Alert readers will have noticed the fewer-than-normal postings over the last couple of weeks. This is related mostly to pressures associated with real work (remember that we do have day jobs). In my case, it is because of the preparations for the next IPCC assessment and the need for our group to have a functioning and reasonably realistic climate model with which to start the new round of simulations. These all need to be up and running very quickly if we are going to make the early 2010 deadlines.
But, to be frank, there has been another reason. When we started this blog, there was a lot of ground to cover – how climate models worked, the difference between short term noise and long term signal, how the carbon cycle worked, connections between climate change and air quality, aerosol effects, the relevance of paleo-climate, the nature of rapid climate change etc. These things were/are fun to talk about and it was/is easy for us to share our enthusiasm for the science and, more importantly, the scientific process.
However, recently there has been more of a sense that the issues being discussed (in the media or online) have a bit of a groundhog day quality to them. The same nonsense, the same logical fallacies, the same confusions – all seem to be endlessly repeated. The same strawmen are being constructed and demolished as if they were part of a make-work scheme for the building industry attached to the stimulus proposal. Indeed, the enthusiastic recycling of talking points long thought to have been dead and buried has been given a huge boost by the publication of a new book by Ian Plimer who seems to have been collecting them for years. Given the number of simply made–up ‘facts’ in that tome, one soon realises that the concept of an objective reality against which one should measure claims and judge arguments is not something that is universally shared. This is troubling – and although there is certainly a role for some to point out the incoherence of such arguments (which in that case Tim Lambert and Ian Enting are doing very well), it isn’t something that requires much in the way of physical understanding or scientific background. (As an aside this is a good video description of the now-classic Dunning and Kruger papers on how the people who are most wrong are the least able to perceive it).
The Onion had a great piece last week that encapsulates the trajectory of these discussions very well. This will of course be familiar to anyone who has followed a comment thread too far into the weeds, and is one of the main reasons why people with actual, constructive things to add to a discourse get discouraged from wading into wikipedia, blogs or the media. One has to hope that there is the possibility of progress before one engages.
However there is still cause to engage – not out of the hope that the people who make idiotic statements can be educated – but because bystanders deserve to know where better information can be found. Still, it can sometimes be hard to find the enthusiasm. A case in point is a 100+ comment thread criticising my recent book in which it was clear that not a single critic had read a word of it (you can find the thread easily enough if you need to – it’s too stupid to link to). Not only had no-one read it, none of the commenters even seemed to think they needed to – most found it easier to imagine what was contained within and criticise that instead. It is vaguely amusing in a somewhat uncomfortable way.
Communicating with people who won’t open the book, read the blog post or watch the program because they already ‘know’ what must be in it, is tough and probably not worth one’s time. But communication in general is worthwhile and finding ways to get even a few people to turn the page and allow themselves to be engaged by what is actually a fantastic human and scientific story, is something worth a lot of our time.
Along those lines, Randy Olson (a scientist-turned-filmmaker-and-author) has a new book coming out called “Don’t Be Such a Scientist: Talking Substance in an Age of Style” which could potentially be a useful addition to that discussion. There is a nice post over at Chris Mooney’s blog here, though read Bob Grumbine’s comments as well. (For those of you unfamiliar the Bob’s name, he was one of the stalwarts of the Usenet sci.environment discussions back in the ‘old’ days, along with Michael Tobis, Eli Rabett and our own William Connolley. He too has his own blog now).
All of this is really just an introduction to these questions: What is it that you feel needs more explaining? What interesting bits of the science would you like to know more about? Is there really anything new under the contrarian sun that needs addressing? Let us know in the comments and we’ll take a look. Thanks.
Gavin, you commented on my 936 that ended with these final 3 paragraphs:
[I wrote; cooling is a] …consequence of evaporation, regardless of any of the many amb ient conditions that can promote it.
Thus, if the current E-T HEAT loss from the surface is ~46% of the terrestrial budget, and E-T were to increase by say 1%, then there would be an increased cooling effect of the order of 0.46% as a consequence of E-T alone.
What the net thermal global outcomes might be when added to that of increased water vapour and clouds from GW, etc, is something else, and cannot be scientifically used to deny the cooling effect of E-T
Well actually, the fuller topic remains pregnant. The main point behind my original question, to ALL, appears to have been lost, maybe because of semantics conflicts, and I would say nit-picking by some. Recapping and breaking it down into the fundamentals in two parts:
~~~1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
E-T is the fundamental driver of water content in the atmosphere, and, in one of its three phases, e.g. vapour, it has been shown to have a positive feedback, which leads to increased “climate sensitivity” to CO2. (bad news)
However, for this feedback to take place, it follows that the fundamental increasing source is E-T. Increasing E-T as a response to global warming is BTW illustrated by the fact, that in the tropics, atmospheric water content is high, whereas at colder latitudes, it is lower, and very low in polar regions. (and per some simple physics)
It is a consequence of E-T, that there is a cooling effect, which you agree is an important energy flux. Thus, this has the effect of reducing climate sensitivity, that is opposite to that of water vapour. (good news)
~~~2~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
According to the IPCC/Trenberth, E-T results in ~46% of the heat loss from the surface in the terrestrial budget. This compares with only ~15% via EMR that is absorbed by the atmosphere. It is within this smaller 15% area that the popular feedbacks, (including secondary non-radiative albedo in clouds), are very widely discussed.
On the other hand, the thumping great 46% area of cooling, (important energy flux you agree), has apparently much lesser attention.
I asked “everyone” if they knew of any discussion on it.
It seems no; that no one is talking openly about this major “thermostatic” cooling effect! It remains a pregnant issue.
[Response: Your case is flawed in a number of respects. The vast majority of the upward energy fluxes are radiative, not latent or sensible, and so your 46% number is not appropriate. Secondly, increased water vapour could be associated with more, less or the same ET depending on the changes to rainfall etc. There simply isn’t a one-to-one correspondence of WV and ET. Third, there is nothing new here. All models include ET and it’s sensitivity on wind, temperature, humidity etc. It doesn’t ‘reduce’ sensitivity since it is already included in all estimates. – gavin]
BobFJ, please read the earlier post in which I wrote:
>Bob_FJ writes:
…
>> Is there something new, more significant, and unpublished
>> by Roy Spencer?
>
> Yes.
>
> http://www.grist.org/article/Looking-for-validation/
—-
At the earlier post I put a short excerpt from the above link, which also links to a more recent published review article you weren’t aware of.
