The Impact of "Small" Volcanic Eruptions on Earth's Climate 11

[Maui]

These "small" volcanic eruptions are being viewed by some scientists as potentially having a greater influence on earth's climate than was previously believed:

http://www.rdmag.com/news/2015/01/s...?et_cid=4359172&et_rid=407330416&location=top

Please do not allow the vitriolic verbal pyrotechnics of your fellow contributors overshadow the points that you are attempting to make in your replies.

Maui

 

[IRstuff]

and the ~$1B from the Koch bros to be spent for the next election isn't to generate artificial bias?

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[cranky108]

The Koch bros live here. Russian oil companies don't. Still you have a point, but not the same point I was making.

My issue is our political figures are moved by the people who elected them. And many of the people who elected them are still in the follow the bouncing ball stage of life (sadly).

I guess both the Koch bros and the Russian oil companies are both trying to sell about the same product, and are both profit based.

Back to the relevent. So if small volcanic erruptions can make a difference in the climate, and those erruptions are semi-random, what value is having a model if it is semi-incorrect?
Has anyone established a periodsity to volcanic erruptions, or base lined the typical amount of discharge? (I assume the goverment has funded something like that).

This goes back to earth science, and might be tied to the rate of energy disapation of the hot core over time. And then I question are we doing anything that will speed up or slow down this rate of energy disapation.

 

[beej67]

The interaction between aerosols and clouds is a heavily researched topic.

Sure is. How the albedo of increased cloud cover dampens the supposed feedback effects of increased water vapor in the atmosphere is definitely not well studied.



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[rconnor]

Cranky,

Volcanic eruptions are unpredictable but only effect climate for ~2 years. They have no impact on long-term climate (unless you had a massive one that destabilizes the climate) and therefore have no likely influence on long-term model projections, regardless of whether they are represented perfectly or not in models.

So why is this research important? For starters, it helps improve our understanding of atmospheric physics, which is a positive thing. However, the major reason this research is relevant is (sadly) because some people keep going off that the “pause” proves that our climate isn’t as sensitive to CO2 than we originally thought and that’s why models are running hot. This research demonstrates that part of the discrepancy between model and observed temperature is that models don’t account for the (short-term) impact of smaller volcanoes. Combine this with the fact that the “pause” has been in an El Nino dominated period and we find that most of the discrepancy is due to internal variability which suggests that we have not over estimated climate sensitivity.

wrt “the rate of energy dissipation of the hot core” – the geothermal flux is very steady and far too weak to explain the recent rise in global temperature. As I said in another thread:

Estimated surface heat flux = 47 +/- 2 TW, equivalent to 0.09 W/m^2. This is much smaller than the estimated 0.58 +/- 0.15 W/m^2 energy imbalance (using a very conservative value, by the way) and rather insignificant when compared to solar radiation at 341.3 W/m^2. Furthermore, the surface heat flux is very consistent, even over geological time frames, let alone over the past 50 years. Even if the surface heat flux went from 0 to 0.09 in the last 50 years, which it of course did not, it would be too small to account for the changes in climate noted.

(Stein and Stein, 1992 and Davies and Davies, 2010)

 

[rconnor]

Cloud Feedback Uncertainly != Large Negative Forcing
There is uncertainty in cloud feedback. Does this mean that cloud feedback will be strongly negative, negating the positive forcing of CO2? No, you cannot conclude that at all. Cloud feedback could be positive, amplifying the positive forcing of CO2, and the research seems to suggest this is more likely (see below). Furthermore, the current scientific understanding takes into account the uncertainty in cloud feedbacks and it is the largest contributor to the large range of model results. So they don’t shy away from the uncertainty, they’ve incorporated it and are looking to reduce it. As I said…

Where possible, you attempt to erroneously conflate "uncertainty" with "my idea is right and the current scientific understanding is wrong"

What the Science Says
Your under-research hypthothesis that “more water vapour=more clouds=greater albedo=cooling” demonstrates your overly simplified understanding of the science. Cloud feedbacks could be negative, if low-level clouds increase and high-level clouds decrease. Cloud feedbacks could be positive, if low-level clouds decrease and high-level clouds increase. The issue is: will anthropogenic climate change lead to more low-level clouds (cooling) or high-level clouds (warming)?

