Naked Science Forum

Life Sciences => The Environment => Topic started by: ROBERT on 29/11/2005 15:55:17

Title: global dimming
Post by: ROBERT on 29/11/2005 15:55:17
(http://i24.photobucket.com/albums/c23/SUEDONIM/th_SUNCLOUD.jpg)

image of "Global Dimming" by Robert.
BBC "Horizon" link:-
http://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_qa.shtml
Title: Re: global dimming
Post by: neilep on 29/11/2005 16:00:16
There was an amazing program on tv a while ago here in the UK which concentrated on a phenonemnon called 'Global Dimming'...it has been proven that in the last 50 years there has been drastically less sunlight reaching the earth. This has been empirically proven by ' Pan Evaporation ' (literally thousands of people filling a pan with water to the same level every single day and noting how much evaporation has ocurred with each refill at the exact same time. Records go back 100 years !!...also, light meters that literally detect the amount of sunlight reaching the Earth. First studies were done in Israel in the 50's, then again in the 80's, and intenationally too. They showed a dramatic decrease in sunlight, by as much as 10 to 30 percent.

It seems that dust particles and soot pollution physically block the sunlight and in clouds , the particles induce more water droplets which in turn create brighter clouds which act as mirrors that reflect the sunlight back.

Furthemore, after 9/11, there was a complete ban of air traffic for three days in the states and therefore there were no planes causing those air plumes/trails( sorry, can't remember the proper term) and during those three days the results of further tests that just in that short time, it mad a BIG difference to the point of 1 degreee celcius, which is astonishing.

It seems that this global dimming has a widespread effect on the environment, and for many years was dismissed by scientists because it goes against the grain of global warming. But do a search on ' global dimming' on google and you'll get quite a few revealing results,.

Men are the same as women.... just inside out !! (http://www.world-of-smilies.com/html/images/smilies/ugly/ugly_bums.gif)
Title: Re: global dimming
Post by: DoctorBeaver on 29/11/2005 18:49:13
Neil - I saw that program too. My initial reaction was sceticism in light (no pun inended) of the bruhaha about global warming; but the evidence put forward was fairly convincing. LIke a lot of people must be, I am now totally confused. Is the Earth warming up or cooling down? [8)]
Title: Re: global dimming
Post by: neilep on 29/11/2005 18:55:20
Perhaps it's just simmering at gas mark 1 ?...and the whole damn thing is a total earthly natural process and that we have only a sopucon of effect after all !...if any !


Men are the same as women.... just inside out !! (http://www.world-of-smilies.com/html/images/smilies/ugly/ugly_bums.gif)
Title: Re: global dimming
Post by: Simmer on 30/11/2005 07:06:23
quote:
Originally posted by neilep

Perhaps it's just simmering at gas mark 1 ?...and the whole damn thing is a total earthly natural process and that we have only a sopucon of effect after all !...if any !


I think what Sington was suggesting was that global dimming has been countering the effects of global warming and, as particulate emissions fall, the full effects of global warming will become apparent.

And I don't understand how you can interpret his statement as ambiguous on the effects of pollution on the environment!

 
quote:
I don't think the figures on global warming are open to interpretation. It is an established fact that global temperatures have risen by 0.6C over the past century. It is also an established fact that carbon dioxide levels have risen by about 100 parts per million over the same period due to human activity. It is a matter of the basic laws of physics that an increase in carbon dioxide will trap more heat in the Earth's atmosphere, which is why almost no respectable and independent scientist doubts the causal link between these two established facts.
Title: Re: global dimming
Post by: another_someone on 30/11/2005 07:47:16
quote:
Originally posted by Simmer
I think what Sington was suggesting was that global dimming has been countering the effects of global warming and, as particulate emissions fall, the full effects of global warming will become apparent.



Which leads one to the question as to whether there was any real joined up thinking over the reduction of atmospheric particulates while increasing concern about global warming.

Th reality is that I doubt we really have the expertise to understand the secondary effects of much of what we do to the atmosphere, which is why I am dubious about all those who insist that we must do this or that to avoid Armageddon we just don't know if doing this or that will have a secondary effect that will simply bring a different  Armageddon upon us.
Title: Re: global dimming
Post by: ROBERT on 30/11/2005 11:34:29
"Global dimming" counteracts "global warming",
is this proof that Gaia hypothesis is correct ?.

http://en.wikipedia.org/wiki/Gaia_hypothesis
Title: Re: global dimming
Post by: DoctorBeaver on 30/11/2005 14:01:14
To which of the Gaia hypotheses are you referring? There are numerous versions: some of which are broadly in line with scientific thinking, some most definitely not. Does the global ecosystem affect microsystems or vice versa? There are too many variables and unknowns for anyone to know exactly how the whole thing fits together.
Title: Re: global dimming
Post by: Simmer on 30/11/2005 19:48:49
quote:
Originally posted by another_someone
[br
The reality is that I doubt we really have the expertise to understand the secondary effects of much of what we do to the atmosphere, which is why I am dubious about all those who insist that we must do this or that to avoid Armageddon we just don't know if doing this or that will have a secondary effect that will simply bring a different  Armageddon upon us.



