That is the record of the Vostok Ice Sheet thickness. Continental drift over the period is relatively small, and that's the only thing we may have to correct for. Otherwise the raw data can be used to give an accurate measurement of the temperature at that point on the Earth's surface, with no corrections, normalisations, or other data massaging needed. It shows a repetitive pattern corresponding to periodic ice ages, a sharp temperature rise, slowly decreasing, in a staggered sawtooth pattern.
So let's look at the highlighted bit. And go to the Greenland Ice sheet thickness on the other side of the world, for a more detailed view of what's happened in the last 15,000 years or so.
This time, we see what happened after the last Ice Age ended. Bumpy, but with a slight downward trend. Again, this doesn't measure global temperatures, but at least gives us a clue as to polar temperatures at that particular spot on the Earth's surface, and not requiring a great deal of massaging to get adjacent data points to be comparable. OK, so let's look at the highlighted part. The bit from about 3000 BCE onwards - human-recorded history.
It looks like things are a bit cooler now than when the battle of Khadesh was fought, and when the Sumerian civilisation was at its height. Cooler by far than the Mycenean period 1500 years later, when Troy fell. At least, they were in Greenland. We must be careful not to make too many assumptions about the correlation between global temperature and polar temperature, or we step from firm ground with a very high degree of confidence indeed, to increasingly risky and uncertain territory.
So on to the highlighted area once more. From 800 AD onwards, about the time when Greenland was first explored by a people who recorded what they saw there.
Sure enough, those who called it "Greenland" weren't lying. There's the MWP, the Medieval Warming Period, blatantly existing at the northern polar region. Quite close to where most of our scripted records of the period were written. Also recorded in the ice are various cold periods that would have led to severe hardship in nearby Western Europe. The first, and probably the most shocking, around 1250. Another around 1425. The "Little Ice Age" around 1660, while a lowpoint in recorded history, seems to be just a relatively minor dip in the long cold time between 1600 and 1820. Again though, we can't automatically assume a high degree of correlation between Greenland and Global temperature, but a relatively high degree between Greenland and nearby Iceland, Scotland, and Newfoundland is more certain.
Now let's look at the highlighted bit again. The age of Political Climatology.
Is the rise at the end due to the Industrial Revolution? It correlates with it rather well, though seems to precede it a bit. What is clear though is that while Humans have had a huge impact on atmospheric CO2 content in the atmosphere, the actual temperature change in Greenland has been relatively minor. If it exists at all. Because variations in temperature far greater than that have been found throughout recorded history, at least in Greenland. In fact, from the looks of it, it may well be just noise.
And the variations in temperature in recorded history truly are noise in the regular staggered sawtooth pattern of periodic Ice Ages in the last 400,000 years. It's been far hotter than this in the relatively recent past - and a heck of a lot colder too.
What seems to be the case is that temperatures (in Greenland, remember, not necessarily elsewhere) are slowly dropping over the last 10,000 years; that we're in a relatively cold patch in the general variation over that period; but that's just part of the long, slow descent to the next Ice Age. Peak warmth in this interglacial has passed.
I have little faith - actually, none whatsoever - in the results from various climate models where the data is extremely sparse, heterogenous, and subject to truly huge uncertainties. Having looked at the Climate Research Unit's initial data set, I don't see how anyone could extract any meaningful conclusions from it with a reasonable degree of confidence. Far too many normalisations, corrections, and guesses to overcome problems of missing calibrated measurements have had to be made.
A thermometer at one station may be moved 200 metres or more in altitude between one year and the next, with no period of parallel running to calibrate the two so that a single set of measurements, like with like, can be formed. Then the thermometer may be discarded, and the "reading" at that point substituted by the results of interpolations from nearby stations - some of whom may in turn just be "readings" that are interpolations from other stations further away. Or even from the previous year's very uncertain results from the thermometer that was first moved, then deleted!
Outlying figures that are obviously wrong, due to local environmental changes, malfunctioning instruments and so on have to be weeded out in any such exercise.
