It does not. Perhaps you should look at the data. Its warming. But the rate is faster than natural... we think, we suspect, we guess. But we don't really know.
The problem is that if you look at natural sources of warming alone, our measurements of the forcings along with our modeling of responses, indicates that it should have cooled instead of warmed. A difference in sign is a pretty significant anomaly.
We may not need 4 billion years of data, but more than 40 (aka satellites and ocean buoys etc) years of good data would be a start.
I certainly agree that more data helps, although the surface temperature record is usefully reliable for longer than 40 years.
Also ice cores have evidence of faster changes than we are experiencing.
The only faster changes we have clear cut evidence for in the ice cores are associated with collapses and restarts of the meridional overturning circulation (e.g., the Dansgaard-Oescher events). The problem with that theory is that the MOC is not now restarting; if anything, it is weakening.
There is *nothing* unprecedented with current weather trends.
There is according to what we've been able to measure with confidence.
Read the scientific papers rather than the news papers
Don't be condescending. I follow all the major climate journals (well, I've gotten behind in the last few months), and have read almost the entire scientific literature on climate sensitivity.
I agree that cloud parameterizations are uncertain; they are very likely the largest uncertainty in GCM feedbacks. If we find out that climate sensitivity is lower than we thought, it will likely be because cloud feedbacks are weaker than we thought.
I do contend, though, that we know the cloud feedbacks aren't so negative as to make the enhanced greenhouse effect a minority contribution to modern global warming, as many skeptics contend. There is a pretty large literature on the error bars of this feedback by now. And my main point was that cloud albedo fluctuations are not ignored by climate scientists, contrary to what the other poster claimed. In fact, a very high priority is placed on measuring and modeling them.
You might say that variations in reflectance are a "well known fact" but the fact is that studies of the effect of reflectance on global warming are relatively recent
Study of stochastic fluctuations in forcing on global warming go back until at least the 1970s; in fact, it was an early competing hypothesis to the greenhouse effect. Hasselmann's 1976 paper is seminal here, although I'm not sure which paper was the first to look at clouds specifically.
and are not properly accounted for in current models.
It's true that clouds are the least properly modeled aspect of the climate. For prediction that's important; for historical attribution, it's less important, because we've measured it. It's not true that you can replace the greenhouse forcing with cloud albedo fluctuations and successfully explain 20th century global warming. The measured albedo changes cause significant variability on sub-decadal scales, but can't explain the main long term trend. You should read the paper that your link cites. They address this exact point.
Would you concede that the alleged 'greenhouse' effect of CO2 warming occurs every year or do you you claim that the CO2 molecules take an occasional year off? If the effect of atmospheric CO2 on heat retention is continuous (which it must be if the theory is correct), then increased heat must be retained every year.
For the third time, this is false: more heat doesn't have to be retained if it doesn't reach the surface in the first place. There are year to year fluctuations in this amount, due to clouds, which on the long term are dominated by CO2 but in the short term cause significant natural variability.
And, once again, even when the oceans are warming, it's very hard to measure on the short term how much heat is actually going into or coming out of the oceans. After a couple decades it adds up, but on decadal scales it's extremely noisy. Right now there are three or four major ocean heat data sets out there (Levitus, Gouretski, Domingues, etc.), and they have first-order differences between each other due to the difficulty in making these measurements. They all show a substantial long term trend over the past 60 years, but they disagree in the magnitude of that trend by up to 30%, and if you start looking at year-to-year measurements, it's much noisier.
You claim that the variation in planetary core heat causes a variation in temperatures on the crust of "a hundredth of a degree" but the fact is that no one has any idea what the variation in heat from the core even is, much less what the magnitude of the temperature variation that might be resulting from it is.
Like most of what you say, this too is wrong. Your personal ignorance is not a proxy for what the scientific community does and does not know. In particular, we have deep borehole measurements into the Earth's crust which do not show significant heat rising from the depths. See, for instance, Beltrami et al.'s 2002 paper in GRL. The heat flux is about two orders of magnitude smaller than what is needed to account for observed global warming. Not to mention the oceans also show a top-down penetration of heat, not bottom-up.
Finally, you claim that variations in solar output are inconsistent with the warming which has been observed in those oceans which, according to you, don't have more heat present every year.
