If the Weatherman can't accurately predict tomorrow's weather, how can they predict Global Warming

Originally posted by Muaddib
I actually gave excerpts of research from Spain, Austria, China, and North America, all which correlate the Roman warming period, the Medieval warming period, and the Little Ice age among others.

Ok, this is what I found you have posted...

In Europe, the Roman Warming lasted from 200 B.C. to A.D. 600. It allowed grapes and olives to be grown farther north, and good rains allowed the Romans to buy abundant grain from across the Mediterranean in North Africa. The Roman Warming was followed by the cold Dark Ages (A.D. 600 to 950). Weather is far less stable during the cold phases of the climate cycle. Widespread droughts and storms drove hordes of hungry barbarians to assault the granaries of the collapsing Roman Empire.


Global warming is not new, said Walker, explaining that a variety of evidence points to a global episode of warming, dubbed the Roman Optimum, which occurred roughly from 200 B.C. and about A.D. 400, and a later episode, the Medieval Optimum, which took place from about A.D. 800 to A.D. 1200. A cooling episode named the Vandal Minimum occurred roughly between the two warmings

China was warmest between the year 1 AD and the year 240 AD (during Europe’s Roman Warming).

And the stalagmite one earlier. Two don't really provide a temperature estimate, just that it was probably warm. Not really a problem.

As I said earlier, it is possible that these were global periods of warming, but they may not have been. And no-one really doubts that there have been periods that have been warmer than now, especially in the deep past.

A full analysis of temperatures around 2000 years past has been provided by Moberg et al. (2005). It is the red line on 2000 year temperature reconstruction I posted earlier. This uses high resolution data from tree rings, lower resolution data from lakes/ocean sediments. It shows that north hemisphere temperatures were at no point higher than the last decade.

Letters to Nature
Nature 433, 613-617 (10 February 2005) | doi:10.1038/nature03265; Received 21 July 2004; Accepted 9 December 2004

There is a Corrigendum (23 February 2006) associated with this document.

Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data
Anders Moberg1, Dmitry M. Sonechkin2, Karin Holmgren3, Nina M. Datsenko2 and Wibjörn Karlén3

Department of Meteorology, Stockholm University, SE-106 91 Stockholm, Sweden
Dynamical-Stochastical Laboratory, Hydrometeorological Research Centre of Russia, Bolshoy Predtechensky Lane 11/13, Moscow 123 242, Russia
Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91 Stockholm, Sweden
Correspondence to: Anders Moberg1 Correspondence and requests for materials should be addressed to A.M. (Email: [email protected]).

A number of reconstructions of millennial-scale climate variability have been carried out in order to understand patterns of natural climate variability, on decade to century timescales, and the role of anthropogenic forcing1, 2, 3, 4, 5, 6, 7, 8. These reconstructions have mainly used tree-ring data and other data sets of annual to decadal resolution. Lake and ocean sediments have a lower time resolution, but provide climate information at multicentennial timescales that may not be captured by tree-ring data9, 10. Here we reconstruct Northern Hemisphere temperatures for the past 2,000 years by combining low-resolution proxies with tree-ring data, using a wavelet transform technique11 to achieve timescale-dependent processing of the data. Our reconstruction shows larger multicentennial variability than most previous multi-proxy reconstructions1, 2, 3, 4, 7, but agrees well with temperatures reconstructed from borehole measurements12 and with temperatures obtained with a general circulation model13, 14. According to our reconstruction, high temperatures—similar to those observed in the twentieth century before 1990—occurred around ad 1000 to 1100, and minimum temperatures that are about 0.7 K below the average of 1961–90 occurred around ad 1600. This large natural variability in the past suggests an important role of natural multicentennial variability that is likely to continue.

No mention of any significant warming around 2000 years ago. So, it is quite possible that the data you have is indicative of local climate only. The fact you only present restricted data suggests there is probably a lot of omission of other data, including that used by Moberg et al.

I also note you ignored the stalagmite research that provides validity to the Mann study and others.

BTW, please stop trying to insult my intelligence, and that of other members, I have given links and excerpts to scientific research papers, but you don't want to accept them and instead keep trying to dismiss them...which reminds me of another member who uses that same tactic...

Aye, you have provided a handful. I don't think I have completely dismissed them. Just provided a considered analysis.

No, that graph was the final revision of the GEOCARB model (Berner, 1991, 1994), [American Journal of Science, Vol. 301, February, 2001, P. 182–204.]
www.geocraft.com...

I assume that was the CO2 construction over millions of years. I was talking about the graph that contained a reference to Houghton (it was the temperature chart with a significant MWP).

....No, i mean that data comes from samples such as stalagmites, ice cores, etc, while the claims that anthropogenic CO2 are causing the current Climate Change are based on computer models which try to "guess" what happens in Earth's atmosphere.....

How do you think the 'hockey-stick' reconstructions are produced?

You think you are the only one with access to such data?.... If you did have access to that data, then you would know that the data is "for scholarly use only", hence noone can link in these forums that data...even if people need access to see it; hence "there is no point in bringing this up except in your dellusion that making such a statement gives more credence to your argument"...

Lots of people have access to this stuff. It is part of being associated with a university.

I have presented abstracts from lots of these studies, if you need the full pdf of any I can access, I can provide them for you.

It was just a statement showing my understanding that it is difficult to gain access to the actual journal studies. Even if you don't agree with the conclusions, the IPCC report contains the current research and is a source of information.

BTW, if you did have access to that data, you would very well know that "anthropogenic CO2 emissions causing Climate Change" is still very debatable, even if the IPCC, and you want to claim the contrary.

If you happen to have access, you can check out the Moberg et al., article and give a considered opinion on their data that shows the last decade to be warmer than anytime for 2000 years (which includes the RWP).

I think some people do still question the details (how much can be attributed to humans, how certain the science is at these levels of attribution) but the actuality of human effects is pretty solid. A few others deny the science completely.

Even Lindzen accepts human activity has been an influence, he just thinks it is minor to some other variable he doesn't have any evidence for. He actually thinks that the increases in CO2 should have had a greater effect than it is.

[edit on 14-2-2007 by melatonin]

Originally posted by melatonin
.......................
As I said earlier, it is possible that these were global periods of warming, but they may not have been. And no-one really doubts that there have been periods that have been warmer than now, especially in the deep past.