A lot of truth in that but it's a council of despair - no point in trying to avoid danger, something's bound to go wrong! [:)]

I think the motive for trying to limit airborne particulates was their direct effect on human health than any global environmental considerations.
Title: Re: global dimming
Post by: another_someone on 30/11/2005 21:21:50
quote:
Originally posted by Simmer
I think the motive for trying to limit airborne particulates was their direct effect on human health than any global environmental considerations.



There is some truth in that with regard to some of the particulate matter particularly the low level stuff, such as domestic or transport generated particulates.  Some of the stuff coming out of factory chimneys (including power stations) was of sufficient altitude that it may not have been as much of a local problem as that, but then would have been considered a problem due to acid rain.

Ofcourse, much of the reduction in particulates is also simply a byproduct of deindustrialisation, and not a consequence of policy at all.
Title: Re: global dimming
Post by: neilep on 04/12/2005 18:17:28
Do you think it is reasonable to assume that all this global warming/dimming is not human made but just a natural process of this planet ?..and that all the reports and endless studies are down to bad science ?...after all..we can not even predict local weather accurately let alone the global climate !

Men are the same as women.... just inside out !! (http://www.world-of-smilies.com/html/images/smilies/ugly/ugly_bums.gif)
Title: Re: global dimming
Post by: Ian33 on 04/12/2005 18:47:12
Perhaps your suffering from a little global dimming Neil ? Climate models are both accurate and scientists are using the best technology available to gather the data. You might not be able to predict local weather, but others in the Met Office can.

I luv2dance
Title: Re: global dimming
Post by: another_someone on 04/12/2005 18:51:31
quote:
Originally posted by neilep

Do you think it is reasonable to assume that all this global warming/dimming is not human made but just a natural process of this planet ?..and that all the reports and endless studies are down to bad science ?...after all..we can not even predict local weather accurately let alone the global climate !



In the broader context, I think we have to say we just don't know what the primary causes of these things are.

What we can say is that firstly, humans are a part of the natural process of this planet, so making a distinction between the two is somewhat artificial.

Secondly, the biosphere is dominated by the byproducts of life.  In the absence of life, there would be no oxygen on this planet.  Human kind is one of the (but by no means the only, and maybe not even the primary) dominant living organism on this planet, and thus unavoidably will have a significant part to play in the natural processes of the biosphere. What we might reasonably also say is that if humans did not do it, then some other species would fill the niches we leave behind, and probably have no less of an impact.  But, despite our arrogance, we are the slaves of nature, not the masters over it, and we may have an influence upon the world, but only such influence as nature dictates we should and can have.

There are two separate issues with regard to global temperature: firstly, how much of an influence does the biosphere have upon the temperature, and how much is due to extraterrestrial influences; and secondly, how dominant a force is human kind within the biosphere in this matter.

To the first question we may answer that we believe that the output of heat from the sun has grown in recent centuries, and so this must have had an influence upon global temperatures.  This does not preclude an influence within the biosphere, only that the evidence is that the biosphere alone does not determine the outcome of future temperature changes.

The second question is more complex because there are so many feedback cycles within the biosphere that no species can claim anything but partial influence upon the outcome, and none is capable of predicting its influence.

Title: Re: global dimming
Post by: another_someone on 04/12/2005 18:57:30
quote:
Originally posted by Ian33

Perhaps your suffering from a little global dimming Neil ? Climate models are both accurate and scientists are using the best technology available to gather the data. You might not be able to predict local weather, but others in the Met Office can.

I luv2dance



Climate models are anything but accurate.

Weather can be predicted probabilistically over relatively short periods of time.  We do not have the ability to state with any reasonable certainty the number of inches of rainfall in any particular part of the country on a given day two years into the future.

The fact that you say that scientists are 'using the best technology available', clearly indicates we are still at the bleeding edge of technology when it comes to climate and weather prediction, and we cannot say that this is stable and well understood technology.
Title: Re: global dimming
Post by: ROBERT on 05/12/2005 12:07:04
quote:
Originally posted by DoctorBeaver

To which of the Gaia hypotheses are you referring? There are numerous versions: some of which are broadly in line with scientific thinking, some most definitely not. Does the global ecosystem affect microsystems or vice versa? There are too many variables and unknowns for anyone to know exactly how the whole thing fits together.




