A question has been bugging me for a while. I'm hesitant to ask it because I feel I might be missing something incredibly obvious. However, after seeing the latest two posts at the blogger Anders's place, I feel I need to ask it. Please try not to be too harsh on me if it's as stupid as I worry it might be.
As you guys probably remember, I am supposed to be posting a follow-up on my discussion of how adjustments to temperature data affect the modern temperature record and how such changes impact our interpretation of the rise in temperature in modern times. If you haven't seen the previous post about this, you can find it here.
It's a somewhat difficult post to write, particularly since I have been having trouble finding data for a number of results that have been shared and discussed online.
As a result, I've been doing more work on other topics. You may have noticed I recently resolved a discrepancy in results posted by Steve McIntyre and those I got for the recent Gergis et al (2016) paper. Steve was kind enough to share his code, and it turns out he had used the wrong data set. With that issue resolved, I'll have more to say about the paper. I do want to talk about the adjustment issue though, so I'll do that today.
This post won't be the last one, but I do think it is an important one. You see, it's not just adjustments to the data we have to worry about. There's another issue that can be just as important, if not moreso.
Hey guys. I've been having trouble finding a topic to write about this week, so I've decided to re-visit an old issue. People familiar with my writing know I have spent a fair amount of time examining what effect human adjustments to temperature data have had on temperature records. This has mostly focused on the work of the (questionably named) BEST group.
I am not going to re-visit the not insignificant history of this topic today. If you want to read a bit about it, this post should give you a bit of an introduction to the matter. There is one historical point I do need to bring up though. A year and a half ago, in April of 2015, the head of the BEST project Richard Muller gave an interview in which he said:
“Furthermore, because of the interest, we re-analyzed all the data with ZERO adjustments, just to see what we would get. These results have been made available online. What we found was that the conclusions we had previously drawn were unchanged. The data are available here
You can read up about the trials and tribulations surrounding that article here if you would like, but the salient point is the data Muller referred to has never been published. It had not been published in April of 2015 when the interview was given, and it has not been published as of today, in August of 2016.
I don't know why Muller claimed data had been published when it had not. I don't know why that data has never been published. That's a matter for another day though. The reason I bring this up today is I want to point out anyone hoping to analyze the effect human adjustments to recorded data have on the BEST temperature results will face the obstacle of the BEST group falsely having claimed to publish the data which would make that possible without completely redoing the BEST analysis.
Fortunately, as you may have noticed while reading the posts I linked to above, the BEST group has shared that data with me. Unfortunately, that only happened after we exchanged a number of e-mails and I publicly criticized them (multiple times) for failing to publish data then turning around and claiming it was published. Still, the result is I have the data. Continue reading
The Intergovernmental Panel on Climate Change said this in its summary (for policymakers) of its latest major report:
It is extremely likely (>95% confidence) that human influence has been the dominant cause of the observed warming since the mid-20th century.
This report, the Fifth Assessment Report, was preceded by one whose summary said:
Most of the observed increase in global average temperatures since the mid-20th century is very likely (>90% confidence) due to the observed increase in anthropogenic greenhouse gases.
Both reports also discuss the total amount of warming observed since the nineteenth century, but as these quotes show, a key issue in the global warming discussion is what portion of the warming since 1950 has been caused by human influences on the planet's climate. Some people would say 0%. Others would say what the IPCC has said in the past, that it is 50+%. Others would say it is over 100%. I think that last one is nonsensical, but that's a topic for another post.
What's most important, however, is there's a group of people who say the answer is influenced by the "fact" human adjustments to the temperature record have artificially exaggerated the amount of warming that has actually occurred. They may think the exaggeration is slight, or they might think it is so large as to completely fabricate the apparent warming trend. Imagine telling them things like:
Wouldn't that seem a little off? If a person's concern is adjustments to data which exaggerate warming, would you think telling them what adjustments do since ~1900 would address their concerns in a clear and convincing manner? I don't think so. I think a lot of people might well look at the IPCC attribution statements and focus on the period after 1950, where the human contribution is said to be the major factor. That's why I told that user, Robert Way:
The Berkeley Earth surface temperature (BEST) project was supposed to be a great thing. It was supposed to resolve the concerns skeptics had raised about the modern temperature record. It was supposed to resolve not just technical issues skeptics had raised, but also basic concerns about openness and transparency.
Once upon a time, people managing the modern temperature records wouldn't even share basic information like what temperature stations they used. It was disgraceful, and it caused a lot of distrust. It was also one of the main reasons BEST was formed. BEST was supposed to help resolve the trust issues by being completely open and transparent. BEST has promoted it's openness and transparency time and time again, and its one of the most touted aspects of their project. The problem is, it's a lie.
It's time to provide the answer to my recent challenge. For those who don't remember, the challenge was to look at three graphs and decide how many sudden, non-climatic shifts were in them. I'll now provide the same image as before, but with the breakpoints indicated:
I happened to come across something which annoyed me on the Berkeley Earth (better known as BEST) website today. I'll discuss it later, but it reminded me of something I've been interested in about that group's efforts. For those who don't know, their project involves creating a record of the planet's temperatures.
To do so, they combine data from many different temperature records across the globe. There are lots of different ways to do this, and there are lots of debates about how good or bad any of them are. I won't get into that, but I want to talk about one newish thing BEST does. Instead of adjusting individual records when it appears there's a shift in data unrelated to climate (such as you'd get if a temperature station moved), BEST simply splits the record into separate series.
It's a good approach. If a temperature station moves three times, we'd have four different segments with little relation to one another. Treating them as four different series makes sense. The problem is figuring out where to split those series. How do you tell when a change in data is and is not related to climatic effects?