Is this the reasoning of all scientists, or just the ones on this board?

Question

Some background before I ask my question.

It was a long held view the earth was warmer than what it is today during a period known as the Medieval warm period (MWP).

There have been studies recently that downplay the MWP and say that 20th century is the warmest. This is a big bone of contention among skeptics who claim that a group of scientists manipulate science to promote an agenda.

In my opinion we can determine who is right by looking at the evidence and history. http://www.archaeology.org/online/features/greenland/
The site above says that settlements are being found in what is now permafrost. The Vikings only practised farming techniques. This suggests that the glaciers were further back, and a warmer climate.

As the weather became colder, the Vikings refused to adapt to the Inuit techniques of survival. They also changed the way they built their houses to cope with the cold.

But when I asked this question yesterday, I was told that is all irrelevant.

So my question is Do all scientists ignore the physical evidence and place their beliefs only on the theoretical?

There is ample evidence from proxies studies that show the MWP was a world wide event, not a localized one. John Daley provides references to peer review articles that suggest otherwise.
http://www.john-daly.com/hockey/hockey.htm

Trevor. Eric the red colonized Greenland at the beginning of MWP, if temperatures rose later, then his accounts are useless in this debate.

Maybe i am not making myself clear. But if settlements are found in what is now permafrost, why does that not indicate a warmer climate? Not only did they build houses but they farmed in what is now permafrost. But yet everybody keeps giving me references to proxy data. The best answers so far are the ones that suggest that the warming of Greenland was a localized event, but the references to the link above shows that that is in dispute.

As for this being a conspiracy, why would this person lie when he said:
“With the publication of the article in Science [in 1995], I
gained significant credibility in the community of scientists
working on climate change. They thought I was one of
them, someone who would pervert science in the service of
social and political causes. So one of them let his guard
down. A major person working in the area of climate
change and global warming sent me an astonishing email
that said “We have to get rid of the Medieval Warm Period"

the sources for the above quote is: Presentation by S McIntyre At Conference Stockholm Sweden, September 9 2006

Answer 1

Most scientists who support the IPCC's theoretical conjecture about climate change are trusting that the voluminous compilation of material that back up their arguments about AGW being the dominant contributing factor of the warming observed in the last 3% of the 20th century based purely on radiative properties of earths atmosphere caused by it's change in chemical composition by humanity, and it's validity based on peer review. Lets not forget that the early IPCC report intentionaly attempted to downplay that the medieval warm period existed (hockey stick), and the material associated with the hockey stick, subsequently passed peer review. Which would lead one to believe that there is a bias in the spirit of compiling the IPCC report. The historical records associated with english wine making during the medieval warm period, as well as other historical accounts from other regions also clearly indicate that the climate warmed rapidly and subsequently cooled rapidly without any human intervention, that is damging testimony to human induced climate change. Lets not forget that if one looks at the temperature of the continent of Antarctica, you will find no warming trend, so this period of alledged global warming is not in fact global.

Answer 2

To answer your main question, yes, most scientists agree that the MWP was colder than today on a global scale. A few key points:

Even IF Greenland were colder during the MWP (Trevor makes a very good case why this was not so), Greenland is not the whole planet. It's not even a very large fraction of the planet. Studies have shown that the warming 1000 years ago only happened in a few isolated locations.

Even IF the MWP were somehow warmer than today on a global scale, that wouldn't be relevant. The problem is not today's temperatures, the problem is that global warming continues to accelerate, and we know it's accelerating due to increased human greenhouse gas emissions.

Even IF the planet has been as hot as it is now in relatively recent history, that doesn't mean it's okay for us to continue to warm the planet.