Oceans will, on average, tend to have more heat present every year. However, as I keep pointing out, from year to year there is substantial variation in the surface heat flux. I know you really want to ignore climate physics in favor of anything that will support your prejudices, but you really need to sit down with a textbook and learn something about how the climate works.
And yes, variations in solar output are inconsistent with both surface warming and ocean heat penetration.
The problem with your entire belief system on this issue is that it is based on what you want the facts to be rather than what they are.
That's a good point: we want to learn about what's near us. But in this analogy, it's foggy, the headlights don't go very far, and if we want to see what's ahead we have to keep driving. So do we slow down while hoping our headlights will warn us in time, or do we keep going at full speed?
And I am saying that the level a belief in this put ways the dataset!
I have no idea what that sentence means, but it doesn't change the fact that CO2 levels can account for the warming we've observed, and the usual natural sources do not. The uncertainty is not whether CO2 is causing significant warming, it's about how much further warming from CO2 will be realized in the future.
The volcanoes are mostly not under the sea ice, their heating doesn't measurably reach above depths of 1500 meters, and the total heat is nothing compared to what it takes to melt siginificant quantities of sea ice. It's rather ridiculous to claim that they have anything to do with sea ice melting.
Michel Jarraud, who is a big fan of global warming, of the World Meteorological Organization reluctantly admitted that global temperatures have not risen since 1998, according to a BBC article.
That's a pretty misleading representation of what he said.
Global snowfall is at record levels
I haven't looked at snowfall records, but global precipitation is expected to increase in a warming world.
and there are fewer, not more, hurricanes.
AFAIK, there are more hurricanes. Some research suggests that there will be yet more in the future, some research suggests there will be fewer; some suggests they will get stronger even if fewer. Hurricanes are a legitimate area of deep uncertainty in climate science; it's not clear how their behavior should change.
Last "Little Ice Age" has ended merely 200 Years ago. It wasn't human-related. Sun-related, most likely.
Sun and volcano related.
What if the temperature pendulum went that high because of this?
For one, because solar output has increased very little over the last 50 years, when we saw the most warming. See, for instance, the review in Science by Foukal et al. in 2006.
We have seen increased sun activity during last decades, now that the sun is calm we see a decrease in global temperatures.
If you think that the climate responds that quickly and largely to a relatively small change in trend, you're going to have an even harder time explaining the previous 40 years of warming than I mentioned above.
Sounds pretty logical for me as I still don't think that human influence would be that significant on the global scale.
Have you calculated the magnitude of the effect? I didn't think so.
Among political scientists perhaps, physical scientists and particularly climatologists would argue otherwise.
You're obviously unfamiliar with the climatological literature. I follow the major journals every month. I invite you to peruse the latest issues of Nature, Nature Geoscience, Science, Journal of Geophysical Research, Geophysical Research Letters, etc., and look at how many papers dispute this point.
The fact is that CO2 is a relatively minor greenhouse gas (the effects of water vapor are several times as great),
The natural greenhouse effect is on the order of 30 degrees C, which is why the planet is not a frozen iceball. CO2 is a smaller effect, but a few additional degrees of warming is still significant.
and anthropogenic contributions are a small percentage of global CO2 production
What is relevant is not the size of anthropogenic sources relative to natural sources, but the size of anthropogenic sources relative to the natural net carbon flux to the atmosphere. There are large natural sources which are normally closely balanced by equally large natural sinks, leading to relatively small natural fluctuations in CO2 levels during the last 10,000 years. Our additional CO2 has upset that balance; only half of it is taken up by natural sinks, leaving the other half to keep accumulating year after year.
Anthropogenic contributions now account for 35% of all CO2 in the atmosphere, and are likely to double or triple CO2 levels by the end of the century.
The fact that you're bringing up such obviously uncontestable scientific facts, such as the major human contribution to current CO2 levels, suggests to me that you're just uncritically copying skeptical talking points. There are legitimate scientific questions about climate, such as the strength of climate feedbacks. But whenever I see someone spouting off about how humans aren't having a significant effect on CO2 levels, or Martian climate disproves global warming, or other similarly nutty positions, I know they haven't seriously researched the issue.
It may not even be the case that increased CO2 (of whatever cause) raises global temperature: the opposite may be true (increases in temperature increase atmospheric CO2 levels).
We might have a fairly good idea for how climate in some areas changed over a period that INCLUDES that time period, but we have no data that is at all similar to what we have for the last maybe 100 years.