One problem though with the CRU work. There is a consistent pattern of the "obviously wrong" figures that disagree with the model's broad results being from the most reliable data sources. Readings every year from actual thermometers that have not been relocated, and where the local environment has remained undisturbed.
16 comments:
I think that the most worrying thing as far as global temperature is concerned is the apparent acceleration of global temperature starting around roughly 1975. I don't know if that's even on these charts, and at best this is only two series of data.
More detail might be useful for your critique of the CRU data. As it is, I have little idea of what you're talking about, other than that you're suspicious of their filters, methodology, and conclusions.
Personally, regardless of this particular data series (there are tens of thousands of data series in the 2007 IPCC report), I think the following is accurate:
Robust findings
Warming of the climate system is unequivocal, as is now evident
from observations of increases in global average air and ocean
temperatures, widespread melting of snow and ice and rising global
average sea level. {WGI 3.9, SPM}
Many natural systems, on all continents and in some oceans,
are being affected by regional climate changes. Observed changes
in many physical and biological systems are consistent with warming.
As a result of the uptake of anthropogenic CO2 since 1750, the
acidity of the surface ocean has increased. {WGI 5.4, WGII 1.3}
Global total annual anthropogenic GHG emissions, weighted
by their 100-year GWPs, have grown by 70% between 1970 and
2004. As a result of anthropogenic emissions, atmospheric concentrations
of N2O now far exceed pre-industrial values spanning many
thousands of years, and those of CH4 and CO2 now far exceed the
natural range over the last 650,000 years. {WGI SPM; WGIII 1.3}
Most of the global average warming over the past 50 years is
very likely due to anthropogenic GHG increases and it is likely that
there is a discernible human-induced warming averaged over each
continent (except Antarctica). {WGI 9.4, SPM}
Anthropogenic warming over the last three decades has likely
had a discernible influence at the global scale on observed changes
in many physical and biological systems. {WGII 1.4, SPM}
I think the remaining questions are what do we do about it, and when.
Why are we looking at the temperatures from a single region instead of the planet as a whole? That's an awfully limited view. This graph shows the average global temperature for the past 1000 years. I see exponential growth in the last century, I have learned from looking at ecology and the economy and population dynamics that exponential growths are far from stable. I expect the same to be true for climate.
I also see that carbon dioxide levels have spiked dramatically, as in this graph. When we look at data over the past 1000 years, this graph, we see that the increase in concentration is again exponential.
As for whether or not carbon dioxide can change global temperatures, well, that's been determined as well using chemistry. Carbon dioxide's electrons are excited from photons from the sun, they can only stay excited for so long and lower their energy level. The energy has to go somewhere, and it is released as heat. This is how greenhouse gases function and is measured with radiative forcing. So far, none of this is outside the fields of physics and chemistry and none of it violates any physical laws.
We can look further back too, this graph has global temperature and carbon dioxide concentrations from the past 500,000 years. The last time it was this warm, well, was over 100,000 years ago. There's been a lot of change since then. There was no civilization, the coast lines, of no importance, now, they are of importance because people live there. Agriculture, that was nonexistent, now, not so much, we need it. It's also worth pointing out the carbon dioxide levels. It's an accepted fact in climatology that it has an influence on temperature. Even this graph shows a correlation (it's the physics and chemistry that back up a causal relationship) and it has not been this high in over 500,000 years. There's not any doubt the temperature of the planet is rising.
Then again, the carbon dioxide alone can be problematic. Easy example, coral reefs. The pH of the ocean is changing. Carbon dioxide and water reaction to form carbonic acid. It's common for chemistry students to measure water's pH, which is supposed to be 7.0, but it's not, because it's not pure water, there is carbon dioxide in the atmosphere and that makes it more acidic. The same thing is happening to the oceans. Rising levels of carbon dioxide mean rising levels of carbonic acid, means lowered pH, which means a threat to marine life. And seeing how marine life is a source of food, that might be a problem. The globe doesn't even have to be warming for us to want to take action against rising carbon dioxide levels.