A full analysis of temperatures around 2000 years past has been provided by Moberg et al. (2005). It is the red line on 2000 year temperature reconstruction I posted earlier. This uses high resolution data from tree rings, lower resolution data from lakes/ocean sediments. It shows that north hemisphere temperatures were at no higher than the last decade.
......................
Even Lindzen accepts human activity has been an influence, he just thinks it is minor to some other variable he doesn't have any evidence for. He actually thinks that the increases in CO2 should have had a greater effect than it is.

[edit on 14-2-2007 by melatonin]

No evidence of any other influence you say?...

October 28th, 2004


The Sun is More Active Now than Over the Last 8000 Years


An international team of scientists has reconstructed the Sun's activity over the last 11 millennia and forecasts decreased activity within a few decades

The activity of the Sun over the last 11,400 years, i.e., back to the end of the last ice age on Earth, has now for the first time been reconstructed quantitatively by an international group of researchers led by Sami K. Solanki from the Max Planck Institute for Solar System Research (Katlenburg-Lindau, Germany). The scientists have analyzed the radioactive isotopes in trees that lived thousands of years ago. As the scientists from Germany, Finland, and Switzerland report in the current issue of the science journal "Nature" from October 28, one needs to go back over 8,000 years in order to find a time when the Sun was, on average, as active as in the last 60 years. Based on a statistical study of earlier periods of increased solar activity, the researchers predict that the current level of high solar activity will probably continue only for a few more decades.

www.mpg.de...



Wow, look at that red line in the graph showing the last 60 years BP.

Originally posted by melatonin

Even Lindzen accepts human activity has been an influence, he just thinks it is minor to some other variable he doesn't have any evidence for. He actually thinks that the increases in CO2 should have had a greater effect than it is.

[edit on 14-2-2007 by melatonin]

Why is it that you are trying to manipulate the facts?...

Do i need to remind you that Lindzen has been a strong critic of anthropogenic global warming theories?

He does accept that warming has occurred, but he thinks "we are not in a position to confidently attribute past climate change to carbon dioxide", maybe that has something to do with the fact that all past climate research have shown that CO2 lags behind temperature?...

[edit on 15-2-2007 by Muaddib]

Originally posted by Muaddib

Why is it that you are trying to manipulate the facts?...

Do i need to remind you that Lindzen has been a strong critic of anthropogenic global warming theories?

Not at all. I know what Lindzen thinks because I have read his testimony to the house of Lords in the UK. No manipulation, just an interpretation of his words.

WHAT IS TRULY AGREED

In order to analyse the meaning of the Prime Minister's claim, it is helpful to break the claim into its component parts. I won't suggest that there is no controversy over details, but there are few that would fundamentally disagree with the following.


1. The global mean surface temperature is always changing. Over the past 60 years, it has both decreased and increased. For the past century, it has probably increased by about 0.6 degrees Centigrade (C). That is to say, we have had some global mean warming.


2. CO2 is a greenhouse gas and its increase should contribute to warming. It is, in fact, increasing, and a doubling would increase the radiative forcing of the earth (mainly due to water vapour and clouds) by about 2 per cent.


3. There is good evidence that man has been responsible for the recent increase in CO2, though climate itself (as well as other natural phenomena) can also cause changes in CO2.


I will refer to this as the basic agreement. To this extent, and no further, it is legitimate to speak of a scientific consensus.

www.publications.parliament.uk...

You can read the rest via the link. He basically suggests it has had a minimal effect, although he accepts that CO2 is a GG and will have caused a degree of warming and will cause a future degree of warming.

He says the same here...

To understand the misconceptions perpetuated about climate science and the climate of intimidation, one needs to grasp some of the complex underlying scientific issues. First, let's start where there is agreement. The public, press and policy makers have been repeatedly told that three claims have widespread scientific support: Global temperature has risen about a degree since the late 19th century; levels of CO2 in the atmosphere have increased by about 30% over the same period; and CO2 should contribute to future warming. These claims are true.

However, what the public fails to grasp is that the claims neither constitute support for alarm nor establish man's responsibility for the small amount of warming that has occurred. In fact, those who make the most outlandish claims of alarm are actually demonstrating skepticism of the very science they say supports them. It isn't just that the alarmists are trumpeting model results that we know must be wrong. It is that they are trumpeting catastrophes that couldn't happen even if the models were right as justifying costly policies to try to prevent global warming.

Says it is warming, says CO2 has increased, says it will contribute.

He just thinks it will be of minimal importance. He has made a statement that if we accept the GCMs as valid, we would have expected more warming than we have seen, can't find where I read it, but I'm quite sure it is true.

However, his claims are very much criticised by other climatologists. If you are interested in an informed criticism of his position (which I doubt, heh), you can find one here and another here and finally a comparison between Hansen's and Lindzen's view on the NASA website here

His opinion is not based on anything in the literature, just a purely faith-based position. I like Hansen's criticism of Lindzen in point 4..

Difference 4 has an academic flavor, and is perhaps not worth special efforts. But it illustrates a lack of understanding of the basic greenhouse mechanism by Lindzen.

heh, not good.

He has also made gaffes before;

In 2001, Lindzen published a paper speculating that as the Earth warmed, water vapor would decrease in the upper atmosphere, allowing heat to escape back into space more efficiently, and thereby reducing overall temperature.

The paper met with vigorous criticism. Eventually, he disavowed the idea. "That was an old view," Lindzen said about his five-year-old hypothesis. "I find it insane that I am still forced to explain this."

hey, no-one's perfect, eh?

But we need skeptics in science, it actually depends on them.

I think his point was legitimate, at the time—the models really hadn't been tested very thoroughly," said Miller. "But there's been a lot of improvement, I think, in large part in response to his criticism. The upshot, at least from my point of view, was that I ended up pretty convinced the models were actually doing the right thing."

From an article here.

[edit on 15-2-2007 by melatonin]

Originally posted by Muaddib

No evidence of any other influence you say?...

October 28th, 2004
The Sun is More Active Now than Over the Last 8000 Years

I guess I'll have to repost the study I posted earlier...

Plus no-one suggests that there are no other influences, just that human effects are significant.