I know. My point was that we can tell tell that there's something odd about the modern warming, based ONLY on the modern data. Specifically, we can measure the various sources of warming and cooling (solar irradiance, volcanism, industrial sulfate aerosols and particulates, natural and manmade greenhouse gases, etc.), and if we leave out the manmade greenhouse gases, we can't account for the atmosphere and ocean warming which we observe.
This I don't understand either. It's like how downloaders can say "Download speed is currently 150kb/s, download will be done in 5 minutes." In reality that 150KB/s was an instantaneous spike--the average is more like 80kb/s.
The difference is that we're not just measuring a transient response and saying "huh, that's weird". We're measuring a response and numerous causes, and seeing which ones match up with the response.
You do realize that all historical data that predates accurate measurements are just very rough estimates that are open to interpretation and completely unopen to experimental proof and disproof, right?
I take your point, but you missed my main point, which is that we don't need paleoclimate data to support the manmade influence on the climate; modern observations are sufficient, although paleo data helps. You're right that there are substantial uncertainties, which is why the projections for 2100 vary by several degrees. But we do know enough to say that less than 1-2 degrees warming is unlikely, which is enough to be worth taking out some insurance against the possibility of greater warming.
Climatology is more or less a pseudo-science, at best a scientific research project. It, by definition, is not humanly possible to prove right or wrong. There is no isolation of variables, perceived close similarities.
I hate to break it to you, but observational sciences are still science. It is possible to know a lot about climate, geology, paleontology, astronomy, etc. without the ability to perform controlled laboratory experiments on the system being studied.
You are conceding, then, that the reflectivity of the cloud cover can vary from year to year. That puts you ahead of many global warming advocates.
No, it's a well known fact.
Isn't it also possible that warmer surface temperatures (which you must admit would be expected with global warming) would lead to increased evaporation, increased atmospheric moisture, and increased cloud cover, thereby increasing reflectivity and providing a global temperature feedback control mechanism?
Yes. There are two major cloud feedbacks, one for cloud albedo cooling as you describe, and one for cloud greenhouse warming.
Yet, current models either don't account for that or simply assume that reflectivity is constant.
That's wrong; dynamic cloud feedbacks are in all modern GCMs.
Nevertheless, the CO2 theory of global warming must result in more heat present in the oceans every year.
No, it doesn't, for reasons I just stated.
Of course, that's not what is observed, which completely undermines the entire simplistic theory of co2-based global warming,
As I just said, (1) cloud modulation alters your claim of "monotonic heat increase", and (2) ocean heat observations are not very accurate.
but its adherents wave that away as a minor point,
That's because there isn't anything yet statistically inconsistent with model predictions.
just as they ignore variations in heat originating in the planetary core
They're ignored because they've been measured and are utterly negligible, on the order of a hundredth of a degree.
and variations in solar output.
Those aren't ignored either; there is a large literature of it, and is in fact one of the pieces of evidence supporting CO2-induced warming. Solar output trends are inconsistent with the warming which has been observed.
The point of my last paragraph in my other response, in case it wasn't clear, was that the costs of making an error aren't symmetric. Even if you ignore the large amount of science which supports the enhanced greenhouse effect, if we cool too much it's easy to make it warmer. But if we warm too much, it's hard to make it cooler. This means we should be concerned more about potential warming than cooling.
And a potential 3-4 degrees C of warming (and larger in boreal regions like Canada) in 100 years, which is in the realm of possibility, is not "minor". It's certainly larger than any natural cooling we're likely to see; the Little Ice Age was smaller and slower than that, and the full glacial cycle is larger but much slower (tens of thousands of years). If you're really concerned about the latter, you should be advocating that we save our CO2 for later when we really need it, rather than using it up now when we don't.
Spending money (that could be used for other things) to reduce CO2 emissions "just in case", or not spending money tinkering with CO2 because if global warming turns out not to be anthropogenic, we could bring on the next (little?) ice age?
I'm sorry, but "Global warming is not anthropogenic" is no longer a credible scientific position. The serious scientific questions are along the lines of "Is climate sensitivity to CO2 closer to 2 degrees, or 4 degrees?"
Incidentally, if you're concerned that reducing CO2 will bring on a "little ice age", then you've already conceded that CO2 levels lead to warming. And it's not hard to add more CO2 if we decide we want/need to. It's adding less that's hard.