For BobFJ: here, if the old method still works, is a link to the earlier post I mentioned:
4 July 2009 at 2:38 PM
For Gavin — hmmm; I tried to preview this, and I find I’m at the bottom of the first page of oldest comments, and not seeing a preview. Guess I”ll post it and see what happens.
For all — caution; now there is a “Leave a Reply” at the bottom of each page of comments, so people may comment after reading very old responses thinking it’s obvious what they’re answering.
Don’t rely on the number you see before the userid –those never were unchanging, and now they start over from “1” on each page of comments.
The name and timestamp will correctly point to a comment.
Above I tried the old method — copying from /ViewSource — to put in a simple copy of the timestamp linking back to an earlier post I made. It should link to
“comment-page-20/#comment-129670” on 4 July 2009 at 2:38 PM
[Response: I think I will turn off the paged comments until I can get to work better. The numbering is all messed up…. – gavin]
BobFJ –
initial warming of the surface and atmosphere will tend increase E-T, and by itself, cause evaporation of clouds. But the increase in water vapor will slow E-T, and by itself, increase cloud mass and precipitation (at constant temperature). My understanding is that E-T does actually tend to rise, especially from wet surfaces in the tropics, but this is at least partly because the same sensible heat transfer from the surface comes along with a greater water vapor flux at high temperatures, other things being equal (it’s an equilibrium Bowen ratio thing). I would imagine greater diffusivity of molecules at higher temperatures (just moving around faster) would have an effect. Locally, wind, relative humidity, and soil moisture and ground cover changes could all affect this, and a reduction in evapotranspiration ‘forced’ by a change in wind, advected relative humidity (I would guess droughts tend to propagate downwind (other things being equal), as floods propagate downstream), or precipitation and runoff patterns, would tend to increase surface temperature locally. However, on the large scale, the tendency is for the surface temperature and tropospheric temperatures to rise and fall together because of convective coupling, so that tropopause level radiative forcing is of greatest importance – but there are regional and seasonal variations; the moist convective lapse rate varies with temperature, so that warming is amplified in the mid-to-upper troposphere relative to the surface in the tropics (surface cooling by evaporation and condensational heating aloft) – but in the polar regions, significant heat is generally transported in the air from lower latitudes, and there can actually be a net transfer of heat from the air to the surface – so the air tends to be stable to convection – and the ice-albedo feedback acts directly at the surface – the increased open water in the summer does not result in much temperature change in summer because of heat capacity, but stored heat is released in the winter, delaying ice formation, and causing winter warming (along with reduced snow cover on land), which is concentrated near the surface.
manacker –
“And it should be kept in mind that the on-line factor for wind plants is at most 30%, as compared to 90+% for thermal or nuclear generation, so the actually produced MWH from wind would only be around 0.4% of the total.”
Be sure you are not double counting the capacity factor. Did the original numbers refer to capacity or to average electric power supply?
“I have seen no studies that demonstrate that these schemes will have any discernable impact on our planet’s climate,”…
“I have figured that the combined efforts of curtailing all new coal-fired plants in the USA starting in 2010 plus shutting down half of the existing coal-fired plants there by 2050 would cost around 1 trillion US$ over the 40-year period, reduce the projected year 2050 atmospheric CO2 content by 5 ppmv (from 462 to 457 ppmv) and avert 0.05 degrees C of global warming. ”
Aside from the specific calculation (I will have to come back to it):
And what about year 2100 ? And what about leading other countries in a positive direction?
What about replacing oil and using electric cars. It may be that we could save money in the long run from reducing fossil fuel usage to near zero while still enjoying a standard of living like we do now (many of us in the U.S. and some other countries). A rather simplified scenario I came up with cuts energy costs by about 90 %, with not much immediate short term increase – but that would require that balance of system costs can be lumped into a $10/average W power with a 1 % per year replacement rate of devices. – however, storage doesn’t become a large issue right away, and so might be payed for with other energy savings. A $30 / average W with 2 % annual replacement still reduces energy costs by roughly 40 %, per unit energy supply replaced, so long as that includes oil in proportion (and we MUST replace that in the long run anyway). (PS $30 / average W ~= nearly $6/peak W with an average panel area insolation of 200 W/m2 and a good fill factor. That’s actually above current commercially available solar panel prices today – and some technologies are reaching the $2 to $1 per peak W range today, leaving room to fold in the cost of inverters, etc, into a larger tolerable price. In the future, when significant energy storage is needed, electrical energy can (depending on technology) be stored with DC electric devices (perhaps utilizing mines used to produce potash for glass making that went to skylights and solar panels, etc.) and regenerated as AC, thus reducing necessary inverter needs. And then there’s solar thermal (concentrating to produce electricity, concentration for direct industrial heat use, and low-grade heat for commercial and residential usage), and wind, waves, geothermal, apetite-friendly biofuels, and passive solar and EFFICIENCY improvements.
(We may need those savings to pay for climate change adaptation costs).
If the U.S. develops a healthy renewable energy -related manufacturing sector, we can then export energy supplies to China, Russia, and maybe even Saudi Arabia.
“One ton of CO2 has the same theoretical impact on our climate as another, no matter where it came from.”
YES. But it does make a difference to the economy and to people.
“The “guilt factor” (i.e. is it China or the USA) leaves me cold, since I believe that “guilt” should be kept out of the equation, as it brings no positive solution.”
…”whereas they will represent a major cost to every citizen of the nations participating and make a few already wealthy individuals ever richer.”
Based on what you were responding to, this reads to me as:
1. you don’t care about fairness.
2. fairness is important to you.
Please do think about that.
Hank (#998),
I know of a few efforts to use concentrators in a home application but cooling is from the air as far as I know and the plan is to use more sophisticated PV (multi-junction) in any case. The water tower set up is cheap because standard panels can be used and the lost energy is still recovered in a useful manner. A problem with home concentrators is the risk of an unmonitored intrusion into the beam by a pet or stick or some such. Having the beam converge at an inaccessible location like the underside of a water tower avoids a lot of issues of that sort.
There are funded projects (state of NM has one) to cool standard panels not used with concentrators and then use the hot water.
Here’s some nice, dry tender for what I’m sure could turn into an argumentative conflagration: shrinking sheep, down to climate change.
“Sheep living on a remote island off the coast of Scotland have been shrinking for 20 years. Now it seems shorter winters caused by climate change are responsible.
…modeling revealed that one of the most powerful influences on [Soay sheep] size was the gradual warming of the climate, driven by changes to the North Atlantic Oscillation ocean current, which has led to shorter winters on the island. As a consequence, the vulnerable smaller sheep were more likely to survive the winter, pushing average size down over successive generations.”