Answer 3

It is irrelevant--but to be fair--her is WHY it is irrelevant:

>first--granted there have been periods of global warming and cooling all through earth's history. And--3 decades ago when scientists first started investigating this , they assumed tto start with that global warming (which at the time they wern't even sure was a long term trend) was probably due to natural causes.
>However--the fact that global warming in the past was natural does not mean THIS global warming is natural
>Over the ensuing decades, schientists did a massive amount of research. In the process (besides verifying that our gloval warming is actually occuring) they did a lot of work to determine the cause(s).
>One after another, the various possible natural factors that could be involved (solar, volcanic eruptions, etc.) were found not to account for the observed level of global warming (as a side observation--the"skeptics" like to talk about volcanic activity as a cause--which just shows their ignorance of even the basics: volcanic eruptions tend to cool, not warm, the Earth).
>a small part of the current global warming IS natural--about 15%. The rest can be accounted for only by a rise of CO2levels in the atmosphere.
>finally, possible sources of the CO2 have been extensively examined. There is a certain level of CO2 produced naturally--but htat is always present and would not account for a change. The factor-and the only factor--that has been fond to have changed significantly in the recent past is the rate at which human caused CO2 emissions are released.
>finally, the amount of human caused emissions and consequent increase of CO2 in the atmosphere has been careflully investigated to determine if it is enough to account for the observed global warming. And the answer is yes--in fact its more than enough.

THAT is how scientists work. It is not the simplistic process of looking at a thermometer a few times and then jumping to a conclusion that the "skeptics" portray it to be. It is a long, painstaking, andexhaustive process.. And once this is all done and the facts are in--as they are--that's it. There is no more debate. The facts are the facts--and someone's "opinion"--or whatever may have happened hundreds or thousands of years ago--is indeed irrelevant.

Answer 4

Yes, the temperatures in parts of the northern hemisphere might have been warmer in the MWP than today, but not on a global scale.

Here's a link to a graph showing the results from the reconstructions of temperatures up to 2000 years back from five different independent studies:

http://www.ncdc.noaa.gov/paleo/globalwarming/images/jones-mann-2004-large.jpg

To learn more on this subject I highly recommend looking thoroughly into the NOAA/NCDC site:

The Medieval Warm Period: http://www.ncdc.noaa.gov/paleo/globalwarming/medieval.html

and

http://www.ncdc.noaa.gov/paleo/globalwarming/paleolast.html

Quote from the site:
"The similarity of characteristics among the different paleoclimatic reconstructions provides confidence in the following important conclusions:

* Dramatic warming has occurred since the 19th century.
* The recent record warm temperatures in the last 15 years are indeed the warmest temperatures the Earth has seen in at least the last 1000 years, and possibly in the last 2000 years."

On a side note I still find it irrelevant if temperatures has been warmer before or not. Everyone knows that there are other natural causes that makes the climate change over time. The important thing now is the speed of the warming, the fact that we are 6.5 billion people on earth which makes it difficult for us to move to new areas and the evidences that greenhouse gases is causing this warming. The fact that we can do something about this makes it our duty to do so.

Answer 5

The problem with the MWP is that more detailed studies have shown it was not a synchronous global warming. There is no doubt the N. Atlantic and Europe were warmer, but there is a lot of evidence that a lot of the world was colder. That is why a lot of global climatologists downplay the MWP as having any relevance to the observed *global* warming we have today. The wikipedia entry on the MWP goes into this distinction and is decent: realclimate.org's entry on this rocks, in my opinion.

You want to believe that scientists are manipulating the data to support the idea man is affecting climate. But why would they do that? Most climatologists are, at heart, computer weenies. Computer weenies don't need any particular topic to be happy, most of them would be just as content modeling nuclear bomb bursts as climate. For example, thirty years ago, all the computer weenies were in theoretical chemisty modeling DNA. Then computers got fast enough to model the oceans and atmosphere and that was where all the cool programming was being done so it wasn't as cool to be a theoretical chemistry computer weenie. If the computer weenies could show global warming wasn't a problem, they would. Then they would move on to simulating supernovas or something.

Don't get me wrong, the world needs computer weenies, but they have no agenda and they will always have something to do. Working on climate change just happens to be what they are doing now.

