How the Climate Science sausage is made

Ten years ago I laid this out.  This is where the action is when it comes to actual climate science.

Originally posted 9 December 2009.

How to create a Scientific Consensus on Global Warming

We keep hearing people tell us that there is a "consensus" that the planet is warming, because the "science is settled". Longtime readers know my feelings on the latter, so there's no need to rehash old arguments. Instead, I'd like to look at how one might go about manufacturing a consensus. It's actually not hard.

Step 1: Change the data

There are a very small number of data sets on global temperatures, and these are used by essentially all Climatologists worldwide. One (CRUt) is from the Climate Research Unit in the UK, the second (GHCN)is the US Historical Climate Network, and the third is GISS (from NASA's Goddard Institute).

However, not all data sets are created equal: GISS and CRU get almost all of their raw data from GHCN, so that's the one that counts. Meaning, that's the one we'll look at today.

There are two parts to the GHCN data: the raw temperature readings, and adjustments to the readings. The raw numbers are easy - they're just the instrument reported temperature for the weather station. Look outside your house at your thermometer - that's the raw data. Here Chez Borepatch, my thermometer says that it's 39°.

Adjustments are modifications to the readings, to "remove inhomogeneities" in the raw data. You (like me) may look at that and say Whiskey Tango Foxtrot are inhomogeneities? CRU helpfully provides an answer:

Most long-term climate stations have undergone changes that make a time series of their observations inhomogeneous. There are many causes for the 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 occur at the same time, as is often the case with the introduction of automatic weather stations that is occurring in many parts of the world. Before one can reliably use such climate data for analysis of longterm climate change, adjustments are needed to compensate for the nonclimatic discontinuities.

OK, we don't want a jump in the historical record if you move a station or replace a thermometer with a better one.

But. All the Climatologists in the world will look at this data. How much do the adjustments change the results?

We don't know, but people are starting to look. They're starting to find that adjustments change the data a lot. They change the data so much that they show that the earth is warming when the raw data may show that it's cooling.

Let me say that again: Thermometers may be showing that the Earth is cooling, but adjustments to this data show a rapid temperature rise.

Let me give three examples.

Darwin, Australia:The blue line is the raw data from the five weather stations in Darwin. It shows a 0.7°C cooling over the 20th Century. The Black lines are the adjustments to this data, showing a big jump in 1940 and a substantial increase since then. They turn the raw data decline into a 1.2°C increase over the course of the 20th Century.

Woah. So what's with the adjustments? Fortunately, there is an explanation:

They pick five neighboring stations, and average them. Then they compare the average to the station in question. If it looks wonky compared to the average of the reference five, they check any historical records for changes, and if necessary, they homogenize the poor data mercilessly. I have some problems with what they do to homogenize it, but that’s how they identify the inhomogeneous stations. OK … but given the scarcity of stations in Australia, I wondered how they would find five “neighboring stations” in 1941 …
So I looked it up. The nearest station that covers the year 1941 is 500 km away from Darwin. Not only is it 500 km away, it is the only station within 750 km of Darwin that covers the 1941 time period. (It’s also a pub, Daly Waters Pub to be exact, but hey, it’s Australia, good on ya.) So there simply aren’t five stations to make a “reference series” out of to check the 1936-1941 drop at Darwin.
...
Yikes again, double yikes! What on earth justifies that adjustment? How can they do that? We have five different records covering Darwin from 1941 on. They all agree almost exactly. Why adjust them at all? They’ve just added a huge artificial totally imaginary trend to the last half of the raw data! ...
Those, dear friends, are the clumsy fingerprints of someone messing with the data Egyptian style … they are indisputable evidence that the “homogenized” data has been changed to fit someone’s preconceptions about whether the earth is warming.

You might think that this sort of "adjustment" process is incompetent. You might also think that this process is convenient (but only if you are as nasty and suspicious as I). There is much, much more, and it's much, much worse.

It's not just Darwin, either. Brisbane sees exactly the same thing:

Just out of interest I decided to plot the raw temperature data for my home city of Brisbane, Australia from the GISS (ie the raw GHCN data) against the homogenized or adjusted GISS GHCN data. The temperature sensor is located at the Brisbane Eagle Farm Airport which is now our busy main international airport. The data used is the series available from 1950 to 2008. I have aniumated the result to highlight the difference.