Hi DoctorBeaver,
by "Gaia Hypothesis" I was referring to the theory that planet Earth is capable of a degree of homeostasis: can self-regulate, (not teleologically).
"Global Dimming" counteracting "Global Warming" seems to be a mechanism by which the Earth could self-regulate temperature.
As the Earth warms due to increased levels of greenhouse gas, ("Global Warming"), increased levels of water vapour enter the atmosphere from the warming oceans. The increased water vapour causes increased cloud cover, which reduces the amout of sunlight reaching the Earth's surface, ("Global Dimming"), so counteracting the temperature rise due to "Global Warming".

So "Global Dimming" coinciding with "Global Warming" could be evidence that Dr Lovelock's theory is correct.
Title: Re: global dimming
Post by: DoctorBeaver on 05/12/2005 12:24:39
Robert - I think there may be something in that. However, any homeostasis would probably be a reaction to natural phenomena. Here, we are talking about something to which mankind has probably made quite a contribution. We are using technology to alter the world. Would a naturally-balancing system, such as is proposed by Dr Lovelock, be capable of a) recognising and b) counteracting changes effected by technological means?
Title: Re: global dimming
Post by: another_someone on 05/12/2005 13:58:41
quote:
Originally posted by ROBERT

Hi DoctorBeaver,
by "Gaia Hypothesis" I was referring to the theory that planet Earth is capable of a degree of homeostasis: can self-regulate, (not teleologically).
"Global Dimming" counteracting "Global Warming" seems to be a mechanism by which the Earth could self-regulate temperature.
As the Earth warms due to increased levels of greenhouse gas, ("Global Warming"), increased levels of water vapour enter the atmosphere from the warming oceans. The increased water vapour causes increased cloud cover, which reduces the amout of sunlight reaching the Earth's surface, ("Global Dimming"), so counteracting the temperature rise due to "Global Warming".

So "Global Dimming" coinciding with "Global Warming" could be evidence that Dr Lovelock's theory is correct.



Any system that is capable of evolution and that is unable to self regulate, will inevitably be unstable, and thus will mutate, and continue to mutate, until it reaches a point where it evolves into a system of self regulation, which will prevent (or at least slow down) further evolution, and thus remain (at least for a time) the stable state of that system.

The distinction between stable and unstable is not absolute, since the only totally stable systems are dead systems (i.e. systems that are impervious to their environment, and are incapable of change).  Any system that is capable of evolution is a living system, and thus must contain some degree of instability, but it will seek to minimise that instability.

With regard to water vapour, there is much debate as to whether water vapour (which itself is a greenhouse gas) contributes to warming or cooling it seems to depend a lot on the nature in which that water vapour persists in the atmosphere.

One factor that is often overlooked is the role of fire, particularly forest fires, as a feedback mechanism within the environment.  Again, as with water, it has both positive and negative feedback components.  It will convert carbon and oxygen back to CO2, thus increasing the level of greenhouse gases (and also why forests should not be thought of as a long term carbon sink), but it also by doing this will limit the amount of oxygen in the environment (an increase in oxygen content will increase the probability of fire).  But, apart from CO2, forest fires also create soot, which should provide a negative feedback mechanism for global warming.  Like water vapour, it is difficult to tell whether the positive or negative feedback aspects of forest fires provides the dominant control feature.
Title: Re: global dimming
Post by: DoctorBeaver on 05/12/2005 14:17:41
quote:
Any system that is capable of evolution and that is unable to self regulate, will inevitably be unstable, and thus will mutate, and continue to mutate, until it reaches a point where it evolves into a system of self regulation, which will prevent (or at least slow down) further evolution, and thus remain (at least for a time) the stable state of that system.


If you are saying that all systems will eventually reach a state of self-regulation, even if only temporarily, then I agree. However, self-regulation is very different from stable. Evolution is based on mutation & instability. The only truly stable state for any system is entropic stability where nothing would ever happen. As the ecology of the Earth is not a closed system, I don't see how that could ever come about.
Title: Re: global dimming
Post by: another_someone on 05/12/2005 15:18:58
quote:
Originally posted by DoctorBeaver

If you are saying that all systems will eventually reach a state of self-regulation, even if only temporarily, then I agree. However, self-regulation is very different from stable. Evolution is based on mutation & instability. The only truly stable state for any system is entropic stability where nothing would ever happen. As the ecology of the Earth is not a closed system, I don't see how that could ever come about.



I don't think there is a huge gulf between what you are saying and what I have said.

You seem to regard dynamic stability as not being stability at all, and regard static stability as the only valid definition of stability.  That I think is more a matter of semantics.

All I was trying to say is that there is nothing particularly special (or Gaia like) about the Earth self-regulating it is a natural feature of all systems of that level of complexity.