Answer 6

SHORT ANSWER

There is far less ice on Greenland today than there used to be. Had Erik The Red set sail today he wouldn't have been restricted to a choice of just two locations but could have settled anywhere on the coast.


LONG ANSWER

A well balanced question.

It's known that Viking settlements were established on Greenland, from memory I believe the first was in 986. This first settlement and the subsequent ones were in the southwest of the country; this being the only part of Greenland that had any habitable land at the time.

We know that the MWP was a period of above average temps for that period of history and that parts of Greenland had a comparatively mild climate. We also know that the subsequent cooling which ultimately led to the LIA caused the advance of glacial ice and the burial of Viking communities (it's not true to say that the glacial ice was the reason for the demise of the Vikings as there were political and economic reasons, armed conflicts, in-fighting and disputes and famine).

The glacial ice (ice sheet) is retreating once more and exposing the long lost settlements.

None of this is in dispute.

Because the glacial ice is retreating we have to accept that global warming is occuring - manmade, natural or otherwise (that's not the issue here).

For the ice to have melted to the extent that it has exposed those settlements means that the current temp has to be the same as the temps in Viking times or certainly very close to it.

But we also need to look at how fast the ice is melting...

18,000 years ago the entire area around Greenland was under a mass of ice, for the next 7,500 years the ice rapidly retreated (the period often referred to as the end of the last ice age). This retreat exposed the landmasses of Northern Europe, Canada, the US and the Greenland periphery.

For the next 9,500 years there was a very slow general warming trend, enough to expose land in some small pats of Greenland - the parts settled by the Vikings.

The glacial retreat that took 9,500 years has been duplicated but this time in less than 100 years. For the ice to melt so much more rapidly now means that the temps have to be considerably higher than they were back in the time of the Vikings.

Further, in Viking times the only land free of ice was in the southwest of the country, nowadays the entire coastline of 40,000km is free of ice with the exception of just a few km. In some parts there are ice free coastal strips more than 100km wide and almost 20% of the landmass is now ice free, see this map http://www.mapzones.com/world/europe/greenland/mapindex.php Today there are many communities all around the coast of Greenland, primarily on the west coast. When Norway laid claim to East Greenland in the 1930's it had a population of 0 and no habitable land.

All this is clear evidence that Greenland is warmer today than it was during the MWP. This evidence is further backed up by analysis of the ice core samples that have been taken from the Greenland Ice Cap. These cores provide an accurate record of the climate and ecology stretching back more than 100,000 years.

If you'd like verification for yourself then perhaps the best possible proof is to read the Saga of Erik The Red, his own journals confirm the entire landmass was ice covered except for two small areas in the southwest. Then compare that with recent satellite images.

Answer 7

I'll repeat what I told you in the last question, because it apparently didn't stick.

Vikings in Greenland cannot act as proxies for the global climate (neither can vineyards in England, ice faires held on the Thames, or whatever else the skeptics dream up). This means we cannot make claims about global temperatures from the fact that Vikings apparently settled regions of Greenland that are uninhabitable today.

The one and only conclusion we can draw from this is that Greenland was apparently warmer around 1200 years ago. It tells us absolutely nothing about the average global temperatures at the time.

Answer 8

I think most authorities would agree the MWP occurred, including the few we have here (I'd say Trevor, Dana and Bob). The things most authorities would disagree with are things like it being a previous instance of Global Warming, worse than today, and similar assertions that are without foundation.

The warming was closely associated with the "Little Ice Age". Both of these were deviations from the earth's long term climate cycle, not examples of it.

