Climate Change & Global Warming

[hoosn]

hope thats no a saltire on a Shetland flag , eeks

[ArabiaTerra]

Oh and BTW, the warming we are experiencing now is already far in excess of that seen in the Medieval Warm Period.

 

According to the latest graphs, that is correct. However, going back to the IPCC report from 1990, the MWP is acknowledged, and is shown on the graph as being warmer than the present. Read the leaked emails to find out how they got rid of the MWP. (clue: politics, not science)

Ok, I see your logic here: The latest research doesn't support my findings, so lets find some older, out of date research that does. Do you really expect me to take that statement seriously?

 

Oh, and are you referring to Michael Manns e-mail about "containing" the MWP? If you are, have you looked into the context of this e-mail? No, of course you haven't because then you would understand it.

 

So let me do it for you. The MWP started in around 800AD, peaked between 1000AD and 1200AD and lasted until around 1400AD. Michael Mann's proxy temperature reconstruction (the hockey stick graph) only went back to 1000AD, so what he is talking about here is extending the proxy record backwards in time to "contain" the MWP, ie to get the start as well as the end of the MWP. This is something that the proxy temperature records now do. See, context is everything.

 

Also:

 

The middle ages were the time of high culture for the Vikings. In this period they expanded into present day Russia and settled Iceland, Greenland as well as parts of Canada and Newfoundland. In Greenland at this time cereal crops could be grown. With the end of the Medieval warm period came also the end of the Viking Bloodtime (heydey). The settlements in Greenland were abandoned and even in the homeland Norway, many of the more northern or higher altitude settlements were left. The history of the Vikings is also in good agreement with the reconstructed temperature record derived from Ice cores. Accordingly, it was at least a degree warmer in Greenland during the time of the Vikings than it is during the modern warming period.

 

If temperatures are really higher at the present time than they were in the MWP, why are the viking farms in Greenland still frozen?

The MWP was a natural variation that took place over the course of centuries. It took a couple of centuries to build up, lasted for a couple of centuries (while the Vikings were having their fun) and then took a couple of more centuries to subside. Man made CO2 emissions have only been affecting the climate for a few decades. The warming caused by CO2 is cumulative. It will take at least a couple of hundred more years for the temperature rises due to the CO2 we have already added to the atmosphere to fully manifest themselves, even if we went to zero emissions tomorrow the warming wouldn't stop.

 

Secondly, the MWP is thought to have been local phenomenon affecting the Northern hemisphere, principally in the North Atlantic. There is much less evidence for it in other parts of the world. AGW is global.

[Malachy]

If temperatures are really higher at the present time than they were in the MWP, why are the viking farms in Greenland still frozen?

 

They're not frozen, they are farms again. I was there last year and people are rearing animals and growing hay in the same places the Vikings did. And in fact, if I remember rightly, they are now introducing some cattle again, for the first time since the Vikings tried it. Their growing season has lengthened by about a month in the last decade, and it wasn't a scientist who told me that, it was Greenlanders, who have to wait each year for the soil to thaw before they can plant their vegetables. They knew the ice was melting because they could see it happening, and they knew the ground was warming because they were planting their neeps four weeks earlier than they used to. I have never met anyone so convinced about climate change as the Greenlanders I spoke to there.

[crofter]

Ok, I see your logic here: The latest research doesn't support my findings, so lets find some older, out of date research that does. Do you really expect me to take that statement seriously?

 

No, my logic is that the IPCC report used to show the reality, but it has been altered as a result of political decisions, not as a result of any new scientific work. The evidence for the MWP is still there, but in the latest IPCC report the MWP has been removed by manipulation of the manipulated proxies.

 

Oh, and are you referring to Michael Manns e-mail about "containing" the MWP?

