Here is a fairly recent summary of solar effects during the modern global warming period. (Conclusion: solar trends have been pretty much flat since the mid-20th century, which fails to explain the late 20th century warming.)
That was from memory, I think from Lean's 2000 reconstruction in GRL. I've heard that Lean is no longer the favored reconstruction, but it's not off by an order of magnitude, that's for sure! I think you must be misremembering the figure. 3% is like a 40 W/m^2 change in irradiance. I've never heard of any reconstruction giving anything nearly that large between the Maunder Minimum and today.
Plugging it back into the StefanBoltzmann law, we need an increase of only 1.003^4=1.01205 times in solar output to _fully_ explain it. That's 1.2% btw. However, over the last 150 years or so, solar irradiance has only increased by about 0.1% (from ~1364.5 to 1366 W/m^2, IIRC).
As an aside, your new link (I only read the abstract) indicates that CO2 will increase surface temperature, but that aerosols counteract it and they believe that, in the end, the aerosols would overpower it. I've heard of studies (read: no link) that, IIRC, indicate that global warming would already be more severe if not for the affect of man-made aerosols in the atmosphere. Yes; see here for a recent discussion.
Seems to me that the linked article may not really be incorrect. Their basic point is correct: large amounts of aerosols do produce large cooling. They didn't claim that aerosols would quadruple, but that if they did, we would experience up to 3.5 C cooling. However, their estimate was off because they assumed a greenhouse effect which is about 3 times weaker than current estimates. If you factor in GHGs as well, the cooling wouldn't be as large as what they estimated. (Actually, I haven't checked their aerosol cooling estimates either, so it's possible those were off too.)
The original poster is confused. The expected effect of global warming is that both summers and winters will warm, with winters warming faster than summers. However, there may also be more short-term extreme events (heat waves and cold snaps), although with extreme highs more likely than extreme lows.
But how is it that man is causing the supposed temperature rise? The enhanced greenhouse effect.
I lived in the same area for 30 years and the summers still have 100+ degree days, and the winters are still freezing cold. If this is suppose to be global warming, where is the warming? Over the last 30 years, there has been less than 1 degree F of warming, globally. It's questionable whether you would notice that in the daily temperatures unless you looked at the historical trends. Even then, not all locations warm at the same rate, and not all of them warm at all. There is just more warming than cooling. here is a map showing the amount of warming in the last 30 years relative to the previous 30.
Rather than letting the UN decide to ban DDT, how about we let the people affected decide if they want it banned. Why not ask them? Yeah, why not ask the people affected? But you didn't ask them. You cited an organization of African Americans talking about DDT in Africa. Why not ask the actual Africans? If you did, you might learn that DDT is not banned in Africa, and that both WHO and USAID recommend limited, targeted DDT use in anti-malarial campaigns. You might also learn that excessive DDT use in Africa has lead to malaria-resistant mosquitoes (particularly in west Africa), and that anti-malarial organizations in those countries recommend moderating DDT use and mixing it with other measures (netting, artemisinin-based combination therapy, etc.). The very web site you link admits that DDT is not banned in Africa for anti-malarial use.
So, tell me, how many millions have died due to "a ban on DDT"? Please be sure to cite the scholarly literature to support your answer.
Methinks you need to find qualified sources. I've read the Newsweek article. It's a scare piece. Despite its dire insinuations, it says virtually nothing about actual scientific studies predicting an imminent ice age. Read it here.
The Newsweek quote above is a fine quote about how the climate cooled in the past — which it did! But that's got nothing to do with whether we were supposed to be "in an ice age right now".
In another comment, you cite Rasool and Schneider. Do you know why you cited Rasool and Schneider? Because that's pretty much the only paper published in the 1970s which predicted large cooling in the near future. The rest were generally either predicting warming, or were agnostic. See here for a literature review.
For that matter, have you even read Rasool and Schneider? Their prediction of strong cooling was based on their assumption that atmospheric pollutant emissions would outpace greenhouse gas emissions. In other words, their main error was not in the climate science, but in their economic/industrial forecasting. (True, they lowballed climate sensitivity as well, but that doesn't imply any cooling, just less greenhouse warming.) Their fundamental climate point was RIGHT: if aerosol emissions really had accelerated they way they speculated, they WOULD have a large cooling effect. In fact, that idea has been floated again recently as a means to combat global warming, under the name "aerosol geoengineering". (There turn out to be undesirable side effects.)
So, tell me, where are all the scientific studies predicting that "we should be in an ice age by now"? Be sure to cite the scholarly literature. And shall we ignore the studies which predicted the opposite?
I wouldn't be surprised if it screwed up the laws of physics and some other fundamental constants, but I'm not a physicist and thus can't attest to it. You're fighting a lost cause. Slashdotters have been pointing this out to him for years, but he just ignores it and repeats the same claims a few stories later. That doesn't keep him from hanging around dead threads for days and weeks coming up with new bogus arguments, though.
Also, I was NOT looking for anything involving global warming, which is why I was so surprised that every source came back to the same point, that temperatures are NOT as warm as they were pre-Little Ice Age Yeah, right. "Every source". Except the majority of the paleoclimate literature.
Tell me, how did you find these sources? Googling "Little Ice Age" and reading skeptic web sites?
(just one example of this is the fact that there were once large vineyards in places that are now too cold to grow grapes, which would NOT happen if we were as warm or warmer as things were pre Little Ice Age). Tell me, where exactly did they grow grapes 1000 years ago that they can't grow today?
Yeah, I've heard that one all the time from skeptics. In fact they're the only one who claim that this proves that the climate was warmer than today, which tells me exactly how "unbiased" your research was. "The Romans grew grapes in England!" You know, people STILL grow grapes in England today.
