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Messages - crandles

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1
Consequences / Re: North Atlantic Ocean Currents
« on: July 19, 2018, 04:56:19 PM »
https://www.bbc.co.uk/news/science-environment-44875508

Quote
Slowing Gulf Stream current to boost warming for 20 years

Thats different interpretation and it is in Nature:

https://www.nature.com/articles/s41586-018-0320-y

Quote
Global surface warming enhanced by weak Atlantic overturning circulation

Quote
Evidence from palaeoclimatology suggests that abrupt Northern Hemisphere cold events are linked to weakening of the Atlantic Meridional Overturning Circulation (AMOC)1, potentially by excess inputs of fresh water2. But these insights—often derived from model runs under preindustrial conditions—may not apply to the modern era with our rapid emissions of greenhouse gases. If they do, then a weakened AMOC, as in 1975–1998, should have led to Northern Hemisphere cooling. Here we show that, instead, the AMOC minimum was a period of rapid surface warming. More generally, in the presence of greenhouse-gas heating, the AMOC’s dominant role changed from transporting surface heat northwards, warming Europe and North America, to storing heat in the deeper Atlantic, buffering surface warming for the planet as a whole. During an accelerating phase from the mid-1990s to the early 2000s, the AMOC stored about half of excess heat globally, contributing to the global-warming slowdown. By contrast, since mooring observations began3–5 in 2004, the AMOC and oceanic heat uptake have weakened. Our results, based on several independent indices, show that AMOC changes since the 1940s are best explained by multidecadal variability6, rather than an anthropogenically forced trend. Leading indicators in the subpolar North Atlantic today suggest that the current AMOC decline is ending. We expect a prolonged AMOC minimum, probably lasting about two decades. If prior patterns hold, the resulting low levels of oceanic heat uptake will manifest as a period of rapid global surface warming.

2
Consequences / Re: Global Surface Air Temperatures
« on: July 19, 2018, 04:52:25 PM »
Slowing Gulf Stream current to boost warming for 20 years

https://www.bbc.co.uk/news/science-environment-44875508

3
The rest / Re: Mueller Investigation & Cohen Investigation
« on: July 19, 2018, 03:16:25 PM »
For your information:

Title: "Bookmaker increases chances of Trump being impeached after Putin summit"

http://thehill.com/blogs/in-the-know/in-the-know/397431-bookmaker-increases-odds-of-trump-being-impeached-after-trump-putin-summit

Extract: "Paddy Power increased the likelihood of Trump being impeached on Tuesday from 8-1 to 2-1, according to Yahoo News. The news outlet first reported that the betting company also increased the likelihood of Trump being impeached this year, from 12-1 to 8-1."

Neven wants to bet at these rubbish odds? huh?

Intrade offers better than 5/2 on Trump leaving office during first term and 13:1 on leaving office this year.

Leaving office through ill health would lead to bet paying out at intrade which makes discrepancy in odds worse, but not sure about any delay between being impeached and leaving office perhaps explaining some of the difference.

Sounds like Paddy power have received large bets and don't want more money placed on those bets.

Don't think intrade takes bettors from Austria either.

4
Consequences / Re: Global Surface Air Temperatures
« on: July 19, 2018, 02:40:04 PM »

eg arctic is 430 ppm and mid canada is 377 ppm - Is that right?

seems unlikely. Hope this graph displays but East Trout Lake, Saskatchewan, Canada latest reading about 395 and lowest reading for last two years about 392 and 390.



Alert around 415 but likely to have dropped rapidly from last reading shown to today:

5
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 12, 2018, 07:47:27 PM »

So let's change the regression formula so that it tries to predict the "June-area minus Sept-extent" variable instead of "Sept-extent" in absolute numbers.

That's mathematically meaningless.  All you're doing is including area as one of your parameters while pretending you aren't.

I don't believe it is. (Though I am not enough of a expert to be sure.)

This is targeting a different metric. With area as a parameter it gets fine tuned as to how much weight is given to this parameter. That isn't happening with setting a different target like that.

Above I suggested using ( Ice Area + 0.5(Extent-area) + 0.25(Land snow) ).
If that was fine tuned to something like ( Ice Area + 0.53(Extent-area) + 0.29(Land snow) ) then this would still be 3 parameters. However if the 0.5 and 0.25 are fixed and come from something objective before you start your analysis, such that it can only be tuned in one way by the weighting the linear regression applies then I suggest it is only one parameter.

