Long range climate History

Sorry unable to copy/paste the grapths

http://web.me.com/sinfonia1/Clamour_Of_The_Times/Clamour_Of_The_Times/Entries/2009/12/8_What_the_UK_Met_Office_is_Not_Telling_Us.html

What the UK Met Office is Not Telling Us
Tuesday, 8 December 2009


Context and contingency are everything when interpreting temperature trends. The UK Met Office wants us to regard the last decade as exceptionally warm, because this hots up the Copenhagen Conference. But four key graphs tell a very different story:


Graph 1: The Last 2,000 Years


[Source: Loehle, C., 2007. ‘A 2000-year global temperature reconstruction based on non-treering proxies.’ Energy & Environment 18(7-8): 1049-1058]



First, let us consider the changing temperature over the last 2,000 years. Because currently-understood tree-ring data have now been exposed as possibly unacceptable for this purpose - their application is even under scrutiny by the inquiries into the hacked/leaked e-mails from the Climatic Research Unit (CRU) at the University of East Anglia - we must turn to a curve produced without such tree-ring proxy measurements. On this curve, I have added MWP for the ‘Medieval Warm Period’, and LIA for the ‘Little Ice Age’. The pattern could not be clearer. With tree-ring proxies removed, the Medieval Warm Period stands out as much warmer than today. No wonder Eric the Red flourished in Greenland [main picture]:

Graph 2: 1975 to 2010





[Source: the HadCRUT3 graph of the global temperature anomaly since 1975. See: ‘Cherrypicking a Standstill’ for a full comment on this graph]



Secondly, if we now turn our attention to the last thirty five years - the very right-hand end of the 2,ooo-year period shown in the first graph - and employ the Climatic Research Unit’s own ‘adjusted’ figures, we can see that, since 2001, the rise in temperature from 1975 has started to flatten out, and perhaps it may even have fallen:


Graph 3: What Does ‘Adjusting’ Do To Weather Station Records?


[Source: ‘The Smoking Gun at Darwin Zero’, December 8, 2009: data from NOAA/GHCN, the Global Historical Climate Network, one of the world’s three main global temperature data sets. Includes a full explanation of the methods employed, and the meaning of the results]


Thirdly, we must refer to a most timely insight into what ‘adjusting’ does to the the overall trend of temperatures from 1880 to 2010, i.e., for the so-called industrial period of ‘greenhouse gas’ emissions. Such adjustments claim to deal with what are termed, somewhat inelegantly, ‘inhomogeneity’. What does this mean? Most long-term climate stations have undergone changes that make a time-series of their observations ‘inhomogeneous’. There can be many causes for these discontinuities, including changes in instruments, shelters, the environment around the shelter, the location of the station, the time of observation, and the method used to calculate mean temperature. Often several of these problems may occur at the same time in the same location. Before one can reliably use such climate data for analysis of long-term climate change, it is thus argued that ‘adjustments’ are needed to compensate for the non-climatic discontinuities. Yet, this is far from easy, and the resultant data is only as good as our understanding of the changes at each particular weather station.


Now, here are the quite extraordinary results of one such set of ‘adjustments’ for a key Australian station, namely that at Darwin Airport. The glaring discrepancy between the raw data and the ‘adjusted’ graph is staggering. The raw, unadjusted, data actually exhibit a steady cooling trend from 1880 to 2010. The IPCC employs ‘adjusted’ data. But, even with the ‘adjusted’ data, note the decline since 2001:


Willis Eschenbach, the very hard-working analyst of all this data, understandably comments:



“What this does show is that there is at least one temperature station where the trend has been artificially increased to give a false warming where the raw data shows cooling. In addition, the average raw data for Northern Australia is quite different from the adjusted, so there must be a number of … mmm … let me say ‘interesting’ adjustments in Northern Australia other than just Darwin.”


You may find this concerning.



Conclusions From These First Three Graphs


As a highly-respected professorial colleague said to me last week: “Whoever would have thought that a retrospective regression fit would ever have constituted ‘foundational’ evidence, or even, dare I say it, ’science’?”
So what can we conclude from an assessment of these first three graphs?