Nature 443, 161-166 (14 September 2006) | doi:10.1038/nature05072

Variations in solar luminosity and their effect on the Earth's climate
P. Foukal1, C. Fröhlich2, H. Spruit3 and T. M. L. Wigley4

Abstract

Variations in the Sun's total energy output (luminosity) are caused by changing dark (sunspot) and bright structures on the solar disk during the 11-year sunspot cycle. The variations measured from spacecraft since 1978 are too small to have contributed appreciably to accelerated global warming over the past 30 years. In this Review, we show that detailed analysis of these small output variations has greatly advanced our understanding of solar luminosity change, and this new understanding indicates that brightening of the Sun is unlikely to have had a significant influence on global warming since the seventeenth century. Additional climate forcing by changes in the Sun's output of ultraviolet light, and of magnetized plasmas, cannot be ruled out. The suggested mechanisms are, however, too complex to evaluate meaningfully at present.

Another recent study that assesses the effect of solar activity suggested around a 25-35% influence (Scarfeta & West, 2006). But as you can see by the Nature article, this is quite questionable.

Originally posted by Muaddib
He does accept that warming has occurred, but he thinks "we are not in a position to confidently attribute past climate change to carbon dioxide", maybe that has something to do with the fact that all past climate research have shown that CO2 lags behind temperature?...

Sorry, missed some of this...

His opinion is his opinion. It is not really based on science, just an opinion. Science is based on evidence. As I keep saying, all he has to do is publish a peer-reviewed article showing why the science is wrong. Newspaper articles and think-tank seminars don't count as science.

Well, even though CO2 rises 800 years after termination of glacial periods, it doesn't negate the physical properties of CO2. You seem pretty stuck on the fact natural pertubations of climate do exist and that, in your opinion, climatologists ignore this. They don't, it is well accepted that other forcings exist. We just see no evidence of a majority effect from other mechanisms.

It takes around 5000 years for complete warming following an ice-age. The first 800 or so is due to whatever causes normal ice-age cycles, is the final 4200 years influenced by greenhouse gases? That's most of the warming period. Thus CO2 acts as an amplifier?

And then we can ask when the last ice-age was? Is the warming period complete? What will the change in the CO2 cycle human activity has unquestioningly caused actually do in this current interglacial period? [I have posted a graph that shows the CO2 levels during a normal ice-age cycle, we have sort of gone past the norm]

The evidence suggests it will produce significant warming.

[edit on 15-2-2007 by melatonin]

If human activity isn't affecting global climate, then the really big question is: why not?

How can you change the albedo of a planet and not affect insolation? How can you destroy so much rain forest and not affect cloud formation?

CO2 isn't the whole story.

Of course, in the meantime, can anyone come up with a logical reason why we should want to continue using up so much fossil fuel? I admit the main advantages of reducing our consumption are lower costs, less general pollution, less reliance on unstable regimes for our fuel etc etc - so maybe not much of an incentive .......

Originally posted by Essan
If human activity isn't affecting global climate, then the really big question is: why not?

How can you change the albedo of a planet and not affect insolation? How can you destroy so much rain forest and not affect cloud formation?

CO2 isn't the whole story.

This is what is hard to get across I think. We can't just destroy massive ecosystems and think it does nothing.

When you analyse the contrarian viewpoint, it is quite inconsistent. Thus, Muaddib is posting research speculating that human activity resulted in climate change in the RWP, with other evidence of a roman optimum, in the hope of showing this period was warmer than now. And then in the next sentence, deny that excessive contemporary human activity can be a major influence on climate.

Quite contradictory.

Climate and weather are two different things.

For measuring climate change, similar aspects to weather prediction are used but in slightly different methods. For climate, it would be ineffective to base global warming on air temperatures since these vary so much. Rather, soil temperature is a better indicator.

Different climate models specialize in the fine details of different global interactions. i.e. someone's lab knows a lot about volcanos another person might know more about the effect of marine algae.

The test for these models is to build a model with just code, and once complete plug in variables for known time periods when we have collected data - i.e. the effect of Mt. Saint Helens or something of that nature. If the model reflects what we know happened, then that data is considered to be useful.

A chapter in a book title "Field Notes From A Catastrophe" describes this in great detail.

Originally posted by melatonin

When you analyse the contrarian viewpoint, it is quite inconsistent. Thus, Muaddib is posting research speculating that human activity resulted in climate change in the RWP, with other evidence of a roman optimum, in the hope of showing this period was warmer than now. And then in the next sentence, deny that excessive contemporary human activity can be a major influence on climate.

Quite contradictory.

It is not contradictory... Dr. Walker's research points to the fact that these events, Roman Warming period, Medieval Warming period also were occurring in the Americas at the same time that they happened in China, Europe and South Africa. Dr. Walker then gives her opinion that that warming period was caused by deforestation from the Romans building their roads.... She is in fact like some other scientists trying to blame mankind for one thing or another for causing Climate Change, when they have happened several times without the help of mankind..

The last part is her opinion...but it doesn't change the fact that The Roman Warming period, the Medieval warming and even the Little Ice Age happened in the Americas just as they happened in China, Europe and South Africa, which is what you were trying to refute.

The Little Ice Age and Medieval Warming in South Africa


P. D. Tyson1, W. Karlén2, K. Holmgren2 and G. A. Heiss3.

1Climatology Research Group, University of the Witwatersrand
2Department of Physical Geography, Stockholm University
3Geomar, Wischhofstr. 1-3, 24148 Kiel, Germany; present address: German Advisory Council on Global Change (WBGU), P.O. Box 120161, 27515 Bremerhaven, Germany, E-mail: [email protected]


Abstract

The Little Ice Age, from around 1300 to 1800, and medieval warming, from before 1000 to around 1300 in South Africa, are shown to be distinctive features of the regional climate of the last millennium. The proxy climate record has been constituted from oxygen and carbon isotope and colour density data obtained from a well-dated stalagmite derived from Cold Air Cave in the Makapansgat Valley.
The climate of the interior of South Africa was around 1oC cooler in the Little Ice Age and may have been over 3°C higher than at present during the extremes of the medieval warm period. It was variable throughout the millennium, but considerably more so during the warming of the eleventh to thirteenth centuries. Extreme events in the record show distinct teleconnections with similar events in other parts of the world, in both the northern and southern hemispheres. The lowest temperature events recorded during the Little Ice Age in South Africa are shown to be coeval with the Maunder and Sporer Minima in solar irradiance. The medieval warming is shown to have been coincided with the cosmogenic 10Be and 14C isotopic maxima recorded in tree rings elsewhere in the world during the Medieval Maximum in solar radiation.

www-user.zfn.uni-bremen.de...