Aside from looking at the universe in its totality, I'm not sure what would be truly a closed system, although there are ofcourse degrees of closure, and some subsystems are more susceptible to external input than other subsystems (an asteroid is internally more impervious to its environment than a full sized planet such as the Earth).
Title: Re: global dimming
Post by: DoctorBeaver on 05/12/2005 16:14:39
quote:
I don't think there is a huge gulf between what you are saying and what I have said


Agreed. I was just trying to nail a couple of definitions.

 
quote:
an asteroid is internally more impervious to its environment than a full sized planet such as the Earth


I'm not sure I understand what you mean by that.
Title: Re: global dimming
Post by: another_someone on 05/12/2005 16:53:21
quote:
Originally posted by DoctorBeaver
 
quote:

an asteroid is internally more impervious to its environment than a full sized planet such as the Earth



I'm not sure I understand what you mean by that.



Not sure that I meant as much as I had thought I might mean by that.

From an anthropocentric perspective, we are very dependent upon solar input in a way that an asteroid is substantially impervious of solar input not least because it lacks any atmosphere or other fluids through which heat can drive convection currents.  On the other hand, from the broader perspective, the biosphere is only a minutely thin layer upon the surface of the Earth, and that which forms the bulk of the Earth is far more influenced by the processes within the core of the Earth than it is by the solar radiation it receives at the surface.  So, ultimately, maybe the comment should be regarded as erroneous.
Title: Re: global dimming
Post by: DoctorBeaver on 05/12/2005 17:25:19
quote:
So, ultimately, maybe the comment should be regarded as erroneous.


*breathes a sigh of relief*
Title: Re: global dimming
Post by: Solvay_1927 on 05/12/2005 23:03:38
quote:
Do you think it is reasonable to assume that all this global warming/dimming is not human made but just a natural process of this planet ?..and that all the reports and endless studies are down to bad science ?...after all..we can not even predict local weather accurately let alone the global climate !


Neil, I wish I was as learned and erudite as Someone and Beaver. But I'm not. So I'll give you my straight answer: No.

It's reasonable to question whether it's human made or due to natural processes.  (The bulk of scientists who are knowledgeable about these things appear to think that human activity is contributing significantly to global warming, but the science is untested and there are too many parameters involved - so they could, just possibly, be wrong.)

But it's kind of dangerous to assume it's not human made.  My motto is "better safe than sorry".  If it's possible (though by no means proven) that we can slow the progress of global warming/dimming (and/or reduce its impact) by taking appropriate action now, I say let's take such action. (Er, provided there's no strong evidence that such action might actually make things worse in some other way, which is another question we don't know the answer to...[:(])


BTW, what happened to that promise of an Environmental Forum on TNS?
Title: Re: global dimming
Post by: another_someone on 06/12/2005 00:10:22
quote:
Originally posted by Solvay_1927

But it's kind of dangerous to assume it's not human made.  My motto is "better safe than sorry".  If it's possible (though by no means proven) that we can slow the progress of global warming/dimming (and/or reduce its impact) by taking appropriate action now, I say let's take such action. (Er, provided there's no strong evidence that such action might actually make things worse in some other way, which is another question we don't know the answer to...[:(])




You ask that we invest heavily in untried and untested solutions that we hope will slow down global warming/dimming, and yet that we refrain from such action only upon the strongest evidence that it be harmful.  Is there not something of an inconsistent bias, that we act upon mere suspicion, and refrain from action only upon strong proof of harm?  Where then your doctrine of 'better safe than sorry'?

I don't think anyone is assuming that humans play no part in any climate change (although I think it certainly wrong, and even arrogant, to suggest humans alone dictate, or might ever be capable of dictating, what changes should befall the climate of this planet), but I think there is a very different perspective we have with regard to what is the 'safe' option to play.

As for my being learned and erudite, I think you flatter me too much.
Title: Re: global dimming
Post by: Solvay_1927 on 06/12/2005 00:25:34
OK, OK!  Gawd, but you're a tough debater. [:D]

You're right, I was being inconsistent saying that we refrain only on "strong" evidence that it's harmful.

I admit I'm displaying subjective opinion rather than objective logic. I'm implicitly giving alot of weight to the body of scientific opinion which suggests that global warming (and/or dimming) is human made and that we can do something to slow it - whereas I'm not yet as convinced by the opposing arguments that it's just a natural process / that the proposed actions may prove detrimental.

Perhaps you can convince me why actions like reducing our dependence on fossil fuels may prove detrimental in the long run ... ?
Title: Re: global dimming
Post by: Solvay_1927 on 06/12/2005 00:32:46
And as for ...
quote:
You ask that we invest heavily in untried and untested solutions ...

