Bishop Hill Abraham on the MWP
Jul 14, 2011 Climate: HSI Climate: MWP John Abraham, the US academic who keeps falling out with Lord Monckton, has written an article about the MWP. It's a bit of a mixed bag, but there is much of interest.
For example, there's this rather naughty bit of quoting out of context:
the National Academy of Sciences thoroughly investigated [the MWP] and concluded, “the late 20th century warmth in the northern hemisphere was unprecedented during at least the last 1000 years."
Unfortunately, examination of the NAS report shows that they actually said:
The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years
So they did not conclude that 20th century temperatures were unprecedented, they made an opening observation that Mann had claimed this. As I'm sure readers here know, they concluded that Mann's claims were "plausible", which is not the same as concluding that they were correct.
Abrahams also gets comments from a number of paleo people in reference to two questions:
- Was the MWP global in extent and warmer than today?
- Does the presence of the MWP call into question human-caused global warming?
The responses are very interesting, because several of the respondents don't seem to have addressed question 1. I'd love to know what they said - my guess is it's something along the lines of "we don't know". Such a response is certainly suggested by Abraham's conclusions:
...the existence of the MWP is not in serious doubt; but whether it was global in extent or warmer than today is. In addition, the presence of a MWP does not call into question whether humans are now causing the Earth to warm.
These two points are both fair I think. The first point is particularly interesting: it's a reasonable interpretation of the science but it's a long way removed from the IPCC's conclusion that temperatures are "likely" the highest in 1300 years.
Reader Comments (71)
Surely the presence of the MWP does call into question whether humans are now causing the Earth to warm. It also calls into question whether such warming, however it is caused, is a bad thing. On the first point, the MWP happened naturally without human interference, meaning that this is a possibility now. On the second point spending billions on trying to head off the effects of global warming can only be justified by claiming that we are headed for some kind of apocolypse, rather that just mild winters and really sunny summers.
Well spotted! Abraham boasts of his scientific expertise and proves unable to extract a quote correctly from the NAS paper!
@Stonyground
How on earth does the existence of the MWP call into question whether humans are now causing the Earth to warm?
Abraham is one of the least impressive thermageddonists.
There is no evidence that the MWP (or the Roman WP, for that matter) was any less global than the late C20th warming.
And of course, whilst this doesn't prove that humans are not causing some warming (they may well be - probably by changed land use) it certainly is no proof whatever that humans ARE causing such warming.
The man is a nitwit, as his tendentious and dishonest attacks on Monckton proved.
Admittedly, as stupid as Abrahams is, some trolls are even stupider.
Indeed they are, Martin.
Look at it this way, Hengist. If the earth was the same temperature during the MWP as it is now and humans were not responsible for that, is it not a reasonable assumption that they are not responsible for the present situation?
And if you disagree with that presumption, can you give reasons?
A reminder about all the climate scares in the past 114 years
Climate Change Timeline – 1895-2009
NEW: 5th Year of Global Cooling, NOAA Says <- Read!
There is most certainly a pattern to climate change…
…but it’s not what you may think:
For at least 114 years, climate “scientists” have been claiming that the climate was going to kill us…but they have kept switching whether it was a coming ice age, or global warming.
33diggsdigg
• 1895 - Geologists Think the World May Be Frozen Up Again – New York Times, February 1895
• 1902 - “Disappearing Glaciers…deteriorating slowly, with a persistency that means their final annihilation…scientific fact…surely disappearing.” – Los Angeles Times
• 1912 - Prof. Schmidt Warns Us of an Encroaching Ice Age – New York Times, October 1912
• 1923 - “Scientist says Arctic ice will wipe out Canada” – Professor Gregory of Yale University, American representative to the Pan-Pacific Science Congress, – Chicago Tribune
• 1923 - “The discoveries of changes in the sun’s heat and the southward advance of glaciers in recent years have given rise to conjectures of the possible advent of a new ice age” – Washington Post
• 1924 - MacMillan Reports Signs of New Ice Age – New York Times, Sept 18, 1924
• 1929 - “Most geologists think the world is growing warmer, and that it will continue to get warmer” – Los Angeles Times, in Is another ice age coming?
• 1932 - “If these things be true, it is evident, therefore that we must be just teetering on an ice age” – The Atlantic magazine, This Cold, Cold World
• 1933 - America in Longest Warm Spell Since 1776; Temperature Line Records a 25-Year Rise – New York Times, March 27th, 1933
• 1933 – “…wide-spread and persistent tendency toward warmer weather…Is our climate changing?” – Federal Weather Bureau “Monthly Weather Review.”