As much as some people would like to portray this as a "he said, she said" debate where all claims are equally valid, this is not really a matter of opinion.
The scientific evidence from past climate changes, present observations, and future physical predictions, is that there are "cliffs" nearby, but we're not completely sure how far away or how high they are. Basically, don't give the system an unprecedented kick unless you know what it's going to do.
Some places colder, some warmer but overall temperatures must increase...every year...all other things being equal.
All else is not equal. For one, there is substantial variability from year to year in cloud cover, which prevents heat from reaching the Earth's surface (reflected into space). Over the long run, the greenhouse effect wins out, but only over the long run. In addition, there is a lot of variation in how much heat ends up in the ocean vs. stays near the surface; in some years, the ocean takes more and the surface gets less, and vice versa. Finally, heat can move from the deep ocean to the surface and vice versa, warming and cooling the surface independent of what the atmosphere is doing. We could in principle account for this by measuring ocean heat as well as surface heat, and we do. The problem is that we can measure ocean heat much less accurately.
No, this report only discusses extent. There are other people who report ice volume, which is more difficult to estimate. I don't know what the current volume estimate is.
You do know that we have a less then 200 years of good data on climate don't you?
Yes, which is what tells us that the late 20th century warming is faster than natural, because we also have data on the usual natural sources of warming and cooling such as solar activity and volcanoes.
But what your so sure of you shouldn't be.
The Earth is 4 billion years old, but we don't need 4 billion years of data to understand something about what's happening to the Earth now. Sure there is uncertainty, and more than a couple hundred years of accurate data helps. But the instrumental data we do have is enough to tell us that something anomalous is going on, when compared to the various measured factors in the climate system which are normally responsible for climate change.
If I'm told to err on the side of caution, do you know what I would do? Nothing!
You're driving in complete darkness and someone tells you there might be a cliff nearby. You're told to err on the side of caution. What do you do? Speed up? I think not. You stop, or at least slow down.
Right now CO2 levels are already higher than they've been in at least a million years, and we're increasing them at an accelerating pace. Basic physics as well as our observations of present and past climate suggest that this will lead to warming, possibly by a dangerous amount.
Continuing to add CO2 at an accelerating pace may be "doing nothing different", but it is not "doing nothing". It is doing a very significant Something.
We don't know everything about the climate, but we know that reducing CO2 back to pre-industrial levels is unlikely to do anything worse than keep us at the present climate (and even then we are likely to still warm a little due to heat already stored in the ocean). By contrast, there are a lot of climate risks associated with staying on our current emissions trajectory.
There is, of course, variation and 'noise' in the air and water surface measurements as well as the effects of mixing and circulation but the general idea should one of steadily increasing temperatures. Your list should have 2nd warmest, warmest, 2nd warmest, warmest, etc. rather than 9th warmest, 10 warmest, 8 warmest, etc.
No. There is quite a lot of interannual weather variation, which you can see in any of the instrumental temperature data sets. The greenhouse effect doesn't predict that every year will break or nearly break the previous year's record in a monotonic increase, and you don't see that in the climate model predictions either. You do see an overall upward trend, but on timescales of a decade or so, there can be considerable short term fluctuation above and below the main trend.
Given the interannual variability in the long term data, differences between 2005 and 2008 levels are almost certainly not statistically significant. The change between the 1950s and today is a different matter.
That's true, but it should also be noted that sea ice extent is still a climatically interesting quantity. Non-submerged ice area is closely related to surface albedo, i.e. how much shortwave solar radiation is reflected from the Earth, which obviously relates to how much the Arctic warms (polar amplification). Both sea and land ice contribute, but sea ice is of particular interest because it is more vulnerable to melting than are land ice sheets in the Arctic. This is due to it being situated on relatively warm water (compared to most land) and the ability of sea ice to be transported to lower, warmer latitudes.
My quick Google search couldn't find the paper with the exact algorithm, but this paper describes a related algorithm. Skimming it, I can't tell what the error bars on 1-day deltas are. I do see from that paper that the biases between different data products can be larger than 4% (although they seem to be most likely more like 2%). I would imagine that time deltas are more accurate than absolute estimates. Anyway, bottom line is I don't know if it is significant, but you could probably dig up the algorithm if you searched more than I.
Slashdot Mirror
It does not. Perhaps you should look at the data. Its warming. But the rate is faster than natural... we think, we suspect, we guess. But we don't really know.