No!  I just think that investing a little more (than the current miniscule amount) on researching and building alternative energy resources is unlikely to lead to major problems for the human race, whereas it might, possibly, help us to avert environmental problems in the future.  (Are you suggesting that wind power, for example, is "untried and untested"?)
Title: Re: global dimming
Post by: another_someone on 06/12/2005 00:54:55
quote:
Originally posted by Solvay_1927

Perhaps you can convince me why actions like reducing our dependence on fossil fuels may prove detrimental in the long run ... ?




Put like that, reducing any dependency, upon anything, can always be said to be purely beneficial.  The trouble is one never just reduces a dependency upon something (except maybe by dying), but rather switches dependency from one thing to another.

I have always believed that diversity in all things is beneficial, and for many reasons beyond that merely of climate change, I would willingly argue in favour of diversifying away from our strong (and in recent years, ever strengthening) dependency upon oil as a raw material.  This is not to say that I believe we should discard the benefits of oil, only that we should encourage greater diversity, and thus reduce both our exposure the loss of supply, and the likely damage we might cause through our use of oil.  If we were to wholly switch from oil to some other technology, with equal sole dependence upon that single technology, I would regard the risks as no less than those we face now with our high dependence upon oil.

The question is what are the alternatives we might use in place of oil.

In part, a reversion to coal, another fossil fuel, would itself help to diversify our risk; and I think it was a mistake to switch so much coal fuelled electricity generating capacity to gas fuelled capacity.  Beyond that, we could also increase the use of coal as a source of carbon for our chemical industry.

There is a resurgent interest in nuclear power, and probably with some merit.

I am very dubious about the use of so called 'renewable' energy sources.  Much has been made of the fact that fossil fuels utilise energy that is not a normal part of our environment (i.e. we have to dig it out of the ground, rather than collect it from our immediate environment).  This is seen by many as a problem, but I would argue it is more probably an asset.  We have already seen what happens when we tried to scale up hydroelectric energy production, the impact upon the environment was at least as great as the equivalent capacity drawn from fossil fuels.  I would argue that any alternative 'renewable' source would be just as risky.  The notion of 'renewable' energy is that we extract that energy from our immediate environment, and thus inherently must divert energy that is being used elsewhere within our environment, as well as having to create very large systems for collecting that energy (e.g. large dams and lakes, or large wind farms, or large cereal farms for biofuel production, or large solar array farms).  None of this is particularly problematic as long as it remains on a small scale, but I would predict it will become very problematic if one were to look towards obtaining 50% of our energy requirements from such sources.  I think there is a role to be played for 'renewable', particularly in small scale local energy production; but I am very wary of scaling it up too far.

Nor do I believe that reducing energy usage is a viable option.  Making more efficient use of energy is certainly desirable, but I will warrant that this will lead not to reduced energy consumption, but rather to increased output with only modest increases in energy usage.

As I said, for many reasons that have nothing to do with climate change, I would favour increased diversity of energy and raw material sources, and each of the above technologies have a valuable role to play; but I do not see CO2 targets as being something we should regard as one of our goals that we should be looking for.  In fact, too great an emphasis on CO2 targets may have the very effect of reducing diversity as we become obsessed about removing CO2 producing technologies rather aiming for a mixed technology base.

The safe option is always to never do too much of any one thing, but to do a little of everything.

Ironically, the NIMBY attitude to environmentalism can often make things a lot worse.  Firstly, one of the major inefficiencies in modern energy usage is energy distribution, in particular, the high cost of moving electricity around the country.  Yet, try convincing people that they should have power generating plants in their own locality and they will be up in arms over local pollution issues.  In particular, one possible source of energy is waste incineration (which will also save on land fill usage), but the NIMBYs wont have it.

Another case in point is zoning and planning permission.  If there was greater ease with which non-residential and residential facilities could be mixed in the same locality, it would reduce some of the transport requirements.  It is true that greater job specialisation has made it inevitable that some people will have to travel further for work, but not all jobs are so specialised that they need to find employees that are willing to commute 100 miles a day, and allowing factories and shops to be built closer to housing could reduce the need for much of the commute.

Again, my arguments for all of this is not because I am concerned about the likely effects upon the planet, but because these improvements in efficiency are beneficial in more direct ways than on a vague and unpredictable planetary basis.

The greater tragedy is that many of these factory have not only moved out of residential areas, but out of the country; thus increasing the amount our goods must travel around the world before reaching us.  This highlights the true hypocrisy of the CO2 targets, since by moving much of our manufacturing capacity overseas, we have made ourselves look like the good boys in environmental terms, while the Chinese and Indian are accused of increasing CO2 production, and we add to that the transportation costs involved.  Are we really buying fewer consumer goods than we did in the past not at all, we simply pay for the Chinese to manufacture them, and generate the CO2 byproduct, and we claim to have reduced CO2 production in this country.  True, if we keep this up long enough, we will run out of money to pay the Chinese, and we will then actually reduce consumption as well but I'm sure that is not in the minds of the politicians and environmentalists as they offshore ever more of our production capacity.