But you made a much bolder claim than that. You claimed that the climate 1000 years ago was 5 degrees warmer than today. Where is the evidence for THAT? Please, be specific. If you're going to make a quantitative claim you need to provide a quantitative estimate.
You show one source that doesn't match what I found, when I had over half a dozen scholarly sources that did. Um, let me clue you in: the IPCC is the world's leading organization for summarizing climate research. Its assessment reports do not contain one study, but rather a scholarly literature review of the entire field. There are fare more than "half a dozen" sources cited in the IPCC reports. Evidently you didn't even READ the source I cited, or you would have noticed that. And we're supposed to trust your research skills?
It seems pretty obvious that you're pushing an agenda instead of just looking at the evidence. What a hypocrite you are.
You claim support from tons of "scholarly papers", which you can't seem to cite, and yet you don't even know what an IPCC report is. It's all too obvious that you weren't researching unbiased sources.
you'd come up with some bogus reason as to why they're not valid (like in Liar Liar "Objection your Honor!" "On what grounds?" "Because it's devastating to my case!") Right. I call you to back up your claims, you can't, so now you have to invent reasons why simple things like supporting your arguments aren't worth your time. Why, if you had to do something absurd like citing scientific research which supports your conclusion, I'd just come up with some "bogus" counterargument. (Here, "bogus" of course means "refutes your position".)
I can tell you, from what you've said here, I am not in the least worried about you producing a "devastating" case.
Feel free to do some research on the Little Ice Age and NOT on global warming, I referred you to an entire chapter which discusses paleoclimate, not modern climate.
The best explanation is that anything related to global warming is mostly about politics and personal agendas and not about science. Very convenient. First you forget all the scientific references which happen to support your views, and then you claim that you arbitrarily large amounts of scientific evidence can be dismissed on the grounds that it's based on "politics and personal agendas", and then you tell ME that I'm being biased!
Hypocrite.
No one has a political agenda about a natural event that happened hundreds of years ago. You've got to be kidding me. That's practically all the skeptics argue about: "natural events hundreds of years ago prove there is no manmade global warming today".
It may be true that through cloud cover and pollutants, the atmosphere would reflect varying amounts of sunlight. If this effect were significant for the long term, then the temperature of the oceans must change to track this. It is likely not significant in the long term, insofar as it causes large and sustained changes in climate by itself. However, these effects (water vapor, clouds, etc.) do amplify other long term sources of warming (solar, greenhouse effect, etc.) The feedbacks are fairly significant (at least as large as the forcing itself). The feedbacks themselves have fast dynamics, but since they're always around, they can continually modulate other, long term radiative imbalances.
(The atmospheric feedbacks, by the way, include not only alterations in the reflection of sunlight, but also in the trapping of outgoing longwave radiation.)
So far at least, the measurements of ocean temperatures are remarkably constant. Ocean temperatures show the penetration of heat into the ocean from the surface which is expected from the known radiative forcings (mostly GHGs). But yes, they have been fairly constant, because of the large heat capacity of the ocean. This is why the ocean delays the warming seen at the surface on land.
Whatever "forcing" theorized to be taking place, is not having a significant effect on the oceans and therefore the Earth as a whole. I don't know what "significant" is supposed to mean, but measurable quantities of heat have been taken up by the ocean during the 20th century (on the order of 10^23 J), this has already had an effect on global surface temperatures, and will continue to do so until the climate comes into a new equilibrium. Even if the forcing ceased, the planet would still warm for a while as the oceans continue to heat up. (See here and here.)
From actual measurements, this balance has not changed much for our planet as a whole, at least as far as we can tell over the short time we have been measuring. Over the last century or so, it has changed by a few watts per square meter (averaged over the surface area of the Earth) top-of-atmosphere, or by maybe 0.5% of the total incoming flux. 0.5% is not "large", but it's large enough to raise the temperature of the planet by about a degree (or, roughly, 0.3% of its absolute temperature).
If that statement were true, the Gulf Stream would not have much of an effect on the Northern European climate. I'm talking about the change in equilibrium global temperature in response to an external forcing. Local temperature patterns are certainly influenced by ocean circulations, but the amount of change in global average temperature due to a radiative imbalance is primarily determined by the forcing and the atmospheric feedbacks.
Compared to water, air has very little heat holding capacity and therefore affects climate only locally, not globally. I'm not talking about the heat capacity of the atmosphere. The atmosphere has a small heat capacity, but a large effect on the Earth's radiation balance. Your conclusion is false, because the atmosphere has global influence on climate other than through its ability to store heat for long periods.
It is the moisture held in the atmosphere, not the air as such that determines weather patterns. I wasn't talking about "air", I was talking about the atmosphere.
Still compared to water itself, even the most moisture laden air contains only a small amount of heat energy compared to an equivalent volume of water. Again, this misses my point.
Therefore, unless the temperature of the oceans change significantly, the overall temperature of the Earth will not vary by much. I think we are talking past each other.
I agree that the oceans moderate the response of the climate to an external forcing. I'm just saying that the ultimate magnitude of that response is determined by the size of the forcing and by the strength of feedbacks which are primarily atmospheric in nature.
The Little Ice age only ended roughly 150 years ago, and we're still warming back up from it. To the contrary, 20th/21st century natural sources of warming (e.g., increased solar activity, decreased volcanism) do not agree with the recent warming in timing, rate, or magnitude.
Temperatures in Europe are still several degrees C lower than they were pre-Little Ice Age (which started between 1350-1450). Provide a citation. This disagrees with the conclusions of the 2007 IPCC assessment report (WG1).
There's plenty of evidence to support this from many universities and various environmental research groups. Then it should be easy to provide such evidence, shouldn't it? Why haven't you?