• 1938 - Global warming, caused by man heating the planet with carbon dioxide, “is likely to prove beneficial to mankind in several ways, besides the provision of heat and power.”– Quarterly Journal of the Royal Meteorological Society
• 1938 - “Experts puzzle over 20 year mercury rise…Chicago is in the front rank of thousands of cities thuout the world which have been affected by a mysterious trend toward warmer climate in the last two decades” – Chicago Tribune
• 1939 - “Gaffers who claim that winters were harder when they were boys are quite right… weather men have no doubt that the world at least for the time being is growing warmer” – Washington Post
• 1952 - “…we have learned that the world has been getting warmer in the last half century” – New York Times, August 10th, 1962
• 1954 - “…winters are getting milder, summers drier. Glaciers are receding, deserts growing” – U.S. News and World Report
• 1954 - Climate – the Heat May Be Off – Fortune Magazine
• 1959 - “Arctic Findings in Particular Support Theory of Rising Global Temperatures” – New York Times
• 1969 - “…the Arctic pack ice is thinning and that the ocean at the North Pole may become an open sea within a decade or two” – New York Times, February 20th, 1969
• 1969 – “If I were a gambler, I would take even money that England will not exist in the year 2000″ — Paul Ehrlich (while he now predicts doom from global warming, this quote only gets honorable mention, as he was talking about his crazy fear of overpopulation)
• 1970 - “…get a good grip on your long johns, cold weather haters – the worst may be yet to come…there’s no relief in sight” – Washington Post
• 1974 - Global cooling for the past forty years – Time Magazine
• 1974 - “Climatological Cassandras are becoming increasingly apprehensive, for the weather aberrations they are studying may be the harbinger of another ice age” – Washington Post
• 1974 - “As for the present cooling trend a number of leading climatologists have concluded that it is very bad news indeed” – Fortune magazine, who won a Science Writing Award from the American Institute of Physics for its analysis of the danger
• 1974 - “…the facts of the present climate change are such that the most optimistic experts would assign near certainty to major crop failure…mass deaths by starvation, and probably anarchy and violence” – New York Times
Cassandras are becoming
increasingly apprehensive,
for the weather
aberrations they are
studying may be the
harbinger of another
ice age
• 1975 - Scientists Ponder Why World’s Climate is Changing; A Major Cooling Widely Considered to Be Inevitable – New York Times, May 21st, 1975
• 1975 - “The threat of a new ice age must now stand alongside nuclear war as a likely source of wholesale death and misery for mankind” Nigel Calder, editor, New Scientist magazine, in an article in International Wildlife Magazine
• 1976 - “Even U.S. farms may be hit by cooling trend” – U.S. News and World Report
• 1981 - Global Warming – “of an almost unprecedented magnitude” – New York Times
• 1988 - I would like to draw three main conclusions. Number one, the earth is warmer in 1988 than at any time in the history of instrumental measurements. Number two, the global warming is now large enough that we can ascribe with a high degree of confidence a cause and effect relationship to the greenhouse effect. And number three, our computer climate simulations indicate that thegreenhouse effect is already large enough to begin to effect the probability of extreme events such as summer heat waves. – Jim Hansen, June 1988 testimony before Congress, see His later quote and His superior’s objection for context
• 1989 -”On the one hand, as scientists we are ethically bound to the scientific method, in effect promising to tell the truth, the whole truth, and nothing but – which means that we must include all doubts, the caveats, the ifs, ands and buts. On the other hand, we are not just scientists but human beings as well. And like most people we’d like to see the world a better place, which in this context translates into our working to reduce the risk of potentially disastrous climate change. To do that we need to get some broad based support, to capture the public’s imagination. That, of course, means getting loads of media coverage. So we have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have. This “double ethical bind” we frequently find ourselves in cannot be solved by any formula. Each of us has to decide what the right balance is between being effective and being honest. I hope that means being both.” – Stephen Schneider, lead author of the Intergovernmental Panel on Climate Change, Discover magazine, October 1989
• 1990 - “We’ve got to ride the global warming issue. Even if the theory of global warming is wrong, we will be doing the right thing – in terms of economic policy and environmental policy” – Senator Timothy Wirth
• 1993 - “Global climate change may alter temperature and rainfall patterns, many scientists fear, with uncertain consequences for agriculture.” – U.S. News and World Report
• 1998 - No matter if the science [of global warming] is all phony . . . climate change [provides] the greatest opportunity to bring about justice and equality in the world.” —Christine Stewart, Canadian Minister of the Environment, Calgary Herald, 1998
• 2001 - “Scientists no longer doubt that global warming is happening, and almost nobody questions the fact that humans are at least partly responsible.” – Time Magazine, Monday, Apr. 09, 2001
• 2003 - Emphasis on extreme scenarios may have been appropriate at one time, when the public and decision-makers were relatively unaware of the global warming issue, and energy sources such as “synfuels,” shale oil and tar sands were receiving strong consideration” – Jim Hansen, NASA Global Warming activist, Can we defuse The Global Warming Time Bomb?, 2003
• 2006 - “I believe it is appropriate to have an over-representation of factual presentations on how dangerous it is, as a predicate for opening up the audience to listen to what the solutions are, and how hopeful it is that we are going to solve this crisis.” — Al Gore, Grist magazine, May 2006
• Now: The global mean temperature has fallen for four years in a row, which is why you stopped hearing details about the actual global temperature, even while they carry on about taxing you to deal with it…how long before they start predicting an ice age?