But again, i am certain that melatonin will try to dismiss the research done by those scientists like he has tried with every other research which contradicts his "opinion".

It is true that we can't predict with 100% certainty the weather, and the same can be said of "Climate Change".

Hansen predicted back in 1988 that world temperatures would increase by the years 2000 by 0.33C, yet they only increased by 0.06C.

People like Hansen and Mann have to constantly change their "predictions" because they have been wrong more times that they have been right...yet these same people, and some others want to claim the certainty that mankind is the cause for Climate Change is at 90%-95% when they have been wrong in their predictions.

Hansen has been wrong on his 1988 prediction by 0.27C, yet we are to believe they can say for certainty that mankind's role on Climate Change is certain by 90%-95%?....

More so when we know from the geological record that dramatic Climate Change have occurred several times in the past without the help of cars, factories and ACs...

large climate changes in Europe/Near East during the last 15,000 calendar years (note that these dates are in 'real' years not radiocarbon years).

14,500 y.a. - rapid warming and moistening of climates. Rapid deglaciation begins.

13,500 y.a. - climates about as warm and moist as today's

13,000 y.a. 'Older Dryas' cold phase (lasting about 200 years) before a partial return to warmer conditions.

12,800 y.a. (+/- 200 years)- rapid stepwise onset of the intensely cold Younger Dryas. Much drier than present over much of Europe and the Middle East, though wetter-than-present conditions at first prevailed in NW Europe.

11,500 y.a. (+/- 200 years) - Younger Dryas ends suddenly over a few decades, back to relative warmth and moist climates (Holocene, or Isotope Stage 1).

11,500 - 10,500 y.a. - climates possibly still slightly cooler than present-day.

9,000 y.a. - 8,200 y.a. - climates warmer and often moister than today's

about 8,200 y.a. - sudden cool phase lasting about 200 years, about half-way as severe as the Younger Dryas. Wetter-than-present conditions in NW Europe, but drier than present in eastern Turkey.

8,000-4,500 y.a. - climates generally slightly warmer and moister than today's.

(but; at 5,900 y.a. - a possible sudden and short-lived cold phase corresponding to the 'elm decline').

Since about 4,500 y.a. - climates fairly similar to the present

2,600 y.a. - relatively wet/cold event (of unknown duration) in many areas

(but; 1,400 y.a. [536-538 A.D.] wet cold event of reduced tree growth and famine across western Europe and possibly elsewhere).

(Followed by 'Little Ice Age' about 700-200 ya)

www.esd.ornl.gov...

In the above they forgot to mention the Medieval Warming event which started in the 800s and lasted until the 1300s.... Yet some scientists can say for certainty "mankind is to blame for the current Climate Change".....

[edit on 15-2-2007 by Muaddib]

Originally posted by carlwfbird
Climate and weather are two different things.

For measuring climate change, similar aspects to weather prediction are used but in slightly different methods. For climate, it would be ineffective to base global warming on air temperatures since these vary so much. Rather, soil temperature is a better indicator.
.....................

Weather models and Climate models work under the assumption that these computer models can predict what happens in the Earth's atmosphere and they can account for every factor which influences the weather and the Climate, but this is not true.

Computer models are flawed because we don't understand every factor that affects the weather and the Climate, it is that simple.

If most scientists were to say this fact their funds would be cut, and i am sure you understand they don't want this, hence they try to make predictions which most of the time are wrong and claim they know with a "certainty of 90%-95%".

By doing this their funds are not cut and later on when we can see they were wrong they can make excuses as to why they were wrong like what happens usually.

Originally posted by Muaddib
The last part is her opinion...but it doesn't change the fact that The Roman Warming period, the Medieval warming and even the Little Ice Age happened in the Americas just as they happened in China, Europe and South Africa, which is what you were trying to refute.

Some of them are easy to refute, they presented no temperature estmates and are therefore of little consequence.

Yeah, I know it was speculation from Walker, I said the same myself. It was just that you presented her work as supporting your position but completely ignored her inferences.

The Little Ice Age and Medieval Warming in South Africa

Cool, a peer-reviewed article. Seems we have another data point that suggests there were areas periods of the MWP that were warmer than today. You now have a small number of isolated data points.

Here's a few more that suggest the MWP was not warmer than the last 30 years...

When was it warm? The warmest 30-year periods prior to 1970 A.D. from a variety of ice core, tree ring, speleothem, sedimentary, and documentary records. Gray diamonds denote first year of record. 1: 18O from Quelccaya Ice cap, Peru. 2: 18O from Sajama, Bolivia. 3: 18O from Huascaran, Peru. 4: Inverted mean of eight tree-ring indices from northern Patagonia (Argentina and Chile). 5: Speleothem 18O from South Africa. 6: Austral summer temperatures from a New Zealand tree-ring series. 7: Tree-ring indices, Tasmania. 8: D Talos Dome, Antarctica. 9: 18O from Guliya, W. China. 10: 18O from Dunde, W. China. 11: 18O from Dasuopu, W. China. 12: Summer temperature from three tree-ring series in the Sierra Nevada, California. 13: Speleothem annual layer thickness, Beijing, China. 14: Winter temperatures from historical documents, E. China. 15: Lamination thickness in lake sediments, Baffin Island, N. Canada. 16: Tree-ring indices from a site in Mongolia. 17: Mean annual temperature of Northern Hemisphere from multiproxy composite. 18: Regional curve-standardized (RCS) temperature-sensitive tree-ring chronology from the Polar Urals. 19: RCS temperature-sensitive tree-ring chronology from the Taimyr Peninsula. 20: RCS temperature-sensitive tree-ring chronology from Tornetrask, Northern Sweden. 21: Lake sediments, Ellesmere Island, N. Canada. 22: 18O from Summit (GISP2), C. Greenland. 23: Solar activity from 10Be. For sources of data, see (16).