The bulk of the research suggests that the net cloud feedback will likely be positive and very unlikely be largely negative. Such papers include Clement et al 2009, Lauer et al 2010 and Dessler 2010. Sherwood et al 2014 compared the observed pattern of convective mixing of water vapour with how models represent this mechanism. They found that models that agreed with observations had positive cloud feedbacks and lead to higher values of climate sensitivity (ECS >3 deg C). Models that did not agree with observations had more negative cloud feedbacks and lead to lower climate sensitivity.

”Iris Effect” and Large Negative Cloud Feedback Papers
Richard Lindzen continually promotes low climate sensitivity based off a strongly negative cloud feedback (Chou & Lindzen 2005, Lindzen & Chou 2009, Lindzen & Choi 2011). This is part of his “Iris Effect” hypothesis (Lindzen et al. 2001). However, this has been largely and continually discredited (Del Genio & Kovari 2002, Lin et al 2002, Hartmann & Michelsen 2002 and Chamber, Lin & Young 2002). Furthermore, each of his low sensitivity papers have been demonstrated to be flawed as well (Rapp et al 2005, Wong et al 2006, Trenberth & Fasullo 2009, Chung et al. 2010, Trenberth et al. 2010, Murphy 2010, Dessler 2013). It’s really a bit of a joke nowadays.

So while there remains a high degree of uncertainty in the exact impact of cloud feedback, the research certainly works against the conclusion that it is strongly negative.

 

[cranky108]

So you admit some uncertainty?

What I am hearing is we can change other things than just carbon to change the feedback loop everyone is concerned about. That there are other possible ends than the total end of carbon fuels?

 

[IRstuff]

Rconnor,

Rarely do I see you in an outright error. Can you explain your value of 341.3 W/m^2 for solar radiation? The MIL-HDBK-310 value is 1120 W/m^2 and the extra-atmospheric solar constant is 1366 W/m^2 per

http://www.britannica.com/EBchecked/topic/552889/solar-constant

and

http://www.ips.gov.au/Category/Educ...olar Activity/General Info/Solar_Constant.pdf

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[rconnor]

1366 W/m^2 is the total value. Only part of the planet receives solar energy at any given time and so you need to average out the value over the entire planet. The standard average value used is 341.3 W/m^2 (at TOA). Using 1366 W/m^2 would actually be inaccurate when doing any sort of energy budget analysis, the number to use is 341.3 W/m^2.

http://www.acs.org/content/acs/en/climatescience/enerybalance/energyfromsun.html

 

[rconnor]

sorry link broke (that's what I get for being lazy and not embedding it!). Here it is again.

 

[IRstuff]

OK, thanks for the clarification. I guess it just wasn't clear from the context that it was averaged over the entire Earth's surface.

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[beej67]

rconnor,

I hear you saying the wide variation in climate sensitivity estimates in IPCC5 is largely because each model is treating clouds differently. And then I note that the climate sensitivity estimates in IPCC5 were more divergent than prior IPCC releases. And I think that's all I really need to say.

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[rconnor]

Beej67,

By “sensitivity estimates in IPCC5 were more divergent than prior IPCC releases” do you mean them going from 2-4.5 deg C to 1.5-4.5 deg C? That had to do with energy budget models (Otto et al 2013 and Lewis 2013), not cloud feedbacks. At the time, these studies had just been released and the criticisms really had not come in. I disagree with the IPCC lowering the range (given the research at the time though, it was the conservative thing to do) and I have no doubt that the research since AR5 (Cowtan and Way 2013, Durack et al 2014, Shindell 2014, Kummer & Dessler 2014, Andrews et al 2014, etc.) will allow the IPCC to put the range back up to 2-4.5 deg C. AR5 even made specific note that more scrutiny was required of the new energy budget model techniques:

…this change reflects the evidence from new studies of observed temperature change, using the extended records in atmosphere and ocean. These studies suggest a best fit to the observed surface and ocean warming for ECS values in the lower part of the likely range. Note that these studies are not purely observational, because they require an estimate of the response to radiative forcing from models. In addition, the uncertainty in ocean heat uptake remains substantial. Accounting for short term variability in simple models remains challenging, and it is important not to give undue weight to any short time period that might be strongly affected by internal variability

As I stated, the change had nothing to do with cloud feedback research and does nothing to defend your point-of-view on that matter. If you’d randomly like to start talking about energy budget model techniques, then I suggest you post on my thread regarding climate sensitivity.