Proportion of horizontal directions that heat could travel in and reach sea ice is what is immediately occurring to me with this.

6
Half of young people in the UK would like to own an electric car – compared with just a quarter of their parents, a survey suggests.

https://www.bbc.co.uk/news/science-environment-44798135

7
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 12, 2018, 01:37:20 PM »
Is it possible to approximate the energy input down to one variable something like

( Ice Area + 0.5(Extent-area) + 0.25(Land snow) )

then use CO2 or time as a second variable?

8
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 12, 2018, 12:37:14 PM »
I have little to offer here, but the 'unphysical' time variable can be replace, I suspect, with the very physical CO2 or 'CO2e in the Arctic'. (Do we even know what it is? Does it matter if it's rate of increase is different from Mona Loa?)

Thanks Tor. I think crandles also made the link to CO2.
Now, there is little doubt in my mind that CO2 is ultimately the driver of Arctic sea ice decline, but it is very hard to prove this scientifically.

A statistician can probably explain this much better detail than I can, but if you have two variables which both correlate well with Arctic sea ice decline, then how do you know which one is the cause of the decline ? And how do we know if one variable is caused by the other ?

So what I am trying to do clarify one step in this process : to look at variables that we KNOW affect the energy input into the Arctic because the albedo changes, and I found out that these variables correlate very well with the observed sea ice decline (especially land snow cover and sea ice area).

If we can somehow find evidence that land snow cover and June sea ice area are going down because of CO2 increases, then we may finally close the link to CO2 as a driver of Arctic sea ice loss.

Thanks for continuing the discussion.

What you want is not two variables that do the same thing, but an extra variable that might explain some of the wriggles that your other variables do not explain.

One approach might be: After choosing best variable, work out unexplained changes and look for next variable that best correlates with that. However, this doesn't guarantee you will find the best combination. An alternative, brute force try everything might find better correlation but risks overfitting effect - ie if you try enough spurious relationships and you will find one that appears to work well but is actually just spurious. Sticking with physically linked variables does seem like a good plan.

Ice Area and land snow do some of the area, albedo and energy input effects but there is little about thickness of the ice. CO2 affects rate of heat loss and hence the equilibrium thickness of FY ice. Yes this is not about energy input, but maybe energy input is not the only thing that matters, state and thickness of ice seems likely to also matter? Thus I tend to think CO2 is a sensible physically linked variable even if it is hard to show that.

It wouldn't surprise me greatly if it turned out CO2 level in Arctic didn't turn out to be better than time: the wriggles in CO2 have certain delay to ENSO and ENSO doesn't seem well correlated with arctic sea ice. It could easily be that there are ocean heat effects and CO2 effects of ENSO that have different effects with different delays such that it is hard to see any correlation effect. Also time may do more than just CO2 effects.

.

When you include 'snow+area+extent' in your table, is this really 'snow' + 'area' + '(extent-area)'? Should you show (extent-area) as a separate variable to extent?

.

Barrow has CO2 data from 1971. Alert is further north but only has data from 1985. Only found graph rather than monthly average table so far. CO2e may be better but I am less sure about the data being findable.

9
Arctic sea ice / Re: Land snow cover effect on sea ice
« on: July 09, 2018, 04:01:31 PM »
1) One could argue that the 'year' variable is indicative of the increase in greenhouse gases as you suggest. But we did not quantify the relation between greenhouse gas increase to sea ice loss yet, so this relation is kind of speculation at this point.

So, is it possible to try using either year or CO2 level in Arctic (during melting season? or annual average given that winter values may have affected thickness of ice?) ?

If 'year' works better than 'CO2 level' then the CO2 effect would appear to be just speculation and may well be grounds for sticking with physical variables.

If 'CO2 level' works better than 'year' as a parameter, then this may be a useful physical parameter. Note the 'may'; it may well still not be useful enough to add it as a parameter. Still, knowing this might be useful, if searching for a better set of parameters.

(Aiming to answer clearly seems a desirable feature of explanations, so thank you for taking the time you are to answer.)

The typical size of errors in forecast mode seems like what we should be trying to minimise and judge models by rather than hindcast standard errors?

It isn't easy to do this consistently across models if you exclude 80s where your model performs badly but other models might have taken different choices. So it seems difficult to compare models via error sizes? Your reasoning for excluding 80s seem sensible to me. However, for purpose of comparing model error sizes is there an argument for requiring all teams to use all data and report average/sd/RMSE/geometric mean forecast mode error over a defined set of years like 2000-current year?

