And now, the most influential station in the GISS record is …

Guest post by John Goetz

#17 - Selinsgrove, PA (in 2003)

The GISS temperature record, with its various adjustments, estimations, and re-estimations, has drawn my attention since I first became interested in the methods used to measure a global temperature. In particular, I have wondered how the current global average can even be compared with that of 1987, which was produced using between six and seven times more stations than today. Commenter George E. Smith noted accurately that it is a “simple failure to observe the standard laws of sampled data systems.” GISS presents so many puzzles in this area, it is difficult to know where to begin.

My recent post on the June, 2009 temperature found that the vast majority of temperatures were taken from airports and urban stations. This would cause some concern if the urban heat island (UHI) effect were not accounted for in those stations. GISS does attempt to filter out UHI from urban stations by using “nearby” rural stations – “nearby” meaning anything within 1000 KM. No attempt is made to filter UHI from airports not strictly listed as urban.

If stations from far, far away can be used to filter UHI, then it stands to reason some stations may be used multiple times as filters for multiple urban stations. I thought it would be amusing to list which stations were used the most to adjust for UHI. Fortunately, NASA prints that data in the PApars.statn.use.GHCN.CL.1000.20 log file.

The results were as I expected – amusing. Here are the top ten, ranked in order of the number of urban stations they help adjust:

Usage Station Name Location From To Note
251 BRADFORD/FAA AIRPORT PA / USA 1957 2004 Airport
249 DUBOIS/FAA AIRPORT PA / USA 1962 1994 Airport
249 ALLEGANY STATE PARK PA / USA 1924 2007 Admin Building
246 PHILIPSBURG/MID-STATE AP PA / USA 1948 1986 Airport
243 WELLSBORO 4SSE PA / USA 1880 2007 Various Farms
243 WALES NY / USA 1931 2007 Various Homes
241 MANNINGTON 7WNW WVa / USA 1901 2007 Various Homes
241 PENN YAN 8W NY / USA 1888 1994 Various Homes
237 MILLPORT 2NW OH / USA 1893 2007 Various Farms
235 HEMLOCK NY / USA 1898 2007 Filtration Plant

Unfortunately, having three of the top four stations located at airports was the the sort of thing I expected.

Looking a little further, it turns out all of the top 100 stations are in either the US or Canada, and none of those 100 stations have reported data since 2007. (By the way, #100 is itself used 147 times.) Several of the top-100 stations have been surveyed by volunteers who have documented siting issues, such as the following:

  • Mohonk Lake, N.Y. (197 times) – much too close to ground, shading issues, nearby building
  • Falls Village, Conn. (193 times) – near building and parking lot
  • Cornwall, Vt. (187 times) – near building
  • Northfield, Vt. (187 times) – near driveway, building
  • Enosburg Falls, Vt. (180 times) – adjacent to driveway, nearby building.
  • Greenwood, Del. (171 times) – sited on concrete platform
  • Logan, Iowa (164 times) – near building, concrete slabs
  • Block Island, R.I. (150 times) – adjacent to parking lot and aircraft parking area.

The current state of a rural station, however, is an insufficient criterion for deciding to use it to adjust the history of one or more other urban stations. The rural station’s history must be considered as well, with equipment record and location changes being two of the most important considerations.

Take for example good ‘ole Crawfordsville, which came in at #23, having been used 219 times. As discussed here, Crawfordsville’s station lives happily on a farm, and does seem to enjoy life in the country. However, up until 16 years ago the station lived in the middle of Crawfordsville, spending over 100 years at Wabash College and at the town’s power plant.

Mohonk Lake, N.Y. (197 times) – much too close to ground, shading issues, nearby building
Falls Village, Conn. (193 times) – near building and parking lot
Cornwall, Vt. (187 times) – near building
Northfield, Vt. (187 times) – near driveway, building
Enosburg Falls, Vt. (180 times) – adjacent to driveway, nearby building.
Greenwood, Del. (171 times) – sited on concrete platform
Logan, Iowa (164 times) – near building, concrete slabs
Block Island, R.I. (150 times) – adjacent to parking lot and aircraft parking area.