These are all derived from the Bradley review of the MWP claims I posted earlier (Bradley et al., 2003, Science). Their conclusion...

The balance of evidence does not point to a High Medieval period that was as warm as or warmer than the late 20th century. However, more climate records are required to explain the likely causes for climate variations over the last millennium and to fully understand natural climate variability, which will certainly accompany future anthropogenic effects on climate.

I will also refer you to the reconstructions that I have continually posted.



That's another 10 studies showing that current temperatures were greater than during the MWP - all based on proxies like the single area proxy data you have supplied.

Seems Bradley is correct in that the balance of the evidence suggests the MWP was not greater than now.

But again, i am certain that melatonin will try to dismiss the research done by those scientists like he has tried with every other research which contradicts his "opinion".

I didn't dismiss them, I accept them as indications of local climatic conditons during the periods they pertain to. There is enough evidence showing large variations in temperatures at different times. When taken together in the reconstructions, they seem to balance out to an overall situation of warm climate but not warmer than 1970+

It is true that we can't predict with 100% certainty the weather, and the same can be said of "Climate Change".

Hansen predicted back in 1988 that world temperatures would increase by the years 2000 by 0.33C, yet they only increased by 0.06C.

People like Hansen and Mann have to constantly change their "predictions" because they have been wrong more times that they have been right...yet these same people, and some others want to claim the certainty that mankind is the cause for Climate Change is at 90%-95% when they have been wrong in their predictions.

Hansen has been wrong on his 1988 prediction by 0.27C, yet we are to believe they can say for certainty that mankind's role on Climate Change is certain by 90%-95%?....

I think that Hansen did a fine job. His scenarios...



Seems the observed temperatures were a fairly good fit. Not bad for models from 1988.

More so when we know from the geological record that dramatic Climate Change have occurred several times in the past without the help of cars, factories and ACs...

Yeah, we know that climate can change through other means. I've accepted that, oh, I dunno, several times already.

large climate changes in Europe/Near East during the last 15,000 calendar years (note that these dates are in 'real' years not radiocarbon years).

Yeah, there will be periods of deeper time when it was warmer than now. I accepted that earlier. Did I say that temperatures are warmer now than ever in the history of the earth?

In the above they forgot to mention the Medieval Warming event which started in the 800s and lasted until the 1300s.... Yet some scientists can say for certainty "mankind is to blame for the current Climate

Maybe that's because it is not generally accepted that the MWP was warmer than now because the evidence suggests so. I doubt any scientist would say 100% certainty.

Can you outline this galactic stardust idea of yours...

Tell me why and how galactic dust will affect climate.

[edit on 15-2-2007 by melatonin]

Originally posted by melatonin
Can you outline this galactic stardust idea of yours...

Tell me why and how galactic dust will affect climate.

May I interject for a moment? Id like to answer that question.

Source

There is some chance that the Solar System will cross small dense clouds that have diameters up to 100 times the distance from the Earth to the Sun. These encounters may increase the number of interstellar charged particles bombarding Earth, with the risk of altering the climate here. Our interstellar environment may thus be important for the short and long-term prospects for life on Earth. Even though there is still some work to be done before it will be possible to construct a 'Galactic weather forecast', it is clear that for the past 200,000 years we have been in a favourable environment that has not altered our climate significantly.

And

The scientists are excited at the prospects: 'Such a probe will explore the nature of the interstellar medium and help predict the long-term influence of charged particles from the Milky Way on our weather and climate'.

Ever get the feeling that the solar system is like a giant organic space ship, with shields and warp drives? OK maybe not warp but going Mach2 isnt bad!

Our solar system, looking like a uber spaceship

Originally posted by Dae
May I interject for a moment? Id like to answer that question.

Our solar system, looking like a uber spaceship

Aye, that's cool.

He/she can now tell me how this all relates to the current period of climate change. ..

Muaddib, If we entered a galactic dust cloud next week, what do you think this would do to the earth's climate and why?

[edit on 15-2-2007 by melatonin]

Originally posted by melatonin
He/she can now tell me how this all relates to the current period of climate change. ..

Muaddib, If we entered a galactic dust cloud next week, what do you think this would do to the earth's climate and why?

Muaddib is not alone in this thinking.

Source: PDF

This highly reactive hydrogen could reach stratospheric heights at 40–50 km by direct inflow and accumulate to levels that may be relevant for ozone depletion, and inevitably cause strong influence on the terrestrial climate (Fahr, 1968a, b; Bzowski et al., 1996).

Source

The interaction of the heliosphere with interstellar clouds has attracted interest since the late 1920's, both with a view to explaining apparent quasi-periodic climate "catastrophes" as well as periodic mass extinctions. Until recently, however, models describing the solar wind - local interstellar medium (LISM) interaction self-consistently had not been developed.
[snip]
The calculation presented here supports past speculation that the galactic environment of the Sun moderates the interplanetary environment at the orbit of the Earth, and possibly also the terrestrial climate.

Source

But if the solar system encountered the much denser cloud, Frisch estimates that the heliosphere could be compressed to within one or two astronomical units of the Sun, not much greater than the Earth’s distance from the Sun. “There would be dramatic effects on the inner solar system,” said Frisch. “It would immediately change the whole interaction between the solar wind and the interstellar medium.” Researchers have predicted increases in the cosmic-ray flux, changes in the Earth’s magnetosphere, the chemistry of the atmosphere and perhaps even the terrestrial climate.

Source

(CNN) -- The Earth has experienced higher surface but not atmospheric temperatures in recent decades. Now a climate scientist thinks he knows why: highly charged particles originating beyond the solar system.

Originally posted by Dae
Muaddib is not alone in this thinking.

The only bit that makes any clear indication of prediction is the CNN news item. It focuses on cosmic rays, myself and muaddib have been there already, it is the current area of study of Svensmark. There is no evidence that cosmic rays have varied sufficiently to account for the current warming. So, it's interesting but inconsequential to this discussion.



I'm really interested in what interstellar dust would do to the earth's climate. I see one peer-reviewed study you posted, Yeghikyan & Fahr, what does it mean? What are the implications of the findings in the context of climate change?

I would be interested in some reasoning as to what it would actually do. I know scientists, like Frisch, have speculated that interstellar dust may affect climate, but how? Warming? Cooling? Lots of rain? Galactic hailstones?