(1)The Medieval Warm Period (MWP) does indeed seem to have been much warmer than today’s warm period, and that certainly wasn’t due to the human emission of ‘greenhouse gases’ And there is one monk [left], at least, who certainly seems to be enjoying the balmy days;

(2)Warming and cooling periods look entirely cyclical over the last 2,000 years, and largely naturally-driven;


(3) Over the last 9 years, the mean world temperature has either flattened off or fallen a little;


(4) Since 1880, it appears that one only achieves a general warming trend by adding in complex ‘adjustments’ to the raw data set, which, at one important sample station, namely Darwin, Australia, actually exhibits cooling;


(5) More importantly, none of this information, ‘adjusted’ or not, tells us about cause. It is a major error in science to move uncritically from form to function, from graph to cause and correlation;


(6)The idea that the ‘science’ is settled is dangerous nonsense;


(7)We cannot commit thousands of billions of dollars at Copenhagen on the basis such a specious retrospective correlation between CO2 and temperature.



Graph 4: The Longer View And The ‘Climatic Optimum’


[Source: Global Warming Art, reproduced here under the GNU Free Documentation License, Version 1.2]


Finally, let us take the very long view, and examine this splendid graph to see precisely where we stand today in relation to the last 12,000 years, since the end of the last Ice Age?


Yes, that is quite right. Despite our little bit of recent warming, we are still in a long-term cooling trend, and we remain cooler than - wait for it - the period we call the ‘Climatic Optimum’. So warm, folks, is good!


Well, I think that graphically exposes the nonsense of our current flunk over climate change, don’t you?



That medieval monk certainly has us over a barrel.

“I’ll drink to that!”


From The Foresight Institute

One thing that Climategate does is give us an opportunity to step back from the details of the AGW argument and say, maybe these are heat-of-the-moment stuff, and in the long run will look as silly as the Durants’ allergy to Eisenhower. And perhaps, if we can put climate arguments in perspective, it will allow us to put the much smaller nano arguments (pun intended) into perspective too.

So let’s look at some ice.

I’m looking at the temperature record as read from this central Greenland ice core. It gives us about as close as we can come to a direct, experimental measurement of temperature at that one spot for the past 50,000 years. As far as I know, the data are not adjusted according to any fancy computer climate model or anything else like that.

So what does it tell us about, say, the past 500 years? Well, whaddaya know — a hockey stick. In fact, the “blade” continues up in the 20th century at least another half a degree. But how long is the handle? How unprecedented is the current warming trend?

Yes, Virginia, there was a Medieval Warm Period, in central Greenland at any rate. But we knew that — that’s when the Vikings were naming it Greenland, after all. And the following Little Ice Age is what killed them off, and caused widespread crop failures (and the consequent burning of witches) across Europe. But was the MWP itself unusual?

Well, no — over the period of recorded history, the average temperature was about equal to the height of the MWP . Rises not only as high, but as rapid, as the current hockey stick blade have been the rule, not the exception.

In fact for the entire Holocene — the period over which, by some odd coincidence, humanity developed agriculture and civilization — the temperature has been higher than now, and the trend over the past 4000 years is a marked decline. From this perspective, it’s the LIA that was unusual, and the current warming trend simply represents a return to the mean. If it lasts.

From the perspective of the Holocene as a whole, our current hockeystick is beginning to look pretty dinky. By far the possibility I would worry about, if I were the worrying sort, would be the return to an ice age — since interglacials, over the past half million years or so, have tended to last only 10,000 years or so. And Ice ages are not conducive to agriculture.

… and ice ages have a better claim on being the natural state of Earth’s climate than interglacials. This next graph, for the longest period, we have to go to an Antarctic core (Vostok):

In other words, we’re pretty lucky to be here during this rare, warm period in climate history. But the broader lesson is, climate doesn’t stand still. It doesn’t even stand stay on the relatively constrained range of the last 10,000 years for more than about 10,000 years at a time.

Does this mean that CO2 isn’t a greenhouse gas? No.

Does it mean that it isn’t warming? No.

Does it mean that we shouldn’t develop clean, efficient technology that gets its energy elsewhere than burning fossil fuels? Of course not. We should do all those things for many reasons — but there’s plenty of time to do them the right way, by developing nanotech. (There’s plenty of money, too, but it’s all going to climate science at the moment. ) And that will be a very good thing to have done if we do fall back into an ice age, believe me.

For climate science it means that the Hockey Team climatologists’ insistence that human-emitted CO2 is the only thing that could account for the recent warming trend is probably poppycock.

As David Farrar would say Indeed!