http://www.ipcc.ch/ipccreports/far/wg_I/... (Page 202, bottom chart)
So we went from the bottom of an ice age to global warming in 0.7 degrees C. Now how did they arrive at that?
According to Wikipedia, "The period for which reasonably reliable instrumental records of near-surface temperature exist with quasi-global coverage is generally considered to begin around 1850. Earlier records exist, but with sparser coverage and less standardized instrumentation.."
Now that is a crock. Philadelphia started officially recording temperatures in 1870. The temperatures were in 1/4 degrees and twice a day.
In Philadelphia the first temperature recording was made by an man named Mr. De S.In 1731. He took temperatures two times a day and in 1/4 degree increments , but he was unofficial.
1849: Smithsonian Institution supplies weather instruments to telegraph companies and establishes extensive observation network. Observations submitted by telegraph to the Smithsonian, where weather maps are created.
By the end of 1849, 150 volunteers throughout the United States were reporting weather observations to the Smithsonian regularly. By 1860, 500 stations were furnishing daily telegraphic weather reports to the Washington Evening Star, and as the network grew, other existing systems were gradually absorbed, including several state weather services.
As to the accuracy of these instruments, we don't know. But you also have to realize that 1850 had 500 weather stations in the US. OK. That was before the Battle of the Big Horn (1876). There were vast areas of the US which were not settled and thus not recorded.
Satellite temperature recording didn't begin until 1979 and even then it wasn't considered accurate.
Even today we don't know enough about sea temperatures both surface and depth, all these factors enter into the global temperature budget.
So with all the instrumental and data collection history it still has to boil down to something less than scientific calculations for a global temperature.
And then to say the earth's temperature rose 0.7 degrees C in 350 years with the crude instruments, which had only 1/4 degree resolution, and haphazard locations, that bears some disbelief.
It would help if (a) your question actually asked what you intended it to and (b) if you were actually interested in learning anything.
Rather than the methods used by scientists150 years ago to calculate the earth's temperature - which is what your question is asking - you seem to mean: How do scientists calculate past mean annual global temperature for periods when there were either few or no climate stations systematically recording temperature data.
The answer is that we mostly use proxy records that have been calibrated against actual temperatures from more recent periods when there is sufficient spatial coverage, develop a mathematical transfer function that converts the proxy data into temperature values, and then use regression techniques to reconstruct the temperature records for length (in years) that is provided by the proxy data.
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And the fact that Rolando and Gryph get thumbed-down for answering the question is just further proof that Deniers' have no objective or scientific interest in the issue, and are here merely as advocates for an anti-science, anti-education, and pro-stupid political agenda (a task for which they are certainly well qualified).
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Kendra H ===
>>...Ian is wrong. Ian is always wrong<<
You got that right.
Not sure where you got the 150 years. That is the first I have seen that but we have had the warmest ten years since record keep began 132 years ago. these were from 1-10:
2010
2005
1998
2003
2002
2006
2009
2007
2004
2012
To be clear these are not models, they are actual temperature readings from cities around the globe.
Before 1880 some cites did keep records, but tree rings and ice core samples were used to estimate temps.
Well that's hard to say because it keeps changing. For example, US Historical Climate Network database recently has undergone revision in October of 2012. "In October 2012, a revision to the version 2.0 dataset was released as version 2.5. The version 2.5 processing steps are essentially the same as in version 2.0, but the version number change reflects modifications to the underlying database as well as coding changes to the pairwise homogenization algorithm (PHA) that improve its overall efficiency." http://www.ncdc.noaa.gov/oa/climate/rese...
Last year HadCRUT4 was updated again and as you can see, even temperatures as far back as 1850 were adjusted: http://www.metoffice.gov.uk/hadobs/hadcr...
James Hansen also adjusted his GISS data set last year. Guess what? The warming trend increased slightly: "With v3.1.0, the adjusted annual global land surface air temperature trend for 1901‐2011 was 0.94°C/Century. Using data from version 3.2.0 this trend is 1.07°C/Century." ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/v3...
And finally, last year NOAA dropped a full degree off of the July 1936 US average monthly temperature.
You'll have to keep asking this question every year because the answer keeps changing.
This question ranks as denier myth number 7 on Skepticalscience dot com, I suggest you read it.
I don't know but Ian is wrong. Ian is always wrong.
They extrapolated temps across thousands of miles and then claim it's completely accurate.
Climatology IS NOT a real science.
@Kendra...My taste in women is questionable but I'm not "always" wrong. I would say I'm seldom wrong and more than willing to admit when I'm right.
whatever you asked, please keep environment safe.
SEA level is growing up. And the poor countries like us are suffering most.
please, no more......
you and i want to live long time in this world.
How was the Earth's temperature calculated 150 odd years ago?
We are constantly being told that we have just had the warmest ten years since 1850 (incidentally the end of the little ice age).
How do we know what the Global, yes that's GLOBAL temperature was in 1850?
One liners like "British Empire" or " Royal Navy" will not be considered answers, they couldn't have been everywhere.
I make no bones about re-asking this question, I shall do so until the warmies admit they do not know.