10
Antarctica / Re: Rift in Larsen C
« on: July 09, 2018, 02:30:59 PM »
The 'monster' iceberg: What happened next?

https://www.bbc.co.uk/news/science-environment-44745734

11
2. Robotaxis are an annoying distraction.

Well people are entitled to their opinions, each to their own. FWIW my opinion is that robotaxis are interesting, potentially significant change and I like to hear what Bob and others have to say.

Posts saying what Bob is writing is rubbish without clearly pointing out what flaws they are attacking seem more like the annoying distraction to me.

12
Consequences / Re: Global Surface Air Temperatures
« on: June 23, 2018, 04:18:13 PM »
Might it be possible that these changes result in ever decreasing winter maxima, but little change in summer minima?

Why?

Surely shallow water freezes and unfreezes easily as not much depth of water gathering heat during summer. So why not maxima decreasing slightly more slowly than without extra water areas and similar for minima (warm land areas further away) so main difference is larger swings between maxima and minima?


I am not convinced about whether the sea level rise effect on the Arctic sea ice is significant for next couple of decades and after that, well there is so much that can happen that seems much more significant. Are we chasing an irrelevance here?

13
Policy and solutions / Re: Oil and Gas Issues
« on: June 23, 2018, 12:27:06 AM »
Robotaxis will operate for many more hours of the day than owner driver cars that spend most of day parked. As such they are bound to aim to minimise fuel cost so will be electric. Don't think any ICE cars are being developed to be self driving.

If they reduce price a lot compared to taxi, they will be used more. But are most of their miles going to be replacing self owned vehicle miles or is significant proportion just going to be instead of walking, busses and other public transport? Even if it is mainly the latter, if charged on renewables the use doesn't cause demand for ff. If it takes 10 robotaxis to remove 11 ICE cars that is still a saving on manufacture and materials to make the vehicles and thus a reduction in ff demand.

It seems quite possible to me that in some countries that have not reached high levels of car ownership that 10 robotaxis only reduces ICE cars by 9 or fewer. People become more mobile at less cost and this boosts the economy causing increase in demand for other goods. People in developed countries can hardly complain or try to prevent this.

14
Arctic sea ice / Re: How soon could we go ice free?
« on: June 21, 2018, 12:55:15 AM »
The test of whether a model is good or not is performed by seeing how it has been able to replicate historic conditions.  If it is good at that then it is a pretty good bet that it will do well going forward.

Actually, I have to disagree with that.  I have never seen any analysis of skill that indicated that hindcast models are better at predicting the future.  They can be better at predicting the past...

I have to disagree with that. Everybody believes models(/parameter sets) that do well in hindcast mode will in general be better in forecast mode. Very little has been done with this because it opens up all sorts of tricky issues. Which data obs do you use to say a model is good? Inevitable you want lots of data not just a single data item to be good but then how do you weight importance of each.

15
Arctic sea ice / Re: How soon could we go ice free?
« on: June 21, 2018, 12:48:46 AM »

The models keeping mean value above 1m km^2 by 2100, have absurdly high levels of ice at all times, way above what we actually have now. Obviously these models do their own thing and have not been adjusted to observations. If they were adjusted to realistic ice now by moving line up or down to match observation or applying a scaling factor, the projections arrived at would be much more consistent.

Yes.  Those are probably the models giving low weighted value to the observational data.  Hard to say if the observations will ever match those models again.

No, observational data haven't been given low weight. Observational data just is not a feature of how the model works at all.

16
Arctic sea ice / Re: How soon could we go ice free?
« on: June 20, 2018, 05:57:15 PM »
The mean value is still above 1.0 M km2 by 2100.

The models keeping mean value above 1m km^2 by 2100, have absurdly high levels of ice at all times, way above what we actually have now. Obviously these models do their own thing and have not been adjusted to observations. If they were adjusted to realistic ice now by moving line up or down to match observation or applying a scaling factor, the projections arrived at would be much more consistent.

17
Arctic sea ice / Re: How soon could we go ice free?
« on: June 20, 2018, 05:11:57 PM »
Maybe there are some but not many. If they are outliers perhaps we shouldn't pay too much attention to such outliers.

Overland and Wang 2013 paper "When will the summer Arctic be nearly sea ice free?" abstract includes

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/grl.50316

Quote
Three recent approaches to predictions in the scientific literature are as follows: (1) extrapolation of sea ice volume data, (2) assuming several more rapid loss events such as 2007 and 2012, and (3) climate model projections. Time horizons for a nearly sea ice‐free summer for these three approaches are roughly 2020 or earlier, 2030 ± 10 years, and 2040 or later.

