It’s become harder and harder to maintain the contrarian postion over the past 10 years. Ten years ago I think anthropogenic global warming was considered to be likely, but not conclusively demonstrated, by many climatologists. With another decade of data, resulting in more trends becoming statisically significant, coupled with more information about past climate change and more sophisticated modeling, it has become a virtual certainty.
You will notice, I think, that none of the contrarians in the other threads has a scientific background, or even seems to understand much about how science works at all. Their positions seem to be shaped almost entirely by politics or other biases rather than any real examination or understanding of the data at hand.
Some of them call themselves “skeptics.” Well, it’s one thing to be a skeptic when there is little evidence or support for an idea. But when you continue to maintain disbelief in the face of very strong evidence in favor of sometbing, I think skepticism is no longer the word for it.
This one looks rather alarming, doesn’t it? But notice that the scale doesn’t start at 0. And the statement ‘The industrial revolution has caused…’ is provided without justification. It may be true, it may not be - note that this was the end of the Little Ice Age. Remember that correllation does not imply causation. And if there were correllation and causation, is it actually a good thing, keeping us out of the next ice age? Given the choice between stopping the next ice age and hundreds of millions of people having to move, which would you choose?
Now take that chart and compare it with this one from the same article. Ignore the models and look at the measurements. Notice that the 30 million year filter shows that modern concentrations of carbon dioxide are vastly less than they have been in the past. They’re a fifth of what they were during the age of dinosaurs. Notice also that the actual measurements vary wildly. Does this mean that present CO2 levels are a normal blip? I don’t know.
(End of example)
I find it odd that we’re pumping out so much CO2 and so little remains in the atmosphere. Take note of the various smogs (e.g. London, Los Angeles, Beijing) and note that the pollution remains close to the ground and disappears after a good rain. I feel that we must be affecting the climate (as I said in the other thread, how can we not be?), but I don’t know. And if we are, is it significant? Is it beneficial? Remember that we need some greenhouse gasses to keep the Earth warm. And for all the protestations of the AGW I see plenty of opinions but a distinct lack of actual evidence and a lot of behaviour very much like the religious fundamentalists so decried in other threads. Articles I’ve cited have been ignored when they’re inconvenient. I’ve been called a conservative, and a fundamentalist. I suppose next I’ll be likened to a Nazi. Oh, wait. This is hardly helpful to their cause.
I would just add to Colibri’s very nice point the fact that the extent to which the science has been piling up in favor of anthropogenic global warming (AGW) is also reflected in the changing attitudes of the business community. Ten years ago, the Global Climate Coalition, a coalition of business groups that included companies like BP and Ford, was actively trying to promote the skeptical viewpoint on AGW. Now that coalition has dissolved and companies like BP, Shell, and Ford have publicly accepted the scientific consensus on climate change and, e.g., in the case of BP, have taken significant steps in cutting their own emissions of greenhouse gases. And, now, more and more companies, including power companies such as Duke Energy, are actually asking the federal government to implement some sort of cap-and-trade system on greenhouse gas emissions. And, evenExxon, who has long funded the climate contrarians, has been subtlely changing its tune and there was some story that they were trying to get involved in talks about how such a trading system on greenhouse gas emissions would be implemented…so it looks like even they may be accepting the inevitability of this.
I expected that someone might question how much warming the increased CO2 levels in the atmosphere would produce but I must admit that I didn’t expect that anyone would question the cause and significance of this rise in CO2 levels itself. That the CO2 levels have increased due to the burning of fossil fuels is known beyond a shadow of a doubt.
First of all, although correlation may not imply causation, it would truly be a coincidence of monumental proportions that CO2 levels suddenly started increasing in the last couple of hundred years to levels higher than the earth has seen through the last ~7 ice age-interglacial cycles going back about 650,000 years (over which we have excellent data from ice cores) and likely higher than levels the earth has seen in 20 million years just at the time when we started to put significant amounts of long-trapped carbon back into the atmosphere in the form of CO2 through the burning of fossil fuels! [I believe that the rate of increase, by the way, is also unprecedented over the period that we have good data for.]
Second of all (and despite your statement in regards to how little of the CO2 remains in the atmosphere), in fact the increase in CO2 is of a similar magnitude as the emissions of CO2 from the burning of fossil fuels. The increase is about half of what one would expect if all of what we emitted remained in the atmosphere, thus demonstrating that various “sinks” such as the oceans, land, and biosphere are able to take up about half of the excess.
Thirdly, one can actually look at the changing isotopic distribution of the carbon in the CO2 and see the signature of the carbon from fossil fuels (which is depleted in one of the isotopes, I believe).
