“Tony Banton wrote this relevant to the discussion here but at JC.
As I’ve tried to explain (along with a few others) to angech. Given that the two sets of instruments are measuring the same thing, then the trend is the same, yes?”
Two wrong comments in one sentence pushing hard to make up a fiction.
First the two sets of instruments are both measuring temperature [not anomalies]. They are however not measuring the same thing.
One is measuring sea water temperature collected by ships,from different levels and heated and cooled by various other inputs on the way.
The other is measuring temperatures in sea water at a set level with hopefully the same sort of thermometer without ship and human interference.
-Second “then the trend is the same, yes?” No.
One is said to be measuring 0.12 C average lower than the other.
That does not tell you the trend of the two types at all
That would be an average of each trend over the same time period for the same number of ships and buoys. It says nothing about the actual trend of each type over that time period.
One could be double the trend of the other but one could still say the average trend is 0.12 lower.
The trends are said to be similar. You need to specify the time intervals for comparison and it is obvious that two such disparate systems should rarely be in synchronicity as to trends.
There is no common period where one can truly compare trends. Buoys go from 0 to 7/8 of measuring system type used over 20 years. There are no true trends to compare.
That is not to say the mathematicians like Zeke cannot do a serial breakdown of the ship and Buoy temperatures over the time period of common use but varying number.
I do not see it?
Could he put it up?
Would be grateful to see the true trends and their correspondence
Anomalies vs. Temperature
“tell what would be a trend you’d consider true.”
There would be a trend for the Buoys, It would start off awkward with only 1 Buoy and as more are added one would have to merge [sigh] the data sets and this would give a buoy only trend.
One would already have a full ship only set of data which again would have to merge the ships as they begin to decrease in number.
Zeke has both of these.
Then to compare trends in general you could have the ship only trend and the buoy only trend.
Obviously due to the much longer ship data length, CO2 warming increase and natural variability these two trends will not match.
Next you could take the period where ship and buoy data are both available and truly compare their anomaly trends on the same baseline.
This also allows you to compare the difference in real temperature between buoys and ships.
This is the average temp over the time period of each data set and Zeke quotes 0.12 but does not give the period this must be quoted for.
It really should be for 30 years but it might be extrapolated out over 20 years of data I guess.
When I say “must be quoted for” I mean you cannot pick a point out in time at the start of the change and say buoy temps immediately dropped 0.12 C below the ships. It had to be worked out over time.
Here is the nub of the problem,
What I would hope to see is quite variable data with an overall match in trend*.
I would expect reasonably marked differences in the data from the two different ways of measuring and the various improvement/changes in ship measuring.
If we found an exact match I would hope everyone knows that is basically impossible.. If we found a highly correlated match we should be extremely suspicious mathematically. If we found quite variable data with an overall match in trend this would be very reassuring that the science is being done correctly.
The trends may be quite different because they are over a fixed time period but the difference in temps is simply the average difference over this time.
Again, like the pause [where one can always find a pause] but in reverse one can always find a matching trend in overlapping trends if they overlap twice while passing and you use those two points.
“why you find it obvious that the two systems can’t have similar trends.”
Not what I said.
I did not say they could not have similar trends*, in fact I would expect similar trends. I said you cannot extrapolate, as Tony did,saying ” Given that the two sets of instruments are measuring the same thing, then the trend is the same, yes?”
They are not measuring the same thing, they are measuring different things, hence the trends can not be the same.
“why you find it obvious that the two systems can’t have exactly the same trend.”
Statistics , Taleb and common sense.
Victor Venema (@VariabilityBlog) says:
“it is your political movement that assumes the global temperature record is so amazingly accurate that minimal adjustments of 0.05°C or less are a political scandal and that the temperature data is so accurate that it is not possible that what you call a “hiatus” is a measurement/estimation artifact.”
Not me, not political.Skeptical, contrarian.
“minimal adjustments of 0.05°C or less are a political scandal”.
Let us both be clear here on the use of the word minimal.
Putting a figure in units giving a reading of much less than one and then claiming it is “minimal” is a political clever gambit.
Remember “Our climate has accumulated 2,455,968,886 Hiroshima atomic bombs of heat since 1998″ raising the ocean temperature less than 0.1 degree.?”
0.05C is not a minimal adjustment, 0.05C per decade is not a minimalist adjustment.
We are blogging on an article by Zeke on the importance of such a critical adjustment.
“assumes the temperature data is so accurate that it is not possible that what you call a “hiatus” is a measurement/estimation artifact.”
Please, I have always maintained that our time intervals are too short to leap to conclusions.
By your logic what you call a recent rise in global temperatures is possibly a measurement/estimation artifact
paulski0 says: February 21, 2017 at 4:06 pm
“There is one true globe. It is the whole globe (and nothing but the globe).”
We are limited in our knowledge of said globe and we choose to represent it by what we have available at the time. A poor example would be that 600 years ago most global representations did oit have Australia in. Hadcrut is and was a representation of the known globe
You assert that HadCRUT4 is then taken to be a normal distribution effectively centered on the result of infilling with hemispherical average in empty cells.This is interesting.
In which case you and Steven and ATTP would be right. But in this case all three of you would have already pointed this out. So it cannot be right.
My understanding is that HADCRUT is not a full hemispheric data set. It is infilled to a certain latitude only and parts of the Arctic and Antarctic are not uncovered cells but excluded cells.
There are uncovered cells in part of the Arctic and Antarctic and Africa in their latitude range due to poor observational areas which are “infilled”.
Could you clarify this?
Steven Mosher says: One simple way I’ve explained it people willing to understand is this. If you want to claim that hadcrut is unbiased, then you are asserting that the true values in the blank regions have rates of warming that are precisely equal to the average of all the covered regions. . In other words you’re asserting something highly unlikely.
Except HADCRUT say that they infill by using the global average, hence it is very likely. Why is this so hard to understand.