...

[chubbs]

Below is a chart showing how GISS compares to warming estimates made using the NOAA GHG index and TCRs of 1.7 and 2.0. A TCR of 1.7 roughly fits the entire GISS series but 2.0 is a better fit since 1970.

 

 

[skierinvermont]

See, this is actually a problem for me (and others who argue the flaws in the models)...they are claiming that we basically did have a 2 sigma event...or that we didn't know what aerosols did in the past 10-15 years until recently. Yet, we assume we know the aerosol forcing from 50 years ago or 100 years ago. These are big assumptions that on the surface can be defended, but when you look closer, the past gets swept under the rug a bit. We make all these fine-tuning to the models in the past 15 years to account for the hiatus, but then assume the previous 100 were fine.

 

It certainly is an explanation and is plausible. I just find it less likely than the other explanation of GCMs having a TCR that is too high.

 

 

The good news is that it won't take very long for us to find out if that explanation is correct. Another 15-20 years will make it more obvious.

 

 

It's not claiming that we didn't know what aerosols did the last 10-15 years until recently. It's just including the cooling effect from aerosols and ENSO in calculating TCR, which other (inferior) studies have ignored.

[stadiumwave]

I doubt there has been much natural contribution to warming between 1979 and 2013 when you include impacts of the most recent hiatus years. My expectation is that we roughly maintain the 0.016 per year trend of the past 35 years going forward. As you say we will find out soon whether the models can climb back from the hiatus induced move to the lower end of the uncertainty band.

You are right that the TCR that matches the observed temperature rise decreases as you extend the record back further in time. Using this same method a TCR of 1.7 is a good match to the entire GISS record from 1880 to 2013 but 2.0 is a better match for the past 50 years. The apparent TCR increase with time is not surprising since a pipeline of future warming has build up gradually with time.

[stadiumwave]

No natural contribution since 1979? You're going to have to support that bold claim with data. That's almost comical! Your saying 100% AGW warming since 1979?

And I suppose you believe hiatus is ALL man to due to aerosols & has nothing to do with -PDO...I've yet to see any convincing literature to support that hypothesis.

[chubbs]

No natural contribution since 1979? You're going to have to support that bold claim with data. That's almost comical! Your saying 100% AGW warming since 1979?

And I suppose you believe hiatus is ALL man to due to aerosols & has nothing to do with -PDO...I've yet to see any convincing literature to support that hypothesis.

 

Let me clarify. Agree that the hiatus is an example of natural variability.There continues to be siignificant natural variability.  Prior to roughly 2000 ENSO+ and PDO+ contributed to warming since then ENSO- and PDO- contributed to cooling so the net natural effect over the entire period was not large.

[ORH_wxman]

It's not claiming that we didn't know what aerosols did the last 10-15 years until recently. It's just including the cooling effect from aerosols and ENSO in calculating TCR, which other (inferior) studies have ignored.

 

 

This is basically a semantics argument...but my main point stands. The paper he cited uses GISS stratospheric optimal thickness data, which includes the OSIRIS time series since 2001. The data before that is more uncertain, especially the further back you go. We're taking more precise data recently and then assuming the data further back is fine. I get that we really don't have any other way, but it's these types of assumptions that tend to get glossed over when defenses of climate models are presented.

 

This is even assuming their aerosol conversion coefficient is accurate which we already know has big error bars.

[stadiumwave]

 

Let me clarify. Agree that the hiatus is an example of natural variability.There continues to be siignificant natural variability.  Prior to roughly 2000 ENSO+ and PDO+ contributed to warming since then ENSO- and PDO- contributed to cooling so the net natural effect over the entire period was not large.

 

K....thanks for clarifying.

[chubbs]

December PDO up to 2.51 bringing 2014 average to 1.13 Both Decembers monthly value

and the 2014 annual average are the highest since 1997.

2013** -0.13 -0.43 -0.63 -0.16 0.08 -0.78 -1.25 -1.04 -0.48 -0.87 -0.11 -0.41

2014** 0.30 0.38 0.97 1.13 1.80 0.82 0.70 0.67 1.08 1.49 1.72 2.51

[AvantHiatus]

Just more partitioned heat for the next event. Upwelling is not very effective at dispersing OHC in the long-run.

[csnavywx]

That 2.51 PDO reading is the highest December value in the entire series and, in fact, the highest reading for DJF as well. Pretty impressive.

[skierinvermont]

Maybe we are entering a +PDO phase?

[ORH_wxman]

That would be strange given the history of the PDO to be entering a longer term warm phase this soon...I think it is most likely a short term jump like we saw in the late 1950s within a negative decadal regime...but we can't know for sure until we have benefit of hindsight.