If the predicted effects of an increase of 5 degrees C are so catastrophic, how come we weren't wiped out 1,000 years ago when temperatures ACTUALLY were where they're predicted to go? Temperatures 1000 years ago were not 5 C warmer than today.
I had to do some research on the Little Ice Age a few years ago and every single source I found came back to the same thing, that we're still warming back up and that it's still significantly colder than it was 1,000 years ago. "Every single source"? You mean every skeptic website? Maybe you should look just slightly harder for a source that doesn't agree with your claims.
Disclaimer: No, referencing research by various groups that contradict "the sky is falling" mentality of global warming is NOT flaimbait. Except you haven't even done that much: you referenced no actual research, just made a bunch of unsupported claims. But hey, we all know that preemptively invoking moderator persecution usually results in comments being modded up.
No, we will most likely not have a huge catastrophe that destroys mankind. Who is claiming that we will have a huge catastrophe that "destroys mankind"? Perhaps you should read this about the likely impacts of climate change.
The hydrosphere strongly influences the rate at which the globe warms, but doesn't strongly control the total amount of warming which is ultimately experienced. The latter is controlled by external radiative forcings, as well as feedback factors which are mostly atmospheric (plus some slower ice and terrestrial vegetation albedo feedbacks).
Yes, CO2 fertilization is a negative feedback on climate, i.e., it helps to stabilize climate. The problem is that we are still emitting CO2 much faster than even a faster-growing terrestrial biosphere can sink it. Vegetation may slow CO2 increases, but it is projected to be centuries to millennia before it can significantly reduce CO2 levels. Indeed, there is some debate that the terrestrial biosphere may switch from a source to a sink (since there are other effects, such as higher temperatures causing rotting wood and carbon in soil to decay faster).
I think many alarmists forget that Earth was once significantly warmer than it is now, and had significantly higher levels of atmospheric CO2 than it has now. Was the Earth a desert? Hardly. The Earth was an even greater oasis of life than it is now. The warm Earth gave us the dinosaurs, and all the massive vegetation required to support such enormous animals. Hey, you might want to live in a Cretaceous climate, but I don't.
We are still living within these natural trends, which we puny humans are powerless to stop or alter in any way. [citation needed]
Well, if that isn't begging the question, I don't know what is. But try reading this.
This is why I oppose ALL of the proposed "solutions" to the "anthropogenic climate change" hoax. EVERY ONE of them, without exception, leaves us in a weaker position to weather change than if we did not follow them. [citation needed]
They all propose some sort of socialistic or communistic top-down managed approach, FORCING people to alter their lifestyles in some vain attempt to "live green". No, they attempt to correct a market inefficiency by accounting for a heretofore unrecognized externality. See, e.g., the work of Pigou, which is the basis for the solution advocated by most card-carrying economists who work in this field. (Cap-and-trade is another, albeit more easily gamed approach.)
I think many alarmists forget that Earth was once significantly warmer than it is now, and had significantly higher levels of atmospheric CO2 than it has now. Was the Earth a desert? Hardly. The Earth was an even greater oasis of life than it is now. The warm Earth gave us the dinosaurs, and all the massive vegetation required to support such enormous animals. Hey, you might want to live in a Cretaceous climate, but I don't.
We are still living within these natural trends, which we puny humans are powerless to stop or alter in any way. this.
This is why I oppose ALL of the proposed "solutions" to the "anthropogenic climate change" hoax. EVERY ONE of them, without exception, leaves us in a weaker position to weather change than if we did not follow them. [citation needed]
They all propose some sort of socialistic or communistic top-down managed approach, FORCING people to alter their lifestyles in some vain attempt to "live green". No, they attempt to correct a market inefficiency by accounting for a heretofore unrecognized externality. See, e.g., the work of Pigou, which is the basis for the solution advocated by most card-carrying economists who work in this field. (Cap-and-trade is another, albeit more easily gamed approach.)
The climate has changed much faster in the past than it is changing today. Of course, this was before SUV's and even man were on the planet. So, if man didn't cause it then, isn't it even remotely possible that man is not causing it today? The changes you allude to are ascribed to the collapse and restart of the thermohaline ocean circulation. In such events, rapid warming is due to the strengthening of the THC. However, observations indicate that the THC is not strengthening; if anything, it is weakening. Furthermore, THC collapses/restarts tend to give rise to hemispheric climate changes, not global ("bipolar seesaw"): if you warm the Northern Hemisphere by transporting more heat there from the Southern Hemisphere, then you remove heat from the Southern Hemisphere and cool it.
This is backed up when you consider that the earth has heated and cooled all on its own throughout history. Yes, but the traditional natural sources of warming (increased solar activity, decreased volcanism) do not explain the modern warming period.
Seeing as we are in a historical cool spell, doesn't it makes sense that the earth would warm itself, with, or without our help? We are in a "historical cool spell" in geologic terms: ice ages have been around for tens of millions of years. If you want to wait a similar period of time, we may leave ice ages behind. It's not something that happens over a hundred years; the geological processes involved (such as tectonics and weathering) are much slower than that. Furthermore, as I said, natural sources of warming do not explain, and are often opposed to, the recent observed warming.
It seems to me that when we see something happen, we immediately try to figure out what WE did to cause it. Perhaps you should educate yourself about the natural and manmade sources of climate change which have been considered in the scientific literature before jumping to conclusions about motives.
Because, frankly, the stated aims of environmentalists - improving the forests, saving the fuzzy animals, and so on, is actually served by the increasing CO2 in the atmosphere, as plants grow better in richer CO2 atmospheres and that leads to a stronger biosphere all round. Oh, right. Increase CO2, plants grow better, and the Earth turns into a new garden of Eden. Where'd you get that, the CEI?