As you can see the raw data shows a downward trend of about -0.6 C per century. The unadjusted data however shows an opposite trend of +0.6 C per century. Intuitively as the airport grew from a quiet strip to a busy international jet airport one would think the more recent data would be adjusted downwards for the heat island effect. Instead we see that the data prior to 1978 is adjusted down and the data in recent times was adjusted up.

He helpfully plots the raw data overlayed with the adjusted data.Don't need a weatherman to know which way the wind blows.

And remember, we already know what the adjustments to the lower 48 states look like:New Zealand, too:Take away the adjustments, and all the warming from 1850 disappears. Change the data, and all the Climatologists will discover that the Earth is "warming". [intentional use of scare quotes]

Let me say this explicitly: I used to believe that the planet was warming, and that this was likely due to natural (as opposed to man made) causes. Now I'm not sure that the planet is warming. The data do not show warming over the last 70 [now 80 - Borepatch] years, maybe longer.

Step 2. Fund only scientific research that confirms warming.

We've seen for some time anecdotal evidence suggesting that researchers are afraid to come out publicly against the "consensus" view:

You can almost smell the fear - the article discusses a series of climate changes over the centuries (not a surprise to either of my regular readers), strongly correlated with changes in Solar activity. But the author feels the need to add a non sequitur about Carbon Dioxide. E pur si muove, indeed.

Well, we now are starting to see explicit charges of warming bias in the research grant application process:

Personal anecdote:
Last spring when I was shopping around for a new source of funding, after having my funding slashed to zero 15 days after going public with a finding about natural climate variations, I kept running into funding application instructions of the following variety:
Successful candidates will:
1) Demonstrate AGW.
2) Demonstrate the catastrophic consequences of AGW.
3) Explore policy implications stemming from 1 & 2.
Follow the money — perhaps a conspiracy is unnecessary where a carrot will suffice.

On a personal note, one of the traits that I find the most charmingly naive among the more shrill of the warming alarmists is their claim that the skeptics are funded by the Oil companies. As if "their side" couldn't possibly have an interest in the outcome.

When you consider that the CRU had received at least £14M and was looking at another £75M more, that's real money.

Opportunity and motive. Does this mean there was a conspiracy? Of course not. It does mean that they data is not to be trusted, that we simply don't know whether the planet is warming or not, and that there is a plausible explanation for why someone would want to manufacture a phony consensus.

The science is settled? Don't make me laugh.

UPDATE 9 December 2009 17:37: Looks like West Point, NY is only warming due to adjustments. Here is the raw data:The Machiavellian explains what's happening:

So, after the raw data is run through the homogenization process, in other words, statistical manipulation, temperatures from 1900 through 1980 are depressed at West Point and temperatures thereafter look as if they are increasing in comparison to the average temperatures based on the raw data.

No warming at all in 100 years in the raw data; a degree warming after adjustments.

UPDATE 9 December 2009 17:47: It looks like the CRU emails include this from Prof. Wibjorn Karlen, who was trying unsuccessfully to reproduce the temperatures shown by the IPCC AR4 report for Scandinavia.

In attempts to reconstruct the temperature I find an increase from the early 1900s to ca 1935, a trend down until the mid 1970s and so another increase to about the same temperature level as in the late 1930s.

A distinct warming to a temperature about 0.5 deg C above the level 1940 is reported in the IPCC diagrams. I have been searching for this recent increase, which is very important for the discussion about a possible human influence on climate, but I have basically failed to find an increase above the late 1930s

This is email 1221683947, to Dr. Jones of the CRU. Jones was particularly unhelpful - essentially blowing Karlen off. So add Scandinavia to the list of places where adjustments look particularly dodgy.

UPDATE 9 December 2009 17:56: Wow, Detroit, too:

Once again, the raw, monthly average temperature for the Detroit area, over the last 111 years shows an amazingly constant climate. It seems that only when the data is run through and adjusted by the proponents of global warming do we get an upward tick in temperatures.

The Machiavellian has more: California, Southwest Ohio.  Click through and scroll.

Here is the $64 Trillion Question: Are there any locations where adjustments are net negative over 100 years? Any at all? I'm willing to listen to justifications why all adjustments are long term net positive, but it will have to be good. There are very well known and documentedissues that cause thermometers to run hot; adjustments for this should cause raw temperatures to decrease, not increase.

UPDATE 9 December 2009 22:24: Joanne Nova has an information-rich post that dissects the adjustments. If the adjustments come mainly from nearby weather stations, what if none of them show warming, either? Someone at GISS or CRU or HCN have some 'splaining to do.