The problem is that if you look at natural sources of warming alone, our measurements of the forcings along with our modeling of responses, indicates that it should have cooled instead of warmed. A difference in sign is a pretty significant anomaly.
We may not need 4 billion years of data, but more than 40 (aka satellites and ocean buoys etc) years of good data would be a start.
I certainly agree that more data helps, although the surface temperature record is usefully reliable for longer than 40 years.
Also ice cores have evidence of faster changes than we are experiencing.
The only faster changes we have clear cut evidence for in the ice cores are associated with collapses and restarts of the meridional overturning circulation (e.g., the Dansgaard-Oescher events). The problem with that theory is that the MOC is not now restarting; if anything, it is weakening.
There is *nothing* unprecedented with current weather trends.
There is according to what we've been able to measure with confidence.
Read the scientific papers rather than the news papers
Don't be condescending. I follow all the major climate journals (well, I've gotten behind in the last few months), and have read almost the entire scientific literature on climate sensitivity.
I agree that cloud parameterizations are uncertain; they are very likely the largest uncertainty in GCM feedbacks. If we find out that climate sensitivity is lower than we thought, it will likely be because cloud feedbacks are weaker than we thought.
I do contend, though, that we know the cloud feedbacks aren't so negative as to make the enhanced greenhouse effect a minority contribution to modern global warming, as many skeptics contend. There is a pretty large literature on the error bars of this feedback by now. And my main point was that cloud albedo fluctuations are not ignored by climate scientists, contrary to what the other poster claimed. In fact, a very high priority is placed on measuring and modeling them.
Yes, I agree. I hadn't heard of the median/mode weighting that you mention as giving the best fit. Do you know a reference? Thanks.
You might say that variations in reflectance are a "well known fact" but the fact is that studies of the effect of reflectance on global warming are relatively recent
Study of stochastic fluctuations in forcing on global warming go back until at least the 1970s; in fact, it was an early competing hypothesis to the greenhouse effect. Hasselmann's 1976 paper is seminal here, although I'm not sure which paper was the first to look at clouds specifically.
and are not properly accounted for in current models.
It's true that clouds are the least properly modeled aspect of the climate. For prediction that's important; for historical attribution, it's less important, because we've measured it. It's not true that you can replace the greenhouse forcing with cloud albedo fluctuations and successfully explain 20th century global warming. The measured albedo changes cause significant variability on sub-decadal scales, but can't explain the main long term trend. You should read the paper that your link cites. They address this exact point.
Would you concede that the alleged 'greenhouse' effect of CO2 warming occurs every year or do you you claim that the CO2 molecules take an occasional year off? If the effect of atmospheric CO2 on heat retention is continuous (which it must be if the theory is correct), then increased heat must be retained every year.
For the third time, this is false: more heat doesn't have to be retained if it doesn't reach the surface in the first place. There are year to year fluctuations in this amount, due to clouds, which on the long term are dominated by CO2 but in the short term cause significant natural variability.
And, once again, even when the oceans are warming, it's very hard to measure on the short term how much heat is actually going into or coming out of the oceans. After a couple decades it adds up, but on decadal scales it's extremely noisy. Right now there are three or four major ocean heat data sets out there (Levitus, Gouretski, Domingues, etc.), and they have first-order differences between each other due to the difficulty in making these measurements. They all show a substantial long term trend over the past 60 years, but they disagree in the magnitude of that trend by up to 30%, and if you start looking at year-to-year measurements, it's much noisier.
You claim that the variation in planetary core heat causes a variation in temperatures on the crust of "a hundredth of a degree" but the fact is that no one has any idea what the variation in heat from the core even is, much less what the magnitude of the temperature variation that might be resulting from it is.
Like most of what you say, this too is wrong. Your personal ignorance is not a proxy for what the scientific community does and does not know. In particular, we have deep borehole measurements into the Earth's crust which do not show significant heat rising from the depths. See, for instance, Beltrami et al.'s 2002 paper in GRL. The heat flux is about two orders of magnitude smaller than what is needed to account for observed global warming. Not to mention the oceans also show a top-down penetration of heat, not bottom-up.
Finally, you claim that variations in solar output are inconsistent with the warming which has been observed in those oceans which, according to you, don't have more heat present every year.