If interstellar dust increased rapidly for 30 years, what would happen and why?

Can it account for current climate change?

He mentioned this in the context of the warming of planets in the solar system (where the evidence doesn't really gel), with a reference to Ulysses and evidence of increasing dust (quote below). I therefore assume he suggests interstellar dust causes warming. I would like to see the reasoning as to why...

Also NASA, and the ESA (European Space Agency) have stated that by 2012-2013 the density of the interstellar cloud we have been entering will be at the highest. It also depends on what sort opf interstellar cloud we are currently going through, whether it is a difuse interstellar cloud or a dense molecular interstellar cloud it will affect the Climate on Earth differently.

As this is muaddib's claim, I would appreciate if he could answer this.

[edit on 15-2-2007 by melatonin]

Originally posted by Muaddib

Computer models are flawed because we don't understand every factor that affects the weather and the Climate, it is that simple.

If most scientists were to say this fact their funds would be cut, and i am sure you understand they don't want this, hence they try to make predictions which most of the time are wrong and claim they know with a "certainty of 90%-95%".

By doing this their funds are not cut and later on when we can see they were wrong they can make excuses as to why they were wrong like what happens usually.

I am more than happy with 90-95% certainty with respect to this topic. I think most of us should be. I am more concerned with the 90% certainty that scientists in the pharmaceutical industry use when they market drugs for any number of ailments without a full understanding of the affects on the body.

But as I stated earlier, no particular model is 100% accurate. Every model specializes in different areas. If we look at the collective sum of all of these that factor in different data, we see that the overwhealming majority of scenarios provide a similar scary vision of the future. I personally feel that all the models underestimate the effect of CO2 on the atmosphere based on the global dimming effect of our more visible pollutants which are slowly being phased out.

Originally posted by melatonin
Some of them are easy to refute, they presented no temperature estmates and are therefore of little consequence.

Easy to refute?... These scientists have their Universities backing their research and conclusions, and you come here "claiming they are easy to refute"?

Amazing....anyways, you obviously didn't even read the excerpts i gave...... They said again...

The five scientists determined that the mean temperature of the Medieval Warm Period in northwest Spain was 1.5°C warmer than it was over the 30 years leading up to the time of their study, and that the mean temperature of the Roman Warm Period was 2°C warmer. Even more impressive was their finding that several decadal-scale intervals during the Roman Warm Period were more than 2.5°C warmer than the 1968-98 period, while an interval in excess of 80 years during the Medieval Warm Period was more than 3°C warmer.

ff.org...

Originally posted by melatonin
Yeah, I know it was speculation from Walker, I said the same myself. It was just that you presented her work as supporting your position but completely ignored her inferences.

I ignored her "opinion because it is obviously very biased"... i don't ignore her research, but to claim that "because the Romans built their roads and cut down trees they caused global warming in that period is quite a presumtuous claim, more so for a scientist to claim this... Not to mention that those periods were shown by the geological records to have occurred in South Africa, China, and the Americas and not only on Europe...

Originally posted by melatonin
Cool, a peer-reviewed article. Seems we have another data point that suggests there were areas periods of the MWP that were warmer than today. You now have a small number of isolated data points.

Here's a few more that suggest the MWP was not warmer than the last 30 years...

Well then, we have several scientists whose research disagree with each other's conclusions....

Sallie Baliunas and Willie Soon of the Harvard-Smithsonian Center for Astrophysics reviewed more than 200 studies that examined climate "proxy" records--data from such phenomena as the growth of tree rings or coral, which are sensitive to climatic conditions. They concluded in the January Climate Research that "across the world, many records reveal that the 20th century is probably not the warmest nor a uniquely extreme climate period of the last millennium." They said that two extreme climate periods--the Medieval Warming Period between 800 and 1300 and the Little Ice Age of 1300 to 1900--occurred worldwide, at a time before industrial emissions of greenhouse gases became abundant. (A longer version subsequently appeared in the May Energy and Environment.)

www.sciam.com...

Originally posted by melatonin
I will also refer you to the reconstructions that I have continually posted.

Those reconstructions do not correlate each other, and there are dozens of other research which do show that the MWP and the RWM were warmer than today...

Originally posted by melatonin
I didn't dismiss them, I accept them as indications of local climatic conditons during the periods they pertain to. There is enough evidence showing large variations in temperatures at different times. When taken together in the reconstructions, they seem to balance out to an overall situation of warm climate but not warmer than 1970+

The scientists who made the research disagree with you....

Originally posted by melatonin
Seems the observed temperatures were a fairly good fit. Not bad for models from 1988.

He was wrong by a longshot...



Yeah, we know that climate can change through other means. I've accepted that, oh, I dunno, several times already.

large climate changes in Europe/Near East during the last 15,000 calendar years (note that these dates are in 'real' years not radiocarbon years).

Yeah, there will be periods of deeper time when it was warmer than now. I accepted that earlier. Did I say that temperatures are warmer now than ever in the history of the earth?

Originally posted by melatonin
Maybe that's because it is not generally accepted that the MWP was warmer than now because the evidence suggests so. I doubt any scientist would say 100% certainty.

Really?...

Science 29 November 1996:
Vol. 274. no. 5292, pp. 1503 - 1508
DOI: 10.1126/science.274.5292.1503
Prev | Table of Contents | Next

Reports

The Little Ice Age and Medieval Warm Period in the Sargasso Sea
Lloyd D. Keigwin

Sea surface temperature (SST), salinity, and flux of terrigenous material oscillated on millennial time scales in the Pleistocene North Atlantic, but there are few records of Holocene variability. Because of high rates of sediment accumulation, Holocene oscillations are well documented in the northern Sargasso Sea. Results from a radiocarbon-dated box core show that SST was 1°C cooler than today 400 years ago (the Little Ice Age) and 1700 years ago, and 1°C warmer than today 1000 years ago (the Medieval Warm Period). Thus, at least some of the warming since the Little Ice Age appears to be part of a natural oscillation.

www.sciencemag.org...

Since 1996 until now temperatures have not risen 1°C...hence the MWP was warmer than today

Originally posted by melatonin
Can you outline this galactic stardust idea of yours...

Tell me why and how galactic dust will affect climate.