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Adam from Kansas

Maybe it’s time a major global mapping project of heatsinks (concrete, roads, highways, air-conditioning units, buildings, skyscrapers, the works) is done to find out how much of the global surface warming in the last century is caused by the creation of such sinks and other artificial surfaces that absorb and release heat and their fallout regions (where forces like wind blow the heat released by such surfaces), something that would go far beyond the surfacestation project.
Over the past 100 years 1000’s of square miles of land has been paved and urbanized, in some areas like China for example the UHI effects can be huge considering there’s cities like Chongqing with nearly 30 million people. The study mentioned above may have to be done to get the full picture of warming in the last century.


What a mish mash malarkey. Are those top three big airports for jets?

Carl Yee

Another question is how far back did they start using that station for correction? Back 80 years ago (for example) it might have been a good reference station to adjust others, but from 19xx it might have been so mutated as to be useless for that purpose. However, knowing how gov’t. works, they most likely just blindly kept using it until the present. IOW, good for one time, good for any time or year. Considering the sorry state of the great majority of stations, I doubt if anyone in NASA has the faintest idea what the actiual conditions are at these “golden” stations being used for reference and adjustments.


1000km would mean that John o’ Groats could “correct” Lands End or even Swedish stations.


I don’t understand. None of the top 100 have reported data since 2007? Is this right?


So to get rid of any UHI contamination that may have been present at existing sites, and to make use ofthe data that came from staions previously shut down in the 1980;s they use stations that are themselves contaminated.
Does it get dumber
How this organisation put men on the moon beggars belief –and they now want to go to Mars !!!!
I wouldnt send them down to the local to get some milk.


Adam from Kansas (15:22:35) : The ironic thing is that UHI have been known to spawn clouds. They will help dissipate the UHI-generated heat, just as (I suppose) clouds do elsewhere. I have to wonder if there will be a net effect on the global average temperature. Hey! Maybe we could model it!!


Say what?! The top 100 “rural” stations that are being used to adjust 100s of urban stations for the UHI effect haven’t reported since 2007?
Can someone explain or provide a link as to how the rural stations are selected and how these data can be used effectively to adjust for urban stations 2 years later? Do they simply create a formula that represents the differences between past rural and urban temps and apply that formula as the adjustment into the future?
Are the same rural stations used to adjust for the same urban stations forever or can they be changed? If so, what criteria are used to change and who gets to decide when to apply it?
Sounds like yet another area that could be subjected to monkey-business as usual.

Joe Black

“File name PApars…”Given the locations of the first five stations, the file naming comvention makes sense.
Note that I only count 9 stations listed.
Reply: A big Homer Simpson “Doh!” I fixed and added the tenth station. – John

Ron de Haan

Anthony already made perfectly clear what’s real problem here:
“How not to measure temperature!”
It would be great if we came to a real clean non bias temperature map.
I think that really would the end of AGW?Climate Change and all the planned policies.
The current AGW doctrine is based on “Junk Science”.


Questions – maybe they can be answered with filtering the data.
What is the most heavily sampled CURRENT station that is used to adjust for others (stations ending in 2009)?
Others might want to filter this data, ranked by FROM and TO dates, by location (what area of the US had the heaviest sampling), and even bumping this list against the files.
Are those heavily used stations CRN 1/2, or CRN 3,4,5?

John F. Hultquist

The not so interesting thing about these 9 stations is that they are in part of the US that has towns about 15 miles apart from each other and sometimes much closer. Thus, I doubt that the 1,000 km measure is ever reached.
An interesting question is what has happened to these stations, such as Bradford and Dubois, where airports still operate (I think – haven’t been to either in years)? Are the airport monitors gone, just dropped from usage, or just no longer using that name? On this last thing, I’m thinking of the American versus English spelling discussed recently when a station got ‘lost’.
Reply: I am working on figuring that one out, but I will point out that there are roughly 2000 stations in the US that have ever been a part of the GISS record, most of them not rural, so a station that is used to adjust 250 non-rural stations is reaching pretty far. – John


This is so bad that you just won’t have to look a Giss anymore.

John F. Hultquist

Weather stations for these two places (from fuzzy photos)
taken from Google Earth
Bradford 41. 798260 N, 78.635408 W
Dubois 41.179509 N, 78.893184 W

At least the business press, such as IBD, will give the skeptics a bit of support. I think Willis should be asked to provide a graph of the Argos buoy data for the last five years, which, he admits, shows no warming. Considering the thousands of buoys scattered over the oceans, the data should be hard to deny.