The actual Global Warming Advocates' chart, overlayed on the "climate change" hysterics of the past 120 years. Not only is it clear that they take any change and claim it's going to go on forever and kill everyone, but notice that they even sometimes get the short-term trend wrong...
Worse still, notice that in 1933 they claim global warming has been going on for 25 years…the entire 25 years they were saying we were entering an ice age. And in 1974, they say there has been global cooling for 40 years…the entire time of which they’d been claiming the earth was getting hotter! Of course NOW they are talking about the earth “warming for the past century”, again ignoring that they spent much of that century claiming we were entering an ice age.
The fact is that the mean temperature of the planet is, and should be, always wavering up or down, a bit, because this is a natural world, not a climate-controlled office. So there will always be some silly bureaucrat, in his air-conditioned ivory tower, who looks at which way it’s going right now, draws up a chart as if this is permanant, realizes how much fear can increase his funding, and proclaims doom for all of humanity.
• 2006 – “It is not a debate over whether the earth has been warming over the past century. The earth is always warming or cooling, at least a few tenths of a degree…” — Richard S. Lindzen, the Alfred P. Sloan professor of meteorology at MIT
• 2006 – “What we have fundamentally forgotten is simple primary school science. Climate always changes. It is always…warming or cooling, it’s never stable. And if it were stable, it would actually be interesting scientifically because it would be the first time for four and a half billion years.” —Philip Stott, emeritus professor of bio-geography at the University of London
• 2006 - “Since 1895, the media has alternated between global cooling and warming scares during four separate and sometimes overlapping time periods. From 1895 until the 1930′s the media peddled a coming ice age. From the late 1920′s until the 1960′s they warned of global warming. From the 1950′s until the 1970′s they warned us again of a coming ice age. This makes modern global warming the fourth estate’s fourth attempt to promote opposing climate change fears during the last 100 years.” – Senator James Inhofe, Monday, September 25, 2006
• 2007- “I gave a talk recently (on fallacies of global warming) and three members of the Canadian government, the environmental cabinet, came up afterwards and said, ‘We agree with you, but it’s not worth our jobs to say anything.’ So what’s being created is a huge industry with billions of dollars of government money and people’s jobs dependent on it.” – Dr. Tim Ball, Coast-to-Coast, Feb 6, 2007
• 2008 – “Hansen was never muzzled even though he violated NASA’s official agency position on climate forecasting (i.e., we did not know enough to forecast climate change or mankind’s effect on it). Hansen thus embarrassed NASA by coming out with his claims of global warming in 1988 in his testimony before Congress” – Dr. John S. Theon, retired Chief of the Climate Processes Research Program at NASA, see above for Hansen quotes
Next time you see the usual "global warming" chart, look carefully: it is in tiny fractions of one degree. The ENTIRE global warming is less than six tenths of one degree. Here is the Global Warming Advocates' own chart, rendered in actual degrees like sane people use. I was going to use 0-100 like a thermometer, but you end up with almost a flat line, so I HELPED the Climate Change side by making the temperature range much narrower, and the chart needlessly tall to stretch the up-down differences in the line.
End of the list.
In c100 years from now, the population of Earth are going to be asking themselves what the hell was going on back in the 20th/21st century!!
"Were they all mad?" will be one of the questions. What kind of voodoo science were they adhering to? will be another.
@Mike Jackson
Yes that would be a reasonable assumption - in the absence of competing theories. Disregard the work of Svente Arrhenius and a large corpus of knowledge built up since him and I think you have a plausible (and reassuring) explanation for current warming by pointing to the MWP . My one problem is that it's not reasonable to disregard the science you find inconvenient. As it happens I'm something of an agnostic on the point of the MWP , but the way you and Stonyground are putting it one would think climate skepticism rests on it.
I have a question
if the MWP was indeed a localized warm area that far up in the northern hemisphere to "green up" Greenland, then would not there been an area that was usually warm, but unusally cold during the same perod to cancel out the global average temperature shown by the proxies? I don't recall a Medieval Cooling Period, perhaps in Central America or the Phillipines, being discussed in school.
Frank
"In addition, the presence of a MWP does not call into question whether humans are now causing the Earth to warm."
This statement goes way beyond disingenuous. Because the MWP would prove the existence of natural climate variability on the same order as "today's warming," the MWP would take away one of the arguments that humans are now causing Earth to warm, namely, the argument that "today's warming" is unprecedented or unnatural.
It would appear that Hengist has never heard of Occams Razor
I just did due diligence and read the article. It uses Monckton for the purposes of constructing a Red Herring argument against the claim that the MWP is important to our understanding of "today's warming." Monckton does exaggerate a bit and so makes himself useful to those who wish to construct Red Herrings. But let's look at the details.