Oceans will, on average, tend to have more heat present every year. However, as I keep pointing out, from year to year there is substantial variation in the surface heat flux. I know you really want to ignore climate physics in favor of anything that will support your prejudices, but you really need to sit down with a textbook and learn something about how the climate works.
And yes, variations in solar output are inconsistent with both surface warming and ocean heat penetration.
The problem with your entire belief system on this issue is that it is based on what you want the facts to be rather than what they are.
What a hypocrite you are.
That's a good point: we want to learn about what's near us. But in this analogy, it's foggy, the headlights don't go very far, and if we want to see what's ahead we have to keep driving. So do we slow down while hoping our headlights will warn us in time, or do we keep going at full speed?
And I am saying that the level a belief in this put ways the dataset!
I have no idea what that sentence means, but it doesn't change the fact that CO2 levels can account for the warming we've observed, and the usual natural sources do not. The uncertainty is not whether CO2 is causing significant warming, it's about how much further warming from CO2 will be realized in the future.
The volcanoes are mostly not under the sea ice, their heating doesn't measurably reach above depths of 1500 meters, and the total heat is nothing compared to what it takes to melt siginificant quantities of sea ice. It's rather ridiculous to claim that they have anything to do with sea ice melting.
Michel Jarraud, who is a big fan of global warming, of the World Meteorological Organization reluctantly admitted that global temperatures have not risen since 1998, according to a BBC article.
That's a pretty misleading representation of what he said.
Global snowfall is at record levels
I haven't looked at snowfall records, but global precipitation is expected to increase in a warming world.
and there are fewer, not more, hurricanes.
AFAIK, there are more hurricanes. Some research suggests that there will be yet more in the future, some research suggests there will be fewer; some suggests they will get stronger even if fewer. Hurricanes are a legitimate area of deep uncertainty in climate science; it's not clear how their behavior should change.
Last "Little Ice Age" has ended merely 200 Years ago. It wasn't human-related. Sun-related, most likely.
Sun and volcano related.
What if the temperature pendulum went that high because of this?
For one, because solar output has increased very little over the last 50 years, when we saw the most warming. See, for instance, the review in Science by Foukal et al. in 2006.
We have seen increased sun activity during last decades, now that the sun is calm we see a decrease in global temperatures.
If you think that the climate responds that quickly and largely to a relatively small change in trend, you're going to have an even harder time explaining the previous 40 years of warming than I mentioned above.
Sounds pretty logical for me as I still don't think that human influence would be that significant on the global scale.
Have you calculated the magnitude of the effect? I didn't think so.
Among political scientists perhaps, physical scientists and particularly climatologists would argue otherwise.
You're obviously unfamiliar with the climatological literature. I follow the major journals every month. I invite you to peruse the latest issues of Nature, Nature Geoscience, Science, Journal of Geophysical Research, Geophysical Research Letters, etc., and look at how many papers dispute this point.
The fact is that CO2 is a relatively minor greenhouse gas (the effects of water vapor are several times as great),
The natural greenhouse effect is on the order of 30 degrees C, which is why the planet is not a frozen iceball. CO2 is a smaller effect, but a few additional degrees of warming is still significant.
and anthropogenic contributions are a small percentage of global CO2 production
What is relevant is not the size of anthropogenic sources relative to natural sources, but the size of anthropogenic sources relative to the natural net carbon flux to the atmosphere. There are large natural sources which are normally closely balanced by equally large natural sinks, leading to relatively small natural fluctuations in CO2 levels during the last 10,000 years. Our additional CO2 has upset that balance; only half of it is taken up by natural sinks, leaving the other half to keep accumulating year after year.
Anthropogenic contributions now account for 35% of all CO2 in the atmosphere, and are likely to double or triple CO2 levels by the end of the century.
The fact that you're bringing up such obviously uncontestable scientific facts, such as the major human contribution to current CO2 levels, suggests to me that you're just uncritically copying skeptical talking points. There are legitimate scientific questions about climate, such as the strength of climate feedbacks. But whenever I see someone spouting off about how humans aren't having a significant effect on CO2 levels, or Martian climate disproves global warming, or other similarly nutty positions, I know they haven't seriously researched the issue.
It may not even be the case that increased CO2 (of whatever cause) raises global temperature: the opposite may be true (increases in temperature increase atmospheric CO2 levels).
In fact, both are true.