Oh, boy! The article even includes a model to dispute!
Probably should read the entire piece before commencing to fire.
http://www.newscientist.com/article/dn17407-incredible-shrinking-sheep-blamed-on-climate-change.html
Max states: “Let’s use the Wiki definition. That is what I think it means.”
Not according to evidence if you think it applies to yourself.
You’re a credulous.
The comments about the low reliabity, the on-line factor, of wind energy are valid. However this could be much increased with the availabilty of cheap electrical batteries.
The batteries in EVs can also be used a source of power to cover the early evening peak period. Denmark is probably the pioneer on Vehicle to Grid work at present.
http://www.reddit.com/r/energy/comments/8u5ba/denmark_to_power_electric_cars_by_wind_in/
http://www.ecogeek.org/content/view/1505/69/
Kevin McKinney, further to my 972:
If you are still struggling in understanding the terrestrial energy budget fundamentals, here is an
image from NOAA which is perhaps the neatest/easiest of all three versions so far linked.
It gives, verbatim, compared with; {IPCC/Trenberth equivalent WORDING}, [clarification]
a) Latent Heat Flux, {Evapo-transpiration}……….. ~45%
b) Net Emission of [ALL] Infrared Radiation from surface, {Not given}…….. ~41%
c) [Of which total] Absorption by H2O, CO2, [{?} Trenberth equiv. is confusing]…. 29%
d) Sensible Heat Flux, {Thermals}…… ~14%
BTW, this budget also adds up: a) + b) + d) to 100%
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The fundamental solution as to why the sun appears to have uniform brightness presented despite that it is a sphere, is that its surface emits EMR equally in ALL directions, hemispherically. (I don’t know why Rod B 981 and Patrick 978 wanted to aggravate this fundamental simplicity).
From this it follows that the Earth’s surface also does this, but at long wavelengths.
It also follows that any elemental package of air emits in all directions, spherically. Furthermore, that adjacent packages, AOTBE, are radiating equally at each other.
Consider the sideways radiation of these packages, AOTBE. Obviously, they do not keep getting hotter, despite all that EMR flying around. WHY?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The answer to the analogous puzzle of what is the net of two opposing EMF’s of 12 volts and 9 volts, is 3 volts. Does this help?
PeterMartin says (5 July 2009 at 6:41 PM):
“The batteries in EVs can also be used a source of power to cover the early evening peak period.”
There seems to be a couple of fairly obvious problems with this idea. First, suppose you’re a typical commuter: you leave home in the morning with a fully charged EV battery. You don’t want to charge it during the day with expensive near-peak power, thus you return in the evening with the battery nearly depleted, so it’s not much use as a source of power.
Second problem is that AFAIK all battery chemistries degrade with increasing number of charge cycles, so some way would have to be found to compensate the EV owners for premature battery wear.
I think a better storage technology would be high-speed flywheels. They have low losses, and with the rotors spinning on magnetic bearings in a vacuum, wear & tear should be miniscule.
“The batteries in EVs can also be used a source of power to cover the early evening peak period. Denmark is probably the pioneer on Vehicle to Grid work at present.”
NO! V2G is evil. Most of V2G is smoke-and-mirrors, aimed at ripping off electric utilities. The peak demand for V2G capacity is precisely when people want to leave, or when the removed capacity would have to be replaced so people can go home. V2G is about collecting money for spinning reserves that aren’t available when needed most.
This is one time I have to agree with James — for short-term balancing energy, which is all V2G can provide, flywheel storage is the best technology going.
James,
Your assumption regarding “nearly depleted” batteries isn’t likely to be correct even with current battery technology. Average daily mileage is quite low so most EVs, including plug in hybrids, would still have usable levels of charge which could be used in the early evening before the battery was recharged in the early hours of the morning.
It would need smart chargers of course and that technology already exists.
What is slightly harder is the development of the right sort of batteries. The current favourite for EVs are Lithium Ion but I’d say longer term something like the Zebra battery or even better Lead Acid batteries along the lines of Caterpillar’s Firefly are definite possibilities and are likely to be cheaper.
Flywheels? Too dangerous for widespread consumer use I’d say. Likewise Hydrogen gas but they will have their applications.
the need for our group to have a functioning and reasonably realistic climate model with which to start the new round of simulations
That sounds desirable. I don’t wish to appear rude, but what sort of model did you have before?
[Response: The same kind. But since 2004 computer capacity and understanding of specific processes have both increased. Thus this year’s model has higher spatial resolution and includes more stuff. When you make those kind of structural adjustments to a model you need to do some work to get it back to where you were, and of course you want it to be better than what you had in 2004. The good news is that it now is. -gavin]
Patrick 027
Thanks for your post (1005)
Yes, there are many potential solutions to the energy crisis, the desire to reduce CO2 emissions, the impending shortage of fossil fuels, etc., such as those you have suggested.
My point was simply that two specific proposals that have been made for the USA in order to slow down global warming (curtailing new coal-fired plant construction starting in 2010 and shutting down half of the existing coal-fired stations by 2050, by replacing all of this capacity with nuclear power, will be very costly ($ 1 trillion) and not bring much as far as averting projected global warming (0.05°C).
Replacing this capacity with something else (like “green” renewable power) sounds good, but is highly unlikely to be technically feasible or economically viable.
So there must be something more intelligent that could be proposed (possibly some of your suggestions).
The world in the year 2100 will definitely look different than it does today.
Will we have fast breeder fission reactors that generate no spent fuel? Probably.
Will we have nuclear fusion reactors? Quite likely.
Will we have better batteries or more efficient electrical automobiles? Surely.
Will presently known renewable power sources play a major role? Maybe.
Will totally new sources of power be invented and developed? Probably.
Will known recoverable petroleum reserves be smaller that they are today? Probably.
Will known coal reserves be less than they are today? Probably.
Will it be slightly warmer than today? Most likely.
Will human activities have been a cause for some of this warming? Possibly.
Will we have adapted to any changes that might have occurred to our climate? Almost certainly.
To your statement about “fairness”, the two points made have nothing to do with one another. If we want to “fairly” reduce CO2 emissions, we should let everyone participate in this effort “fairly”. One ton of CO2 is as harmful as another.
If we want to implement a cap and trade scheme, knowing full well that everyone will be paying a high price so that a few wealthy individuals can get even richer, and consider this to be “fair”, so be it.
Max
Doug Bostrom (1007)
Warmer climate due to changes in the NOA are giving the smaller Soay sheep off the coast of Scotland a chance to survive the shorter winters, thereby reducing the average size of the species?