Title: Re: global dimming
Post by: another_someone on 06/12/2005 01:06:09
quote:
Originally posted by Solvay_1927
I just think that investing a little more (than the current miniscule amount) on researching and building alternative energy resources is unlikely to lead to major problems for the human race, whereas it might, possibly, help us to avert environmental problems in the future.  (Are you suggesting that wind power, for example, is "untried and untested"?)



Wind power is a well established technology, just as water power is a well established technology.  The problem is that scaling up wind power generation is an untested solution, just as scaling up water power was untested, and hydro power was at one time seen as the new clean source of fuel, until it was realised that that which worked happily on a small scale created problems when scaled up beyond a certain point.

It may even be argued that the backlash against hydro has now also gone too far, and maybe there is still a future role for hydro, but simply recognising that there are clear limits to how far it should be scaled up.

The problem with hydro, as with nuclear, and with oil, is that people have taken an all or nothing approach either it is good, and we should have ever more of it, or it is bad, and we should have none of it.  Neither is a healthy position to take with regard to any technology.
Title: Re: global dimming
Post by: DoctorBeaver on 06/12/2005 02:16:24
I agree with Another_someone that we need to diversify more.
If I may be allowed to throw another hat into the ring - the coast of north Norfolk is being eroded at an alarming rate. Hundreds of thousands of pounds has been spent trying to stop, or at least slow down, the damage. In many places the effort has now been stopped mainly for economic reasons. Why the hell wasn't a wave farm built just off the coast? Not only would that have provided electricity for at least the local area, but would have lessened the power of the waves hitting the coast thus slowing erosion dramatically. For some reason, though, it is offshore wind-farms that are being built.
Tides are much more predictable & reliable than winds, plus wind turbines are very intrusive on the landscapes. For maximum efficiency they are commonly built on high ground which makes them visible for miles around. Wave farms, on the other hand, are low & would not intrude on the environment to anywhere near the same extent.
However, I have seen it estimated that providing the UK with renewable energy would necessitate wind or wave farms covering an area the size of Kent. As energy usage is still increasing, that estimate may well be outdated before too long. Having that many wind or wave farms is obviously just not feasible.
AS we are no longer self-sufficient in coal, we are dependent on other countries to provide it; but their reserves won't last much longer either. North Sea oil & gas are running out fast.
With current technology, that leaves only nuclear power. I think I remember reading that 1 nuclear plant can generate the same power as a thousand-acre wind farm - plus the power output is predictable. Even though the disposal of waste from nuclear plants is very problematic, there really doesn't seem to be a viable alternative.
Title: Re: global dimming
Post by: DoctorBeaver on 06/12/2005 02:31:58
quote:
It may even be argued that the backlash against hydro has now also gone too far, and maybe there is still a future role for hydro, but simply recognising that there are clear limits to how far it should be scaled up.


One of the biggest problems with hydro power is geology. I can't think of many places south of Derbyshire where a viable hydro plant could be built. You, therefore, return to the cost of distribution. Plus, I think you will find that most places where a hydro plant would be viable are in areas where the staff would have trouble getting to work in the winter - the Peak District, Lake District, Wales, or the Scottish mountains. Roads are regularly impassable in those areas when it snows. Short-staffed during the worst weather when demand for power is highest? Not a good plan, methinks.
Waste incineration is an option, but again would not provide more than a very modest contribution to the power demands of a country like the UK. I think the strongest argument in favour of incineration is that of ecology rather than power generation.
Title: Re: global dimming
Post by: DoctorBeaver on 06/12/2005 02:32:42
Erudite? I thought that was an epoxy resin!
Title: Re: global dimming
Post by: another_someone on 06/12/2005 11:44:32
quote:
Originally posted by DoctorBeaver
I agree with Another_someone that we need to diversify more.



A problem I see with diversity is psychological.  People like to compete, to prove themselves the best at something.  In order to be the best, you have to have something to measure.  It is (at least in principle, if not always in practice) easy to measure the amount of carbon you consume, and so create a race to reduce carbon consumption, but how do you measure diversity?

The very nature of diversity is that it is not one dimensional, and so you cannot have a single number that shows one person is best, and another is worst.

quote:

If I may be allowed to throw another hat into the ring - the coast of north Norfolk is being eroded at an alarming rate. Hundreds of thousands of pounds has been spent trying to stop, or at least slow down, the damage. In many places the effort has now been stopped mainly for economic reasons. Why the hell wasn't a wave farm built just off the coast? Not only would that have provided electricity for at least the local area, but would have lessened the power of the waves hitting the coast thus slowing erosion dramatically.