Graph from paper:

18
Arctic sea ice / Re: How soon could we go ice free?
« on: June 20, 2018, 04:57:46 PM »
What models? Only extrapolations produced results like in 2020s or 2016 +/-3 years
Is not an extrapolation just a continuation of a model outside of the data range?

That is talking about extrapolating a model but the data extrapolations use actual data not model output.

It may well be possible to claim a data extrapolation is a model but it is a very simple naive model whereas a GCM type model has lots of physics built into it. Very different things even if you want to claim the term model can be applied to both.

19
Arctic sea ice / Re: How soon could we go ice free?
« on: June 20, 2018, 02:59:52 PM »
Obviously, the models predicted an ice-free Arctic several years ago were wrong, but what about those predicting ice-free in the 2020s, 2060s, never?

What models? Only extrapolations produced results like in 2020s or 2016 +/-3 years

20
Arctic sea ice / Re: How soon could we go ice free?
« on: June 19, 2018, 05:34:40 PM »
Are you saying that the worst case scenarios are not so, because we have not come close to experiencing them?

I think he is saying

'the worst case scenarios are not so, because we have already come close to experiencing worse.'

Quote
For SAT a large positive anomaly occurs between October and February after the initial perturbation, with a peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability.


doesn't seem to get to 11C but perhaps

does on some days in November.

This is comparing 2016 to 1958-2002 average whereas paper is presumably comparing year with ice removed to nearby years without ice removal.

Hmm. not exactly apples to apples comparison? Since both are large differences we shouldn't be surprised both show large anomalies, is partly my reaction.

Still at least there is some substance to the arguments rather than just saying Tietsche et al is 'dated'. Schroeder and Connolley reached similar conclusions to Tietsche et al.

Just saying Tietsche at al is rubbish isn't very robust/sufficiently complete, where are the rebuttal papers or where is something better?

21
Science / Re: 2018 Mauna Loa CO2 levels
« on: June 19, 2018, 01:15:21 PM »
.......
Until I see significant sustainable change in Fossil Fuel use and the economy wide drivers of AGW then my answer to the Poll above;

By 2023-2028 period, what will happen to emissions and airborne fraction?

Cannot be anything other than: 1. Emissions continue to rise at increased rate, airborne fraction increases

For the period 2018 to 2023, I would have to agree with emissions continue to rise at increased rate. Airborne fraction and later 2023-2028 period seems much less clear to me.

22
Consequences / Re: Global Surface Air Temperatures
« on: June 19, 2018, 12:56:34 PM »
Thanks wili.



Should the model lines be moved up or down so they go through 2017 temp (perhaps as adjusted for ENSO) in 2017?

Not sure that makes a huge difference to the date range range, so probably OK as is, but I thought I would mention it to see what others think.


I was a little surprised at the median sharply accelerating from about now: 0.7C in last 50 years to 3C in 66 years. I would expect acceleration over this period but more smoothly not so much jerk just about now. Is that likely to really happen soon or is it just random wiggle in median line that is not likely to happen?

23
Arctic sea ice / Re: How soon could we go ice free?
« on: June 18, 2018, 02:36:17 PM »
(Turning point probably isn't strictly correct term but discontinuity in rate of decline seems a bit of a mouthful.)

Are you referring to the jerk?

(speed is rate of change in distance over time.  Acceleration is rate of change in Speed. Jerk is rate of change in acceleration.  By analogy the same terms have been used for other basic derivatives.)

Jerk is nice and short rather than a mouthful. Is it a non smooth change in speed rather than a "rate of change in acceleration"?

Might work OK as long as not misinterpreted as a name calling insult. 'kink' in the graph may have different interpretation issue.

24
Arctic sea ice / Re: How soon could we go ice free?
« on: June 18, 2018, 01:16:15 PM »
Can we stick to 2005 as the point of inflection.

98 is more significant I think

With data to 2017, 1998 may well be a more significant turning point than the 2012 turning point. (There is only 5 years data after 2012 which might not be enough. Maybe with more data which one of these turning points is more significant might change.)

There is only one point of inflection which is 2005.

I am trying to say, please get the nomenclature right. Only 2005 (+/- a year or 2) is a point of inflection. Getting nomenclature right helps avoid talking at cross purposes.