Seems that AGW has, at least, been given a “clean bill of health” on this development (unless we believe that our CO2 emissions are causing the changes in the NOA). So this would tend to leave the sheep discussion (unlike the survival of the hapless polar bears) out of the more emotionally and politically charged subject area of AGW.
But there is the economic question to consider: If we assume that the Soay sheep are being raised for their wool and meat production, does the smaller size of the shrinking species cause these to also shrink (in proportion to the average outside surface area and body mass, respectively, of the sheep), or does the larger number of winter survivors result in a net increase of the total wool and meat production?
Believe a model study could be justified. But since it is highly unlikely to be tied to AGW, funding could be a problem.
Max
Doug Bostrom
Re my 1014 response to your 1007
NOA should be NAO, of course. Sorry for typo.
Mark
You questioned the meaning of “rational skepticism”, and I believe we covered that.
Rational skepticism seeks empirical evidence to prove or disprove a hypothesis, regardless of the prevailing expert opinion on that hypothesis.
In the case of projections for the future it is more difficult to find empirical evidence to support a prediction, and we are often left with no choice but to rely on expert opinion, including model studies, trend analyses, etc.
There are those that defer to the “experts” on all predictions for the future: be that on the stock market or other financial developments, on anticipated demographic, social or economic developments or even on climate forecasts.
Then there are those that regard the “expert predictions” with a degree of rational skepticism, despite the obvious fact that they have been made by acknowledged and respected “experts” in their fields, who certainly understand all the nitty-gritty details far better than non-experts.
In his book “The Black Swan”, author Nassim Taleb presents good reasons for regarding “expert predictions” with some degree of rational skepticism; he shows us how these can be (and often are) more wrong than random guesses by non-experts using nothing more than common sense.
One reason cited by Taleb is that while “experts” know very well “what they know”, they are often overly confident and therefore more arrogant in their assumption of their knowledge and, as a result, blinder than non-experts to “what they do not know”.
Physical scientists are no more immune to this problem than economists, sociologists, etc.
In a “previous life” I worked together with a few “scientists” as well as “engineers”. I had a lot of respect for (and relied on) the knowledge of these “experts” and saw that these individuals certainly knew much more about their special field of knowledge than I did. But I also learned very quickly not to just blindly accept their prognoses for the future (ex. cost and timing of R+D programs or new capital investment projects, etc.), but to dig into their forecasts to find out not so much “what they know”, but more importantly, “what they do not know”.
In the absence of clear empirical evidence I believe that this is the way for any rational skeptic to approach the current “scientific debate on global warming, including its impact and humanity’s political response”.
Maybe this can help explain how I see the role of the rational skeptic, as it relates to the definition of the term.
Max
“You questioned the meaning of “rational skepticism”, and I believe we covered that.”
No, I questioned the meaning of “rational skepticism” applying to you.
It doesn’t.
Gullible, maybe, irrational, no problem. skeptic? no. rational? no. Not unless you have a rationality you aren’t promoting here to explain your gullibility.
“You don’t want to charge it during the day with expensive near-peak power, ”
Therefore you plug it in in your company’s solar cell covered carpark.
And there is a peak in supply during daytime for solar power, the law of supply/demand therefore means that even though demand may deem to have increased, the increased supply will reduce the cost.
Bob: “It also follows that any elemental package of air emits in all directions, spherically.”
But that means that it hangs about in the atmosphere longer, the size of the sphere you “expect” to radiate out to before losing it depending on the density of the obscuring media.
Apart from that, your post made no sense anyway, but that bit did though it didn’t make any sense in the context of the post.
#1016 Manacker:
“If we assume…”
Too funny. You didn’t read the article. The Soay sheep are not used for any purpose other than for biologists to study.
“Believe a model study could be justified. But since it is highly unlikely to be tied to AGW, funding could be a problem.”
That remark just cracks me up, in part because you make yourself sound so ignorant by taking a guess when you could have been informed and also because it’s so revealing of your biases. Guess what? If you’d read the article, you’d have known that a model was created and used as a key part of producing the result described in the article.
Next time I read one of your posts, I’ll of course be unable to avoid remembering this input to your net credibility level.
#1010 BobFJ:
Never heard of limb darkening, have we?
Morale (for several other “contributors” as well): if you don’t know what you’re talking about, listening is the better option :-)
PeterMartin says (6 July 2009 at 3:02 AM):
“Flywheels? Too dangerous for widespread consumer use I’d say.”
Why? Read up on the subject a bit, and reflect that for residential use, they could easily be placed in a pit, so that if one did fail, the fragments would simply embed themselves in the earth.
Mark says (6 July 2009 at 10:47 AM):
“Therefore you plug it in in your company’s solar cell covered carpark.”
Assuming of course that your company A) has one; and B) isn’t more interested in using its output to displace the expensive on-peak power used to run the building.
But if you have solar cells on your roof at home, and an efficient flywheel storage unit, you come home to a fully-charged (since nothing much was running while you were gone) house. You use your stored electricity to run your house during those peak evening hours
(shaving a bit off the peak in the process). After you go to bed, the remaining power, perhaps supplemented with nighttime grid generation, charges your car. And in the morning, the cycle repeats.
Indeed, a fairly smart controller could e.g. look at weather forecasts and plan ahead, saving energy for predicted rainy days, or shipping watts to the grid when the sun shines…
Max –
“Will human activities have been a cause for some of this warming? Possibly.”
Almost definitely (unless CO2,CH4,etc. emissions are rapidly reduced to perhaps negative net values, in which case the smaller changes with significant probability of occuring ?might? yet be dominated by internal variability and natural forcings (not counting most of the changes that have already occured in the last several decades)). Which is not to say with certainty that is is the cause of precisely 100 % of all change, no less, no more. It could be 80 % or 110 % … you get the idea.
“Will we have adapted to any changes that might have occurred to our climate? Almost certainly.”
How much of that adaptation is through making do with less, accepting more suffering and perhaps war? How much is through greater acceptance of climate change refugees, increased acceptance of responsibility on a global scale, investment in water supply infrastructure, reduced human fertility, higher efficiency, medical advancements, and reduced dietary reliance on animal protein?
“To your statement about “fairness”, the two points made have nothing to do with one another. If we want to “fairly” reduce CO2 emissions, we should let everyone participate in this effort “fairly”. One ton of CO2 is as harmful as another.”