 

There are plenty of emails discussing the MWP. For example:

 

>I know there is pressure to present a

>nice tidy story as regards 'apparent unprecedented warming in a thousand

>years or more in the proxy data' but in reality the situation is not quite

>so simple. We don't have a lot of proxies that come right up to date and

>those that do (at least a significant number of tree proxies ) some

>unexpected changes in response that do not match the recent warming....I believe that the recent warmth

>was probably matched about 1000 years ago. I do not believe that global

>mean annual temperatures have simply cooled progressively over thousands of

>years as Mike appears to

 

Read it in context here:

http://www.eastangliaemails.com/emails.php?eid=136&filename=938018124.txt

 

Furthermore, it may be that Mann et al simply don't have the

long-term trend right, due to underestimation of low frequency info. in the

(very few) proxies that we used. We tried to demonstrate that this was not

a problem of the tree ring data we used by re-running the reconstruction

with & without tree rings, and indeed the two efforts were very similar --

but we could only do this back to about 1700. Whether we have the 1000

year trend right is far less certain (& one reason why I hedge my bets on

whether there were any periods in Medieval times that might have been

"warm", to the irritation of my co-authors!). So, possibly if you crank up

the trend over 1000 years, you find that the envelope of uncertainty is

comparable with at least some of the future scenarios, which of course begs

the question as to what the likely forcing was 1000 years ago.

 

Read it in context here:

http://www.eastangliaemails.com/emails.php?eid=172&filename=963233839.txt

 

>> >>I do think that the Medieval Warm Period was a far more significant event

>> >>than has been recognized previously, as much because the high-resolution

>> >>data to evaluate it had not been available before. That is much less

>>so the

>> >>case now. It is even showing up strongly now in long SH tree-ring series.

>> >>However, there is still the question of how strong this event was in the

>> >>tropics. I maintain that we do not have the proxies to tell us that now.

 

Read it in context here:

http://www.eastangliaemails.com/emails.php?eid=228&filename=988831541.txt

 

>>In one of the pre-interviews they asked about the "Hockey Stick". I

>>told them of my doubts about the intercentury precision of the record,

>>especially the early part, and that other records suggested the period

>>1000 years ago was warmer. I remember saying that "you must give the

>>author credit for including the large error bars for that time series in

>>the figure." I also specifically said that the most precise record of

>>century scale precision, Greenland Borehole temps, was very important to

>>note but that the figure was not in the IPCC. I then looked quickly at

>>the IPCC reference list and saw the citation of Dahl-Jensen and assumed

>>that it was at least commented on in the 1000 year time series material

>>and told ABC as much.

>>

>>ABC called back a few days later and said they couldn't find a reference

>>to the Greenland stuff in the IPCC discussion of the past 1000 years.

>>So I read the final version, and ABC was right. I said this was an

>>omission that should not have happened

 

Read it in context here:

http://www.eastangliaemails.com/emails.php?eid=230&filename=990718382.txt

 

Of course he and other members of the

MBH camp have a fundamental dislike for the very concept of the MWP, so I tend to view

their evaluations as starting out from a somewhat biased perspective

 

Read it in context here:

http://www.eastangliaemails.com/emails.php?eid=310&filename=1051638938.txt

 

The MWP was a natural variation that took place over the course of centuries. It took a couple of centuries to build up, lasted for a couple of centuries (while the Vikings were having their fun) and then took a couple of more centuries to subside. Man made CO2 emissions have only been affecting the climate for a few decades.

 

Make your mind up! It's only a couple of days since you said:

 

Oh and BTW, the warming we are experiencing now is already far in excess of that seen in the Medieval Warm Period.

 

 

 

The warming caused by CO2 is cumulative. It will take at least a couple of hundred more years for the temperature rises due to the CO2 we have already added to the atmosphere to fully manifest themselves, even if we went to zero emissions tomorrow the warming wouldn't stop.

 

Have you got any evidence for this "hundreds of years" claim?

 

Secondly, the MWP is thought to have been local phenomenon affecting the Northern hemisphere, principally in the North Atlantic. There is much less evidence for it in other parts of the world. AGW is global.

 

Have you seen this?