Abraham writes:
'Dr. Raymond Bradley responded, “No, I do not think there is evidence that the world was warmer than today in Medieval times.”'
See the trick there? Abraham did not ask "Was the MWP of the same order as today's warming?" Rather, he asked "Was the MWP warmer than today?" See the difference. To undermine the argument that "today's warming" is unprecedented or unnatural, all one need do is show that the MWP was of the same order of magnitude. To change to the question "Are we warmer today?" is to substitute a question about which scientists are unlikely to have an opinion because it would require evidence that is far more refined and far more secure than anything actually available.
People who construct Red Herrings in this fashion are either ignorant of the logic of their peculiar questions or not to be trusted.
Peter W - fantastic list. I can just imagine sitting round the dinner table reciting that one. Brilliant ;-)
What is so special about the MWP ? Why is it not the Roman Warm Period or the PETM or any other warming event that disproves AGW? I have heard of Occam's Razor, the simplest argument is probably the best. 97% of climate scientists agree on this thing - simples. Your argument that warming at some point in the past disproves the heat trapping effects of carbon is not quite so simple at all.
@Hengist McStone
I think that Mike Jackson has already clarified my first point quite well. The fact that the climate has varied to a very large extent in the past, specifically, before the industrial revolution, means that the burden of proof, that current changes, unlike 100% of the earlier ones, rests upon the warmists.
It is not true that the sceptic's case rests solely upon this one issue. One of the best arguements for the sceptic position is how difficult it is to predict the future and how those who try without sufficient evidence tend to fail. Astronomers can predict the future with pin point accuracy because their science now contains lots of hard data with very few variables. Climate science has very little hard data and a whole mountain of variables. This is why the weather can be accurately predicted for only about two days in advance. Predictions made by climate scientists twenty years ago are now being shown to be false.
Hengist
I'm quite happy to include the Roman Warm period as well, but remember that it was the current crop of climate researchers (or one of them at any rate) that said "we need to get rid of the MWP" and it was that newly-qualified, still wet-behind-the-ears PhD Michael Mann that obliged. Or tried to.
To that extent the MWP has become the "poster child" for this argument.
Arrhenius is a red herring. We all know that he modified (I won't go so far as to say 'recanted') his views on the effects of CO2.
I agree with Stonyground; the case for scepticism does not rest solely on the MWP. Neither does it rest solely on Occam's Razor though that should always be a starting point in looking at new, and apparently needless, complex theories.
Given that RWP and MWP and 20thCWP are broadly similar in temperature there is a very heavy burden on the climate science community to come up with a very convincing reason as to why this time it's different. So far the best they can manage is "it must be CO2 because we can't think of anything else", which shows a marked lack of imagination since several people (Svensmark most recently) have thought of something else.
Go and read Peter Walsh's posting if you haven't done so already and then come back and tell me that this generation has got it dead right all of a sudden when for the last 100+ years they couldn't agree whether it was warming or cooling from one day to the next.
And please in the interests of your own credibility stop quoting Doran et al. Their own summary is here:
http://tigger.uic.edu/~pdoran/012009_Doran_final.pdf
For heavens sake read it properly; it must be one of the most loaded pieces of non-research anyone has dared publish as a serious piece of work.
And that's before you start on whether or not the questions they asked made any sort of sense or allowed for meaningful answers.
You might be convinced by "we asked 3146 people if they thought the earth was warmer and about one-third of them replied and we rejected 900-odd and then found that 75 out of the 77 that were left did".
Personally I think that is the sort of thing that gets scientific research a bad name.
@Hengist,
Short answer.The CO2 "Attribution" Claim rests, in the main, on the fact that the recent warming cannot be explained by natural factors (e.g. Sun and Volcanoes according to Jones) alone - AKA Natural Climate variability. If the MWP is "real" and saw temperatures as high as today, then the extent of this Natural Climate variability has been substantially underestimated by the current "science".
There are other arguments for "Attribution" but if the current warming is within the bounds of what the planet is perfectly happy doing all on its own, not even you (hopefully) will be pushing the "End of the World is nigh" stuff over CO2.
Simples!
CO2science.org has a very large collection of papers showing evidence of the MWP in both hemispheres:
http://www.co2science.org/subject/m/subject_m.php
I wonder why this is constantly ignored
Egil Skalagrimson presented clear evidence many centuries ago, and as recently as last month some Chilean glaciologists at La Joya simposium on sea level changes showed large trees, about 300 years old, discovered just under the ice of retreating Patagonian glaciers. That obviously were growing on a region that today is barren and ice covered. Sometimes this obfuscated blindness to evidence is shocking
Hengist writes:
"Your argument that warming at some point in the past disproves the heat trapping effects of carbon is not quite so simple at all."