As for whether we are stopping the next ice age, the general belief is that the next ice age would not have come for another ~40,000 years. However, there is a minority viewpoint, a hypothesis by Ruddiman, that we would already be descending into the next ice age were it not for the CO2 that humans started releasing ~8000 years ago when we started agrarian societies (with clearing of forests, cultivation of rice paddies, and such causing some CO2 release). A few contrarians have embraced Ruddiman’s hypothesis because it makes humans seem like we are the “heroes” rather than the “villians”. However, this makes for a case of rather strange bedfellows since Ruddiman’s hypothesis appears to require that the sensitivity of the climate to CO2 be near or above the high end of what it is commonly believed to be. This would imply that the climate change we will produce by our much larger and more rapid increase in CO2 levels through the burning of fossil fuels will be worse than expected. And, even if humans accidently saved themselves from another ice age, it does not imply that it is perfectly okay to pump as much CO2 into the atmosphere as we are able (and, far beyond what is needed to delay the next ice age for at least a very long time). As an analogy, you need water to survive but the cops probably wouldn’t accept that as an excuse if I immersed you completely in water!
As for the CO2 levels if you go back tens to hundreds of millions to billions of years, yes, it is true that CO2 levels were higher back then. (And, by the way, the reason the data is so noisy is that ice core data, which provides a very accurate measure of CO2 concentrations, only goes back about 650,000 years and after that we have to rely on much less accurate sources to estimate the CO2 levels.) However, the climate was also much different during some of these eras. For example, Wyoming apparently had tropical vegetation at some point back then. Noone is saying that the earth can’t survive these changes or that they unprecedented in the full 4.5 billion years of the earth’s history…but merely that it may not be the wisest thing for our own species (for which they are unprecedented!) and many other species. And, the danger now is also the rapidity of the change and also, for other species, the fact that we have fragmented habitats and otherwise stressed various species. [Colibri can presumably speak to this issue much more than I can.]
Quartz, I understand that everyone cannot be an expert on everything. However, don’t you think that in the absence of being an expert on something, it might sometimes be wise to listen to the vast majority of the expert opinion on a subject, rather than remaining stubbornly agnostic? Surely, there must be cases in your own life when you would do this…e.g., when you have a medical issue, do you generally give equal weight to the opinions of a tiny minority of the medical profession over the weight of what most of the profession would tell you?
Indeed, at some point you’re going to have to acknowledge that there are limits to your knowledge even in the field in which you nominally practice. The trick then is to discern between what is consistent internally and with your base of knowledge. This is true in any field of ongoing development.
We can’t establish as abosolute, inviolate fact that carbon emissions are the cause of the recent global warming trend in the sense of tracking a cloud of emissons and measuring the effects; it just doesn’t work that way because the system is too big and complex. However, we can combine an analysis of incidental correlations with numerical models that simulate, on a sufficiently fine level, the behavior of climate systems. When those models become sufficiently refined that we can use them to predict past and future behavior, we develop a confidence that the model is valid, at least within certain parameters. We (or I should say, computational climatologists) are at the point of trying to develop that confidence, hence, considerable disagreement on the magnitude and duration of change, but there is an overall consensus that anthropogenic climate change is occuring and represents a significant shift from anticipated trends.
The thing is that **Quartz ** is no newcomer to these debates. He’s certainly familiar with these issues, and has had them explained to him patiently over and over again. I don’t know why he seems to be so completely uneducable on the issue. Rather than a skeptic, Quartz seems to be one of the true Fighting Ignorant.
Here’s several previous threads in which aspects of global warming are discussed in which Quartz has participated. They also contain a wealth of information from jshore and many others to which Quartz, as per his name, seems absolutely impervious:
Alrighty then. In that vein (no pun intended, Quartz), I showed this thread to a contrarian family member of mine. She directed me to this, a 53-minute video of a lecture by a Dr. Art Robinson. This is the same guy who organized a petition, signed by 17,100 scientists, saying that anthropogenic global warming is bunk.
Anyway, this family member and I sat and watched the whole damn thing. Now, granted, it’s over five years old. But I come away from it a bit confused again (back to square one, I’m afraid).
If you’re interested in watching it, you can skip the first 5 minutes or so. Go right to where he starts putting up slides. And if you’re Colibri, or any other serious biologist, you’ll want to avoid the last 7 minutes or so, where he discusses how increased atmospheric C02 actually helps ecosystems. Not that you can’t handle it: I’m just concerned about you laughing yourself off your chair and sustaining injury.
But beyond the rubbish, he presents some interesting points. Just a few of them:
He puts up a graph of solar cycles plotted against global temperature trends. They match up almost perfectly, including the upturn during the end of the 20th century.