 

http://pages.science-skeptical.de/MWP/MedievalWarmPeriod1024x768.html

[ArabiaTerra]

Crofter, are you blind?

 

This graph is the latest composite proxy record, and it shows the MWP! So where's your political manipulation? Seriously, where's the conspiracy to hide the MWP?

 

It_does_not_exist!

 

http://www.realclimate.org/images/m08.jpg

 

It also shows clearly that we are already warmer than the MWP and, as I said, it is only going to get warmer.

 

Edit: More here.

 

Edit 2: I found a better version of the graph here.

[crofter]

If temperatures are really higher at the present time than they were in the MWP, why are the viking farms in Greenland still frozen?

 

They're not frozen, they are farms again. I was there last year and people are rearing animals and growing hay in the same places the Vikings did. And in fact, if I remember rightly, they are now introducing some cattle again, for the first time since the Vikings tried it. Their growing season has lengthened by about a month in the last decade, and it wasn't a scientist who told me that, it was Greenlanders, who have to wait each year for the soil to thaw before they can plant their vegetables. They knew the ice was melting because they could see it happening, and they knew the ground was warming because they were planting their neeps four weeks earlier than they used to. I have never met anyone so convinced about climate change as the Greenlanders I spoke to there.

 

Interesting. Where were you? I must admit that my impression came from an archaeologist who spent some time there in the late 1990s and said that it was the most inhospitable place imaginable with a constant freezing wind, even at the height of summer.

[crofter]

Crofter, are you blind?

 

This graph is the latest composite proxy record, and it shows the MWP! So where's your political manipulation? Seriously, where's the conspiracy to hide the MWP?

 

It shows it as an anomaly of 0.2 degrees. In the 1990 IPCC report, it is shown as 0.6 degrees. It has been smoothed, although you are correct, not (quite) removed.

[ArabiaTerra]

Crofter, are you blind?

 

This graph is the latest composite proxy record, and it shows the MWP! So where's your political manipulation? Seriously, where's the conspiracy to hide the MWP?

 

It shows it as an anomaly of 0.2 degrees. In the 1990 IPCC report, it is shown as 0.6 degrees. It has been smoothed, although you are correct, not (quite) removed.

Does this report exist anywhere online? I would be interested to see this graph you are quoting.

 

One point though, has the baseline been changed? A lower baseline would show a correspondingly larger anomaly.

 

Edit: The baseline of the new graph is 1961-1990.

[crofter]

 

 

Does this report exist anywhere online? I would be interested to see this graph you are quoting.

 

One point though, has the baseline been changed? A lower baseline would show a correspondingly larger anomaly.

 

Edit: The baseline of the new graph is 1961-1990.

 

Interesting comment about the reference period. It is indeed different in the 1990 report, although not very specific, "The dotted line nominally represents conditions near the beginning of the twentieth century."

 

Clearest graph I can find:

 

http://www.climatedata.info/Temperature/assets/00-Alternative%20temperature%20reconstructions.gif

And the actual figure from the 1990 report:

 

http://www.climateaudit.org/wp-images/ipcc1.jpg

 

Original Caption: Figure 7.1. Schematic diagrams of global temperature variations since the Pleistocene on three time-scales: (a) the last million years; ( the last ten thousand years, and © the last thousand years. The dotted line nominally represents conditions near the beginning of the twentieth century.

[Malachy]

If temperatures are really higher at the present time than they were in the MWP, why are the viking farms in Greenland still frozen?

 

They're not frozen, they are farms again. I was there last year and people are rearing animals and growing hay in the same places the Vikings did. And in fact, if I remember rightly, they are now introducing some cattle again, for the first time since the Vikings tried it. Their growing season has lengthened by about a month in the last decade, and it wasn't a scientist who told me that, it was Greenlanders, who have to wait each year for the soil to thaw before they can plant their vegetables. They knew the ice was melting because they could see it happening, and they knew the ground was warming because they were planting their neeps four weeks earlier than they used to. I have never met anyone so convinced about climate change as the Greenlanders I spoke to there.