The reason England is warmer than Newfoundland (at the same latitude) is that an ocean current brings warm water from the Caribbean across the north Atlantic to Britain and Europe. It's called the Gulf Stream in the USA and the North Atlantic current by most others.
http://go.hrw.com/atlas/norm_htm/natlantc.htm
Ben Franklin suggested that it could be diverted by damming a strait between Newfoundland and Labrador to make the weather colder for the British during the Revolutionary War. If you look at Figure 12 you see it's position during the MWP
http://www2.sunysuffolk.edu/mandias/lia/vikings_during_mwp.html
You can see it is west of it's current position and flowing almost directly towrd Europe. That's the reason for the MWP I heard stated most frequently as I was growing up, and the one I believe to be correct. It was a local effect, not global, and no mystery at all. The reason was probably ice doing what Mr. Franklin suggested, randomly, during it's normal seasonal advance and retreat.

There is also little doubt that it was the "Little Ice Age" that ended the MWP.
http://www2.sunysuffolk.edu/mandias/lia/end_of_vikings_greenland.html
http://www2.sunysuffolk.edu/mandias/lia/decline_of_vikings_iceland.html
Understood much less well is the cause of the Little Ice Age. At this time there is no clear consensus as to the cause.
http://www.grisda.org/origins/10051.htm
http://www2.sunysuffolk.edu/mandias/lia/little_ice_age.html
One theory is based on the idea that blockage of ocean currents by ice floes could have cooled the northern latitudes by directing warmer currents away (similar to Mr. Franklin's idea). There isn't much evidence for that one, and there's no record of another similar event. Another theory is that some volcanic or celestial event(s) could have added enough soot and debris to the atmosphere to cool things down for that short period. There are many examples of that type of short term cooling from these type occurrances. The most familiar one is the eruption of Krakatoa, which resulted in "The Year Without a Summer". This is one of several unrelated phenomenon people call "dimming" nowadays.
http://volcano.und.edu/vwdocs/frequent_questions/grp7/asia/question879.html
One strike of a meteor, comet or asteroid ended the reign of the dinosaurs. There are many other documented cases throughout the earth's history. None of them amounted to long term climate changes. They were transient events with a specific cause.
http://csep10.phys.utk.edu/astr161/lect/meteors/impacts.html
http://www.cnn.com/2003/TECH/science/11/21/antarctica.meteor.ap/

When the "alarmists" say global warming they are not talking about these types of one time events. They are talking about a long term warming trend caused by human production of greenhouse gases, superimposed on whatever natural cycles are present. There is no precedent to what we are observing, as far back as the Permian extinction. Confusing Global warming with things like MWP may be well intentioned, but it just muddies the waters.

Answer 9

The key phrase is "This suggests". Your data is qualitative. It's not irrelevant, but it's inferior.

And not "all" scientists agree. Just most all.

That the proxy data shows QUANTITATIVELY that we're now warmer than the MWP was.

http://www.globalwarmingart.com/wiki/Image:2000_Year_Temperature_Comparison_png

Science is based on numbers, not descriptions and suggestions. Which is why:

"There's a better scientific consensus on this [climate change] than on any issue I know... Global warming is almost a no-brainer at this point. You really can't find intelligent, QUANTITATIVE arguments to make it go away."

Dr. Jerry Mahlman, NOAA

Good websites for more info:

http://profend.com/global-warming/
http://environment.newscientist.com/channel/earth/dn11462
http://www.ucsusa.org/global_warming/science/
http://www.realclimate.org
"climate science from climate scientists"

5_for_fighting - There hasn't been a scientific consensus that the world is flat for over 2000 years. That's when Eratosthenes measured, quantitatively, the diameter of the world. After that most anyone who deserved the word scientist accepted the quantitative data and the fact that the world was round.

Only "skeptics" who ignored the data and made qualitative arguments said the world was flat.

The key phrase in the article about disagreements is "Not all of these researchers would describe themselves as global warming skeptics".

Very few would. The authors took every paper that discussed small differences but supported mostly man made global warming and counted them. Their work doesn't affect the consensus that global warming is mostly man made.

It simply shows what people will do to sell a book.

Answer 10

I think you will find that there are very few real scientists on this board. Mostly teenagers I suspect.