He says that water vapor also acts as a greenhouse gas. He puts up a graphic showing water vapor’s effect on global temperatures as compared to CO2’s effect on global temperatures. On the graphic, CO2 is dwarfed. (One immediate problem I see with this is that water vapor in the atmosphere condenses into clouds, doesn’t it?)
He addresses the computer models by showing a bar graph. There are, I think, four bars filling the whole graph, and each one represents the uncertainty produced from a different environmental variable (one is ocean temperatures, one is cloud cover, etc.). And the fifth bar on the graph is maybe 5% the size of the others, and it represents the degree of CO2 complicity in climate change that the scientists are trying to determine. (Possible counterargument: perhaps computer modeling has advanced in the last 5 years since this lecture was delivered?)
He spends a lot of time discussing the degree to which the climate has or hasn’t changed. I had understood this to be a foregone conclusion. One compelling point he makes on this front, though, is that anthropogenic climate change(ACC) proponents like to say that “the 20th century was the warmest century in thousands and thousands of years.” He shows that all the temperatures pushing the average up occurred in the '30s and '40s, while 80% of carbon emissions happened after 1940.
All the cool kids seem to be on the pro-ACC side of the debate. I’d like to be too, so can someone please debunk this for me? It does not count as debunking if you just say that so-and-so many thousands of scientists have voted that such-and-such is the case. As the guy in the lecture points out, science is not decided by vote, but by truth. (Kind of strange coming from the guy organizing a petition. But whatever.)
(P.S. My anti-ACC family member does not accept cites from the IPCC. Very frustrating for me, since most pro-ACC stuff eventually traces its information from them. She says that, yes, the IPCC may be composed of thousands of reputable scientists, but all the reports produced by the organization are written by the same ten-or-so extremely biased individuals. Whatever. Anti-IPCC and anti-UN sentiments seem to be pretty common amongst the anti-ACC crowd. I’ll accept cites from IPCC, but if you must cite them, could you pretty-please also cite a non-IPCC source as well?)
Sorry if this seems a silly question, but I’m not up on the hard science myself, and this is something I think about from time to time.
You hear about all the disasters that might happen in a century or so with the rising temperatures. Are there any models that predict the possible extermination of the entire human race from global warming? Maybe even something like what some think might have happened on Mars, with the atmosphere just blowing out? How likely is it that no matter how bad it gets, it’s ultimately something that humans can eventually adapt to and will settle down into new patterns?
I just wanted to interject that Mars’ atmosphere getting stripped is seemingly a result of the loss of its magnetic field, Siam Sam. Here is the wikipedia article, with well-cited atmosphere and magnetosphere sections. Earth won’t face anything like that (not for another billion years or so, when increasing solar activity will start boiling off the oceans*). As for what is most likely to happen in the nearer-term, jshore and Colibri have covered that quite ably.
*intriguing, but without cites it might as well be scifi
“The time has come,” the Walrus said,
“To talk of many things
Of shoes, and ships, and sealing-wax,
Of cabbages, and kings,
And why the sea is boiling hot,
And whether pigs have wings.”
That, and the fact that the amount of water vapour in the atmosphere stays relatively stable, globally. There isn’t vast quantities of new water being produced and injected into the system. The same cannot be said for CO2, which we are pumping out at prodigious rates.
As a species? Almost certainly not, unless there is some kind of severe runaway feedback mechanism of the sort that AFAIK is generally considered extremely low-probability in current climate models. As in: accelerated warming from rapid glacier calving and loss of albedo is accompanied by decreased CO2 absorption capabilities in oceans, rain forests die, oceans rapidly acidify, devastating droughts and severe weather essentially eliminate agriculture. Final scenario: anything from an almost-complete human extinction except for a few surviving pockets of populations in areas that lucked out in terms of food-species survival, to absolute extinction due to a sudden change in composition of the atmosphere to the point where it’s actively poisonous to humans.
This is not going to happen. At least, in the sense that I’m not going to win the multimillion-dollar lottery jackpot. Both outcomes are theoretically possible, if we assume a whole heap of highly unlikely events and strained coincidences. But as far as we now know, they are so unrealistically improbable that it isn’t worth seriously considering them.
However, just because the worst-case scenario of total human extinction is massively unlikely doesn’t mean that climate change can’t be a serious threat in other respects. Severe droughts, floods, storms, sea level rise, decline of various food species and decreased agricultural yields have the potential to kill huge numbers of people. And all of them have been identified as probable consequences of some not-too-distant level of greenhouse-gas-driven global warming. We certainly can’t predict for sure exactly how global warming will change global climate, but we have no reason whatever to assume that all the effects will be either positive or negligible.