Focus, Hengist; it is all a matter of focus. No one has said that the MWP disproves the heat trapping effects of carbon. What the MWP proves is that natural variation covers the kind of warming that we have today. Focus. The point is that the existence of "today's warming" cannot be taken as evidence that it is manmade. "Today's warming" might be manmade. But you need something more than the existence of "today's warming" as evidence for the claim that it is manmade.
The discovery of corpses in hitherto frozen Alpine passes is trumpeted as a proof of global warming (which it is). Little, if anything, is heard of the fact that the pass must have been passable, so to speak, at some time in the past.
Likewise, we are perhaps supposed to believe that Vikings had JCBs to hack out graves from the ice in Greenland!
I am not making a scientific judgment in either case, just suggesting that an occasional note of caution mught be welcome. :-)
Anyone who today still uses the thoroughly discredited "97% of climate scientists agree" statement in argument is merely demonstrating his own ignorance.
Peter Walsh
Interesting timeline. However in the 1970s, when you show that some people were talking about global cooling / imminent ice age, you missed out:
1972 -
Met Office projects global warming of 0.6 degrees C by year 2000 due to ongoing CO2 rise
(Sorry the article is behind a paywall to non-Nature subscribers, I'll be happy to send a pdf if anyone wants it)
OK the warming wasn't as much as 0.6 degrees - more like 0.5 - but the point is there was some warming and the Met Office were projecting that in the early 1970s on the basis of projected increases in CO2, even though global temperatures hadn't risen in the previous couple of decades and other people were (as you say) talking about global cooling. So you have to admit we're consistent..... :-)
(Actually I shouldn't let the Met Office take all the credit there. Sawyer's projection was based on a seminal paper a couple of years earlier by Manabe and Wetherald, which used one of the earliest climate models to estimate warming under doubled CO2 - Sawyer just interpolated that from 1972 to 2000 using an estimate of the CO2 rise.)
And yes yes I know we will now get into an argument about "where has the warming gone since 1998" but I think you all know that I'll just end up saying it's decadal averages that are important :-)
But yes we do need to understand more about sub-decadal variability. Is it all internal variability or is there some external forcing that is important on these timescales? Does the solar cycle play a role? What about aerosols? Still lots to do ... but my point is merely that the decade-by-decade warming was predicted with a reasonable level of success in the early 1970s.
“the late 20th century warmth in the northern hemisphere was unprecedented during at least the last 1000 years."
He's right in that such warm temperatures have only happened once in the last 1000 years (the Roman warm period peaked at 200 AD). But why would he call it unprecedented when only one warm event has happened in that time scale. That's just silly (and disingenuous).
And I'll step into the fray of man influenced climate:
There is an underlying natural variation involving various time scales, ranging from the 7 year El nino / El nina events, to a much larger warming/cooling events over 1000 year time scale, to the very much larger interglacial periods.
Since the Little Ice Age peaked at 1600AD and has been warming ever since, the questions that remain are:
1. What is the underlying "base" natural variation temperature right now.
2. How much increase AND decrease have humans influenced the temperature.
3. Does the human influence on the base line temperature make any difference.
@ Richard Betts
Come off it. If you make enough predictions, one of them is going to be right now and then.
Richard Betts writes:
"...but my point is merely that the decade-by-decade warming was predicted with a reasonable level of success in the early 1970s."
It was projected. If it was predicted then someone has a set of physical hypotheses which can be used to explain and predict the phenomena described. To make the point clear, just ask yourself what hypothesis would have been falsifed if no warming had occurred. You can't name one. No physical hypotheses means no predictions means no science.
You can't say that it was predicted from Arrhenius' hypotheses because those have to be supplemented by other physical hypotheses which cover forcings.
Please stop trashing the good name of science by saying that something has been predicted when you cannot produce the physical hypotheses from which it was predicted.
John Abraham is a weird guy.
He is abject proof of someone sucking up to the consensus to advance one's career outlook.
To add to that list of Peter Walsh's, I have a CIA report from 1974 entitled: "A Study of Climatological Research as it pertains to Intelligence Matters."
It begins:
Some points:
1) When people say the 1970s cooling scare was entirely media-driven, it is not so.
2) Scientists are frequently wrong when they extrapolate from past events (especially in a field as complex and chaotic as climate)
For example, the alarm back then was buttressed by numerous events which included: Soviet crop failures in the mid-1960s; failure of the African monsoon (1968) and subsequent famine; drought in Burma, Costa Rica and Honduras (1973); US flood of the century (April 1973); unprecedented cold in Japan (1973); Pakistan drought (April 1973); Pakistan flood (August 1973); and on and on....
The report notes that: "the politics of food will become the central issue of every government....the climate of the neo-boreal time period has arrived .... the economic and political impact of a major climatic shift is almost beyond comprehension ...." and onto projections of hundreds of millions of climate refugees, even fall of civilisations.
It's all been done before. I would think that any climate scientist with a smidgen of humility would recognise these past blunders and stop being so arrogantly certain about their results and projections.