Six or seven times as many stations in 1987. Top 100 “best” stations shut down. What happened? Was the funding cut off?
Or has the funding skyrocketed in recent years because of the Pending Doom of Global Warming?
The whole thing smacks of deliberate monkey wrenching. Sorry, but when the magnitude of failure reaches this level, I have a hard time blaming incompetence. What does the Director of GISS have to say about this situation? Oh yeah, that would be James E. Hansen …


OK, so we risk our economy on two bit tin horn stations with known unreliable siting issues and data. What’s the problem. It’s only a few trillion dollars.
You would have really hoped someone other than a bunch of rank amateurs were doing this, because if they aren’t then what are they trying to do. The last thing that comes to mind is science.
A simple question: What do they do with the money they get?

Antonio San

So this is manufactured warming for Copenhagen.

I don’t think I’ve ever read a darker comedy.


“Looking a little further, it turns out all of the top 100 stations are in either the US or Canada, and none of those 100 stations have reported data since 2007.”
OK, please let me know if I understand this correctly Anthony. In order to adjust properly, they use stations that do not report data, and so these stations actually ‘report’ the data that is filled into them, and then this data is used to adjust for UHI? Is that correct?
Reply: Some of the stations continue to report data, but it is not currently captured by NOAA’s GHCN V2 record and therefore does not get reported to GISS. – John

John S.

What a curious choice by GISS! The Crawfordsville record has more gaps than nearby Rocksville, and is only marginally longer. Might the choice be related to the much shallower dip seen in 1979? The attenuation of that dip–which produced the lowest average temperatures of the 20th century in the USA–seems to be a persistent feature of GISTEMP analysis.

And a fair number of the “best” stations were tarmac bakeovens anyway. The whole system stinks of crock-itude. And we are supposed to sacrifice $trillions based on this snake oil? $Trillions that the “universal consensus” admits will have no effect on global temperatures?
These are the times that try men’s souls. The summer soldier and the sunshine patriot will, in this crisis, shrink from the service of their country; but he that stands it now, deserves the love and thanks of man and women. Tyranny, like hell, is not easily conquered…. If there be trouble, let it be in my day, that my child may have peace. ~Thomas Paine


This is an issue I often deal with in my role as an engineer. People often use automated algorithms / SQL’s etc… to process large data sets automatically. The problem is a computer can not solve problems like a human and as soon as you start to delve in it, the problems start appearing everywhere.
The interesting thing is what happens when these stations stop reporting, how is the UHI then adjusted for? Linear extrapolation of the 1978 – 1998 trend? mmm


I think I’ve figured this out. The people who run GISS obviously work for the Yu Wan Mei Amalgamated Salvage Fishery and Polymer Injection Co. . Who, btw, just bought out The Onion.

David Jay

So Anthony – Now that you are over 80%, what will it take to get a usable temperature record, based on raw data from the CRN 1 and 2 stations?

old construction worker

David (17:12:51) :
‘OK, please let me know if I understand this correctly Anthony. In order to adjust properly, they use stations that do not report data, and so these stations actually ‘report’ the data that is filled into them, and then this data is used to adjust for UHI? Is that correct?’
Bingo We Have A Winner.
As a tax payer, I all for spending money for climate research. I want to thank all of you that have spent their own time and dime doing their own research.
The tip is in the jar.
I hope that everyone would fax this artical to their Senators.

You are getting close, the details are more hideous than most of us expected. It’s hard to imagine that people spend their lives working on ground temp. and don’t know the detail.
I wonder why Jones at Hadcrut won’t come clean.

Geoff Sherrington

Does it make much difference if an airport is used for jets or pistons? Two aircraft of about the same weight would throw out about equal heat on takeoff. The question might be whether jet use implies bigger aircraft and more frequent flights. But, in any case, I’ve been unable to find a difference between airport and non-aitport locations in a subset of stations from Australia. It’s a rural subset, so the big internationals are not included. It’s also a fairly small set and it does not resolve the questions. It just does not show a difference I can see. (Until the adjusters get to it).
Reply: I think it is more an issue of whether or not the measurement instrument is close to the tarmac or not. Year round, that black surface will have a warmer temperature than the surrounding ground. Some may believe it is small … fractional. But in this (now settled) debate, we are arguing about fractional degrees. – John