Quote
noun: point of inflection
1. MATHEMATICS
a point of a curve at which a change in the direction of curvature occurs.

https://en.wikipedia.org/wiki/Inflection_point#/media/File:X_cubed_plot.svg

You might find two turning points at circa x=-1 and +1 but the curve only changes direction of curvature once ie there is only one inflection point at x=0

(Turning point probably isn't strictly correct term but discontinuity in rate of decline seems a bit of a mouthful.)

25
Arctic sea ice / Re: How soon could we go ice free?
« on: June 17, 2018, 12:57:26 PM »
Can we stick to 2005 as the point of inflection.

For piecewise linear fits there may well be discontinuities in the rate of decline at around 2000 and 2012. Can we call these turning points?

Then there is catastrophe theory and its state changes.

Catastrophe theory is discussed in the literature so shouldn't be dismissed. I admit the possibility but it doesn't seem very likely. Even if it is likely, is it useful? Or do we just end up concluding well something might happen at some time?

Is it likely? Weather is chaotic but generally climate is stable. Arctic sea ice seems to be showing slow steady changes. Do we have any evidence of chaotic / catastrophic behaviour?

So wrong to conclude there won't be catastrophic change but if no such evidence is it reasonable to conclude it is unlikely in the near term?

Maybe we don't need much possibility to judge we need more action on cc, but for the purpose of predicting what will happen in next few years to decades is low probability and low usefulness a reasonable conclusion?

26
Arctic sea ice / Re: How soon could we go ice free?
« on: June 17, 2018, 12:25:37 PM »
To me, the residuals look fairly random and have no obvious particular trend in residual size.

27
Arctic sea ice / Re: How soon could we go ice free?
« on: June 16, 2018, 04:00:09 PM »
... If the models show a slowdown in the rate of decline as zero ice is approached and also the data is tending to show this recently...

Which models are you referring to? I've never seen a physics-based model with good predictive ability on this trend. True, there are models that don't work well, e.g. for the IPCC studies. If the model can't find the recent trend then it's not much use for predicting future trends.

Why do you say the data is showing a slowdown recently? If I look back at the linear fit of #97 then the residuals are all over the place and I don't see that trend. Based on the second plot, I suspect a quadratic fit would also curve downwards rather than upwards.

Lots of models. There are lots of graphs like attached below, some with many more model runs on them.

>" good predictive ability on this trend."

Clearly not they are all over the place on level of ice and also the trend. While some don't have enough data to see, all the model runs where you can see the change in trend where ice approaches zero is for the trend to get less steep as zero ice is approached.

Do we throw out all evidence because they are all over the place wrt level and trend? Or, do we say yes not much good for level or trend, but it looks like they all agree on trend in slope as zero ice is approached? So don't use them where they are bad but do use them for what they are good at, ie suggesting the change in trend as zero ice is approached declines.

>"Why do you say the data is showing a slowdown recently?"

The 4 parameter gompertz fit has a single inflection point. Whether I use Sept or April, that inflection point occurs in 2005. We have 12 years data since that inflection point. If there was only ~6 or fewer years data since the inflection point, I would be inclined to the opinion that 4 parameters might be too many parameters and I was overfitting. So just random residuals in last few years was allowing a better fit by using too many parameters. However with 12 years data past the infection point, that is too much data led and seems to me to be indicative that the data is showing a decline in the rate of decline.

See 4 parameter gompertz fit at top of this page.

>"If we're looking for a physical reason for a slowdown then I would point to the existence of a 'sanctuary region' against the North side of the CAA and Greenland where the ice hasn't melted out in any year."

Certainly wouldn't disagree with that being one physical reason, but I think there are lots of others.

I would tend to add in albedo feedback to this explanation (as well as deep water). In areas where ice moves out of the area, melting and ice movement allows albedo to drop and more sunlight energy be absorbed and this obviously helps additional melting. In contrast where ice piles up against Greenland & CAA, ice tend to move into area. So rather than melting and movement of ice causing extra area to open up, movement tend to close up areas opened by melting so it is much harder to get albedo drops to assist the melting.


If the ice retreats to a smaller area, that relevant area receives less sunlight energy so less volume melts seems quite possible. I guess this is complicated by winds bringing warmer temperature air so it isn't clear whether this accelerates or decelerates the volume of melt so maybe we need to look to the data and/or models?