The ideal I put forth is a flat-rate global emissions tax. Poor countries might accept this to the extent that their emissions are as low as their GDP (aside from the other imperfections of the global market economy). Revenues would be divided among 0. emissions sequestration, 1. mitigation R&D and strategic subsidies, 2 adaptation R&D, 3 adaptation costs and reparation for climate-change injuries, 4. equal per capita rebate, 5. cuts in other taxes (this is where policy on the international level is especially tricky), 6. environmental protection (actually a part of 2)… (noting that population growth reduction and agricultural and other land use changes fall into more than one category).
“If we want to implement a cap and trade scheme, knowing full well that everyone will be paying a high price so that a few wealthy individuals can get even richer, and consider this to be “fair”, so be it.”
What version of cap-and-trade are you anticipating?
“Assuming of course that your company A) has one; and B) isn’t more interested in using its output to displace the expensive on-peak power used to run the building.”
True. Then again, if there’s more carpark space than needed to create the power needed to operate, you have some to spare. Accounting for the kWhs can cost time and money, so why not remove that by just pumping it into the cars.
And remember, most car journeys in the UK are less than 2 miles. And the 30 mile journey you may have to manage elsewhere is still going to be fairly uncommon and doesn’t use up much of the “tank”.
But you still have more sunlight in the daytime, so using up peak isn’t a huge problem.
“In the case of projections for the future it is more difficult to find empirical evidence to support a prediction, and we are often left with no choice but to rely on expert opinion, including model studies, trend analyses, etc.”
If expert opinion logically follows from model studies, trend analyses, proxy data, … then it is more than just opinion. Of course something could be missing, but climate science seems to full of an awareness that we do not everything – why else would scientists still be hard at work? Besides, as a general rule, it is not necessary to know everything in order to know something (there are more equations than variables; possibilities are not entirely limitless; uncertainty is often finite).
“Then there are those that regard the “expert predictions” with a degree of rational skepticism, despite the obvious fact that they have been made by acknowledged and respected “experts” in their fields, who certainly understand all the nitty-gritty details far better than non-experts.”
…which does not necessitate reaching a conclusion that differs much from what the experts have.
“In his book “The Black Swan”, author Nassim Taleb presents good reasons for regarding “expert predictions” with some degree of rational skepticism; he shows us how these can be (and often are) more wrong than random guesses by non-experts using nothing more than common sense.”
Is Nassim Taleb an expert on this? He wrote a book about it, so it might be that he has studied it more than I have – in which case, if what he says is true, I should be aware of the possibility that he is somehow wrong – ?
I didn’t really get a good answer to my previous point about the logarithmic nature of CO2 concentrations v temperature, and so, at the risk of boring everyone, I thought I would have one last try at the subject.
Arrhenius, at the turn of the previous century, famously stated:
“if the quantity of carbonic acid increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression.”
So, what he was saying was that the relationship is logarithmic as follows:
CO2 concentration: 1,2,4,8
Temperature Rise : 1,2,3,4
And I asked the awkward question, in effect, of what happens when the C02 concentration is zero. Shouldn’t the temperature rise be zero too?
If Arrenhius had been studying the current flowing in a diode (‘cats whiskers’ were the first ones) he might well have come up with the same geometric progression/arithmetic progression relationship between voltage and current. And, yes, it (the logarithmic relationship) is a valid approximation over certain ranges of current and voltage.
However, the relationship is defined more accurately as a combination of af an exponentional and a linear term, which does give the right answer that when there is no volatage across the diode, then there is no current either.
Couldn’t there be a better equation for CO2 and temperature too?
Peter, no you didn’t.
And we never got a good answer as to what you’re looking for, what level of education you have and so on.
Go get some journals on the radiative balance equations. Someone here can give you a link to them (probably Hank…).
They won’t be easy to read, but they will prove why there’s a log relationship.
Everything less than that is merely a model, and we might as well just leave it with “it is, because that’s what works”.
Patrick 027
To your comments on Nassim Taleb’s book (which has nothing to do directly with climate change, but a lot to do with “expert predictions” gone awry), I can only recommend that you read it.
Taleb is probably among the most intelligent individuals alive on the planet today.
It will give you a totally new perspective on the validity of the 100-year predictions being made based on climate model outputs.
One part of the message: the longer the forecast period, the more likely it is that an unanticipated “outlier” (the “Black Swan”) will render the whole forecast obsolete and meaningless.
This goes directly against the climate modelers’ postulation that forecasting 10 to 15 years in advance is more difficult than forecasting 100 years in advance.
This is often justified with the “double-talk” rationalization that the shorter forecast is distorted by short-term “weather noise” which hides the long-term “climate signal” of the longer term forecast. This silly rationalization is often backed by analogies to totally irrelevant “coin tosses” or other simple “games of chance” examples.
Read Nassim Taleb, Patrick. You will learn something new.
Max
“And I asked the awkward question, in effect, of what happens when the C02 concentration is zero. Shouldn’t the temperature rise be zero too?”
No, you asked the stupid question.
It is officially “undefined”.
Like dividing an equation by zero leaves it undefined. How you get the zero and how your equation works at that point defines what you get, 0, 1, infinity or any number at all (cf relativistic mass of massless photons, where E=hv=mc^2, therefore your mass is proportional to the frequency of the light).
Then again, you can’t double 0 and get any change.
Hence you get a non-exponential part.
As an example, take optical depth. Every time you double the concentration, you double the optical depth. And the transmission halves.
So transmission varies with concentration in the same way as temperature varies with CO2 concentrations.
So ask the question about the optical depth model.
So if your question is insurmountable, how come we know the optical depth of a translucent material at all?
Another question to ask Peter is what happens when you reduce the current so that only one electron moves through your resistor at one time interval.
Or when your Ideal Gas which has obeyed the Ideal Gas Laws quite happily fail because you have pumped out a near vacuum (near but not complete).
The relationships you could make by averaging out all the effects don’t work when you can no longer use the fuzzy law of large numbers.
This has not stopped us inventing and perfecting the internal combustion engine or the jet engine.
Arrhenius didn’t have 0ppm CO2 available to him. And couldn’t measure the change if he did.
We don’t have 0ppm CO2 in our troposphere either.
1028 Peter said, “CO2 concentration: 1,2,4,8
Temperature Rise : 1,2,3,4
And I asked the awkward question, in effect, of what happens when the C02 concentration is zero. Shouldn’t the temperature rise be zero too?”
How is it awkward? You asked about temperature rise, not absolute temperature. Yep, at zero concentration CO2, the temperature rise due to CO2 will be zero. Case in point is the moon, which lacks a greenhouse effect.
