Global Dimming/Horizon

[daverobev]

Anyone watch this? Was on BBC2 just now, 9pm to 9:50 I think.

Basically the reason Global Warming hasn't been "terrible" is that Global Dimming has been a force pulling in the opposite direction. Lots of smog particles (incompletely combusted fuel etc) go into the atmosphere and thus into clouds. Many more of these than of natural ones (like pollen) that rain droplets condense on, making a cloud consist of many more, but smaller, rain drops.

Net effect? Higher reflection rate of sunlight by clouds - 10% or more, i.e. 10%+ LESS sunlight getting through. Probably to blame for drought in north africa.

Fine, so its being fixed by more complete combustion of fuels...but its going to stop countering Global Warming. So temperatures are going to rise. By maybe 10 degrees C in the next hundred years - way past the point of no return.

Any thoughts? Anyone going to give up their car, central heating, etc??

Personally I'm very, very scared...

[Byatt]

I saw this, hope it's wrong, if it isn't, we're buggered, there's no way we're going to be able convince the world to stop spewing out CO2 fast enough, I think.

Might be a good weekend to spend planting sodloads of trees.

[GreenPiggy]

basically the world is pretty much screwed unless someone can invent a CO2 condenser.
Forget what Bushes oil buddies say.

[BUFF]

More nuclear powerplants fast (but the Greens won't like it).

Oh & if somebody could find away to cool the Sun down to it's older temps that would be mighty useful too. Basically whatever we do on Earth could be negated by the Sun's continuous increase in heat as it ages.

[TiG]

Workable Fussion will be here in ten years if the plans of european body governing the work gets its way.

as a concept its very effective at generating huge amounts of energy, is virtually limitless in its fuel source and doesn't pollute.

that said, that doesn't power cars, make plastic and the hundreds of other uses that oil does...

Substitute to oil is more important imo...

TiG

[Rcb]

It was very scary

I really don't want to live in an apocalyptic wasteland.

[Zedmeister]

Tis an interesting topic. Shame that many oil industry lobbyists keep trying to push the idea that "There is no global warming"...

I really don't want to live in an apocalyptic wasteland.

Never been to Cov on a saturday night then?

[Gunbuster]

Yeah it was pretty scary. One positive thing to take away though is that the effects of countering the causes of global dimming are making an impact. So if we can manage that I'm sure we can manage something.

Is it actually possible to remove green house gases from the atmosphere? rather than just count on reducing output?

[daverobev]

Tis an interesting topic. Shame that many oil industry lobbyists keep trying to push the idea that "There is no global warming"...

But thats the point...global warming has been seen as less of a problem up to now BECAUSE global dimming has been shielding us from the worst, its a counter to GW in some ways.

Did you see the bit with the guy who takes readings of net temperature change over a day? After 9/11, when there were no planes flying over the USA, temperature change increased by a degree, more than he'd ever seen...basically even the vapour trails of planes is shielding us from global warming...

Anyone know about home energy production? Surely sitting on a bike and pedalling for a while would produce some energy? And solar panels for hot water and so on? I reckon I'm gonna have a look at investing...but I guess really it needs change on a country wide level...

[malfunction]

Just to try and put some of this in perspective... No one in their right mind thinks that polluting the planet is a good idea.

But a 1 degree change in a day. Blimey - that MUST be down to pollution. The temperature never changes for any other reason now does it?

Also - and I'm not saying I know anything at all about it but back in college when learning about the carbon cycle we discussed global warming and there's also the theory that:

1) Carbon dioxide stops heat from leaving the earth...

2) 2/3rds of the earth surface is water

3) As things get hotter more water evaporates

4) Water vapour blocks the heat from getting down to the earth's surface in the first place

A LOT more probable than the above IMO

[Zedmeister]

Actually to see extreme global warming look at the planet Venus which has a runaway greenhouse effect.

[daverobev]

Just to try and put some of this in perspective... No one in their right mind thinks that polluting the planet is a good idea.

But a 1 degree change in a day. Blimey - that MUST be down to pollution. The temperature never changes for any other reason now does it?

Also - and I'm not saying I know anything at all about it but back in college when learning about the carbon cycle we discussed global warming and there's also the theory that:

1) Carbon dioxide stops heat from leaving the earth...

2) 2/3rds of the earth surface is water

3) As things get hotter more water evaporates

4) Water vapour blocks the heat from getting down to the earth's surface in the first place

A LOT more probable than the above IMO

Hmm, no.

Not 1 degree C difference, a change of max temp-min temp of a degree, throughout the 24 hour period. IE, if it was 33 during the day and 12 at night thats 21 degrees, you would expect the next day max and min to be about 21 degrees also..as the guy said its not variation in temperature, its variation in the max-min temps for a period relative to the day before and after. There was a jump which is unprecedented when there were no vapour trails. That is hotter during the day and colder at night combined - the DIFFERENCE was greater by a degree. This had never been seen in decades of keeping records, but happened when there were no planes, after 9/11. That isn't global warming its dimming - the vapour trails were keeping sun out.

Also, there were some Australian scientists/climatologists who were studying "pan evapouration" rates - put x amount of water in a big pan, and see how much evapourates. Rates have been decreasing lately. How so when the global temperature is up? Well, it turns out that evapouration is MOSTLY governed by light, not heat. Photons from the sun hitting the surface of the water kick H2O out, not just general warmth.

You're mixing up CO2 which causes heat retention/global warming, and sooty particles which sit in the atmosphere and make clouds with more, but smaller, raindrops, which reflects the sunlight (dimming).