Then there is oft discussed failure of MYI to make it around Beaufort gyre leading to rapid collapse of MYI to much lower proportion of the ice over a few years, but once we are down to these lower levels there is more FYI which almost completely recoveres itself each winter.

Are the people on these forums thinking through these reasonings and rejecting them because they don't believe they are significant compared to positive feedbacks they believe in? Or are they just rejecting the reasonings because it is just not exciting or they want to see catastrophic decline in sea ice or .... ?


28
Arctic sea ice / Re: How soon could we go ice free?
« on: June 16, 2018, 03:10:37 PM »
What observation? That the basic data clearly indicates a poof? That's not iffy. That must be the base assumption. In my opinion, the "iffy" assumption is to use a 2 dimensional, enthalpy ignoring mechanism to determine the first ice free Arctic. Any model that uses a "slab of ice" to analyse the past and make projections for the future is missing the big picture.



I'm not making any assumption, I'm only looking at the linear trends and that's what they show.

"I'm only looking at the linear trends" is just another way of saying 'if the linear trend continues' and that is an assumption you are making even if you want to try and say you are not making any assumption. FWIW I think you are making yourself sound ridiculous by clearly contradicting yourself.

As Ned W said

Yes, I agree with crandles.  Currently, some ways of extrapolating the past data show volume reaching zero before extent reaches zero.  There are three possible implications of that:

(1) Extent loss could speed up to match volume
(2) Volume loss could slow down to match extent
(3) Both extent and volume could change to reach zero at some other point

For some reason, a lot of people around here simply assume that (1) is the only possible outcome.  That's wrong. 

We both think the other is making big iffy assumptions. I think I have made the point and attempted clarification enough times, time to agree to disagree.

29
Arctic sea ice / Re: How soon could we go ice free?
« on: June 16, 2018, 01:40:11 PM »
I didn't attack anyone.

Sorry if the word attack came across as implying acrimonious discussion.


I'm not making any assumption, I'm only looking at the linear trends and that's what they show.

I think the observation stands.

30
Arctic sea ice / Re: How soon could we go ice free?
« on: June 15, 2018, 05:45:38 PM »

Every time I see your 4 parameter gompertz fit curve it gives me a chuckle until I realize that you actually seem to believe that this is a potential reality going forward.

I see this assertion of future ice conditions without model or even realistic physical mechanism as a kind of magical thinking.  It would be akin to claiming that butterfly wings in the Amazon are driving sea ice variability and creating a curve to fit this idea.

Then I just figure you are trying to make a point about uncertainty and are just being contrary.

I do try to say every time that I don't literally believe the completely horizontal path extrapolation. I do believe in a continuing downwards path but rate of decline could well be getting a less steep as practically all the models show

>"without model or even realistic physical mechanism"

I see lots of people here doing this (i.e. ignoring models and not considering some physical mechanisms which I believe are realistic) whereas I believe I have considered the major physics involved regarding the slow transition that MYI doesn't get replaced quickly but FYI does essentially get almost completely replaced each year. I don't believe I can prove this is highly significant nor that it is insignificant from basic reasoning of the physics. But discussion of it is in the scientific literature suggesting it is likely to be significant and the data of the last 5 to 12 years seems to be coming down on the side of a slowdown in the rate of decline.

If the models show a slowdown in the rate of decline as zero ice is approached and also the data is tending to show this recently, then assuming the rate will be steady or increase needs some substantial explanation. Without such substantial explanation, the default assumption should be of a declining rate of decline.

I see lots of people here just not wanting to see this.

31
Arctic sea ice / Re: How soon could we go ice free?
« on: June 15, 2018, 05:03:54 PM »
These three graphs from Arctische Penguin really say it all. Linear trend shows 0 volume in 2033, exponential in 2023 while gomperz curve seems to trend to the mid thirties. So a ballpark guess of 2025-2035 ?

But why those three? There are any number of curves that fit the data and then do different things.

A 4 parameter gompertz fit is shown below and goes flat pretty much immediately and never gets down to 1000km^3 let alone 0. I don't believe it should or will go flat, as GW continues. But clearly 3 parameter gompertz hitting 1000 km^3 in 2025 is not the most conservative possibility so your 3 graphs don't show the full range of possibilities.

32
Arctic sea ice / Re: How soon could we go ice free?
« on: June 15, 2018, 04:49:17 PM »
Ken Feldman your assumptions are not correct.

 First you should use volume, not extent. Volume hits 0 much sooner than extent, but they must hit 0 at the same time. That means a poof.
...
I used a linear trend line using the years 2007-2018 and extended it until 2035.