It is not "an idea of mine".... in fact there has been research on this subject for decades, and even more recent research which correlate the fact that intergalactic clouds affect the environmet of planets.

Title:
Is the solar system entering a nearby interstellar cloud
Authors:
Vidal-Madjar, A.; Laurent, C.; Bruston, P.; Audouze, J.
Affiliation:
AA(CNRS, Laboratoire de Physique Stellaire et Planetaire, Verrieres-le-Buisson, Essonne, France), AB(CNRS, Laboratoire de Physique Stellaire et Planetaire, Verrieres-le-Buisson, Essonne, France), AC(CNRS, Laboratoire de Physique Stellaire et Planetaire, Verrieres-le-Buisson, Essonne, France), AD(Meudon Observatoire, Hauts-de-Seine; Paris XI, Universite, Orsay, Essonne, France)
Publication:
Astrophysical Journal, Part 1, vol. 223, July 15, 1978, p. 589-600. (ApJ Homepage)
Publication Date:
07/1978
Category:
Astrophysics
Origin:
STI
NASA/STI Keywords:
ASTRONOMICAL MODELS, DEUTERIUM, HYDROGEN ATOMS, INTERSTELLAR GAS, SOLAR SYSTEM, ABUNDANCE, EARLY STARS, GAS DENSITY, INTERSTELLAR EXTINCTION
DOI:
10.1086/156294
Bibliographic Code:
1978ApJ...223..589V

Abstract
....................
Observational arguments in favor of such a cloud are presented, and implications of the presence of a nearby cloud are discussed, including possible changes in terrestrial climate. It is suggested that the postulated interstellar cloud should encounter the solar system at some unspecified time in the 'near' future and might have a drastic influence on terrestrial climate in the next 10,000 years.

adsabs.harvard.edu...

ESA sees stardust storms heading for Solar System

Until ten years ago, most astronomers did not believe stardust could enter our Solar System. Then ESA's Ulysses spaceprobe discovered minute stardust particles leaking through the Sun's magnetic shield, into the realm of Earth and the other planets. Now, the same spaceprobe has shown that a flood of dusty particles is heading our way.
...........
What is surprising in this new Ulysses discovery is that the amount of stardust has continued to increase even after the solar activity calmed down and the magnetic field resumed its ordered shape in 2001.

Scientists believe that this is due to the way in which the polarity changed during solar maximum. Instead of reversing completely, flipping north to south, the Sun's magnetic poles have only rotated at halfway and are now more or less lying sideways along the Sun's equator. This weaker configuration of the magnetic shield is letting in two to three times more stardust than at the end of the 1990s. Moreover, this influx could increase by as much as ten times until the end of the current solar cycle in 2012.

www.spaceref.com...

If you don't know how intergalactic clouds can affect the Climate of planets, it only shows how much research you have really done in the factors that affect our climate...

Intergalactic clouds have excited particles, such as plasma, they have gases such as hydrogen and they do affect the climate on planets. Depending on the type of cloud, the climate on planets are changed by intergallactic clouds by cooling the planet, or warming the planet.

Cosmic rays also affect the Climate on planets, as they are nucleons, composed of protons and electrons, which when they hit the Earth's atmospheric molecules, they release heat, heating the atmosphere, but they also produce cloud cover, as recent research shows. Of note our particle accelerators cannot produce the amount of energy found in cosmic rays.

[edit on 16-2-2007 by Muaddib]

Here is a more recent study on cosmic rays and how they can affect the climate on planets.

Astrophysics, abstract
astro-ph/0602092 version 1
From: Mikhail V. Medvedev [view email]
Date (v1): Sat, 4 Feb 2006 08:41:11 GMT (144kb)
Date (revised v2): Sat, 8 Apr 2006 07:53:56 GMT (228kb)
Do extragalactic cosmic rays induce cycles in fossil diversity?
Authors: Mikhail V. Medvedev, Adrian L. Melott (University of Kansas)
Comments: 13 pages, 3 figures, submitted to Nature
Subj-class: Astrophysics; Geophysics; Plasma Physics; Atmospheric and Oceanic Physics; Populations and Evolution

The idea of cycles in fossil diversity has recently been put on a firm statistical footing, revealing a 62[plus-minnus]3-million-year cycle in the number of marine genera. The strong signal requires a periodic process extending back at least 540 My, which is difficult to explain by any terrestrial process. While astro- and geophysical phenomena may be periodic for such a long time, no plausible mechanism has been found. The fact that the period of the diversity cycle is close to the 64 My period of the vertical oscillation of the Solar system relative to the galactic disk is suggestive. However, any model involving cosmogenic processes modulated by the Sun's midplane crossing or its maximal vertical distance from the galactic plane predicts a half-period cycle, i.e. about 32 My. Here we propose that the diversity cycle is caused by the anisotropy of cosmic ray (CR) production in the galactic halo/wind/termination shock and the shielding effect of the galactic magnetic fields. CRs influence cloud formation, can affect climate and harm live organisms directly via increase of radiation dose. The CR anisotropy is caused by the galactic north-south asymmetry of the termination shock due to the interaction with the ``warm-hot intergalactic medium'' as our galaxy falls toward the Virgo cluster (nearly in the direction of the galactic north pole) with a velocity of order 200 km/s. Here we revisit the mechanism of CR propagation in the galactic magnetic fields and show that the shielding effect is strongly position-dependent. It varies by a factor of a hundred and reaches a minimum at the maximum northward displacement of the Sun. Very good phase agreement between maximum excursions of the Sun toward galactic north and minima of the fossil diversity cycle further supports our model.

arxiv.org...

Interstellar or intergalactic clouds, these clouds can be neutral, ionized, or molecular clouds. Neutral and ionized clouds are also known as diffused clouds.

Our Solar system has entered this cloud also known as the Local Fluff, and we know that the density of this cloud varies, as these clouds are composed of cluodlets of different density, and btw, the cloud our solar system is in also does contain CO.

We have been entering a denser part of this cloud, and recent research shows us that the density of the cloud will be exponentially increasing at least until 2013.

Originally posted by Muaddib

Originally posted by melatonin
Some of them are easy to refute, they presented no temperature estmates and are therefore of little consequence.

Easy to refute?... These scientists have their Universities backing their research and conclusions, and you come here "claiming they are easy to refute"?