Hengist,
The "existence" of the MWP calls into question the AGW assertions that the current warming is the most extreme on record - which technically is true, since no one was measuring temperatures at the time, and hence no records, but essentially false. More to the point, the CRUgate emails make it clear that AGW theorists consider the MWP a problem for the theory. The MWP and other, earlier warm periods, as well as a geological record of immensely higher levels of atmospheric CO2 during the Phanerozoic also falsify the entire "tipping point," global doom scenarios that are being promulgated as "problems" we need to address via social and political "engineering."
Last night, I watched the following programme, where it was suggested that certain people in the 12th century had suffered from malaria. Surely, they must have been wrong if there was no WMP?
http://www.bbc.co.uk/iplayer/episode/b0125kbf/History_Cold_Case_Series_2_The_Bodies_in_the_Well/
@Theo Goodwin
We have something more than the existence of "today's warming" as evidence for the claim that it is manmade - Carbon is being pumped into the atmosphere at industrial levels and has been for the past century and a half. Carbon traps heat , and is and will raise the average temperature of the planet therefore . All very basic stuff.
You assert that because the MWP was a natural event current warming is also a natural event. That can be summarised as a hypothesis that the MWP had the same cause(s) as current warming. So we should find solar irradiance (the cause of the MWP) is rising, but we dont.
OK there could be other causes for the MWP . To examine your hypothesis properly we need to know what you think is the common cause for the MWP and current warming.
@ Hengist,
If, as you state 'carbon traps heat' then there is no problem with AGW as the effect would be extremely small. It needs a multiplier of some sort to become significant. That multiplier is claimed to be atmospheric water vapour. The only 'proof' of that is the measurement of global temperature. As global temperatures have risen in pre-industrial times, disappearing of the MWP becomes necessary to support the 'proof'.
And by-the-way, carbon is an element that occurs in diverse forms from graphite to diamonds and exists as a solid, CO2 is a compound that exists as a gas above -78.5C. Just thought I'd mention that in case pencils and marriage get banned inadvertently.
"97% of climate scientists agree on this thing" oh dear it's that 97% again !!
@simpleseekeraftertruth
Yes 'carbon traps heat' is a starting point for me. I really don't follow what you're saying, nor do I see that it has any relevance to the question Ive put to Theo. Perhaps you could direct me to support for your statement "That multiplier is claimed to be atmospheric water vapour". Whether GHG warming is significant or not depends on your definition of significance. GHGs account for approx 33degrees of warming, before man had anything to do with the planet. Without the greenhouse effect Earth would be an icy desolate place.
"Carbon traps heat "
*Sigh*
Hengist,
"We have something more than the existence of "today's warming" as evidence for the claim that it is manmade - Carbon is being pumped into the atmosphere at industrial levels and has been for the past century and a half. Carbon traps heat , and is and will raise the average temperature of the planet therefore . All very basic stuff."
Right. Now let's keep our focus. The earlier topic was what could be inferred from the existence of a MWP on the same order as "today's warming." The new topic is the warming effect of CO2.
According to Arrhenius' hypotheses, the sum total effect of a doubling of CO2 in the atmosphere would be a rise in temperature of about one degree centigrade, a harmless change. However, as Arrhenius understood, there is the question of "forcings." A forcing is a change in the behavior of Earth's atmosphere-ocean system caused by CO2. The most interesting forcing is a change in cloud cover. A change in cloud cover could be positive or negative; that is, it might increase the warming effect of CO2 or it might decrease it. Now, we must focus again, because it is time for the big point.
No one, not Hansen, not Schmidt, no Warmista has created physical hypotheses which describe the changes in cloud cover caused by CO2. This should be the great scandal of the CAGW hysteria. They have not so much as tried. They are not physical scientists and they should stop masquerading as physical scientists. They bring shame on Arrhenius, who was a physical scientist.
As regards the point under discussion, warming caused by manmade CO2, no one knows the effects of forcings because no one has done the scientific legwork necessary to describe them and embody them in physical hypotheses. All of their vaunted claims about warming depend on two things: Gaia Models and simple minded statistics of the kind produced by Mann and The Team. You cannot do physical science if you spend all your time sitting at a computer or your work produces nothing but correlations.
Back to your comments.
"You assert that because the MWP was a natural event current warming is also a natural event."
Nope. Focus. I asserted that because the MWP was a natural event then "today's warming," which is of the same order, has a ready explanation in nature. In other words, what we experience now has occurred before and was caused by nature alone.
"That can be summarised as a hypothesis that the MWP had the same cause(s) as current warming. So we should find solar irradiance (the cause of the MWP) is rising, but we dont."
You changed topics. Focus.
"OK there could be other causes for the MWP . To examine your hypothesis properly we need to know what you think is the common cause for the MWP and current warming."
Nope. This is the great fallacy that prevents most people from understanding Scientific Method. Science is the critical enterprise par excellence. Some scientist proposes a hypothesis and all scientists criticize it, including the one who proposed it. The ball is in the Warmista court. They have to prove their claims. I have done my work as a critic of science.
