Climate Modeling using a Leaky Integrator

[VillagePlank]

Are there any figures available as to how much area tarmac and concrete has increased by? I would imagine that the storage effect there would be noticeable.. ? Can't find any figures though at the mo.. Or is there a way to factor in the re radiation of stored heat?

I suspect the albedo effect would be exponential with population growth if we are talking about a global model. Does anyone have good population figures? And is it suitable to extrapolate the two?

I don't have any stats unfortunately, but I also imagine that, in particular, large areas of dark concrete (such as the dark grey road surfaces that are widespread in the UK) would also increase the surface albedo.

Another point re. albedo that I don't think has been fully accounted for in the scientific literature- could urbanisation be contributing to global warming, be it through albedo, the output of heat via the urban heat island etc? It would certainly be interesting to see what climate models made out of the effects of adding urban heat sources to the mix. However I don't know if that would be within the scope of the leaky integrator model or not.

Good post.

Albedo is one of the dark areas of study. Not because it's some conspiracy, but rather, it's so damn hard to quantify. If you can't quantify you can't include it in a model. I think PottyProf is onto something if my assertion that we an assume that population is somehow linearly connected to albedo.

[tundra]

I don't have any stats unfortunately, but I also imagine that, in particular, large areas of dark concrete (such as the dark grey road surfaces that are widespread in the UK) would also increase the surface albedo.

Don't you mean decrease the surface albedo.(high albedo=snow,and ice etc)

[Thundery wintry showers]

Aye- well spotted! For reasons that I can't fathom I somehow got the impression that it was the other way around- but the facts say otherwise.

[pottyprof]

I've found this on world population..

http://www.census.gov/ipc/www/idb/worldpop.html

Any good??

[Admiral_Bobski]

Thinking about the ENSO/temperature correlation over on Android's thread has got me thinking.

We are trying to use a perturbative approach to this problem, which means, basically, that we're trying to find the single biggest factor and then add on successively smaller factors to further refine the graph.

Our one main assumption of the LI is that the biggest factor is the Sun.

After that we added in Volcanic data. How about we go back to square one (sorry!) and try a graph using just Sunspots and ENSO? Just to see what happens.

(To be continued...!)

:lol:

CB

Edited May 1, 2009 by Captain_Bobski

[Methuselah]

Probably missed something here; but how much has been agreed on cloud feedbacks?

This is one area in which I remain highly sceptical on just about any claim being made - including those of the IPCC! :lol:

[Thundery wintry showers]

Aye- and if I remember rightly, reading between the lines of the IPCC report they were even pretty sceptical of their own claims re. clouds!

A graph with just sunspots and ENSO would certainly be interesting.

[Methuselah]

A graph with just sunspots and ENSO would certainly be interesting.

Agreed!

[Admiral_Bobski]

As I understand it, low clouds are supposed to cause warming and high clouds are supposed to cause cooling.

How in the name of heck anyone is supposed to figure out high cloud to low cloud ratios in the historic record is beyond me! I would wager that it just can't be done. Is anyone anywhere recording high cloud/low cloud ratios? Even if someone did when the AR4 came out it would only give us about a year's worth of data, which is fairly useless at present - maybe in 30 years time?!

Cloud feedbacks are a gaping hole in our understanding of climate, and I can't see any easy way around it at the moment. Perhaps it's something to look deeper into - maybe somebody has figured some kind of proxy out...

Still...

Let's all ask VP very nicely if he could knock together a Sunspot+ENSO graph for us

CB

[Methuselah]

How in the name of heck anyone is supposed to figure out high cloud to low cloud ratios in the historic record is beyond me!

CB

I was pondering the very-same thing on my way in to work today (that's 20 mins); I came up with b****r all!

[jethro]

I was pondering the very-same thing on my way in to work today (that's 20 mins); I came up with b****r all!

Beyond everyone I think.

I suppose (Dawnie logic, could be way off beam) the positive feedback loop is more heat contained, more evaporation, leading to more heat retention, leading to more evaporation ad infinitum - if that's true and happening, wouldn't humidity levels reflect this? Or is that utter gibberish from me?

[Methuselah]

Beyond everyone I think.

I suppose (Dawnie logic, could be way off beam) the positive feedback loop is more heat contained, more evaporation, leading to more heat retention, leading to more evaporation ad infinitum - if that's true and happening, wouldn't humidity levels reflect this? Or is that utter gibberish from me?

From a purely peterolgical standpoint - it might!

[Red Raven]

Going back to albedo for one moment I'm not so sure that urbanisation will have a great effect. There is no doubt locally it will but the proportion of covered land is very small.

It has however made think of other possibilities to do with deforestation. A couple of trains of thought...

Large forested areas are dark and therefore absorb more heat but does this heat cause more heat transfer due to evaporation of the associated water content - ie does it lead to a net heat reduction.

Deforestation opens up land and potentially decreases moisture content - does this allow air to warm more rapidly or does the extra dust cause a reduction in albedo.

I don't have the answer afraid - just questions.

[Admiral_Bobski]

Thanks to everyone so far for chipping in :unsure:

With regards humidity levels, I had this thought a while back, but I can't seem to find a data set that covers humidity globally, or for very long. There's a few places (especially in America and Australia) that provide local humidity data, but I somehow doubt that local data would be able to be extrapolated globally.

It may be an area worth looking into further, if I only knew what to search for! Any ideas, anyone?