Amazing....anyways, you obviously didn't even read the excerpts i gave...... They said again...

You're starting to be disingenuous again.

If the articles don't present temperature estimates of course they are easy to refute. If you note, that is what I said.

I ignored her "opinion because it is obviously very biased"...

Oh right, it must be yeah...

Well then, we have several scientists whose research disagree with each other's conclusions....

Sallie Baliunas and Willie Soon of the Harvard-Smithsonian Center for Astrophysics reviewed more than 200 studies that examined climate "proxy" records--data from such phenomena as the growth of tree rings or coral, which are sensitive to climatic conditions.

And you talk about flaws in the Mann study and biased research, heh.

I would like you to tell me the methodology of Soon & Baliunas study, how did they determined a climate anomaly? It's in the paper. Read it.

Their methods, and the fact it passed peer-review, led to the resignation of half the editorial panel of the Journal it was published in. Authors of the studies they used produced a rebuttle of their findings and methods. It was an inherently flawed study. Even if we accept their findings as valid, which it is not, there are many more that actually used standardised temperature measurements rather than anything that looked 'anomalous' in a 500 year period and then claim it to be global.

The study was a joke.

From the managing editor.

In conclusion: Quality control at CR was practised along generally established lines. There were no problems over the 13 years of CR existence. But there was insufficient attention to the methodological basis of statements that touch on hotly debated controversies and involve pronounced political and economic interests. CR should have been more careful and insisted on solid evidence and cautious formulations before publication.

....

The paper that caused the storms (Soon & Baliunas, Clim Res 2003, 23:89–110) evoked heavy criticism, not least in EOS 2003 (84, No 27, 256). Major conclusions of Soon & Baliunas are: ‘Across the world, many
records reveal that the 20th century is probably not the warmest nor a uniquely extreme climatic period of the last millenium.’ (p. 89) and ‘Overall, the 20th century does not contain the warmest anomaly of the past millenium in most of the proxy records which have been sampled world-wide’ (p. 104). While these statements may be true, the critics point out that they cannot be concluded convincingly from the evidence provided in the paper. CR should have requested appropriate revisions
of the manuscript prior to publication

www.int-res.com...

I won't mention that most of the authors involved in the paper were funded by Exxon and are associated with oil-funded think-tanks, oh, I just did. Shouldn't matter really, the science is what counts, and this was, unsurprisingly, bad science.

No other reconstruction validates this study, not one.

Those reconstructions do not correlate each other, and there are dozens of other research which do show that the MWP and the RWM were warmer than today...

No you have isolated records from various areas of possible high temperatures during a 500 year period. The reconstructions, bar the Soon & Baliunas 'study', do generally show the same thing - 20th century warming is greater than anything seen in 1000 years.

The scientists who made the research disagree with you....

I didn't see any of the isolated and localised studies say that their results were indicative of global climate. Just local climate.

Originally posted by melatonin
Seems the observed temperatures were a fairly good fit. Not bad for models from 1988.

He was wrong by a longshot...

You don't know how to read a graph then

He presented Scenario B as the most plausible outcome. It was very close to the reality.

Look closely...

Really?...

Since 1996 until now temperatures have not risen 1°C...hence the MWP was warmer than today

Yes, really.

You have just presented another localised measure of temperature. This time the Sargasso sea, see we've moved to sea temperatures now...

Obviously you don't get the difference between a localised area and more global measures.

I can provide another more up-to-date study for you, just to show I'm not disingenuous like some;

Science 23 June 2000:
Vol. 288. no. 5474, pp. 2198 - 2202

Reports

Coherent High- and Low-Latitude Climate Variability During the Holocene Warm Period

.....

[from figure label]

Oxygen isotopic analyses of planktonic foraminifera in a well-dated, high-deposition-rate sediment core from the Bermuda Rise (25) also document a twin-event, 1°C cooling signature of the LIA (Fig. 4) that was preceded by the MWP, which was about 1°C warmer. At Hole 658C, the LIA cooling is also indicated by two distinct cooling events of 3° to 4°C amplitude between ~1300 and 1850 A.D.; the earlier MWP between ~800 and 1200 A.D. was only marginally warmer than present. These results suggest that the most recent LIA-MWP climatic cycle occurred synchronously at these three locations within the dating uncertainties.

So, the north atlantic was only marginally warmer than now. That is still only localised to the north atlantic.

So, seeing we are moving to other indices of climate change, lets have something completely different. Climate change measured via coastal upwelling...

Science 2 February 2007:
Vol. 315. no. 5812, pp. 637 - 639

Reports
Rapid 20th-Century Increase in Coastal Upwelling off Northwest Africa
H. V. McGregor,1* M. Dima,2,3 H. W. Fischer,4 S. Mulitza1,5

Near-shore waters along the northwest African margin are characterized by coastal upwelling and represent one of the world's major upwelling regions. Sea surface temperature (SST) records from Moroccan sediment cores, extending back 2500 years, reveal anomalous and unprecedented cooling during the 20th century, which is consistent with increased upwelling. Upwelling-driven SSTs also vary out of phase with millennial-scale changes in Northern Hemisphere temperature anomalies (NHTAs) and show relatively warm conditions during the Little Ice Age and relatively cool conditions during the Medieval Warm Period. Together, these results suggest that coastal upwelling varies with NHTAs and that upwelling off northwest Africa may continue to intensify as global warming and atmospheric CO2 levels increase.

If you assess the study in detail it shows upwelling is greatest in the last century than in 2500 years.

Summer temperature variations in the European Alps, AD 755-2004
Author(s): Buntgen U (Buntgen, Ulf), Frank DC (Frank, David C.), Nievergelt D (Nievergelt, Daniel), Esper J (Esper, Jan)
Source: JOURNAL OF CLIMATE 19 (21): 5606-5623 NOV 1 2006

Six of the 10 warmest decades over the 755-2004 period are recorded in the twentieth century. Maximum temperature amplitude over the past 1250 yr is estimated to be 3.1 degrees C between the warmest (1940s) and coldest (1810s) decades

But single reconstructions and localised proxies are not a great indication of global trends. This is especially true when the reconstruction is from a group of oil-funded researchers who can't do proper research...

[edit on 16-2-2007 by melatonin]