We might have a fairly good idea for how climate in some areas changed over a period that INCLUDES that time period, but we have no data that is at all similar to what we have for the last maybe 100 years.
I know. My point was that we can tell tell that there's something odd about the modern warming, based ONLY on the modern data. Specifically, we can measure the various sources of warming and cooling (solar irradiance, volcanism, industrial sulfate aerosols and particulates, natural and manmade greenhouse gases, etc.), and if we leave out the manmade greenhouse gases, we can't account for the atmosphere and ocean warming which we observe.
This I don't understand either. It's like how downloaders can say "Download speed is currently 150kb/s, download will be done in 5 minutes." In reality that 150KB/s was an instantaneous spike--the average is more like 80kb/s.
The difference is that we're not just measuring a transient response and saying "huh, that's weird". We're measuring a response and numerous causes, and seeing which ones match up with the response.
You do realize that all historical data that predates accurate measurements are just very rough estimates that are open to interpretation and completely unopen to experimental proof and disproof, right?
I take your point, but you missed my main point, which is that we don't need paleoclimate data to support the manmade influence on the climate; modern observations are sufficient, although paleo data helps. You're right that there are substantial uncertainties, which is why the projections for 2100 vary by several degrees. But we do know enough to say that less than 1-2 degrees warming is unlikely, which is enough to be worth taking out some insurance against the possibility of greater warming.
Climatology is more or less a pseudo-science, at best a scientific research project. It, by definition, is not humanly possible to prove right or wrong. There is no isolation of variables, perceived close similarities.
I hate to break it to you, but observational sciences are still science. It is possible to know a lot about climate, geology, paleontology, astronomy, etc. without the ability to perform controlled laboratory experiments on the system being studied.
You are conceding, then, that the reflectivity of the cloud cover can vary from year to year. That puts you ahead of many global warming advocates.
No, it's a well known fact.
Isn't it also possible that warmer surface temperatures (which you must admit would be expected with global warming) would lead to increased evaporation, increased atmospheric moisture, and increased cloud cover, thereby increasing reflectivity and providing a global temperature feedback control mechanism?
Yes. There are two major cloud feedbacks, one for cloud albedo cooling as you describe, and one for cloud greenhouse warming.
Yet, current models either don't account for that or simply assume that reflectivity is constant.
That's wrong; dynamic cloud feedbacks are in all modern GCMs.
Nevertheless, the CO2 theory of global warming must result in more heat present in the oceans every year.
No, it doesn't, for reasons I just stated.
Of course, that's not what is observed, which completely undermines the entire simplistic theory of co2-based global warming,
As I just said, (1) cloud modulation alters your claim of "monotonic heat increase", and (2) ocean heat observations are not very accurate.
but its adherents wave that away as a minor point,
That's because there isn't anything yet statistically inconsistent with model predictions.
just as they ignore variations in heat originating in the planetary core
They're ignored because they've been measured and are utterly negligible, on the order of a hundredth of a degree.
and variations in solar output.
Those aren't ignored either; there is a large literature of it, and is in fact one of the pieces of evidence supporting CO2-induced warming. Solar output trends are inconsistent with the warming which has been observed.
The point of my last paragraph in my other response, in case it wasn't clear, was that the costs of making an error aren't symmetric. Even if you ignore the large amount of science which supports the enhanced greenhouse effect, if we cool too much it's easy to make it warmer. But if we warm too much, it's hard to make it cooler. This means we should be concerned more about potential warming than cooling.
And a potential 3-4 degrees C of warming (and larger in boreal regions like Canada) in 100 years, which is in the realm of possibility, is not "minor". It's certainly larger than any natural cooling we're likely to see; the Little Ice Age was smaller and slower than that, and the full glacial cycle is larger but much slower (tens of thousands of years). If you're really concerned about the latter, you should be advocating that we save our CO2 for later when we really need it, rather than using it up now when we don't.
Spending money (that could be used for other things) to reduce CO2 emissions "just in case", or not spending money tinkering with CO2 because if global warming turns out not to be anthropogenic, we could bring on the next (little?) ice age?
I'm sorry, but "Global warming is not anthropogenic" is no longer a credible scientific position. The serious scientific questions are along the lines of "Is climate sensitivity to CO2 closer to 2 degrees, or 4 degrees?"
Incidentally, if you're concerned that reducing CO2 will bring on a "little ice age", then you've already conceded that CO2 levels lead to warming. And it's not hard to add more CO2 if we decide we want/need to. It's adding less that's hard.