Some points to consider:
1. Plant growth is often not CO2 limited, but rather temperature limited, moisture limited, nutrient limited, etc. And not all plant species experience significant CO2 fertilization (). Increasing CO2 doesn't automatically increase plant growth, and increasing it to arbitrarily high levels does not produce arbitrarily large growth. The FACE CO2 manipulation experiments have shown interesting results in this area. 2. Increasing CO2 increases global temperature, on average, which has a number of negative effects on forests, fuzzy animals, and the biosphere. 3. There is more to environmental health than "increased terrestrial vegetative biomass".
By and large, there's very few better things we could have done with our intelligence for the continuance of life on Earth than releasing all of the trapped CO2 back into the atmosphere so that it can be used again. That's pretty hilarious.
Plants grew really well in the Cretaceous. Doesn't mean we necessarily want to return to that climate, though.
The only species that are going to really be adversely affected by this sort of change are those who have set up permanent settlements right next to the water and can't easily retreat further inland as the water rises. Or has critical infrastructure that can be easily destroyed by hurricanes and tornadoes as the weather becomes more chaotic. Or species which can't take climate extremes or climatic impacts on their food chain. Which can't migrate fast enough to keep up with shifting temperature zones and precipitation bands. Especially if we put up a lot of roads and buildings and disrupt migratory pathways and eliminate available habitats. Or the ocean species which can't take drops in pH from dissolved CO2. Or the ones which depend on sea ice. How fast do we expect them to adapt?
John, I really enjoyed your posts on the comp.sys.next.* groups, but you're embarrassing yourself here.
As the other poster correctly noted, it's a sleazy rhetorical technique — not to mention hypocritical — to make a bunch of broad and unjustified claims, and then refuse to defend them on the basis of someone else's supposed zealotry. It's Usenet "Get out of a losing argument 101": if you don't have a leg to stand on, make up some excuse for why your opponent is unworthy of your attention, and declare victory. Maybe keep it going a little while with continued cheap potshots, but never return to any matter of substance.
Showy skepticism may win you karma on Slashdot, but you've totally avoided the factual merits of your position, and as the other poster also correctly noted, your economic/political conspiracy theories not only are unsupported, but don't even make sense.
If you have some scientific arguments supporting your skepticism, I would be happy to discuss them with you, as I have with others in this thread. But if you're just going to come back with some obnoxious accusation about my "orthodoxy" as a way of shutting down discussion, or make yet another unsupported claim, don't bother. I'm also totally uninterested in your economic and political theories. If those are your only basis for skepticism, it's pretty clear who's making emotional arguments here. But I will discuss the science with you, if you're interested. It's a very interesting subject, and would make for a much more productive and civil thread than the one you've created so far.
I guess I can't explain that the studies you are referencing are completly different then the ones I am.
You haven't referenced any studies. You've referenced some conservative's self-published web site ranting against "wacko liberals". And I explained why his conclusions were wrong.
Yes, the feedback mechanism of CO2 exists, as does any greenhouse gas from methane on down. But these are based on studies of local weather patterns, and experiements in labs which I agree try their best to replicate what the Earth experiences.
CO2 feedbacks are not that relevant to the question of attributing modern global warming. (They may become more relevant in the future, and certainly were relevant in the distant past.) What is relevant is the greenhouse effect, and other feedbacks which act upon it.
The greenhouse effect is not based merely on "studies of local weather patterns". It is based on observations of the global temperature profile from satellites and surface stations, as well as lab experiments and physical theories.
I just don't think we can model climate based on models that don't completly understand or explain why we have cooling periods and warming periods both inside of era's of increased CO2.
Models don't have to be perfect to be useful. We certainly can rule out the "CO2 causes cooling" hypothesis, which is in disagreement with theory, paleoclimate data, modern instrumental data, and lab experiments. And we can explain why there are cooling periods and warming periods during eras of increased CO2, namely that other radiative forcings exist, and sometimes they're stronger than the CO2 forcing. Sometimes they're not.
In the case of the ice age cycle, the Milankovitch insolation variations outweigh the small increase in CO2 during interglacials. These orbital variations can be calculated quite accurately via celestial mechanics.
In the case of the 1940s-1970s, the stratospheric aerosols from industrial pollution had a cooling effect which outweighed the warming of CO2. (The strength of this aerosol cooling effect is also independently verified through the observed cooling following major volcanic eruptions.) Since then, aerosol emissions slowed as CO2 emissions accelerated, and the latter wins out.
You don't even need a climate model to see this; it's just the relative amounts of these substances in the atmosphere.
These models make sense today because both CO2 in the atmosphere is going up, as is the global climate temperature.
Climate models work pretty well for the ice age cycle as well, without making any major changes in the model, and in particular without changing how it treats CO2. (We have to run simpler models though, since they need to be run for longer periods of time.)
But is there some other feedback mechanism that is yet undiscovered?
There are surely undiscovered feedback mechanisms. The real question, though, is whether any of them are as large as the feedbacks we already know about. Arguably, there is not much room for such large feedbacks, considering that the feedbacks we already know about give rise to something rather close to the observed climate; adding a large new feedback would very likely predict either more or less warming than is observed.
In fact, we can ignore the issue of accounting individual feedbacks altogether, and just look at the total feedback, independent of the individual feedback mechanisms which contribute to it. We can do so by comparing the measured changes in radiative forcing (CO2 levels, solar irradiance, aerosols, etc.) to the measured change in climate. This can be done in a relatively model-independent manner using basic energy balance constraints, although you have to be careful to reasonably handle inertial lags. When we do so, we find that the total feedback necessary to explain the observed warming is positive and induces a warming of at least 2 or 3 times larger than wha
It's a common thought that the ice core samples show temperature rising before CO2, not the other way around. Yes. That's still contested in the data (which are of pretty coarse resolution), but it's not surprising. Some papers which make this claim include this, this, and this.