However, in this case, I have a ready answer and it is that Natural Variation explains "today's warming" just as it explains the MWP. What makes up natural variation? We do not know. There is much work to be done before we have a science, a set of physical hypotheses, which can be used to explain and predict Earth's behavior. (The Warmista are not even working on this. They are navel gazing through their Gaia Models and worshiping their sky god, CO2). Scientists show great humility. Warmista show cock-sure self confidence. You judge.
Hengist: "GHGs account for approx 33degrees of warming, before man had anything to do with the planet. Without the greenhouse effect Earth would be an icy desolate place." I'm only guessing Hengist, and may be wrong, but I don't believe you have a scientific background, nor are you inquisitive about what you're told. While it is true that the current temperature of the earth is 33K above what it would be without our GHG, that is it's around 14C, for the majority of the life of the earth it has been around 22C, we are living in a particularly cool period of the earth's existence with CO2 levels being at historical lows.
Now that's not to say that humans aren't having an effect on the environment, every living creature does, it's part of the nature of things that we're part of the environment, the question is whether the piffling rise in CO2 over the last 150 years is going to bring catastrophe on the planet. Sceptics have three real scientific problems that you clearly don't understand;
1. The current basis for the IPCC and the scientific establishment position is that the temperatures have risen by a massive 0.75C since pre-industrial times. They can explain about 50% of this through natural causes - and now the leap to religious beliefs - therefore because CO2 has risen during the same period it must be the cause of the other 50%. That, is about as far away from science as you can get;
2. So we look into the records to see if there is a glimmer of truth, and lo! not a scintilla of a relationship can be found in the historical records. But 97% (77 out of 79) climate scientists say it's CO2 that is driving climate so it must be true. 100% of geologists say there is no relationship, (but Sir Paul Nurse sees anyone doubting the climate scientists as attacking science). I leave aside the relationship that shows that the degassing of the oceans after a rise in temperature causes a rise in the CO2 in the atmosphere, that's GCSE level science;
3. Finally we have the IPCC's own forecasts that the future temperatures will be higher, that there will be more precipitation and that the atmosphere will be carbon enriched. Yet there is not one benefit to the human race to be had from this increase in tropical conditions, not one, it's all doom and gloom, flooding, droughts, (but more precipitation), more storms (when the temperature gradient between the poles and the equator will have been reduced by around 4C?), rising sea levels caused by the melting of the antarctic caps where the ambient temperature is supposed to drop form -40C to -36C, or by the melting of the greenland ice-caps, well they may well melt over thousands of years, but will the water be able to make it to the Antlantic?
4. Did I say three reasons, that's because I wasn't going to mention that the climate has been seen to be a non-linear chaotic system, and the climate science community have no idea how it will behave and are using models that reflect the lack of knowledge in the climate science community admirably. So there are four reasons.
Hengist, you ask;
Perhaps you could direct me to support for your statement "That multiplier is claimed to be atmospheric water vapour" (?)
At first I thought you were joking but on reflection, I believe you were not. So in response - Try the IPCC, specifically the section on climate sensitivity to CO2. I am not here to do your research for you even though I have pointed out the differences between carbon and carbon dioxide which is more of a misunderstanding on your part than a lack of knowledge. BTW, you may wish to thank Theo Goodwin and Geronimo for their patience and time to help you on your way.
"The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century
warmth in the Northern Hemisphere was unprecedented during at least the last 1,000
years. This conclusion has subsequently been supported by an array of evidence that
includes both additional large-scale surface temperature reconstructions and pronounced
changes in a variety of local proxy indicators, such as melting on ice caps and
the retreat of glaciers around the world, which in many cases appear to be unprecedented
during at least the last 2,000 years."
From page 3 of the Summary. http://books.nap.edu/openbook.php?record_id=11676&page=3
@Theo
It's agreed that natural variability caused the MWP but what are the causes of the natural variation? It's a perfectly reasonable question to ask under the circumstances because you are insisting that those causes are the same as today's causes. I find your statement that we do not know what makes up the natural variation which caused the MWP disingenuous; how can you be so sure that that unknown is the same cause for today's warming then? Here is a link to some science looking at the causes for the MWP .
Your position that todays warming is natural because the MWP was natural relies on a leap of faith. Moreover it is not falsifiable it's therefore not science.
Hengist,
your link appears to use skeptical science and real climate as its sources of information! Not exactly encouraging as an un-biased science link is it?