If the winter degradation continues as it has steadily for decades,

Just an observation: you attack others for their assumptions being incorrect, then immediately draw a wrong conclusion and use your own big iffy assumptions.

Just because extent and volume must hit zero does not mean there has to be a poof. It is quite possible for both extent and volume to slow down their rate of decline so they both reach zero at the same time which is well after the linear trends.

I can follow what you are saying as an explanation of what you think is the situation but with big iffy assumptions, that doesn't make it correct.


33

These are the September averages for the last 13 years (in millions km2, found here):

    2005: 5.50

The URL doesn't link, missing a : after ftp. Experimenting to see if it is fixable. Nope forum seems to insist on putting http:// first and removing the : after ftp

34
Science / Re: 2018 Mauna Loa CO2 levels
« on: June 07, 2018, 02:00:10 PM »
Peak month CO2 at Mauna Loa:

Quote
May 2018:       411.25 ppm
May 2017:       409.65 ppm

Up 1.6 ppm

35
Policy and solutions / Re: The Hyperloop
« on: June 06, 2018, 01:09:55 AM »
Elon is a genius engineer? 

I don't know about that.

Vertical powered rocket landings not enough to convince you? (He was chief designer for Falcon 1, perhaps by time of falcon 9 more supervising larger team but spends quite a bit of his time on design.)

36
Arctic sea ice / Re: Latest PIOMAS update (May mid-monthly update)
« on: May 31, 2018, 03:58:03 PM »
so I'm not sure what Tenney's on about.

Glad I am not the only one.  I did wonder if we were just talking past each other.


How are you ruling out slow rate of decline now the MYI is down to minimal levels (and FYI replaces itself each winter) and some natural variability?

I am not taking your point, crandles.  I have been saying for many years that PIOMAS cannot be right, that the increases in volume from the low must be due to problems with the algorithms.  Of course, there might have been some increase due to natural variation, but the consistent increase over several years cannot have been right, IMO. Tell me how the water-logged slush can be measured in the same way that a similar section of tightly compressed multi-year ice can?  Further, slushy ice cannot be same temperature.  And, there is the stuff that resembles swiss cheese.  How is that being handled?

This seems based on assuming a rapid rate of decline and therefore does not appear to address the issue at hand of how to rule out slow rate of decline and some natural variability.

37
Arctic sea ice / Re: Latest PIOMAS update (May mid-monthly update)
« on: May 31, 2018, 12:30:13 AM »
I do not agree that common sense would tell us that sea ice volume would go consistently up for 5 straight years when we know that the temperatures in the Arctic have also been going up.  Is it also common sense that PIOMAS shows the sea ice increasing over the past few months?  In any case, by the end of this summer, I think we'll have some answers.

http://psc.apl.uw.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.1.png




Looking for 5 years of consistent gains. May 2011 to May 2015 looks like it does so and I don't see many if any other occurences.

If the trend is flat, which I agree I don't think it is, the chances of this happening is 1 in 16. Given the number of potential start points in above graph (about 33*12 = 396) so should happen about 25 times if trends were flat and changes not correlated. Occurring ~once instead of 25 times is not a sign of upward trend but of downward trends and a bit of natural variability.

38
Arctic sea ice / Re: Arctic sea ice minimum early prediction
« on: May 30, 2018, 03:26:24 PM »
Like I asked above, and how I always vote.  Is there any good reason to vote anything other than the lowest?

Of course there is:

If too many people just go for the lowest and this turns out not to be the case, then this is setting up a 'those environmentalists are always crying wolf' defence for ff companies to continue not to act. Why hand them such a defence?

39
Arctic sea ice / Re: Latest PIOMAS update (May mid-monthly update)
« on: May 27, 2018, 12:26:08 PM »
Re: PIOMAS

The high volume for 2009 and 2015 are nearly the same on the graph.

Doesn't stand to reason.

How are you ruling out slow rate of decline now the MYI is down to minimal levels (and FYI replaces itself each winter) and some natural variability?

[Or does this sound like cognitive dissonance: I was expecting a crash and it hasn't happened but I don't want to change my views and admit the rapid Arctic ice free sceptics were right.]