Doug Borstom 1022
Yep. I read the article. The sheep are “doing their own thing” up there without any human interference (except climate scientists checking their average weight and winter survival rate from time to time).
Has anyone tried to tie the shifts in the NAO to AGW?
Where are the papers on this?
One would think that with rampant anthropogenic global warming (AGW) these islands would become a primary immigration target for Scotsmen driven from their homes by the oppressive heat of AGW.
Why has this not happened?
Max
peter,
The logarithmic relation only applies to the regime between 1 and 1440 ppmv, roughly. Below that it is linear. The log relation is only an approximation for a good range around present Earth conditions. You couldn’t use it to predict the surface temperature of Venus, for example.
Mark (1031/1032)
As much as I hate to admit it, Mark, I agree with your response to Peter 100%.
Max
PS I know that this may not make you happy.
“Read Nassim Taleb, Patrick. You will learn something new.”
But will it be
a) useful
b) right
?
His theory seems to be merely a more complete theory of “well, somethings bound to go wrong”.
Doesn’t seem like of much use or even genuinely correct.
Does he have anything on enumerating this black swan? Or anything on its appearance rate in 100 years?
And does it say that if you haven’t modelled it, it won’t turn up? Because this seems like it is not adding anything. It doesn’t say that GW isn’t being caused by humans, it doesn’t say that the predictions absent any black swan event will be wrong. It just says that something will happen.
So do we do nothing because something worse will happen ON TOP OF what we’re doing? Or do we sit in hope of some Deus Ex Machina coming along and undoing the damage done?
That’s either fatalism or extreme and unwarranted optimism.
You may as well say that “stopping CO2 production and going to 100% renewables” will be the black swan event. After all, it isn’t in YOUR model.
Hank Roberts, 998, 1002, 1003:
This is a self edited post of an earlier version that seems to have been deleted in moderation.
Thanks for your interest concerning peer reviewed & non peer reviewed work by Roy Spencer.
Unfortunately, I need to prioritise and pass, for the time being, on your recommendation to study Andrew Dessler’s post on Gristmill.
Meanwhile, I’m reasonably content to be aware that Spencer has had Peer reviewed publication in the respected journal GRL, identifying a significant negative cloud feedback, a publication process that took ~6 months of interchange! Admittedly, there were spatial and temporal limitations in his work, but the same is also true of Andrew Dessler’s work published in the very same journal.
It does not surprise me that Roy Spencer has recent unpublished work including a slide show. Neither would it surprise me if Andrew Dessler has some unpublished stuff too. It’s all ongoing, after all!
PeterMartin, nope, don’t rely on me for the raadiation math; but using the Search box at the top of the page should help.
We’re in a planetary atmosphere, interacting with the oceans and rocks, so you can’t have the atmosphere free of CO2 forever, no matter what else happens.
Have you read the Science Fiction Atmospheres article? Click Ray Pierrehumbert’s link in the right hand column under Contributors, it’s under his publications link.
See also the closest this planet may have come — a change not initiated by reducing CO2, though: http://scholar.google.com/scholar?sourceid=Mozilla-search&q=%22snowball+earth%22
“As much as I hate to admit it, Mark, I agree with your response to Peter 100%.
Max”
Doesn’t bother me.
If you get something right or not wrong enough to be worth picking a bone over, I’ll say so.
I’ve agreed sometimes with some who lead along the denialist creed. Someone’s past “form” will make me decide how strongly to bother reading or working out what’s going on (Patrick027 for example posts such long posts I just skim past and ignore it) and I’d be more skeptical of your pronouncements than, say Hank’s.
But I’ve disagreed with Hank too.
I’ve bolstered his arguments sometimes as well.
I use “form” to decide what and how much effort I spend. But in that effort, “form” doesn’t come into it.
Patrick 027 Reur 1004:
Thank you for your comments about the many complexities surrounding E-T (Evapo-Transpiration).
I agree with the broad brush of what you say, the difficulty I have is, that it seems to be an intuitive ensemble for which, as far as I’m aware, there is little to see in the way of data in the literature.
Furthermore, there are a host of other peripherals that could be added to yours for consideration. For instance, variations in rainfall have many different impacts, depending on where and when. Such as:
* Take a dry continent like Australia: It only takes a minor reduction in rainfall especially in the more marginal cropping areas, for it to be declared as drought or a disaster. However, in the global budget of rainfall, we are talking peanuts.
* It makes a huge difference in re-evaporation rate if rainfall is on the sea versus on land and WRT the type of soil and/or forest and whatnot involved.
* If it falls as snow, even on old snow, there is an increase in surface albedo, (of fresh snow), and thus an additional cooling effect.
And so-on, keeping it to just three.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I think you have expressed an opinion that it is unlikely that there is a significant response to global warming, of average global E-T. (based on your intuition).
On the other hand, my intuition (and that’s all it is) is that there is a fundamental increase in E-T of global significance, as a response to global warming. Furthermore, that the spatial and temporal variations of the many but secondary factors probably net to low significance as a global effect.
That’s keeping it brief.
#1034 Manacker:
“I read the article.”
Belatedly, if that, and with poor comprehension if you actually did so. Here’s a clue to why I wonder: did you notice the work was not performed by “climate scientists”? I actually suggested reading the paper before remarking on the finding; your credibility would be better served by not pretending you’d taken that advice.
Ordinarily I don’t really care about the background of folks I have discussions with on the ‘net. In your case, being struck by your handle, I took a moment to look it up before replying to your original post, thinking perhaps it was a pun or other obscure referential pseudonym similar to “Anne T. Cyclone” et al.
I found out otherwise, but I also could not help noticing something else. If you’re the archetypal “manacker”, you’re also a major figure on various discussion boards, with a bent. The tone of your writing seems to vary according to your audience. Here on RC, you seem measured, thoughtful. I don’t know about RC, I did not bother to look, but on other factually-based websites you frequently dip from a comparatively small well of academic works to shore up your position, which appears to centrally hinge on the notion that IPCC is a global mafia of unprecedented efficiency and airtight message discipline.
When writing in other places with less focus on the topic of climate change, you appear to style your work according to the credulity of your readers, with a tendency to sneer. Here’s what you’ve said, featuring some remarks that I think speak of how seriously any discussion here with you should be entertained (I apologize in advance if you’re not the same “manacker”, and I’ve included your own thinking on unscientific remarks about other persons and organizations, valuable advice you should follow):
“First of all, “we will continue to change the climate” implies that we really are changing the climate. Sure, some “scientists” and computer nerds are telling us this, but it is just based on a hypothesis, some agenda-driven “science” and a bunch of GIGO computer studies, no facts.”
