Bishop Hill A pickle
The must-read post this morning is Judith Curry's coverage of a new paper by Kosaka and Xie in Nature. The paper received some attention yesterday, the BBC reporting that it explained the 21st century temperature plateau, saying it was due to...
natural cooling in part of the Pacific ocean.
Although they cover just 8% of the Earth, these colder waters counteracted some of the effect of increased carbon dioxide say the researchers.
But temperatures will rise again when the Pacific swings back to a warmer state, they argue.
However, as Judith Curry notes, if the cause of the pause is the Pacific Decadal Oscillation then size of the rise in the last decades of the twentieth century must have been heavily influenced by it too. And, unmentioned in the text of the Kosaka and Xie paper, she notes that when the paper's authors ran their climate models without greenhouse gas forcings they still got a considerable rise at the end of the twentieth century: in her (eyeball) estimate, more than half the magnitude of the rise when greenhouse gases were included.
In other words the majority of the 20th-century warming may be natural rather than anthropogenic.
Which looks like a bit of a problem for the IPCC's imminent announcement that it's all down to us.
Footnote: I'm going to get into terrible trouble with Doug Keenan if I don't mention this paper by Gerald Roe of the University of Washington. It's entitled "Feedbacks, Timescales and Seeing Red" and looks at applications of feedback analysis to geophysical systems, including the PDO. Roe concludes that "By these statistical measures, the PDO should be characterized neither as decadal nor as an oscillation (but it is in the Pacific)", although this statement comes with caveats that are worth reading. I surmise that we are still far from understanding what is going on here. It's all a bit of a pickle.
Reader Comments (60)
TheBigYinJames - Aug 29, 2013 at 9:35 AM | Unregistered Commenter
"And my 2013 new year prediction comes to pass... by the end of the year models will be backward-predicting the hiatus."
You need to get up to speed boy.
On Guemas et al (2013) “Retrospective prediction of the global warming slowdown in the past decade”
http://wattsupwiththat.com/2013/04/08/on-guemas-et-al-2013-retrospective-prediction-of-the-global-warming-slowdown-in-the-past-decade/
Someone up-thread mentioned Fiona Harvey spinning the Kosaka & Xie paper. You many remember the paper by Otto et al., published earlier this year, which reported a most likely ECS value of around 2 deg C, and TCR of 1.2 deg C, notably lower than the IPCC values. One might think this would signal a reduction of alarm.
I had occasion yesterday to read Ms Harvey's coverage of the paper, an article entitled "Climate change: human disaster looms, claims new research", with a subhead of "Forecast global temperature rise of 4C a calamity for large swaths of planet even if predicted extremes are not reached". From the article, it's hard to imagine that she was reading the same paper.
So why did Kosaka and Xie put Figure 1b in their paper?
If the model doesn't fit, modify the model do it fits the data.
Then use the model to predict new data.
I'm holding my breath for the next 20 years.
"The abstract from the Nature paper follows an increasingly familiar pattern: Firstly, a description of their work...Secondly, a slightly incongruous sentence or two, perhaps hastily added, to the effect that CO2-based global warming is still coming to get us." --michael hart
It is obligatory in post-Normal science to say the shibboleth, to utter the ecco la fica without fail, no matter what the actual content.
'Although they cover just 8% of the Earth, these colder waters counteracted some of the effect of increased carbon dioxide say the researchers'
I can hear Professor Steig mumbling - 'Why didn't I think of that?'
(sarc)
I wonder how the current crop of scientists will feel in 30 years when all their erroneous readings are adjusted?
Aug 29, 2013 at 12:36 PM | Unregistered CommenterLord Beaverbrook
Rich. Having lived high on the public purse for fifty years; paying their mortgages and car payments off, and putting their kids through college.
Dr. Curry has obtained a smallish response from Xie which she posts as an update. Xie writes:
"1975 was a La Nina year, and 1998 followed the strongest El Nino in the instrumental record. My estimate indicates that the El Nino-La Nina difference accounts for 0.2-0.3 C difference of her 0.4 C in POGA-C. So for multi-decadal trend, PDO accounts for only 0.1-0.2 C for the longer period of 1950-2010. El Nino and La Nina are part of the short climate cycle of ENSO, averaged out over several decades. Our paper noted that the warm phase of the tropical Pacific Decadal Oscillation contributed to the fast warming during the 1970s-1990s."
Here we see standard Alarmist talking points. Short climate cycles "average out" over longer time periods. Anyone want to take a bet on whether there is empirical research underlying that claim? No need to. There is no empirical research. The claim is just a typical Alarmist presumption. Because the short cycles average out then we have to look at 1950-2010 to see the actual contribution to warming from ENSO and we find that it is only .2C. Of course, that lowers the effect of natural variability. Good old Alarmist computer modeling shuffling of the cards. I guess someone let Xie know that he just might be thrown under the bus.
"Although they cover just 8% of the Earth, these colder waters counteracted some of the effect of increased carbon dioxide say the researchers."
Note that the same 8% of the Earth produced a strong El-Nino event in 1997-98 and generated the record warm year so beloved of the "no warming since 1998" crowd.
The ENSO forecasters are starting to suggest a move towards El-Nino conditions from late 2014. It will be interesting to see what the global average temperature does.
Theo Goodwin
If any of those electronic engineers are out there , I'd like them to try filtering the GISS global temperature data through some of their signal analysis software.
http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt
This might show up some of the cycles under discussion.
My own prediction, based on inspection, would be that there is sub decadal random noise.
Superimposed on that is a 10-11 year cycles whose maxima tracks the peaks of the solar cycle, with about 0.1C variation.
Superimposed on that is an approximaly 60-year cycle of about +/- 0.2C
Finally there is a long term warming trend of 0.6C/century.
Pehaps Martin A or Michael Hart would like to test my hypothesis.