In principle, I would agree with you, but to play devils advocate, I would put forward the following issues.

Firstly, the east coast of England, particularly the South-East, is the most heavily populated region of the UK, both on land and at sea (with regard to shipping lanes, etc.).  Any risk associated with any venture there will have the largest human impact, and the most visible political impact.  Sticking something out into the Atlantic is well out of sight of most of the population, so if it works, it can be trumpeted as a great success, and if it has adverse side effects, these can be kept out of the public eye.

For this reason, just getting planning permission to do anything off the coast of Norfolk would be infinitely more problematic than doing the same off the west coast of Scotland.

Again, I suspect it goes back to what I was saying about NIMBY.

quote:

AS we are no longer self-sufficient in coal, we are dependent on other countries to provide it; but their reserves won't last much longer either.



The reason we are no longer self sufficient in coal is not because we ran out of it, far from it, we still have lots left to dig up; it is because UK labour rates were uncompetitive at the prevailing currency exchange rates, making it cheaper to have other people dig up their coal using their cheap labour (or, in some countries, state subsidised labour) than to have our people dig up our coal.

quote:

 North Sea oil & gas are running out fast.



If the high oil prices are maintained for any length of time, I suspect we will find that we have not run out of oil as much as we thought we had.  We had simply run out of that oil which could economically be extracted (in fact, it is the exploration rather than the extraction cost which is the dominant factor) at the prices that were current a few years back.

quote:

With current technology, that leaves only nuclear power. I think I remember reading that 1 nuclear plant can generate the same power as a thousand-acre wind farm - plus the power output is predictable. Even though the disposal of waste from nuclear plants is very problematic, there really doesn't seem to be a viable alternative.



I accept there are challenges associated with waste disposal from nuclear plants, but I also think people can get far too hysterical about waste disposal in general.

Heavy metals, such as lead and cadmium, are substances that we dig out of the ground; and yet people get panicked at the thought of disposing of them by putting them back into the ground.  Uranium is one of the most ubiquitous elements in the environment (albeit, in low concentrations), and yet people get panicked at even the most dilute amounts of uranium being leaked back in to the environment.  I agree that we should not create high concentrations of these substances in one place, but the very nature of lowering concentrations is that they should be spread over a large area.

The case of nuclear power is somewhat unique in that we create elements and isotopes that are rarely if ever found naturally on this planet.  Much of the radiation risk I suspect is overhyped, since long lived isotopes (such a uranium 235/238, or even plutonium 239 assuming they are not involved in a fission chain reaction) by their very nature cannot be very radioactive.  It is the short lived isotopes (such as the cobalt 60 so beloved of the medical profession but people are much less panicked about the use of cobalt 60 in hospitals than they are by uranium in nuclear power plants) that will carry greater radiation risk.

Ofcourse, we must also take into account the chemical risks that these exotic elements produce, but that is no different to the chemical properties of the non-radioactive isotopes of the same elements (although there is ofcourse no such thing as a non-radioactive isotope of plutonium, even though plutonium is not highly radioactive).  Nonetheless, it is the word 'radioactive' that causes so much public alarm, particularly in conjunction with the word 'nuclear' (it always amuses me that people found it politically necessary to relabel 'NMR' to 'MRI' in order to remove the reference to 'nuclear'; and the use of the term 'radiotherapy' rather than 'radiation therapy', because radio is a benign word, and radiation is not).  I have in the past had long debates with people about the long term risks of DU (depleted uranium, as used in munitions), and for the most part, it seems that the risk posed by DU is comparable to, but slightly less than that posed by an equal amount of lead.  Nonetheless, because lead is not radioactive (the fact that DU has a half life of 4.5 billion years scarcely makes it radioactive at all) makes for far more hysteria over that element than the concern over lead in munitions.
Title: Re: global dimming
Post by: another_someone on 06/12/2005 11:49:53
quote:
Originally posted by DoctorBeaver

Waste incineration is an option, but again would not provide more than a very modest contribution to the power demands of a country like the UK. I think the strongest argument in favour of incineration is that of ecology rather than power generation.



I agree, it would only be a modest amount of power; but the very nature of diversity is that one would not expect a single source to solve all our needs, and it is a source that is almost begging to be utilised, so why not use it for what we can get (apart from the NIMBY factor).  Furthermore, it is a source, which if managed properly, can be generated close to point the end user demand (since the greatest volume of incineratable  waste will be most likely be in the same geographic locality as the greatest demand for power exists), thus reducing the cost of energy transportation.