40
Arctic sea ice / Re: "Stupid" Questions :o
« on: May 24, 2018, 02:31:08 PM »
And right now there's no night in the Arctic.  :)

Don't get any melt ponding in winter/night in Arctic either  ;)

41
Arctic sea ice / Re: "Stupid" Questions :o
« on: May 24, 2018, 12:54:25 PM »
So when the pressures higher is the temp higher simply as a result of the pressure, say 1030 being 3% warmer for instance?

No, high pressure generally means clear sky rather than cloudy so if it is daytime it tends to be warmer but at night colder.

42
Arctic sea ice / Re: "Stupid" Questions :o
« on: May 24, 2018, 11:32:10 AM »

Quote
4) Can high pressure + slightly below freezing temps still produce melt ponding, or do temps need to be above freezing?

I believe it can. And humidity also plays a role.

Yes, to attempt further explanation, it is the heat balance that matters not the temperature. Melt water can increase with (air) temp below zero: Due to albedo difference the water accepts more solar heat than ice not covered with water, that heat has to find a heat sink rather than raise the temp above zero but that is entirely possible as it gets used melting ice. You might object to this as patches of water have to get above zero to melt the ice, but the more general air temperature over large area can stay below zero.

Yes, humidity does play a role with latent heat being released where it condenses and absorbed where it evaporates/sublimates.

(I think)

43
Science / Re: 2018 Mauna Loa CO2 levels
« on: May 17, 2018, 04:58:11 PM »
May 14:      412.45 ppm

Probably a record daily reading at MLO

Did that a little up thread:
412.63 26th April 2017
still retains record.

44
Science / Re: 2018 Mauna Loa CO2 levels
« on: May 17, 2018, 03:31:30 PM »
April 2018:       410.26 ppm

Record high monthly value and first over 410.

45
The forum / Re: Comments/posts can be liked now
« on: May 12, 2018, 04:23:29 PM »
That's something I can fix, crandles! And I'm also seeing the Like button now.

So, it's back to square one.
Yes fixed.  :)

46
The forum / Re: Comments/posts can be liked now
« on: May 12, 2018, 02:24:58 PM »
Tried to like a post (link to do so visible) but now a pop up window says only people who have received 5 likes can like posts.

47
Policy and solutions / Re: Batteries: Today's Energy Solution
« on: May 11, 2018, 09:16:45 PM »
Well, they took 55% of 10%, which means around 5% of previous cost with 2 % of previous capacity. This looks ok, just that the others only share 5% of previous incomes.

If the savings are $30 million then the cost has fallen from ~$33 million to ~$3million and Tesla battery takes just 55% of that so $1.65 million. So $1 million in a few days and has only received $0.65 million in the rest of the six months. Looks like the $1 million is a one off and not being repeated frequently if at all. Is $0.65 million over 6 months sufficient to be profitable?

Or maybe there is other income besides that $1.65 million?

Maybe it is a loss leader period demonstrating what it can do before threatening to turn it off unless they are paid 2 or 3 times as much. $30 million cost or 3* $1.65 million isn't a difficult choice.

48
Policy and solutions / Re: The Hyperloop
« on: May 09, 2018, 12:17:15 AM »
Quote
79.4 kWh

At the wholesale rate of $0.06/kWh that's less than a nickel.

Less than a nickel or less than 5 dollars?

49
Science / Re: 2018 Mauna Loa CO2 levels
« on: May 07, 2018, 02:56:02 PM »
Quake was May 4th
Eruption: 2 May 2018 news was saying: "A Hawaiian volcano could be set to erupt after hundreds of earthquakes and the collapse of a crater floor."
Also presumably later "Hundreds of residents were told to flee as lava eruptions occurred at the Big Island volcano."

No readings on or since May 4th.

No idea if readings before quake and eruption might be affected. Nor if May 3rd reading of 409.23 might be affected. Seems quite low while volcanos' do give off CO2 so maybe not affected?

50
Science / Re: 2018 Mauna Loa CO2 levels
« on: May 07, 2018, 12:51:42 PM »
Something is clearly wrong with products at ESRL during the last month. Is there other co2 stations that produce recent 2018 data for CO2 readings for their stations with archived historical records for comparison like at  Mauna Loa on ESRL? I have searched already with no luck so far. thanks

https://www.esrl.noaa.gov/gmd/dv/iadv/
Provides a choice of sites

eg Tutuila, American Samoa


(bit further south than Mauna Loa probably altering the pattern a little)

April 2017 saw swings from under 407 to over 412.6 so I am not sure that last month isn't reasonably normal. (Err well 6 consecutive day gap without any values is not normal but swings in values don't seem untypical for time of year.)

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