You mentioned that causation was backwards. Can you supply me with a quick thought on that? Chemistry dictates that warming temperatures influence the ocean's physical pump of CO2, i.e., a warmer ocean can contain less dissolved CO2, which gets released to the atmosphere. The timing of the warming agrees with the timing of variations in the Earth's orbit (Milankovitch cycles), which determine how much sunlight the Earth receives, at what latitudes it's received, and how much the received sunlight seasonally varies in strength. CO2 is a greenhouse gas, which causes warming. Thus, the scenario for deglaciation is:
1. Something (probably orbital variations) starts a prolonged warming episode. 2. After a while, CO2 starts to come out of the oceans. 3. This excess CO2 amplifies the warming already underway.
For cooling into a glacial period, the process is reversed, with cooler temperatures leading to more uptake of carbon leading to more cooling.
Ocean sediments can reveal prehistoric carbon content (locked up in shells and such as carbonates), but they're not as good as atmospheric CO2 measurements from ice cores. So we don't know for sure that the CO2 came from the oceans, but it had to either come from the oceans or the land, and the oceans are by far the largest carbon sink. In addition, a lag of about 1000 years agrees well with the estimated vertical mixing time of the ocean (i.e., the time it takes for tracers to be transported between the surface and deep ocean).
So, it's not controversial that CO2 can be produced in response to temperature changes, with some centennial to millennial scale lag. Greenhouse physics says that such CO2 will produce warming. In addition, the amount of warming (cooling) observed in the glacial-interglacial cycle is much larger than what can be explained if you ignore the warming effect of greenhouse gases such as CO2. On the other hand, if you plug in modern CO2 temperature sensitivity estimates, you get temperature differences of approximately the right magnitude.
OK, I built a simple model using the data from the ice cores from this website. The model says with 99.9% certainty that in the next 5000 years we will experience an ice age.
For the Nth time, pure statistical extrapolation is a lousy way to do prediction, compared to building a physical model which can describe the causal mechanisms involved in the glacial cycle. For instance, the Milanokovitch cycle. Hell, your model doesn't even include data from more than one glacial cycle.
Pretending that the current interglacial period will look exactly like the previous one is a really bad assumption, which is why nobody actually tries to predict using such methods.
And I although I will state this a million times here on out: No one really understands how CO2 effects global climate.
Repeating an unsupported assertion a million times doesn't make it valid.
We certainly understand that CO2 causes warming, and we have a decent estimate of the amount of warming it produces (3 +/- 1.5 degrees C for a doubling of CO2 on centennial scales, possibly larger during glacial periods when large ice sheet feedbacks can kick in).
As for the physics vs. data mining, are you kidding? I am disputing the physics behind these models.
You haven't disputed, or even mentioned, any physics so far; you've just complained about statistics. Go ahead and dispute it then.
I do question whether these models were created correctly, but even if I assume they are, they are incorrect because they are based on what I have shown to be a very weak if not false premise.
On the contrary, the temperature-CO2 record is quite consistent with the predictions of climate models.
I am disputing trusting statistics because we do not understand our climate enough to draw conclusions on what our impact on the Earth is going to be.
You use the word "we" very liberally.
Yes, CO2 has a certain effect on the earth's climate. What is that effect?
Tropospheric warming and stratospheric cooling, amplified near polar regions, with a decreased diurnal temperature range. Which is what is both predicted by theory and observed in reality. Among other many other effects which you can read about in the IPCC WG1 report.
There are so many other factors that you can not even begin to tell me that simply making a model based on the premise that the only changes are going to be more greenhouse gases can be correct in any manner.
That is of course not the "premise" of climate models.
So now you argue that I am wrong simply because experiments in labortories say otherwise?
No, you're wrong because:
1. Experiments in laboratories say otherwise. 2. The laws of physics say otherwise. 3. The conclusion that CO2 causes cooling is physically absurd even in the absence of 1 or 2, purely on the basis of the observed ice core record.
It's exactly the naive correlation-causation fallacy that you incorrectly, and hypocritically, accuse scientists of. At the time when temperatures start dropping into the next glacial, CO2 increases by no more than 5 ppm. You'd have us believe that CO2 increases by 100 ppm over 100,000 years causing cooling (despite the Earth warming that whole time), but as soon as it pushes up another 5 ppm above 280 or so, it has an enormous cooling effect and plunges the planet into an ice age. Give me a break. Not to mention that we've already passed that limit this time around over a century ago, with no such cooling taking place. And we'll completely ignore your total lack of any kind of proposed physical mechanism which can cause such effects. Never mind the agreement of models, using known CO2 warming physics, with the observed data. I'm sure your totally implausible hypothesis with utterly no basis in physics is equally good.
Slashdot Mirror
Here is a fairly recent summary of solar effects during the modern global warming period. (Conclusion: solar trends have been pretty much flat since the mid-20th century, which fails to explain the late 20th century warming.)
That was from memory, I think from Lean's 2000 reconstruction in GRL. I've heard that Lean is no longer the favored reconstruction, but it's not off by an order of magnitude, that's for sure! I think you must be misremembering the figure. 3% is like a 40 W/m^2 change in irradiance. I've never heard of any reconstruction giving anything nearly that large between the Maunder Minimum and today.
To question (A), start here, particularly chapter 9. To question (B), start here.
The original poster is confused. The expected effect of global warming is that both summers and winters will warm, with winters warming faster than summers. However, there may also be more short-term extreme events (heat waves and cold snaps), although with extreme highs more likely than extreme lows.
