 years. Not a big enough sample, IMO. Lets try and keep politics out of it. Edit: Missed a graph. The graph on page 5 shows we are par for the course...
"The farthest back those graphs go is 150 years. Not a big enough sample, IMO." There are other lines of evidence (e.g., ice cores) that go back much farther than 150 years. "Lets try and keep politics out of it." Politics is already 'in it'. Science denial, whether you're talking about climate change, creationism, or stem cell research, is the province of the political right.
I have been reading lately that our current trend is pointing toward a cooling phase. What then? (point being, as posted above, that our sample size is entirely too small to know what exactly is happening yet)
The planet is ever changing. For us to be able to keep the earth at a constant climate during the duration of our existence would be a huge scientific accomplishment. The fact that we are even having this discussion is evidence of how far the human race has come as a whole. I am confident that when a final, indisputable scientific conclusion is reached, we will take the steps necessary to preserve ourselves. It is human nature... I mean, we outlasted the neanderthals for a reason, right?
"I mean, we outlasted the neanderthals for a reason, right?" 35 thousand years isn't really all that long. We may not make 36K.
A few notes from the NAS document: 1. It is a nice explanation of the popular theory regarding GW/CC in lay language. A few of my comments might be answered if I looked up all of the underlying, more technical, papers. 2. Figure 3 is a great graphic to demonstrate the related nature of CO2 and temperature. There appears to have been a rise in CO2 (less than "modern" but still significant) over the last 5,000 years without a concomitant warming trend. At some points (e.g., ~57k and 66k years ago) CO2 and temperature appear to react in synchronization, while at others (e.g., 110k-120k years ago) the temperature effect precedes the CO2 effect by thousands of years. This graphic is much better evidence of a shared cause than of GHGs changing T. 3. Also looking at figure 3, it appears that the latest warm period was later than expected and cooler than expected based on previous temperature spikes. Are we "due" for some more warming based on a cycle that predates civilization by at least hundreds of thousands of years? 4. Figures 2 and 8 demonstrate the anomaly I mentioned in my original post: increasing CO2 with decreasing temperatures in the mid-20th century. 5. Figure 4 states, in part, "After 1950, the temperature rises can not be explained by natural causes alone." This is science of the worst sort. This is like saying the lights in the sky can not be explained without the effect of alien spacecraft. Unexplained is very different from inexplicable. In fact, explanations are out there, varying in likelihood from laughable to possible. Assuming, arguendo, that CO2 is the principal agent responsible for the temperature variability in earth's atmosphere (and elsewhere), are there strong reasons why the timing of its effect varies so greatly? While even the most strident skeptic will have to concede the strong correlation between data for temperatures and CO2 levels, the correlation is imperfect. Is the Vladivostok data defective, or can CO2 elevations really cause temperature changes that precede them by 5000 years? Here is one thought I had: perhaps the CO2 variation is normally an effect of temperature changes (through some mediator such as greater proliferation of mature forests and animal life). At sufficiently elevated concentrations of CO2, though, it feeds back positively on the temperature which caused it. At higher levels still, and at higher temperatures, negative feedback mechanisms drop the temperature. In this case, the important question might not be whether we are emitting too much GHG material, but rather what (else?) are we doing that might be altering earth's capacity to engage the negative feedback. It also still leaves open the possibility that we are flattering ourselves regarding our power over the environment.
KGP Another reference you will like is a summary of the scientific group work under the recent UN study, made popular/unpopular by its policy arm work. At any rate, Sci. Am. published a very accessible summary in August. You can get it from their website. The modeling work is presented in sensitivity and probablistic format, not rhetorical arguments. Its fairly persuasive, IMHO, that we, the US, ought to be acting with some responsibility, along with others. That is, Houston, we may have a problem. Here in Honolulu this week, the paper showed a map of what Waikiki would look like with a sea level rise of 3 feet. I wouldn't be buying any condos (there).