I don't see a problem with you being skeptical, skepticism is a good thing. But I do raise issue with you using very regional data for an issue that is global. I do raise issue with you going against the consensus of climatologists, 97.5% of them doing climate change research say the globe is warming and that human activity is a contributing factor. At least, I have issue with it unless you have solid evidence against the consensus. I do respect you, the studies you present on gender are very interesting and I do think your training as an engineer is useful for evaluating data. I'd just like it if you looked at global data.
Does that chart only go to 1900?
Why are we looking at the temperatures from a single region instead of the planet as a whole?
Because we don't have data for the planet as a whole. Take a spot mid-Pacific, somewhere within a 100km radius. Where are the metrics that will reliably tell us what the temperature was like over the last 400,000 years, or even the last 400, for that?
What about anywhere on the granite shield of Western Australia? Same deal.
The CRU's input data is horrible. For example, one of the major contributors to their model relies on the assumption that tree ring thickness is proportional to temperature.
Well, they've calibrated that now, directly measuring temperature and directly measuring tree ring thickness in the areas of interest, and they found a zero correlation. The assumption was wrong - or at least, the noise overwhelms the signal over historical periods.
I'm saying that the confidence I have in any figures for global temperatures, no matter what they say, is near zero. The amount of massaging they've had to do is so large, the error bounds greatly exceed any plausible signal.
I recommend reading this piece by Megan McArdle.
Also this piece discussing the sources of error for the Darwin weather station - the star of the previous article.
Remwmber that the models have a quite coarse spatial scale. They are not compared to the results of individual stations but to regional average results.
And remember that the models are not statistical fits to the data. They are deterministic physical models with some adjustable parameters and other parameters calculated from physical principles. The presence of adjustable parameters does not necessarily make them as tweakable as their detractors claim.
I need time to read through the book I recently got on these models to see more details about how they are evaluated.
Also remember that we are interested in quite coarse results. Global and lattitude band temperatures and precipitation.
Also the paleoclimate results for the past 2,000 years is not used much for placing constraints on climate sensitivity to CO2 forcing. There are several such and I think they all hindicate the same result.
It looks like the sensitivity estmates that have been around for a while are probably spot on. And the rate of sea level rise will probably be worse than expected. Fortunately I think the lower scenarios for CO2 increase are more likely. But we're still in trouble.
What to do? At the moment the main thing to do is replace coal as much as possible with nuclear, geothermal and wind. Leave oil shale in the ground and use natural gas as much as possible. And work on petroleum replacements but they are not as technologically mature as coal replacements.
@Zoe- erm... yes. I'm not clear what you're trying to point out here. Data from multiple (possibly changing) sources is a mess, and can be difficult to get into a useful form. Fortunately, there are multiple bodies of science, based on even older mathematics to handle these issues.
The confidence in Global Warming is neither from a particular data point (of which there are millions), particular data set (of which there are tens of thousands), nor a particular methodology (of which there are a number, although in general, the further back in time, the greater the methodological error) nor a particular paper (of which there are many) nor even a particular group of scientists. Climatology is not a "new" science, nor is Anthropogenic global warming a "new" theory. Since 2007, no national or international scientific body formally rejects anthropocentric climate change (the last holdout was the American Association of Petroleum Geologists - who obviously have a vested interest in rejecting it).
Or to put it another way, other than the U.S.A., one of the more anti-global warming countries (in terms of policy, for a highly developed nation) is Australia. They also have one of the best Oceanic level monitoring stations for the Pacific. The most recent THE AUSTRALIAN BASELINE SEA LEVEL MONITORING PROJECT ANNUAL SEA LEVEL DATA SUMMARY REPORT JULY 2008 - JUNE 2009, on pages 34-35, shows data consistent with thermal expansion due to warming. If there were a political motive, I'd expect their data to be inconsistent with global warming.
As the second article you posted points out, there are indisputably some data sets that show cooling. The most recent IPCC report has a rather nice graphic showing the percentage of different types of data consistent with the theory of global warming versus ones that aren't.
Really, if you have questions about global warming, read the IPCC's most recent reports. Since you seem more interested in the physical science aspects, it's here. They represent fairly closely the state of climatology at the time of publication, and have both far more expertise than I ever will, and hundreds more pages to explain what they do, how they did it, what the results are, and what the ramifications of those results are.