“Real Climate is selling AGW hysteria. ”
“Stick with factual argumentation, not silly name-calling.”
“Instead of relying on RealClimate or other AGW-fundie sites for your info on solar impact on climate…”
“Forget the alarmist junk science sites like RealClimate and read the many original studies out there, if you really want to know what’s going on.”
“Didn’t your Mommy tell you it was bad manners to call people names?”
“The “consensus” argument is flawed. The belief that “scientists know best” is flawed (after all, “climatology” is still in its infancy as a “science” and many of the so-called climate “scientists” are in fact only computer jockeys.”
“As such, it [the IPCC report] is full of agenda driven pseudo-scientific exaggerations and distortions, which all go in the direction of making its “pitch”.
“It appears that you prefer to talk in generalities and insults…”
So I personally am not going to bother discussing anything with you, not the NAO or anything else. It’s clear you’ve got a set of beliefs about the IPCC and consequently climate science in general that is based on the notion that IPCC is a conspiracy, that further most climate scientists when they’re not overtly incompetent are instead malefactors. There’s no possibility of fruitful discussion when confronted with such a bizarre set of beliefs.
Mark,
There is no such thing as a stupid question! There may be a stupid answer and you now probably realise that you’ve given one. You’ve got Max agreeing with you :-)
(BTW. MSc in Electronics to your question. Does that make a difference? Is that enough to gain entrance to the club?)
RichardC,
You ask “how is it awkward”? Well if you care to look at the two series the preceding term in the AP is clearly 0 but the preceding term in the GP is 1/2.
Barton,
I have seen numbers ranging from 1ppmv to 100ppmv ( the latter from Gavin I think), for the lower limit of the logarithmic range. And yes , I have said it many times, I do know that the logarithmic approximation is a good one over the likely concentrations fo Co2 that we will experience practically.
However, just as it isn’t too difficult to get the diode (not resistor Mark!) equation right at low voltages and currents, and I don’t mean Quantum Mechanically low, by using a combination of an exponentional and a linear term, shouldn’t it be possible to do the same with the “LogCO2” relationship? Whether its 1ppmv or 100 ppmv for the lower limit?
Max –
1. Mark has it exactly right in 1037
2.
“It will give you a totally new perspective on the validity of the 100-year predictions being made based on climate model outputs.”…”One part of the message: the longer the forecast period, the more likely it is that an unanticipated “outlier” (the “Black Swan”) will render the whole forecast obsolete and meaningless.”…”This goes directly against the climate modelers’ postulation that forecasting 10 to 15 years in advance is more difficult than forecasting 100 years in advance.”…”This is often justified with the “double-talk” rationalization that the shorter forecast is distorted by short-term “weather noise” which hides the long-term “climate signal” of the longer term forecast. This silly rationalization is often backed by analogies to totally irrelevant “coin tosses” or other simple “games of chance” examples.”
If you understood weather and climate, you would not have refered to the explanation of the difference as double-talk or as silly rationalization. Though it is ture that there is some internal variability which acts over longer time periods than ENSO, the principle is clear – weather prediction is an initial value problem that becomes intractable over time because of chaos; climate prediction is a boundary value problem whose solution is a range of specific weather trajectories – it doesn’t matter which specific trajectory is ‘correct’ because and so long as over time they all look the same in their texture.
Unforced variability can occur, but external forcing limits how far it can go. A weather pattern change can be self-reinforcing via momentum and energy fluxes; drought can be self-reinforcing via reduced evapotranspiration due to reduced precipitation – yet, even when anomalies lack an intrinsic limit to longevity, there are spontaneous perturbations that tend to occur with some frequency (or how else would such anomalies arise in the first place), and the probability that a given anomaly will interupted accumulates over time. Furthermore, external forcing provides an anchor that can pull weather patterns back from extrmes. For example, if there were a decrease in overturning motions within the troposphere, thermal gradients would tend to build up, increasing the tendency for overturning motions.
What kind of outlier would render a climate prediction meaningless? An outlier in cloud feedback would merely make most models inaccurate, but important though it would be, it would not make models meaningless. An outlier in forcing? Well, Yellowstone or Toba(?) could erupt (or not), Apophis could hit, a new plague could wipe us out. An outlier in internal variability? There have been some big rainfall pattern shifts during the Holocene, but some of that has been driven by the ~ 20,000 year precession cycle, with the complexity of vegetation feedbacks; as for shorter term fluctuations – well, if we go by paleoclimate records, we would likely not be looking at outliers.
Whatever long-period internal variability happens, it happens; we could get a little lucky with a natural cooling, or unlucky with a natural warming, but the reasonable expectation is that anthropogenic warming will dominate. Natural variability in regional climate, including precipitation, might add to anthropogenic changes in some places while subtract from it in others – my understanding is that anthropogenic effects still add to the overall regional changes (natural variations do not saturate the potential range for regional change). As for outliers, sure, I could die tonight, but I think I should be prepared for the ‘off-chance’ that I do wake up tomorrow. We shouldn’t just be prepared for the unexpected; we should be prepared for the likely as well.
3. Modes of internal variability (NAM (AO) and NAO,SAM,ENSO,PDO,QBO,AMO, and shorter term ‘weather’) are not just ways in which climate fluctuates in the absence of changes in external forcings, they also characterise (as do the shorter term weather patterns) an overall climate state, and occur and behave as they do contingent on an overall larger state (that encompasses such variability). Things that force climate change may force changes in the characteristics of internal variability
—
(somewhat hypothetical examples: in the time it takes for the warming signal to penetrate through the deep ocean, regions of upwelling water will tend become more cold relative to the global average (to the extent/in the case that upwelling rates do not change), which suggests that the temperature difference across the tropical Pacific will grow, which suggests by itself that ENSO variations could become more extreme; furthermore, higher average sea surface temperatures tend to increase the effect of a given sea surface temperature anomaly on large scale weather patterns via the impact on stationary Rossby wave trains; if the production of vertically-propagating equatorial waves of various kinds changes, this could change the average period of the QBO.).
—-
Furthermover, some portion of the time-average (over years for a particular month or season, or the annual average, etc.) climate change may project onto modes of internal variability. For example, there is some expectation that midlatitude storm tracks will tend to shift poleward on average; NAM and SAM both involve latitudinal shifting of midlatitude storm tracks.
BobFJ – “I think you have expressed an opinion that it is unlikely that there is a significant response to global warming, of average global E-T. (based on your intuition).”