So, tell me, how many millions have died due to "a ban on DDT"? Please be sure to cite the scholarly literature to support your answer. Methinks you need to find qualified sources. I've read the Newsweek article. It's a scare piece. Despite its dire insinuations, it says virtually nothing about actual scientific studies predicting an imminent ice age. Read it here.
The Newsweek quote above is a fine quote about how the climate cooled in the past — which it did! But that's got nothing to do with whether we were supposed to be "in an ice age right now".
In another comment, you cite Rasool and Schneider. Do you know why you cited Rasool and Schneider? Because that's pretty much the only paper published in the 1970s which predicted large cooling in the near future. The rest were generally either predicting warming, or were agnostic. See here for a literature review.
For that matter, have you even read Rasool and Schneider? Their prediction of strong cooling was based on their assumption that atmospheric pollutant emissions would outpace greenhouse gas emissions. In other words, their main error was not in the climate science, but in their economic/industrial forecasting. (True, they lowballed climate sensitivity as well, but that doesn't imply any cooling, just less greenhouse warming.) Their fundamental climate point was RIGHT: if aerosol emissions really had accelerated they way they speculated, they WOULD have a large cooling effect. In fact, that idea has been floated again recently as a means to combat global warming, under the name "aerosol geoengineering". (There turn out to be undesirable side effects.)
So, tell me, where are all the scientific studies predicting that "we should be in an ice age by now"? Be sure to cite the scholarly literature. And shall we ignore the studies which predicted the opposite?
But, for your own edification, try here.
Tell me, how did you find these sources? Googling "Little Ice Age" and reading skeptic web sites? (just one example of this is the fact that there were once large vineyards in places that are now too cold to grow grapes, which would NOT happen if we were as warm or warmer as things were pre Little Ice Age). Tell me, where exactly did they grow grapes 1000 years ago that they can't grow today?
Yeah, I've heard that one all the time from skeptics. In fact they're the only one who claim that this proves that the climate was warmer than today, which tells me exactly how "unbiased" your research was. "The Romans grew grapes in England!" You know, people STILL grow grapes in England today.
But you made a much bolder claim than that. You claimed that the climate 1000 years ago was 5 degrees warmer than today. Where is the evidence for THAT? Please, be specific. If you're going to make a quantitative claim you need to provide a quantitative estimate. You show one source that doesn't match what I found, when I had over half a dozen scholarly sources that did. Um, let me clue you in: the IPCC is the world's leading organization for summarizing climate research. Its assessment reports do not contain one study, but rather a scholarly literature review of the entire field. There are fare more than "half a dozen" sources cited in the IPCC reports. Evidently you didn't even READ the source I cited, or you would have noticed that. And we're supposed to trust your research skills? It seems pretty obvious that you're pushing an agenda instead of just looking at the evidence. What a hypocrite you are.
You claim support from tons of "scholarly papers", which you can't seem to cite, and yet you don't even know what an IPCC report is. It's all too obvious that you weren't researching unbiased sources. you'd come up with some bogus reason as to why they're not valid (like in Liar Liar "Objection your Honor!" "On what grounds?" "Because it's devastating to my case!") Right. I call you to back up your claims, you can't, so now you have to invent reasons why simple things like supporting your arguments aren't worth your time. Why, if you had to do something absurd like citing scientific research which supports your conclusion, I'd just come up with some "bogus" counterargument. (Here, "bogus" of course means "refutes your position".)
I can tell you, from what you've said here, I am not in the least worried about you producing a "devastating" case. Feel free to do some research on the Little Ice Age and NOT on global warming, I referred you to an entire chapter which discusses paleoclimate, not modern climate. The best explanation is that anything related to global warming is mostly about politics and personal agendas and not about science. Very convenient. First you forget all the scientific references which happen to support your views, and then you claim that you arbitrarily large amounts of scientific evidence can be dismissed on the grounds that it's based on "politics and personal agendas", and then you tell ME that I'm being biased!
Hypocrite. No one has a political agenda about a natural event that happened hundreds of years ago. You've got to be kidding me. That's practically all the skeptics argue about: "natural events hundreds of years ago prove there is no manmade global warming today".
(The atmospheric feedbacks, by the way, include not only alterations in the reflection of sunlight, but also in the trapping of outgoing longwave radiation.) So far at least, the measurements of ocean temperatures are remarkably constant. Ocean temperatures show the penetration of heat into the ocean from the surface which is expected from the known radiative forcings (mostly GHGs). But yes, they have been fairly constant, because of the large heat capacity of the ocean. This is why the ocean delays the warming seen at the surface on land. Whatever "forcing" theorized to be taking place, is not having a significant effect on the oceans and therefore the Earth as a whole. I don't know what "significant" is supposed to mean, but measurable quantities of heat have been taken up by the ocean during the 20th century (on the order of 10^23 J), this has already had an effect on global surface temperatures, and will continue to do so until the climate comes into a new equilibrium. Even if the forcing ceased, the planet would still warm for a while as the oceans continue to heat up. (See here and here.) From actual measurements, this balance has not changed much for our planet as a whole, at least as far as we can tell over the short time we have been measuring. Over the last century or so, it has changed by a few watts per square meter (averaged over the surface area of the Earth) top-of-atmosphere, or by maybe 0.5% of the total incoming flux. 0.5% is not "large", but it's large enough to raise the temperature of the planet by about a degree (or, roughly, 0.3% of its absolute temperature).
I agree that the oceans moderate the response of the climate to an external forcing. I'm just saying that the ultimate magnitude of that response is determined by the size of the forcing and by the strength of feedbacks which are primarily atmospheric in nature.