As an obvious example, you'd find in the IPCC reports that the ice cores actually helps to demonstrate why there's concern about CO2/temperature feedback. "The ice core record indicates that greenhouse gases co-varied with antarctic temperature over glacial-interglacial cycles, suggesting a close link between natural atmospheric greenhouse gas variations and temperature (Box 6.2). Variations in CO2 over the last 420 kyr broadly followed antarctic temperature, typically by several centuries to a millennium (Mudelsee, 2001). The sequence of climatic forcings and responses during deglaciations (transitions from full glacial conditions to warm interglacials) are well documented. High-resolution ice core records of temperature proxies and CO2 during deglaciation indicates that antarctic temperature starts to rise several hundred years before CO2 (Monnin et al., 2001; Caillon et al., 2003).
...
The present atmospheric concentrations of CO2, CH4 and nitrous oxide (N2O) are higher than ever measured in the ice core record of the past 650 kyr (Figures 6.3 and 6.4)."
@Lloyd Flack-
Here's a chapter of an IPCC report describing their models, and their evaluation of those models "Climate Models and Their Evaluation". My apologies if you've already read it.
Variations in Co2 levels *followed* temperature changes rather well. They did not *lead* them.
We have pretty good evidence to show that either global warming causes a rise in CO2 levels directly, or whatever causes a rise in global temperature also causes (with some tens or hundreds of years time lag) a rise in CO2.
The unknowns though are huge.
What I would really like in order to validate and verify existing models is some really top-notch measurements over 20 years. Ones not requiring a great deal of massaging in order to normalise.
I'm not convinced that the current situation can provide that. Too many weather stations on heat islands.
Zimbel - thanks for providing that link on model verification. If I had more confidence in the massaged measurements they're using to check against, I'd be happier about the validity.
One thing this exercise has done for me - I'm no longer nearly as confident as I was that AGW isn't happening. I think anyone who says that they know with a very high degree of certainty what is happening is incorrect, no matter what they say.
Box 6.4 Figure 1 - is it me, or do I see a 3SD deviation between the same methodology used in different places, and different methodologies used in the same place?
If I interpret this correctly - and I may not be doing - it seems to me that all of the proxies we're using disagree with each other so much that it suggests that we can't have a great deal of confidence in any of them. Not individually, not in aggregate, not in average. The noise swamps the signal.
We have some excellent but spotty proxies - historical records of crops, even account books of agricultural produce - that indicate large historical anomalies that the other proxies that we assume to be valid just don't show.
Even if things weren't so politicised (on both sides I might add) trying to extract some meaning, and trying to estimate confidence levels, would be hard enough. See Feynmann's remarks about the Millikan drop experiments as to why I'm dubious about this.
I have another problem - I'm rapidly getting out of my depth here, and in order to judge the IPCC report, I'd need to really devote a lot more time to it than is available. All I can do is point out some of the more obvious to me - but possibly completely erroneous - apparent anomalies.
In the cchange from glacials to intercglacials and back changes in CO2 are a part of an amplifying feedback mechanism. The other main part is albedo changes. Neither is the trigger for the transition. They are what keeps the climate in either state.
The trigger appears to be Summer insolataion at about 65 degrees N. That determines whether or not continental glaciers will build up. But this apparent trigger is too weak to do the job by itself. THe albedo amplification is through ice caps reflecting heat. The CO2 amplification comes about through more CO2 dissolving in the ocean at lower temperatures and this in turn causing the greenhouse effect to weaken causing temperatures to drop further. The lag of several centuries is exactly what you would expect to happen.
The last Glacial Maximum can and has been used to obtain an aestimate of the sensitivity of the climate to CO2 forcing. This estimate is similar to those obtained from events last century. Climate reconstructions over the past 2,000 years are of little use for putting constraints on the climate sensitivity and are not used for that.
The exchange of CO2 between the atmosphere, the biosphere and the upper ocean is on a scale of decades. The exchange withe the deep ocean, a much larger reservoir is on a scale of centuries. The exchange with carbonate rocks, the biggest reservoir is on a scale of tens of millenia.