Gary Pearse

Does this mean that, say, the 243 stations are adjusted the same amount, or do they all get corrected to become parallel with the reference? Here I thought that that the existence of microclimates made differences of even a few degrees within a 100s of metres. What if you have a stationary cold front between the reference station and a number of the adjusted stations? I’ve driven from winter in Canada, across the snow belt south of the Great Lakes and into spring weather within 1000 km in a day.
I guess if you can adjust the data any way you like you can be an expert on “what’s going on in the depth of the oceans, the lands, the ice caps and the upper limits of the stratosphere” or whatever it is they say they are knowledgeable about.
Reply: The amount of correction (or the amount of a station’s “influence” is inversely proportional to the distance of the rural station from the urban station it is correcting. – John


It’s ironic that GISS has greatly reduced the number of stations in its calculation process. Subsequent to 1940 (the mid-century high as well as the start of increasing CO2 concentrations), the number of stations was increased from ~ 3000 to ~ 6,000 ( In a sense, these additional stations were taken out of context. That is to say their period of record was incomplete. Out of those 3,000 I found only 400+ stations
outside the US with reasonably looking records. Their composite temperature increase from their 1940 high to 2005 was only 0.3 deg C. And that without any UHI correction. US increase from USHCN was the same. My conclusion: the only significant net temperature increase occurred before CO2 rose.
Reply: Well … on the one hand GISS does not “collect data”. They use data collected from other sources, primarily NOAA, and they tend to take a transparent attitude that their analysis is only as good as the data collected by their “subcontractors”. This somehow seems to work for them but not for the corporate world.


My feeling now is – don’t even bother collecting temperature records other than for local interest. There are just too many problems with trying to take the temperature from everywhere and have it mean something. You just end up with junk information.


Geoff Sherrington (18:46:45) :
Here in Taranaki, New Zealand, we moved the weather station used at our air port for the district Temperatures, because it was felt that it measured too low and was adverse to domestic tourism. LOL. It was only about twenty yards from the gas fire training facility… Anthony would have loved it! 😉 I think local topography can overide other factors.

Again, I find more and more that the debate about TEMPERATURES is meaningless! The ONLY thing that counts. The ONLY thing that is important is RADIATIVE BALANCE.
And the ONLY reliable information on that comes from SATELLITES!
Heaven help us from the people who do not understand the OXYMORON of “average temperature”.


Reply: Some of the stations continue to report data, but it is not currently captured by NOAA’s GHCN V2 record and therefore does not get reported to GISS. – John
Oh. Now I am confused. the stations are active, but not included in GISS, I got that part, but does GISS check the values on the stations or just fill them in with the algorithm? And if they are valuable enough to use to correct stations, why not include them in the record in the first place?
Reply: I was going to say “GISS does not fill in missing data” but then stopped myself.
After a station “stops reporting” (which means NOAA has a back-level copy), GISS will not create more recent entries. There are cases, however, where up to six months of a twelve month record might be missing and GISS will magically create an estimate.
Example: A station reports data from 1940 to 1990, but in 1985 the station curator lost his job and was preoccupied. The curator missed reporting data for Feb / Mar / Apr / May / Jun and Oct. GISS is capable of calculating an annual average nonetheless for that station. – John

Jimmy Haigh

“I have wondered how the current global average can even be compared with that of 1987, which was produced using between six and seven times more stations than today.”
I would have thought that if they were serious about getting a good measure on ‘average global temperature’ – which, when you think about it, is quite a concept in itself – that they would have used more temperature measuring stations and not thrown away the vast majority of them?
When you combine the information you have reported here with your surfacestation project statistical analysis you’ll come up with quite a tangled web. My brain hurts just to think about it all.

John Goetz

It seems the influential stations are centered on … central Pennsylvania … home of Penn State … and Michael Mann …
As much as I do not believe in conspiracy theory, this is just too funny !!

Gary Pearse

I’m puzzled by the number of stations this appears to indicate. If the 100 most used reference stations average about 200 stations each that are adjusted to them, many more than 20,000 stations (probably more than 40,000) are monitored, unless the adjusted stations rely on several reference stations which would be an even greater nightmare. If there are indeed 30 or 40 thousand stations that are being monitored by the weather service, then an idea for an alternative array of stations would be to select at random, say, 2,000 stations and use these as a base for monitoring trends. Possibly one could reject the worst located ones and end up with 1200 (the number used by GISS).
Reply: Multiple rural stations are “averaged” together before they are used to adjust an urban station. And that average depends on how far away the rural stations are from the urban station.
As an example, a station A in Connecticut and a Station B in New Jersey can be used to adjust both New York City and Philadelphia. However, A will have a larger influence on NYC than B, while the opposite is true on Philadelphia.