Again, while we are wildly digressing from the original point, another case where I think the NIMBY factor is counter-productive is in the rush towards electric powered cars.  I am not talking about hybrid cars, where electricity is used as a temporary power storage mechanism, which I believe is a positive step in power management; but in pure electric cars.  The more I look at the inefficiencies in power transmission, the more I conclude that any system that relies on the creation of electricity in one location, and its use hundreds of miles away, is counter-productive both in resource utilisation and in waste production.  The problem is that electricity consumption is seen as 'clean', while electricity production is seen as 'dirty', so the NIMBYs are quite happy to see lots of local electricity usage, so long as the generating capacity is moved well beyond their horizons.
Title: Re: global dimming
Post by: DoctorBeaver on 06/12/2005 12:46:35
quote:
Firstly, the east coast of England, particularly the South-East, is the most heavily populated region of the UK, both on land and at sea (with regard to shipping lanes, etc.)


The north coast of Norfolk is fairly sparsely populated & the shipping in that area round to the Wash is negligible.

 
quote:
A problem I see with diversity is psychological. People like to compete, to prove themselves the best at something. In order to be the best, you have to have something to measure. It is (at least in principle, if not always in practice) easy to measure the amount of carbon you consume, and so create a race to reduce carbon consumption, but how do you measure diversity?


"We're more diverse than you are so ner ner". Crudely put, but it makes my point LOL


 
quote:

The reason we are no longer self sufficient in coal is not because we ran out of it, far from it, we still have lots left to dig up; it is because UK labour rates were uncompetitive at the prevailing currency exchange rates, making it cheaper to have other people dig up their coal using their cheap labour (or, in some countries, state subsidised labour) than to have our people dig up our coal.


Very true. I didn't say otherwise. But would people be prepared to pay a lot more for electricity generated from coal-burning than by nuclear? Somehow I doubt it.



 
quote:

If the high oil prices are maintained for any length of time, I suspect we will find that we have not run out of oil as much as we thought we had. We had simply run out of that oil which could economically be extracted (in fact, it is the exploration rather than the extraction cost which is the dominant factor) at the prices that were current a few years back.


I'm not sure that's entirely true but I don't have any figures to hand so I can't argue the point.

 
quote:
I accept there are challenges associated with waste disposal from nuclear plants, but I also think people can get far too hysterical about waste disposal in general.


 
quote:
Much of the radiation risk I suspect is overhyped, since long lived isotopes (such a uranium 235/238, or even plutonium 239 assuming they are not involved in a fission chain reaction) by their very nature cannot be very radioactive. It is the short lived isotopes (such as the cobalt 60 so beloved of the medical profession but people are much less panicked about the use of cobalt 60 in hospitals than they are by uranium in nuclear power plants) that will carry greater radiation risk.


Agreed 100%
Title: Re: global dimming
Post by: Solvay_1927 on 06/12/2005 13:34:13
Someone - yep, I agree with all you say.  Thanks for the education.

Eth - same to you - you're very learned and araldite too. [;)]
Title: Re: global dimming
Post by: DoctorBeaver on 06/12/2005 14:12:22
"Leaned" rather then "Learned" methinks
Title: Re: global dimming
Post by: AlphBravo on 08/12/2005 23:34:28
The thing I notice about Global warming+Dimming is that regardless of the cause we are now facing a period of transition, and the fact that as Twain said, over a century ago: "Everyone talks about the weather, but no one does anything about it". It is probably more pertinent than ever today, after all the foodstocks etc are not that resilient to withstand a mega drought, which is what we are lead to believe we are facing drier dries and wetter wets and maybe out of kilter.
Title: Re: global dimming
Post by: another_someone on 09/12/2005 00:36:20
quote:
Originally posted by AlphBravo

The thing I notice about Global warming+Dimming is that regardless of the cause we are now facing a period of transition, and the fact that as Twain said, over a century ago: "Everyone talks about the weather, but no one does anything about it". It is probably more pertinent than ever today, after all the foodstocks etc are not that resilient to withstand a mega drought, which is what we are lead to believe we are facing drier dries and wetter wets and maybe out of kilter.



On the contrary, our capacity to grow food today is greater (even taking into account population size) than it has at any time in history, which is why farmers in the wealthier parts of the world are unable to get even half decent prices for their products, and why so many farmers are going out of business (not because they can't grow the food, but because they can't sell it).

There is a problem that the Third World neither has the efficiency of food production that the industrialised world has (and often has internal political problems that compound the technical ones), and cannot afford the prices (even those prices that Western farmers consider uneconomically low) to buy food from the industrialised countries.

The only problem that any reduction in the environmental conditions for growing food may have is because so many farmers have left the business that it will take time to get them back into the food growing business.