The delay in getting CO2 into these larger reservoirs is the cause of our problems. That is why in the glacial cycle CO2 lags several centuies behind temperature.
Whether CO2 is a feedback or a forcing variable depends on circustances. In the glacial cycle it is a feedback variable. Right now it is aforcing variable.
Well let me say this again, your graph only goes to 1900.
How about observed phenomenon and the principle of risk management. Don't endorse denial and complacency.
http://www.abc.net.au/rn/ockhamsrazor/stories/2009/2767715.htm#transcript
Well Chris Textor of WhackingDay keeps deleting my comments so I will post my reply which was directly to you here:
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Jake McCrann said: 2009.12.17 23:12
what is the whole Jihad concept Zoe? The Man Pig Bear?
If I controlled the media and had an agenda for South Americans to fear the US so much that they need to decide to act, I could make them think that all Americans dressed up in white cone hats and hung niggers for breakfast.
I lived in North Coburg for a year in my last stint in Melbourne and met alot of muslims. They are absolutely nothing like the media is portraying. We have so many documented cases of jews dressing up as arabs and pretending to be extremist jihadis. Their first give-away is that they always say “Death to Israel. Death to America”. You see, its very critical that these psychopathic idiots who created the state of Israel convince Americans that Israel’s enemies are America’s enemies.
I keep meaning to get my website up to start documenting all the false-flag efforts of jews we have discovered over the last decade. The last one I discover was Revolution Muslim. Have a look at these jews:
http://www.youtube.com/watch?v=5vU9lwJ_5JY
I knew they were Mossad jews straight away but then was stunned when CNN finally admitted that!
I lived amongst the densist muslim community in Melbourne for 1 year. I am telling you that your impression of Islam faithfuls is totally distorted by Jew TeeVee. These people are respectable, proud, and peaceful.
Now, if you invaded my country I would be making IEDs and blowing you the fuck out of their too.
The market-place bombings in the middle-east killing innocent muslim poor people trying to trade fruit and veggies? All Mossad operations. Why the hell would Islamics kill their own people like that? What kind of a strategy is that?
In order for you to sustain the delusion you need to believe that all muslims are anti-human in their thinking, that they are of a different race. The irony is that Islam is not a blood-line mafia like Judaism. Its the Jews stupid. Look, if you want to be on the side of people dragging Australia into a pile of shit then keep your shit up Zoe.
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Jake McCrann said: 2009.12.17 23:18
Hye Zoe, email me at jbmccrann@gmail.com and I will speak more with you. Tex will keep deleting my comments as he does 90% of the time. If I mention his name here he deletes the comment or changes it to Tex. Talk about conscious slef-delusion! The guy provokes criticism and then deletes dialogue to suit his enforced state of reality. Its a “Textor Tragedy”
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Jake McCrann said: 2009.12.17 23:26
Notice how they use the Revolution Muslim incitements to question the first Ammendment? Well “four morons shouting at the top of their lungs” on a street corner in a city would have no impact on the community but when CNN decides to air it then it hits 10 million homes.
Do you see the picture? Are you still goofed to the scam? The guys are a Mossad operation. Obviously CNN had to adopt they were “former jews who abruptly changed to Islam” because too many people out there were exposing that fact and therefore exposing the sham jew-sucking propaganda of CNN.
How long until the penny drops?
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Jake McCrann said: 2009.12.17 23:28
CNN couldn’t find any extremist muslims arabs so they had to mop up the Mossad operation Revolution Muslim in order to continue to maintain the JIHADIST problem you cite here Zoe like its as real as a waterfall. Its beyond me how goofed otherwise good Australian citizens have been to this.
Yes everybody, Climate Change is NATURAL. You know, there is WINTER SPRING SUMMER AND AUTUMN in many places and in others like in northern Australia we only see two seasons. The dry season and the wet season.
Yep, its NATURAL. But you keep farting away and help the Globalists get their One World Government.
The Club of Rome published their plans in 1975 that they would invent Global Warming.
I see somewhere Zoe Brain is doing a PHD at ANU? OMG, what has become of our education system.
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