"Civilization advances by extending the number of important operations which we can perform without thinking of them."
— Alfred North Whitehead
The hydrosphere strongly influences the rate at which the globe warms, but doesn't strongly control the total amount of warming which is ultimately experienced. The latter is controlled by external radiative forcings, as well as feedback factors which are mostly atmospheric (plus some slower ice and terrestrial vegetation albedo feedbacks).
Yes, CO2 fertilization is a negative feedback on climate, i.e., it helps to stabilize climate. The problem is that we are still emitting CO2 much faster than even a faster-growing terrestrial biosphere can sink it. Vegetation may slow CO2 increases, but it is projected to be centuries to millennia before it can significantly reduce CO2 levels. Indeed, there is some debate that the terrestrial biosphere may switch from a source to a sink (since there are other effects, such as higher temperatures causing rotting wood and carbon in soil to decay faster).
Well, if that isn't begging the question, I don't know what is. But try reading this. This is why I oppose ALL of the proposed "solutions" to the "anthropogenic climate change" hoax. EVERY ONE of them, without exception, leaves us in a weaker position to weather change than if we did not follow them. [citation needed] They all propose some sort of socialistic or communistic top-down managed approach, FORCING people to alter their lifestyles in some vain attempt to "live green". No, they attempt to correct a market inefficiency by accounting for a heretofore unrecognized externality. See, e.g., the work of Pigou, which is the basis for the solution advocated by most card-carrying economists who work in this field. (Cap-and-trade is another, albeit more easily gamed approach.)
Why do you hate the free market?
Why do you hate the free market?
Some points to consider:
1. Plant growth is often not CO2 limited, but rather temperature limited, moisture limited, nutrient limited, etc. And not all plant species experience significant CO2 fertilization (). Increasing CO2 doesn't automatically increase plant growth, and increasing it to arbitrarily high levels does not produce arbitrarily large growth. The FACE CO2 manipulation experiments have shown interesting results in this area.
2. Increasing CO2 increases global temperature, on average, which has a number of negative effects on forests, fuzzy animals, and the biosphere.
3. There is more to environmental health than "increased terrestrial vegetative biomass". By and large, there's very few better things we could have done with our intelligence for the continuance of life on Earth than releasing all of the trapped CO2 back into the atmosphere so that it can be used again. That's pretty hilarious.
Plants grew really well in the Cretaceous. Doesn't mean we necessarily want to return to that climate, though. The only species that are going to really be adversely affected by this sort of change are those who have set up permanent settlements right next to the water and can't easily retreat further inland as the water rises. Or has critical infrastructure that can be easily destroyed by hurricanes and tornadoes as the weather becomes more chaotic. Or species which can't take climate extremes or climatic impacts on their food chain. Which can't migrate fast enough to keep up with shifting temperature zones and precipitation bands. Especially if we put up a lot of roads and buildings and disrupt migratory pathways and eliminate available habitats. Or the ocean species which can't take drops in pH from dissolved CO2. Or the ones which depend on sea ice. How fast do we expect them to adapt?
John, I really enjoyed your posts on the comp.sys.next.* groups, but you're embarrassing yourself here.
As the other poster correctly noted, it's a sleazy rhetorical technique — not to mention hypocritical — to make a bunch of broad and unjustified claims, and then refuse to defend them on the basis of someone else's supposed zealotry. It's Usenet "Get out of a losing argument 101": if you don't have a leg to stand on, make up some excuse for why your opponent is unworthy of your attention, and declare victory. Maybe keep it going a little while with continued cheap potshots, but never return to any matter of substance.
Showy skepticism may win you karma on Slashdot, but you've totally avoided the factual merits of your position, and as the other poster also correctly noted, your economic/political conspiracy theories not only are unsupported, but don't even make sense.
If you have some scientific arguments supporting your skepticism, I would be happy to discuss them with you, as I have with others in this thread. But if you're just going to come back with some obnoxious accusation about my "orthodoxy" as a way of shutting down discussion, or make yet another unsupported claim, don't bother. I'm also totally uninterested in your economic and political theories. If those are your only basis for skepticism, it's pretty clear who's making emotional arguments here. But I will discuss the science with you, if you're interested. It's a very interesting subject, and would make for a much more productive and civil thread than the one you've created so far.
I guess I can't explain that the studies you are referencing are completly different then the ones I am.
You haven't referenced any studies. You've referenced some conservative's self-published web site ranting against "wacko liberals". And I explained why his conclusions were wrong.
Yes, the feedback mechanism of CO2 exists, as does any greenhouse gas from methane on down. But these are based on studies of local weather patterns, and experiements in labs which I agree try their best to replicate what the Earth experiences.
CO2 feedbacks are not that relevant to the question of attributing modern global warming. (They may become more relevant in the future, and certainly were relevant in the distant past.) What is relevant is the greenhouse effect, and other feedbacks which act upon it.
The greenhouse effect is not based merely on "studies of local weather patterns". It is based on observations of the global temperature profile from satellites and surface stations, as well as lab experiments and physical theories.
I just don't think we can model climate based on models that don't completly understand or explain why we have cooling periods and warming periods both inside of era's of increased CO2.
Models don't have to be perfect to be useful. We certainly can rule out the "CO2 causes cooling" hypothesis, which is in disagreement with theory, paleoclimate data, modern instrumental data, and lab experiments. And we can explain why there are cooling periods and warming periods during eras of increased CO2, namely that other radiative forcings exist, and sometimes they're stronger than the CO2 forcing. Sometimes they're not.
In the case of the ice age cycle, the Milankovitch insolation variations outweigh the small increase in CO2 during interglacials. These orbital variations can be calculated quite accurately via celestial mechanics.