No, actually my understanding was that there would be a significant increase in global E-T, but this corresponds to a significant increase in latent heating within the troposphere. I don’t think any of the complexities you’ve mentioned have been neglected by the scientists.
Martin Vermeer 1023:
You quoted, ridiculed, and complicated a paragraph from my 1010, but without the original clarifying bold emphasis shown in it. (despite that you know about html tags used for text enhancement) Here it is again, but this time properly displayed:
In the context of addressing an issue to Kevin, who does not even appear to know the difference between HEAT and EMR, you should be aware that I was trying to keep it simple for him.
Here are some dictionary* meanings for two key words in that paragraph, in that context:
‘Fundamental‘
2. central: serving as an essential part of something
‘Appears‘
4. Vti seem likely: to seem likely or true
The three men appear to have left the city.
Here are some questions for you:
a) What significance do you think there is concerning my emphasis on the word ‘fundamental‘?
b) Why do you think I included the word ‘appears’, rather than ‘is‘?
d) Do you believe that it is a common perception of people at large that the sun does NOT have uniform brightness across what appears to be a flat disc?
* Microsoft Works
> the sun appears to have uniform brightness
_Anything_ looks like it has uniform brightness when it’s badly overexposed.
“This is Jupiter, badly overexposed” http://www.cactuscomputing.net/images/AstroPics/Jupmoons.jpg
Peter Martin – I don’t know exactly, but I think the tropopause level CO2 forcing with stratospheric equilibration for removing all CO2 is somewhere around -20 W/m2 (for ~ 300 ppm initial).
If it is -20 W/m2 going from ~300 ppm to 0, and each halving is -3.7 W/m2 (I think that’s about it, but don’t take my word for it; I usually say ‘about 4 W/m2 per doubling’), then only 5 full halvings are allowed before the logarithmic proportionality must break down (~ 9.4 ppm).
But the change in accuracy will not be discontinuous, so different cutoff points might be given depending on the error tolerance.
The relationship may break down at very very high CO2 levels because of additional band(s) that become important; before that, it is concievably (I don’t know all the details) adjustments might be needed if the shape of the absorption spectrum farther out from 15 microns is a little different or due to changes in overlaps and blackbody radiation as the wavelength interval where the next doubling is most important shifts.
There is some additional complexity, though, when the changes are so large. For small changes (relative to the totality of greenhouse effect (approx. 155 W/m2 including water vapor and clouds, top-of-atmosphere value (see Kiehl and Trenberth), solar forcing (approx. 235 W/m2 global annual average), ice albedo, cloud cover, humidity, etc.), some linear approximations can be used. The tropopause level radiative forcing for a 30 % increase in CO2 would be about the same as the next 30 % increase given small tropopause position changes, humidity feedbacks and cloud feedbacks, changes in the lapse rate, the effect of temperature, pressure, and composition on the CO2 absorption spectrum, etc. But the changes going from 300 ppm to 0 (or 10,000 ppm, for that matter) may be so large that the magnitude of the tropopause level forcing for CO2 going from 0 to 300 ppm may be significantly different than the magnitude of the forcing of going from 300 ppm to 0. The difference would be made up for by the difference in feedbacks (other things aside, the magnitude of the water vapor feedback (in terms of W/m2) after 300 ppm CO2 is added would be a bit less due to overlap with the 300 ppm CO2, as compared to the magnitude of the water vapor feedback after the same 300 ppm CO2 is removed – and the feeback magnitudes would depend on order taken), after sufficient time to reach equilibrium.
” and the feeback magnitudes would depend on order taken), after sufficient time to reach equilibrium.”
And also assuming no hysteresis, so that the finish point is at the starting point. This may well not be the case for going to 0 CO2 and back, because when the ice line (limit of snow and ice cover) is in a range of low latitudes, climate sensitivity is negative – the equilibrium is unstable. To actually get back to the start, you’d have to go from 300 ppm to 0 ppm then up to … some really high number, then after sufficient time, come back to 300 ppm. And that’s without biological evolution (including the mass extinctions that would result from all this change). See “Snowball Earth”.
Correction to my big huge comment 895 above:
“(PS combining seperate parts of my knowlegde, I conclude that the acceleration of electrons must involve changes in energy level by thermal excitations and relaxations (interaction with phonons – quanta of atomic/molecular/crystal-lattice vibrations (there are thermal and acoustic phonons)), with some statistical organization by variation in potential (and magnetic fields, where that comes into the picture) over space on any given locally defined energy level (relative to local zero energy).”
Actually, when there is an electric field (PS built in potential is not an electric field (except for the space charge region that is related to the fermi level shifting relative to the electronic states), but a shift in the electronic states relative to the fermi level), electron wave packets moving with some group velocity do work, and that causes an acceleration, and specifically requires a change in energy, which involves a shift to different k values within the band.
From “Electronic Structure and the Properties of Solids”, Walter A. Harrison, Dover Publications, 1989, p.37:
where E is energy, k is wave vector, r is position vector, * indicates a dot product when vectors are involved.
group velocity = 1/h’ * del(E)/del(k)
(where del indicates a partial derivative, and the partial derivative with respect to a vector to be equal to the gradient in the corresponding vector space)
(where h’ is either h with a bar through it or just h – Planck’s constant (I’ve seen hbar (Which I think is Planck’s constant divided by 2*pi) used where h should really be used, so I’m not going to assume).
change in k due to a spatially-varying electric potential V (PS I’m pretty sure in this context this is the potential for an electron, and not a positive charge) is given implicitly via:
del(E)/del(k) * dk/dt = dE/dt = -velocity * dV/dr = – 1/h’ * del(E)/del(k) * dV/dr
therefore
dk/dt = – 1/h’ * dV/dr
Thus k increases in the direction of decreasing V, as expected. But if E(k) is a maximum at k=0 (as it often is in a valence band), the corresponding acceleration of group velocity would be the opposite of what one would expect for a free electron … ??? Well I’m not sure what happens in that case. But generally, the way electron motion responds to an electric field is modulated by the way the slope of E(k) varies over k, and at a minimum E value in a conduction band or maximum E value in a valence band, the group velocity acceleration depends on the curvature of E(k), so electrons and holes may seem ‘light’ or ‘heavy’, depending.
And a magnetic field will cause k to rotate, I think. But there may be reflections/refractions/diffractions??? in that process via bragg (??) planes, so that the k value of an electron might rotate around a leaf-shape…? Etc. Interesting stuff, and I definitely do not know the half of it.