Now that we have a station survey which rates each according to the CRN standards, perhaps NOAA and GISS will factor that into their correction algorithms.
Right, that’s gonna happen!


So – at the risk of being redundant – UHI is adjusted using sites that themselves are susceptible to UHI? Priceless. Is this a case where these people never leave their cubbies to see what the field really looks like?
Statistically – if the population of sites keeps shrinking, and the sites themselves are contaminated by their proximity to heat sinks/radiators, I can’t see anything of value coming from this data. The adjustments themselves stink to high heaven.

Gary Pearse

Mark Hugo (18:56:30) :
“Again, I find more and more that the debate about TEMPERATURES is meaningless! The ONLY thing that counts. The ONLY thing that is important is RADIATIVE BALANCE.”
RB may be more interesting to atmospheric physicists but surely you are not saying that if the average temperature were to fall 10C over the next 10 years, that this would not be interesting. Heck its a perfect proxy for radiative balance. This kind of viewpoint among sceptics is why the AGW crowd have been winning the all important public relations war despite bad science.

Brandon Dobson

The exploration of global climate change is of necessity the domain of scientists with an appropriate background, armed with accurate data to synthesize and support their hypotheses. However, the current debate is often dry and lacks historical depth. Information has been uncovered that places global warming square in the middle of startling revelations grounded in fact.
Have you wondered about the origin of the name Greenland? Wikipedia admits that ice-core studies in Greenland reveal rapid shifts in the climate of the Northern Hemisphere going back 100,000 years, but chooses to frame the information in the context of catastrophic global warming. This paragraph, which appears to contradict mainstream AGW, survives:
“Scientists who probed two kilometers (1.2 miles) through a Greenland glacier to recover the oldest plant DNA on record said the planet was far warmer hundreds of thousands of years ago than is generally believed… That view contrasts sharply with the prevailing one that a lush forest of this kind could only have existed in Greenland as recently as 2.4 million years ago.”
Wikipedia claims that the name Greenland was chosen to entice people to settle there, however other sources indicate that the region was quite warm during the time from 900 to 1200 AD, and named appropriately:
“…The next migration came from the east, following “Erik the Red” Thorwaldsson’s exploration of the southern coast of Greenland between 982 and 985 AD…The climate at this time was very warm, much warmer than it is today, and crops were able to do well. It seems likely that the name “Greenland” was given to the country, not just as wishful thinkful, but because it was a climatic fact at that time.”
Far stranger is the case of the map of Oronteus Finaeus. A good picture of it is available here:
“This map was found in the Library of Congress, Washington DC in 1960 by Charles Hapgood. It was drawn by Oronteus Finaeus in 1531. As with the Piri Reis map, Antarctica is shown to be ice free with flowing rivers, drainage patterns and clean coastline. Some of the mountain ranges shown were only discovered recently. The deep interior didn’t show any rivers or mountains which some believe means it was already covered in ice at the time. The Oronteus Finaeus map is more accurate than any other map of the same time. In fact, it is more accurate than any map made anywhere up to the year 1800.
Another tidbit of proof is the Ross sea. Today huge glaciers feed into it, making it a floating ice shelf hundreds of feet thick. Yet this map and the Reis map show estuaries and rivers at the site.
In 1949 coring was done to take samples of the ice and sediment at the bottom of the Ross Sea. They clearly showed several layers of stratification, meaning the area went through several environmental changes. Some of the sediments were of the type usually brought down to the sea by rivers. Tests done at the Carnegie Institute in Washington DC, which date radioactive elements found in sea water, dated the sediments at about 4000 BC, which would mean the area was ice free with flowing rivers up until that time – exactly what is recorded on the Reis and Finaeus maps.”
Much information regarding the map is available on the Internet. I stumbled upon it at the skeptical website Pete’s Place, Ancient map Disproves Global Warming by Allen Quist July 17, 2009
Many have tried to dispute the map of Oronteus Finaeus, but there is no definitive argument to disprove it. How it achieved such accuracy remains a mystery.
It is often claimed by proponents of AGW that we are entering “uncharted territory” with current levels of CO2. The geologic record shows that levels of CO2 were much higher in the past, and other records give weight to climatic swings beyond what we are currently experiencing, all without anthropogenic influence. And hey, the lousy GISS temperature record doesn’t help any.