As much as some people would like to portray this as a "he said, she said" debate where all claims are equally valid, this is not really a matter of opinion.
The scientific evidence from past climate changes, present observations, and future physical predictions, is that there are "cliffs" nearby, but we're not completely sure how far away or how high they are. Basically, don't give the system an unprecedented kick unless you know what it's going to do.
Some places colder, some warmer but overall temperatures must increase...every year...all other things being equal.
All else is not equal. For one, there is substantial variability from year to year in cloud cover, which prevents heat from reaching the Earth's surface (reflected into space). Over the long run, the greenhouse effect wins out, but only over the long run. In addition, there is a lot of variation in how much heat ends up in the ocean vs. stays near the surface; in some years, the ocean takes more and the surface gets less, and vice versa. Finally, heat can move from the deep ocean to the surface and vice versa, warming and cooling the surface independent of what the atmosphere is doing. We could in principle account for this by measuring ocean heat as well as surface heat, and we do. The problem is that we can measure ocean heat much less accurately.
No, this report only discusses extent. There are other people who report ice volume, which is more difficult to estimate. I don't know what the current volume estimate is.
You do know that we have a less then 200 years of good data on climate don't you?
Yes, which is what tells us that the late 20th century warming is faster than natural, because we also have data on the usual natural sources of warming and cooling such as solar activity and volcanoes.
But what your so sure of you shouldn't be.
The Earth is 4 billion years old, but we don't need 4 billion years of data to understand something about what's happening to the Earth now. Sure there is uncertainty, and more than a couple hundred years of accurate data helps. But the instrumental data we do have is enough to tell us that something anomalous is going on, when compared to the various measured factors in the climate system which are normally responsible for climate change.
If I'm told to err on the side of caution, do you know what I would do? Nothing!
You're driving in complete darkness and someone tells you there might be a cliff nearby. You're told to err on the side of caution. What do you do? Speed up? I think not. You stop, or at least slow down.
Right now CO2 levels are already higher than they've been in at least a million years, and we're increasing them at an accelerating pace. Basic physics as well as our observations of present and past climate suggest that this will lead to warming, possibly by a dangerous amount.
Continuing to add CO2 at an accelerating pace may be "doing nothing different", but it is not "doing nothing". It is doing a very significant Something.
We don't know everything about the climate, but we know that reducing CO2 back to pre-industrial levels is unlikely to do anything worse than keep us at the present climate (and even then we are likely to still warm a little due to heat already stored in the ocean). By contrast, there are a lot of climate risks associated with staying on our current emissions trajectory.
There is, of course, variation and 'noise' in the air and water surface measurements as well as the effects of mixing and circulation but the general idea should one of steadily increasing temperatures. Your list should have 2nd warmest, warmest, 2nd warmest, warmest, etc. rather than 9th warmest, 10 warmest, 8 warmest, etc.
No. There is quite a lot of interannual weather variation, which you can see in any of the instrumental temperature data sets. The greenhouse effect doesn't predict that every year will break or nearly break the previous year's record in a monotonic increase, and you don't see that in the climate model predictions either. You do see an overall upward trend, but on timescales of a decade or so, there can be considerable short term fluctuation above and below the main trend.
Given the interannual variability in the long term data, differences between 2005 and 2008 levels are almost certainly not statistically significant. The change between the 1950s and today is a different matter.
That's true, but it should also be noted that sea ice extent is still a climatically interesting quantity. Non-submerged ice area is closely related to surface albedo, i.e. how much shortwave solar radiation is reflected from the Earth, which obviously relates to how much the Arctic warms (polar amplification). Both sea and land ice contribute, but sea ice is of particular interest because it is more vulnerable to melting than are land ice sheets in the Arctic. This is due to it being situated on relatively warm water (compared to most land) and the ability of sea ice to be transported to lower, warmer latitudes.
My quick Google search couldn't find the paper with the exact algorithm, but this paper describes a related algorithm. Skimming it, I can't tell what the error bars on 1-day deltas are. I do see from that paper that the biases between different data products can be larger than 4% (although they seem to be most likely more like 2%). I would imagine that time deltas are more accurate than absolute estimates. Anyway, bottom line is I don't know if it is significant, but you could probably dig up the algorithm if you searched more than I.