 

Interesting. Where were you? I must admit that my impression came from an archaeologist who spent some time there in the late 1990s and said that it was the most inhospitable place imaginable with a constant freezing wind, even at the height of summer.

 

Perhaps the archaeologist was in the north somewhere. The southern Viking settlements were at the far south of Greenland (around 60 degrees north), which is where I was. Narsaq, Qaqortaq, - that kind of area. Believe it or not, the first week I was there was very warm indeed, and that was early May. I was wearing a t-shirt and got burnt to a crisp.

[ArabiaTerra]

Interesting comment about the reference period. It is indeed different in the 1990 report, although not very specific, "The dotted line nominally represents conditions near the beginning of the twentieth century."

I would expect that to account for the discrepancy in the anomaly regarding the size of the MWP. I would say though that it's not the numerical size in relation to some arbitrary zero point that matters, but the rather the relative difference in size when comparing two different periods (ie: now and MWP). And according to the latest data, the difference is large and getting larger.

 

Oh, you asked about the lifetime of CO2 in the atmosphere. This is what Wiki says (taken from the IPCC Fourth Assessment Report). Hope that helps.

[oddtablet]

anybody read the Shetland News letters recently and the 'rant ' from the editor of the Shetland Times

 

Have just had a look at the links...interesting

[crofter]

More on the base period (my bold):

 

http://www.eastangliaemails.com/emails.php?eid=462&filename=1105019698.txt

 

Neil,

Just to reiterate David's points, I'm hoping that IPCC will stick with 1961-90.

The issue of confusing users/media with new anomalies from a

different base period is the key one in my mind. Arguments about

the 1990s being better observed than the 1960s don't hold too much

water with me.

There is some discussion of going to 1981-2000 to help the modelling

chapters. If we do this it will be a bit of a bodge as it will be hard to do

things properly for the surface temp and precip as we'd lose loads of

stations with long records that would then have incomplete normals.

If we do we will likely achieve it by rezeroing series and maps in

an ad hoc way.

There won't be any move by IPCC to go for 1971-2000, as it won't

help with satellite series or the models. 1981-2000 helps with MSU

series and the much better Reanalyses and also globally-complete

SST.

20 years (1981-2000) isn't 30 years, but the rationale for 30 years

isn't that compelling. The original argument was for 35 years around

1900 because Bruckner found 35 cycles in some west Russian

lakes (hence periods like 1881-1915). This went to 30 as it

easier to compute.

Personally I don't want to change the base period till after I retire !

Cheers

Phil

At 09:22 05/01/2005, Parker, David (Met Office) wrote:

 

Neil

There is a preference in the atmospheric observations chapter of IPCC

AR4 to stay with the 1961-1990 normals. This is partly because a change

of normals confuses users, e.g. anomalies will seem less positive than

before if we change to newer normals, so the impression of global

warming will be muted. Also we may wish to wait till there are 30 years

of satellite data, i.e until we can compute 1981-2010 normals, which

will then be globally complete for some parameters like sea surface

temperature.

[crofter]

Oh, you asked about the lifetime of CO2 in the atmosphere. This is what Wiki says (taken from the IPCC Fourth Assessment Report). Hope that helps.

 

CO2 from burning fossil fuels will result in an effective lifetime of tens of thousands of years.

 

My understanding was that some CO2 will indeed remain in the atmosphere almost indefinately, but most will be fairly quickly absorbed, most likely by the oceans or forests. Somebody suggested that it can be compared to radioactive half life: concentrations drop rapidly to begin with but this slows as time passes.

[crofter]

Perhaps the Independent is simply giving the hack the attention it deserves?

 

Phil Jones has now "stepped aside" as head of the CRU

 

http://www.uea.ac.uk/mac/comm/media/press/2009/nov/homepagenews/CRUupdate

 

Newsworthy enough for the Independent yet?