[chubbs]

I took a look at Lewis and Curry's TCR estimate using the NOAA GHG forcing index. As shown below I was able to match their results pretty well for the two main evaluation periods of 1859-82 and 1995-2011. The  method, which was was developed by others, is simple and boils down to comparing average temperature and GHG forcings in two periods. There is no problem with their TCR derivation but the overall approach does not look definitive to me because they are ignoring data outside of the evaluation periods and the result appears to vary with the periods chosen. Over the past 40 years temperatures have been increasing faster than projected by this method.  A better approach would be to use regression analysis to make use of all of the temperature and forcing data both manmade and natural.

 

[ORH_wxman]

Lewis chose those periods because they best matched in terms of volcanism and multi-decadal ocean oscillations. If you compared 1890-1915 to 1925-1950, you'd get an inflated TCR because natural variaiblity greatly assists during that period. Or comparing 1955-1970 to 1995-2011.

[chubbs]

Lewis chose those periods because they best matched in terms of volcanism and multi-decadal ocean oscillations. If you compared 1890-1915 to 1925-1950, you'd get an inflated TCR because natural variaiblity greatly assists during that period. Or comparing 1955-1970 to 1995-2011.

 No two periods will ever match. Regression could account for volcanism, sun, ocean oscillations etc. As you pointed out previously the farther back you extend the temperature record the lower the TCR becomes. This suggests that a linear model is not valid or at least not useful for projecting the future. Going forward will need temperature increases of no more than 0.1C/decade to maintain a 1.33 TCR. I would take the over.

[Mallow]

Of course the model mean won't get every small detail correct, but they aren't getting the larger picture correct either. That's the whole point. The models have no idea on natural variability.Theoretically, if they did, then we would see many models within a large ensemble forecast a hiatus, but they don't. Something like 2% of them forecasted anything close to what has happened. That's inadequate. It means that even the models that try and put us in a natural cooling cycle for 15-20 years are overwhelmed with their GHG forcing to produce higher trends than what actually happened. We can chalk this up to either a >2 sigma natural variation event or that the models are probably fundamentally flawed. We can't completely rule out idea #1, but the smart money would be on the latter scenario.

 

There's recent papers on this exact topic and that is where the science is headed right now.

 

When I discuss it though, i always get this underlying feeling that many people take it as the same thing as denying global warming or something similar which is patently ridiculous. A slower warming trend vs a fast warming trend isn't that strange of a concept to debate. Though I know it is more popular on the blogospheres to have the strawmen fights between deniers and alarmists...it's never anything in between where the real science is. Always about zero warming vs the worst case scenario.

 

It may not be as exciting as that, but I do find it very interesting where the actual debate in the literature is and not just the rhetoric on the blogs.

 

This statement (the bolded) seems a bit disingenuous to me, though. Climate models don't correctly predict PDO/ENSO variability, so I think we mostly agree, but the only way to state that "only 2% of the models forecasted anything close to what happened" is to put a level of confidence in the models that I don't think ANYONE would claim to be accurate. Specifically, that statement may be true for the SPECIFIC 10-20 year period we're talking about, but a much larger fraction of ensemble runs of climate models forecast hiatus periods LIKE the one we've seen, just at different times and for different lengths of time. The point is, one should never interpret a 100 year ensemble mean climate forecast as being representative over short time periods. Which isn't what you're doing, I know, but I think you're being unduly critical in expecting not only that ensemble members should capture the TYPE of internal variability we see, but also the exact TIMING. Because nobody in their right mind would suggest we should be looking at the timing of hiatuses on individual model runs.

[ORH_wxman]

This statement (the bolded) seems a bit disingenuous to me, though. Climate models don't correctly predict PDO/ENSO variability, so I think we mostly agree, but the only way to state that "only 2% of the models forecasted anything close to what happened" is to put a level of confidence in the models that I don't think ANYONE would claim to be accurate. Specifically, that statement may be true for the SPECIFIC 10-20 year period we're talking about, but a much larger fraction of ensemble runs of climate models forecast hiatus periods LIKE the one we've seen, just at different times and for different lengths of time. The point is, one should never interpret a 100 year ensemble mean climate forecast as being representative over short time periods. Which isn't what you're doing, I know, but I think you're being unduly critical in expecting not only that ensemble members should capture the TYPE of internal variability we see, but also the exact TIMING. Because nobody in their right mind would suggest we should be looking at the timing of hiatuses on individual model runs.

 

 

I would expect something inside the confidence interval to forecast the hiatus...not outside. That is, if the GCMs are able to capture natural variability in a realistic manner.

 

My point was...they don't.

 

I don't expect a big number, but the point of mentioning the 2% was that it wasn't even 5% or 10% like we might expect.

 

There's a select few that do forecast hiatuses at certain time periods, but IIRC, the study that showed that still only chose a subset of a very small percentage of the GCMs in the CMIP5 ensemble.

[ORH_wxman]

 No two periods will ever match. Regression could account for volcanism, sun, ocean oscillations etc. As you pointed out previously the farther back you extend the temperature record the lower the TCR becomes. This suggests that a linear model is not valid or at least not useful for projecting the future. Going forward will need temperature increases of no more than 0.1C/decade to maintain a 1.33 TCR. I would take the over.