@ Mike 5:40 PM
"Many true research advances in reconstructing ancient climates have occurred over the past two decades," Soon says, "so we felt it was time to pull together a large sample of recent studies from the last 5-10 years and look for patterns of variability and change. In fact, clear patterns did emerge showing that regions worldwide experienced the highs of the Medieval Warm Period and lows of the Little Ice Age, and that 20th century temperatures are generally cooler than during the medieval warmth."
http://www.cfa.harvard.edu/news/archive/pr0310.html
I had another interesting experience around the time my paper in Science was published. I received an astonishing email from a major researcher in the area of climate change. He said, "We have to get rid of the Medieval Warm Period."
http://epw.senate.gov/hearing_statements.cfm?id=266543
geronimo said, "100% of geologists say there is no relationship," between CO2 levels and climate change.
That is a lie.
"Changes in the abundance in the atmosphere of gases such as water vapour, carbon dioxide and methane affect climate through the Greenhouse Effect – described below." -- UK Geological Society, http://www.geolsoc.org.uk/climatechange
"Decades of scientific research have shown that climate can change from both natural and anthropogenic causes. The Geological Society of America (GSA) concurs with assessments by the National Academies of Science (2005), the National Research Council (2006), and the Intergovernmental Panel on Climate Change (IPCC, 2007) that global climate has warmed and that human activities (mainly greenhouse‐gas emissions) account for most of the warming since the middle 1900s. If current trends continue, the projected increase in global temperature by the end of the twentyfirst century will result in large impacts on humans and other species. Addressing the challenges posed by climate change will require a combination of adaptation to the changes that are likely to occur and global reductions of CO2 emissions from anthropogenic sources." http://www.geosociety.org/positions/position10.htm
@Jul 15, 2011 at 7:40 PM | simpleseekeraftertruth
For a million dollars I'd lie the way Soon does too. NAS trumps million dollar Soon. And no one says there was no MWP - the issues are the scope, magnitude and causes. The current warming by most accounts is greater in scope and magnitude. But the real issue is that the current warming has been caused by our GHG emissions. And how do you account for "The Bishop" hiding the sentence after his quote from the NAS report? If you are seeking after truth, are not you a little curious about why he lied to you?
@Richard Betts
They were a bit more sober on those days at the met office. The paper you mention concludes that even doubling of CO2 is of little concern, as the earth has gone through larger and more intense warming in the past. Curiously enough the example they give for economic impacts is about cooling.
------------------
About the other discussion,
There is ample evidence of the MWP being warmer than the present in both hemispheres, as I said before
Here is an interesting paper about a Viking farm in Greenland. What raised my eyebrows were the estimates of livestock populations in a single district. (100,000 sheep and goats; 2000 cows.)
http://www.collectionscanada.gc.ca/obj/s4/f2/dsk2/ftp04/mq22551.pdf
There is some farming being attempted in Greenland today, but even with all modern advantages they can't match these populations. It is one reason I "suspect" the MWP was warmer than today.
However, if I was a scientist with my reputation to look after, I wouldn't say this is "proof" it was warmer.
Scientists have to be careful what they say, in public, which is why we see this sort of caution:
'Dr. Raymond Bradley responded, “No, I do not think there is evidence that the world was warmer than today in Medieval times.”'
A follow-up question would then be, "Does that mean, Dr. Bradley. that you think there is evidence that the world is warmer now than in the MWP?"
His answer might very well be, "No, I don't think there is evidence for that either."
For a scientist a "hunch" is very different from "proof."
It just occurred to me that trolls such as Hengist actually have a useful function; they irritate those individuals with a thorough grasp of physics and other scientific disciplines plus a gift for teaching so much that those individuals post brilliant expository explanations in reply to the inanities of said trolls, and thus impart essential scientific understandings to people like me who have a Fine Arts education rather than a scientific one.
Every thread at the Bishop's place that a troll attempts to derail actually becomes a golden learning opportunity for people such as I. But I doubt that the trolls gain much as they appear to be such blinkered individuals, so I will not attempt to censure Hengist again as he truly defines the term 'useful idiot'.
So to sum up the causes of the MWP : natural variability. Causes of the natural variability in Mediaval times: we don't know. As Theo explains "the MWP was a natural event then "today's warming," which is of the same order, has a ready explanation in nature. In other words, what we experience now has occurred before and was caused by nature alone"
Not much of an enquiry in that quarter is it.
@Alexander K In scientific and polite discourse that would be described an ad hominem , and if you can't do any better then it's probably best to say nothing. If this was an unbiased blog I would expect your remark to be snipped.
Hengist
Never do this at BH. You may not like this blog, but it is not run on the lines you are familiar with:
.Or you would not be here.
@Mike 8:06
"For a million dollars I'd lie the way Soon does too."
&
"And how do you account for "The Bishop" hiding the sentence after his quote from the NAS report?"
1. Sorry to hear that.
2. I don't have to. I have read the report through once and thank him for drawing it to my attention. If you believe he is hiding something, then you should take that up with him directly,
Oh, and on the report, what did I think should you ask?
IPCC lite.
I think I get the picture: We don't know what caused the MWP but whatever it was it's the ready made explanation that accounts for current warming.
At the risk of being called a troll with a red herring can I ask how can that explanation be said to be falsifiable?