But back to the subject at hand (well actually you derailed the conversation on volcanoes and started talking about clouds but no matter):
[ul][li]You guessed that cloud feedback had to be negative due to albedo – That is wrong. Low-level clouds do increase albedo and result in cooling but high-level clouds block outgoing radiation and lead to warming.[/li]
[li]You guessed that cloud feedback was going to be so strongly negative that it would counter act all positive forcings – That is wrong. The most likely value for cloud feedbacks is slightly positive. It’s possible it could be negative but it is very unlikely to be strongly negative.[/li]
[li]You guessed that climate scientists and the IPCC are ignoring the possibility of negative cloud feedback – That is wrong. The IPCC includes research that concludes a negative cloud feedback (ex. Lindzen & Choi 2011). The uncertainty of cloud feedbacks is built into models.[/li]
[li]You guessed that observations probably support a negative cloud feedback – That is wrong. Sherwood et al 2014 compared observations to the way models represent convective mixing. They concluded that high sensitivity models with positive cloud feedbacks matched observations and low sensitivity models with negative cloud feedbacks did not.[/li][/ul]

 

[beej67]

So what, in your opinion, is wrong with the models, rconnor? Do you think that the volcano thing is the key to unlocking what's wrong with our climate models, or do you think something else is at fault?

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[rconnor]

So what, in your opinion, is wrong with the models, rconnor? Do you think that the volcano thing is the key to unlocking what's wrong with our climate models, or do you think something else is at fault?

Re-read my post here at 4 Apr 14 17:45. In a nutshell, the bulk of the variance between models and observations can be explained by:
- ENSO (Kosaka and Xie 2013, England et al 2014, Foster and Rahmstorf 2011 and many others)
- Lack of coverage of arctic warming in some data sets (Cowtan and Way 2013)
- Underestimating the amount of anthropogenic aerosols
- Underestimating the short term impact of smaller volcanic activity (Santer et al 2014, Ridley et al 2014)
- Required update to OHC (Durack et al 2014)
- The fact that models were never intended on matching short-term fluctuations perfectly

When you account for these factors (which are mainly notable over the short-term but not the long-term) models match observations very well (Schmidt et al 2014, Huber and Knutti 2014). None of these factors suggest that climate sensitivity is too high in models. None of these factors suggest that we are greatly underestimating a negative feedback or greatly overestimating a positive feedback. And so there appears very little to no evidence that the recent variances between models and observations severely threatens the core of our understanding of climate science.

(Regarding the image, GCM’s aim to calculate surface temperature. Balloons and Satellites measure the mid troposphere temperature. No one that knows what they’re talking about and is trying to be honest would compare the two. It’s apples and oranges or, at best, red delicious and granny smith.

Averaging model runs, without showing the range, is meaningless. The average isn’t the “best guess”. Models incorporate the uncertainty of various factors; some are stochastic (volcanoes and ENSO), others we don’t know with 100% certainty (cloud feedbacks). So, over the short term, models that get the short-term variability right (i.e. predict the right ENSO state) will be accurate and ones that don't will not. The average might mean more over the long-term but is rather meaningless in the short-term. No one that knows what they’re talking about and is trying to be honest would represent short-term model predictions as a single, averaged line.

The graph, which you didn’t source (but no worries, I know it was from CATO), is meaningless but purposefully designed to get a mistaken point across. Completely (yet unsurprising) garbage from a garbage institution.)

 

[beej67]

Did every single model overestimate global warming over the past 15 years, or did any of them actually get it right?

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[rconnor]

Risbey et al 2014 found that models that matched ENSO conditions with the actual observed states were very accurate at reproducing the observed temperature trend.

 

[rconnor]

Oh, and I just caught wind of this paper today – Marotzke & Forster 2015. It is basically a repeat of what I just said.

The claim that climate models systematically overestimate the response to radiative forcing from increasing greenhouse gas concentrations therefore seems to be unfounded.

 

[rb1957]

@rconnor,

but i thought you repeatedly posted that ENSO are isolated events and not significant to the long term climate trend ?

another day in paradise, or is paradise one day closer ?

 

[rconnor]

Yes, and what contradicts that?

 

[rb1957]

"Yes, and what contradicts that?" ... your previous post ... "found that models that matched ENSO conditions with the actual observed states were very accurate at reproducing the observed temperature trend." isn't that saying that models that included ENSO produced better matching ? doesn't if follow then that the forecasts of these models include the effects of future ENSO events ? so that ENSO events are important for the long term climate trend ?

For me, if ENSO events are irrelevant to long term climate (something that surprises me) then the models should not try to match the historical data and should predict a mean trend though these oscillations. that would, in my mind, pose difficulties in choosing data to calibrate the model to (choosing data that are not affected by these events).

another day in paradise, or is paradise one day closer ?