By the way, Arthur Robinson is not a climate scientist, and has been severely criticized for misrepresenting research on climate change:
What kimstu said. The only real sense in which I personally worry about the human species driving itself extinct…or maybe not extinct but really severely messing itself up…is through some sort of thing like a big nuclear war and probably the closest we have come to that is the Cuban missile crisis. To the extent that global warming might cause stresses that lead to more fights over resources and such, I do worry that it increases the odds that humanity will have such a major conflagration, but obviously estimates of that sort of thing come down to your guess being as good as mine.
Randy Selzer: I do have lots of comments in response to what you wrote summarizing what was said on the Robinson video but that will have to wait for when I have more time!
Who is pigheaded? Me? I’m trying to fight my ignorance here. I don’t think that counts as ‘pigheaded.’
Thanks for the info. I figured there was probably something out there against him, and the info on the blog you reference does make him look pretty slimy. But what I really want is something to refute his scientific arguments, not just vilify him personally. And speaking of which…
I think Bridget was talking about GW skeptics in general, who often display quite astonishing levels of pigheadedness, as you can see in theseGD threads and this Pit thread, all currently ongoing.
Here’s a start at some response to the points in that video.
Well, I am not sure exactly what source he is getting it from but the most reputable paper purporting to show such a connection was published in 1991 by Lassen and Friis-Christensen that compared temperature and sunspot cycle length. However, in 2000, Lassen and a colleague updated the plot and discovered that the correlation that they had found broke down starting around 1980, with the temperature continuing to rise while the sunspot cycle length leveled off and fell. Here is a discussion of this:
It’s also worth noting that the extent to which the correlation was significant even before ~1980 remains controversial (even though scientists generally agree that the sun was playing an important role in climate fluctuations back then). Here [PDF file] is a paper discussing problems with the various correlations that have been claimed between temperature and some sort of solar measurement. (Here [PDF file] is a paper by one of the same authors with more details.)
Well, there are a number of issues to point out here:
(1) It is true that water vapor acts as a greenhouse gas and that it gives a larger contribution to the natural greenhouse effect (which warms our planet by about 30 C from what it would be otherwise) than CO2. Although how much it dominates over CO2 is sometimes exaggerated…It is not completely straightforward to calculate how much each contributes since the effects are not strictly additive. I.e., if you start with the atmosphere without either gas and then add the CO2, you get a larger number for how much it warms than if you start with the atmosphere with water vapor already present and add CO2 (see [for details).
(2) The reason why we are concerned about human additions of CO2 to the atmosphere and not human additions of water vapor to the atmosphere is because humans can directly affect the amount of CO2 in the atmosphere whereas we cannot have a significant direct effect on water vapor. The reasons for this are two-fold: First of all, there is more water vapor already in the atmosphere than CO2 and it turns out that the climate forcing goes as the logarithm of the concentration which means that what matters is not the absolute change in concentration but the fractional change in concentration. To get the same fractional change in concentration, you would have to add much more water vapor than CO2 (even in the absence of any processes that remove it from the atmosphere). Second, and even more important, is the fact that the lifetime of CO2 in the atmosphere is much longer than for water vapor. CO2, very roughly speaking, has a lifetime of ~100 years (although there is actually a long tail so that a significant fraction…like 25% of the CO2 that we add) will stay around for thousands of year (see [url=RealClimate: How long will global warming last?]here](]here[/url)). By contrast, water vapor takes about a week to “rain out”. The net result of these different lifetimes and concentrations is that the amount of water vapor in the atmosphere is essentially determined by the temperature and we cannot significantly change it by adding water vapor to the atmosphere in any amount that we could realistically contemplate doing.
(3) Having told you that we can’t directly affect the amount of water vapor in the atmosphere, I now need to add that we can indirectly affect the amount. By adding CO2 to the atmosphere, we cause warming and then because the equilibrium vapor pressure of water rises strongly with temperature, this means more water evaporates and its concentration in the atmosphere increases. And, because (as Dr. Robinson has correctly pointed out) water vapor acts as a greenhouse gas, this causes a further increase in temperature. This is what is known as a “positive feedback” effect and is in fact the most important one. I think estimates are that it about doubles or triples the amount of warming that would occur due to the increase in CO2 alone. In fact, you can often tell the difference between global warming skeptics who are really trying to snow you on the science and those who are being a little more honest about the science in that the former try to point out that water vapor is a greenhouse gas whereas the latter (e.g., people like Richard Lindzen) try to downplay it or, more specifically, come up with reasons why the water vapor feedback doesn’t occur.
