[ROBERT]

image of "Global Dimming" by Robert.
BBC "Horizon" link:-
http://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_qa.shtml

[neilep]

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 !!

[DoctorBeaver]

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? []

[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 !


Men are the same as women.... just inside out !!

[Simmer]

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 0.6°C 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.

[another_someone]

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.

[ROBERT]

"Global dimming" counteracts "global warming",
is this proof that Gaia hypothesis is correct ?.

http://en.wikipedia.org/wiki/Gaia_hypothesis

[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.

[Simmer]

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.

[another_someone]

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.

[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 !

Men are the same as women.... just inside out !!

[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

[another_someone]

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.

[another_someone]

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.

[ROBERT]

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.

[DoctorBeaver]

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?

[another_someone]

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.

[DoctorBeaver]

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.

[another_someone]

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).

[DoctorBeaver]

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.