In the case of the 1940s-1970s, the stratospheric aerosols from industrial pollution had a cooling effect which outweighed the warming of CO2. (The strength of this aerosol cooling effect is also independently verified through the observed cooling following major volcanic eruptions.) Since then, aerosol emissions slowed as CO2 emissions accelerated, and the latter wins out.
You don't even need a climate model to see this; it's just the relative amounts of these substances in the atmosphere.
These models make sense today because both CO2 in the atmosphere is going up, as is the global climate temperature.
Climate models work pretty well for the ice age cycle as well, without making any major changes in the model, and in particular without changing how it treats CO2. (We have to run simpler models though, since they need to be run for longer periods of time.)
But is there some other feedback mechanism that is yet undiscovered?
There are surely undiscovered feedback mechanisms. The real question, though, is whether any of them are as large as the feedbacks we already know about. Arguably, there is not much room for such large feedbacks, considering that the feedbacks we already know about give rise to something rather close to the observed climate; adding a large new feedback would very likely predict either more or less warming than is observed.
In fact, we can ignore the issue of accounting individual feedbacks altogether, and just look at the total feedback, independent of the individual feedback mechanisms which contribute to it. We can do so by comparing the measured changes in radiative forcing (CO2 levels, solar irradiance, aerosols, etc.) to the measured change in climate. This can be done in a relatively model-independent manner using basic energy balance constraints, although you have to be careful to reasonably handle inertial lags. When we do so, we find that the total feedback necessary to explain the observed warming is positive and induces a warming of at least 2 or 3 times larger than wha
1. Something (probably orbital variations) starts a prolonged warming episode.
2. After a while, CO2 starts to come out of the oceans.
3. This excess CO2 amplifies the warming already underway.
For cooling into a glacial period, the process is reversed, with cooler temperatures leading to more uptake of carbon leading to more cooling.
Ocean sediments can reveal prehistoric carbon content (locked up in shells and such as carbonates), but they're not as good as atmospheric CO2 measurements from ice cores. So we don't know for sure that the CO2 came from the oceans, but it had to either come from the oceans or the land, and the oceans are by far the largest carbon sink. In addition, a lag of about 1000 years agrees well with the estimated vertical mixing time of the ocean (i.e., the time it takes for tracers to be transported between the surface and deep ocean).
So, it's not controversial that CO2 can be produced in response to temperature changes, with some centennial to millennial scale lag. Greenhouse physics says that such CO2 will produce warming. In addition, the amount of warming (cooling) observed in the glacial-interglacial cycle is much larger than what can be explained if you ignore the warming effect of greenhouse gases such as CO2. On the other hand, if you plug in modern CO2 temperature sensitivity estimates, you get temperature differences of approximately the right magnitude.
OK, I built a simple model using the data from the ice cores from this website. The model says with 99.9% certainty that in the next 5000 years we will experience an ice age.
For the Nth time, pure statistical extrapolation is a lousy way to do prediction, compared to building a physical model which can describe the causal mechanisms involved in the glacial cycle. For instance, the Milanokovitch cycle. Hell, your model doesn't even include data from more than one glacial cycle.
Pretending that the current interglacial period will look exactly like the previous one is a really bad assumption, which is why nobody actually tries to predict using such methods.
And I although I will state this a million times here on out: No one really understands how CO2 effects global climate.
Repeating an unsupported assertion a million times doesn't make it valid.
We certainly understand that CO2 causes warming, and we have a decent estimate of the amount of warming it produces (3 +/- 1.5 degrees C for a doubling of CO2 on centennial scales, possibly larger during glacial periods when large ice sheet feedbacks can kick in).
As for the physics vs. data mining, are you kidding? I am disputing the physics behind these models.
You haven't disputed, or even mentioned, any physics so far; you've just complained about statistics. Go ahead and dispute it then.
I do question whether these models were created correctly, but even if I assume they are, they are incorrect because they are based on what I have shown to be a very weak if not false premise.
On the contrary, the temperature-CO2 record is quite consistent with the predictions of climate models.
I am disputing trusting statistics because we do not understand our climate enough to draw conclusions on what our impact on the Earth is going to be.
You use the word "we" very liberally.
Yes, CO2 has a certain effect on the earth's climate. What is that effect?
Tropospheric warming and stratospheric cooling, amplified near polar regions, with a decreased diurnal temperature range. Which is what is both predicted by theory and observed in reality. Among other many other effects which you can read about in the IPCC WG1 report.
There are so many other factors that you can not even begin to tell me that simply making a model based on the premise that the only changes are going to be more greenhouse gases can be correct in any manner.
That is of course not the "premise" of climate models.
So now you argue that I am wrong simply because experiments in labortories say otherwise?
No, you're wrong because:
1. Experiments in laboratories say otherwise.
2. The laws of physics say otherwise.
3. The conclusion that CO2 causes cooling is physically absurd even in the absence of 1 or 2, purely on the basis of the observed ice core record.
It's exactly the naive correlation-causation fallacy that you incorrectly, and hypocritically, accuse scientists of. At the time when temperatures start dropping into the next glacial, CO2 increases by no more than 5 ppm. You'd have us believe that CO2 increases by 100 ppm over 100,000 years causing cooling (despite the Earth warming that whole time), but as soon as it pushes up another 5 ppm above 280 or so, it has an enormous cooling effect and plunges the planet into an ice age. Give me a break. Not to mention that we've already passed that limit this time around over a century ago, with no such cooling taking place. And we'll completely ignore your total lack of any kind of proposed physical mechanism which can cause such effects. Never mind the agreement of models, using known CO2 warming physics, with the observed data. I'm sure your totally implausible hypothesis with utterly no basis in physics is equally good.