 

The reason your TCR is higher going back to 1970 is the two base periods are not very comparable from a natural variability standpoint. At least that is what Lewis argues in the paper. You'll have to give a good reason why it's a flawed argument.

 

His calculated TCR could very well be too low. But OTOH, those values in the 1.8-2.0 range could very well be too high.

[skierinvermont]

Only 2% of the models forecasted that a specific chosen period (2005-2015?) would have such a slow warming period. However, I would guess that nearly all models show a period at some point with a similar warming rate.

 

Yes the selection of 2005-2015 is 'random' but it also just so happens to encompass a switch to a -PDO and a huge +ENSO to -ENSO shift. Once you recognize this, it's not so surprising that few models actually got the temperature trend for that period right. 

[chubbs]

The reason your TCR is higher going back to 1970 is the two base periods are not very comparable from a natural variability standpoint. At least that is what Lewis argues in the paper. You'll have to give a good reason why it's a flawed argument.

 

His calculated TCR could very well be too low. But OTOH, those values in the 1.8-2.0 range could very well be too high.

Don't disagree with your last sentence. Again I would let regression analysis using all the data narrow the range. When making future projections though I have more faith in the recent data  We haven't seen much variation in 30-year trends even through the recent hiatus.

[ORH_wxman]

Only 2% of the models forecasted that a specific chosen period (2005-2015?) would have such a slow warming period. However, I would guess that nearly all models show a period at some point with a similar warming rate.

 

Yes the selection of 2005-2015 is 'random' but it also just so happens to encompass a switch to a -PDO and a huge +ENSO to -ENSO shift. Once you recognize this, it's not so surprising that few models actually got the temperature trend for that period right. 

 

 

It depends on the forcing scenario used. The higher emission scenarios have an extremely low probability of a hiatus, it was approcahing 0% by 2030-2040 IIRC from the study. The RCP 4.5 scenario actually showed hiatuses becoming more common in the 2nd half of the 21st century since the forcing is leveling off some.

[chubbs]

PDO set a February monthly record of 2.30. That is the third monthly record in a row. What a turn-around vs. the -PDO of a couple of years ago - showing how unpredictable PDO turning points are.  Note that the long-term PDO chart below shows 3-month (plus)  and 12-month (line) running means updated through Jan. Given the time needed to reverse current conditions in the Pacific, it is hail Mary time for the hiatus.

2013**  -0.13  -0.43  -0.63  -0.16   0.08  -0.78  -1.25  -1.04  -0.48  -0.87  -0.11  -0.412014**   0.30   0.38   0.97   1.13   1.80   0.82   0.70   0.67   1.08   1.49   1.72   2.512015**   2.45   2.30                                                                      

[chubbs]

Dennis Hartmann has a new paper on how the 2013 record NEPAC blocking which continues to this

day lead to these three consecutive monthly record high PDO values. This follows the other 2014

paper on this topic.

 

 

Hartmann, Dennis L., 2015: Pacific Sea Surface Temperature and the Winter of 2014. Geophys. Res. Lett. , , submitted. Paper and Supplementary Materials in one pdf

 

http://www.atmos.washington.edu/~dennis/

 

ENSO blog entry:

 

http://www.climate.gov/news-features/blogs/enso/tropics-prime-suspect-behind-warm-cold-split-over-north-america-during

 

Another recent paper on this topic:

 

http://cliserv.jql.usu.edu/paper/CA_drought_final.pdf

 

Thanks for posting. Hartman's paper makes a lot of sense. If I am reading the second paper right, it appears that AGW contributes to the prolonged pre-+ENSO tropical forcing of the past two winters. 

[ORH_wxman]

Thanks for posting. Hartman's paper makes a lot of sense. If I am reading the second paper right, it appears that AGW contributes to the prolonged pre-+ENSO tropical forcing of the past two winters. 

 

 

It appears that since 1970, the observations showed a definite increase in variance of their "dipole" configuration of the large western ridge and coinciding eastern trough...which matched the models that showed an increase with GHGs...however, they noted that the observed variance was pretty high in the 1940-1960 timeframe as well, and then never really referenced that period again.

 

That lends to the argument that we probably need to study the pattern further to determine just how much GHG influence is really there.

[chubbs]

It appears that since 1970, the observations showed a definite increase in variance of their "dipole" configuration of the large western ridge and coinciding eastern trough...which matched the models that showed an increase with GHGs...however, they noted that the observed variance was pretty high in the 1940-1960 timeframe as well, and then never really referenced that period again.

 

That lends to the argument that we probably need to study the pattern further to determine just how much GHG influence is really there.

Agree that AGW role is uncertain and more study is needed. While the source of the forcing the past couple of winters can be linked to the tropics, its not clear what triggers the tropical forcing and why it has been so persistent. We seem to be moving through this ENSO cycle at a very slow pace.