Steve Hempell

OT but I just saw this posted at CA under “Christy et al 2009: Surface temperature….”
I actually bought the paper and it sent my BS meter a-clanging. Any chance Anthony that this could be discussed on WUWT?

John F. Hultquist

Brandon Dobson (20:28:27) : “ Have you wondered about the origin of the name Greenland?”
There is some evidence that the voyage to what is called Greenland was not pleasant and seasoned sailors preferred not to go. Thus the crews were mainly young and inexperienced, that is to say ‘green’ and those that sailed and landed there were called ‘greenlanders’. This comes from a book from one of the last captains of the ships of the British tea trade and I’ve loaned it to a friend in another state. Best I can do at the moment.

Bill Illis

We can officially change the name to GAS.
Goddard Airport Studies.
Seriously they use light measurements to choose the rural stations to adjust out the urban heat island.
That might also making them in charge of GASlighting.

Oliver Ramsay

Svante Arrhenius mused a lot;
Is the Earth warmed, or not,
By carbonic acid in the cloud?
Would that, in physics, be allowed?
Was this the way the ice retreated?
Could such a thing be repeated?
If not by Nature, then, by Man.
And so, the scientist began
To think about how he could best
Perform the perfect climate test.
To start, he said, we must be sure
About the present temperature
Of everywhere around the Earth
From Nunavut, clear through to Perth.
But, sad to say, upon reflection,
He was consumed by dejection;
The task was greater than he’d thought
To find the numbers that he sought
And though he really, really tried
He’d made no progress when he died.
There have been some others, since,
Whose attempts have made us whince;
Perhaps, there is no way to say:
Two hundred eighty-seven K


The picture I get is that the worse the urban station’s heat problem, and the more erratic the reporting, the more GISS uses it to overwrite rural stations that give the correct temperature.
GISS when you thought that they couldn’t be that bad, it get’s worse.
Dead sensor, no problem.

Justin Sane

Are their Surface Station reports on these multiply used stations? Whatever they have wrong is multiplied by hundreds of times due to their usage to correct other stations.


As for why Greenland is called Greenland it is told in the Icelandic sagas (which are the only contemporary sources) that the name was chosen by Erik the Red to attract colonists (sounding decidedly better than Iceland).
And yes, it was warmer there during the MWP, and yes, it was possible (though marginally profitable) to grow barley there (according to the Konúngs Skuggsja, a very reliable 13th century norwegian source).
As for 16th century maps of Antarctica, may I point out that nobody visited Antarctica until 1820. And as for it having been ice-free then, forget it. In the Ross Sea area for example it is possible to date the fluctuations in the ice cover (and there have been such) by dating the deep-frozen remains of penguin colonies which go back many thousands of years, wouldn’t they have rotted if temperaturres had ever gone much over freezing during that time?

stas peterson

Mike d,
Yes there were 6 or 7 times more weather reporting in 1987, before th East Bloc collapsed. Now consider this: What if a terrorist organization arranged to destroy all the weather stations North of the Mason Dixon line in Maryland and the only reports that you continued to receive were from places South of it, like Florida, Texas, Arizona and Southern California. Do you think a plot of temperatures just might show it a smidgen warmer. Wouldn’t you say that the entire time series was destroyed, and rendered useless?
Well that is EXACTLY what Herr Hansen and his cronies do, and more as well. Global Warming based on Weather Station data is a complete farce. Plus the extrapolations of the weather stations is used to create nonfactually precise climate data. If I have a thermometer that can read accurately to a degree, then averaging a bundle of such measurements and reporting changes to a few hundredths of a degree accuracy from the computed averages is pure nonsense. Yet the Global Warming is meassured in such imprecise changes.
I suggest you acquire Gavin Mencies “1421”, which records the maritime expeditions of the Ming dynasty, including their mapping of the entire World including Africa, the E and W coast of the Americas, Australia, New Zealand, the Antarctic, the Arctic Ocean, a mapping of all Greenland that could only have been accomplished by circumnavigation in an ice free environment . This was done around 1420, at the middle-end of the Medieval Warm Period after all the ice had melted. Maps of the Ming expeditions circulated in Europe from Arab traders. Indeed Magellan had a copy of a Chinese map that showed the “Straights of Magellan ” before he sailed from Europe.


Been checking this map daily and today it seems like the temperatures went down all over the north.