With regards urbanisation, I'm not sure how easy it would be to quantify the effect. The albedo effect is quite probably minimal because, as Red Raven says, urban land coverage is proportionally small. However, what about the UHI? In Winter, urban areas churn out heat from central heating, in Summer they churn out heat from air conditioning and so. All this heat is created by the conversion of energy from one form (electrical or chemical) into another (heat). Does this extra heat have a significant effect globally?

Again, any ideas or thoughts?

CB

[Thundery wintry showers]

To my knowledge, the current consensus view among scientists is that the UHI has a negligible effect on global temperatures- but this is open to question. Some recent research provided climate model based analysis which tended to underestimate summer temperatures unless the effects of the UHI were added to the model. The researchers in question didn't look strongly into the possibility, but it certainly had me wondering about questions along the lines of what Capt.Bob posted above, and I remember raising a couple and getting a positive response.

Unfortunately the climate scientists are only just getting into the idea, and I'm not aware of any "sceptic" research into it, so we may well be on our own here!

[The Penguin]

I think the effects of UHI are relevant but not significant. There is a recordable air temperature difference within and over cities and the magnitude of this varies with latitude, greater where ambient temperatures are lower. The average appears to be 4 to 5 degrees C for large cities, although London has been recorded at 10 degrees C above the surrounding countryside. Again, in the instance of large cities, cloud formation, rainfall patterns and even wind direction and velocity can all be modified by the UHI influence. However, in terms of the planet’s surface area the zone of influence covered by the sum of all UHI’s is tiny and therefore so is the effect on global weather.

[weather eater]

Thanks to everyone so far for chipping in

With regards humidity levels, I had this thought a while back, but I can't seem to find a data set that covers humidity globally, or for very long. There's a few places (especially in America and Australia) that provide local humidity data, but I somehow doubt that local data would be able to be extrapolated globally.

It may be an area worth looking into further, if I only knew what to search for! Any ideas, anyone?

With regards urbanisation, I'm not sure how easy it would be to quantify the effect. The albedo effect is quite probably minimal because, as Red Raven says, urban land coverage is proportionally small. However, what about the UHI? In Winter, urban areas churn out heat from central heating, in Summer they churn out heat from air conditioning and so. All this heat is created by the conversion of energy from one form (electrical or chemical) into another (heat). Does this extra heat have a significant effect globally?

Again, any ideas or thoughts?

CB

And how much heat does the use of dark materials like tarmac absorb, very difficult to quantify. Some urban areas in Mediterranean areas for instance use pale materials or whitewash and so urban areas may well reflect as much heat as they absorb.. Even if calculations could be made on modern urbanisation reconstructing the past would be impossible.

[The Penguin]

And how much heat does the use of dark materials like tarmac absorb, very difficult to quantify. Some urban areas in Mediterranean areas for instance use pale materials or whitewash and so urban areas may well reflect as much heat as they absorb.. Even if calculations could be made on modern urbanisation reconstructing the past would be impossible.

Ah, but urban areas are drier, the surfaces are impermeable, water is carried away in sewers and therefore evaporation is far less than the organic, rural hinterland whether or not heat is reflected or absorbed.

[weather eater]

Ah, but urban areas are drier, the surfaces are impermeable, water is carried away in sewers and therefore evaporation is far less than the organic, rural hinterland whether or not heat is reflected or absorbed.

Doesn’t make it any easier to make calculations though. On a slightly less savoury note what about methane emissions caused by 6.77 billion people.

[The Penguin]

Doesn’t make it any easier to make calculations though. On a slightly less savoury note what about methane emissions caused by 6.77 billion people.

Oh tsk, you know quite well that only half of them live in cities....

[tundra]

As I understand it, low clouds are supposed to cause warming and high clouds are supposed to cause cooling.

CB

I think you will find its the other way around.

[Admiral_Bobski]

I think you will find its the other way around.

Is it?

I thought it was the high clouds that reflected incoming sunlight and the low clouds that trapped outgoing radiation...I could be wrong - it does happen from time to time!

Anyone care to cast the deciding vote?

CB

[Thundery wintry showers]

To be honest, I don't know about the feedbacks that most types of clouds give. There is considerable uncertainty generated by aerosol inputs in particular.

Contrails & high cloud have a well-known forcing of reducing the diurnal range, for instance diurnal ranges increased by 1.1C over the USA following September 11th. Whether the overall forcing is towards warming or cooling I'm not sure, but it will probably be more towards warming at high latitudes and cooling at low latitudes. Indeed, that is probably true of most clouds. But I have no idea about the net global effect, and I'm not sure the IPCC has much more of an idea than I have!

With regards the urban heat island, one thing worth noting (and that I didn't think of until today) is that even if the UHI has a significant impact on the UK mean temperature it doesn't mean it has a significant impact on global temperatures- as the UK has far more urbanisation per unit area than the globe as a whole. I hope that the scientists will get down to researching into this one day, though gut feeling suggests to me that it won't be among the bigger forcings.

[Solar Cycles]

What about the decrease in heat trapping cirrus clouds, these have served as proxies in the past!

[tundra]

I am not sure how to copy and post text so i have had to do this the long way.

WBZ-tv in Boston ran a short video interview with harvard astrophysicist Dr Willie Soon back on the 14.04.09 discussing the plausible scenarios of a dimmer sun on the Earth's climate.