In the past the effect of reflecting light back and CO2 keeping heat in has maintained the temperature, or at least held it in check. Because we are now cleaning our fuel - performing complete combustion and emitting less soot, basically - global dimming is waning, meaning the full force of warming (with more sunlight getting through, thus more being held in) could be felt...

They were saying that 10% of light was being reflected, about that over the globe. So if nothing else global warming will speed up because there is more heat getting in to begin with.

*Edit* and with respect to more heat in, more evapouration, thus more cloud and more blocking....well remember the "natural" clouds actually reflect a lot less light than the sooty ones...

[malfunction]

Hmm, no.

Not 1 degree C difference, a change of max temp-min temp of a degree, throughout the 24 hour period. IE, if it was 33 during the day and 12 at night thats 21 degrees, you would expect the next day max and min to be about 21 degrees also

Oh please. Use your brain. I don't care what that guy was paid to say.

Look here:

http://www.bbc.co.uk/

Look at the bit that says weather

Today
max 6°C
min 5°C

Tomorrow
max 9°C
min 3°C

OH NO! WE'RE ALL DOOMED! DOOOOOOMED!

[malfunction]

Hmm, no.

Also, there were some Australian scientists/climatologists who were studying "pan evapouration" rates - put x amount of water in a big pan, and see how much evapourates.

And that's a scientific experiment is it? Again... On any given day there are loads of things that could affect the evaporation (moisture content in the air, air pressure, temp, whether or not you turned the hob on)

[daverobev]

Okey dokey:

Full transcript http://www.bbc.co.uk/sn/tvradio/prog...ng_trans.shtml

I quote:

"DR DAVID TRAVIS: Here are some examples of what we call outbreaks of contrails. These are large clusters of contrails. And here's a particularly er good one from Southern California. Here's the west coast of the United States. And you can see here this lacing network of contrails er covering at least fifty per cent, if not seventy five per cent or more of the sky in that area. It doesn't take an expert to er realise that if, if you look at the satellite picture and see this kind of contrail coverage that they've got to be having an effect on temperature at the surface.

NARRATOR: But the problem Travis faced was to establish exactly how big an effect the contrails were actually having. The only way to do that was to find a period of time when, although conditions were right for contrails to form, there were no flights. And, of course, that never happened. Until September 2001. Then, for three days after the 11th virtually all commercial aircraft in the US were grounded. It was an opportunity Travis could not afford to miss. He set about gathering temperature records from all over the USA.

DR DAVID TRAVIS: Initially data from over 5,000 weather stations across the 48 united states, the areas that was most dominantly affected by the grounding.

NARRATOR: Travis was not looking just at temperature - that varies a lot from day to day anyway. Instead he focused on something that normally only changes quite slowly: the temperature range. The difference between the highest temperature during the day and the lowest at night. Had this changed at all during the three days of the grounding?

DR DAVID TRAVIS: As we began to look at the climate data and the evidence began to grow I got more and more excited. The actual results were much larger than I expected. So here we see for the 3 days preceding September 11th a slightly negative value of temperature range with lots of contrails as normal. Then we have this sudden spike right here of the 3 day period. This reflects lack of clouds, lack of contrails, warmer days cooler nights, exactly what we expected but even larger than what we expected. So what this indicates is that during this 3 day period we had a sudden drop in Global Dimming contributed from airplanes.

NARRATOR: During the grounding the temperature range jumped by over a degree Celsius. Travis had never seen anything like it before.

DR DAVID TRAVIS: This was the largest temperature swing of this magnitude in the last thirty years.

NARRATOR: If so much could happen in such a short time, removing just one form of pollution, then it suggests that the overall effect of Global Dimming on world temperatures could be huge."

Thats about 7/8ths of the way down.

And pan evapouration rates:

"PROF GRAHAM FARQUHAR (Australian National University): It's called pan evaporation rate because it's evaporation rate from a pan. Every day all over the world people come out in the morning and see how much water they've got to add to a pan to bring it back to the level it was the same time the morning before. It's that simple.

NARRATOR: In some places agricultural scientists have been performing this rather dull daily task for more than a hundred years. PROF GRAHAM FARQUHAR: The long-term measurements of pan evaporation are what gives it its real value.

DR MICHAEL RODERICK (Australian National University): And the fact that they're doing the same thing day in day out with the same instrument.

PROF GRAHAM FARQUHAR: Yeah, they deserve a medal. Each of them.

DR MICHAEL RODERICK: Yeah.

NARRATOR: For decades, nobody took much notice of the pan evaporation measurements. But in the 1990s scientists spotted something very strange, the rate of evaporation was falling.

PROF GRAHAM FARQUHAR: There is a paradox here about the fact that the pan evaporation rate's going down, an apparent paradox, but the global temperature's going up.

NARRATOR: This was a puzzle. Most scientists reasoned that like a pan on the stove, turning up the global temperature should increase the rate at which water evaporated. But Roderick and Farquhar did some calculations and worked out that temperature was not the most important factor in pan evaporation.

DR MICHAEL RODERICK: Well it turns out in fact that the key things for pan evaporation are the sunlight, the humidity and the wind. But really the sunlight is a really dominant term there.

NARRATOR: They found that it was the energy of the photons hitting the surface, the actual sunlight, that kicks the water molecules out of the pan and into the atmosphere. And so they too reached an extraordinary conclusion.

DR MICHAEL RODERICK: You know, if the pan is going down then maybe that's the sunlight going down. NARRATOR: Was the fall in pan evaporation in fact evidence of Global Dimming? Somewhere in the journals, they felt, must be the hard numbers that could tie the two things together.

DR MICHAEL RODERICK: And then one day, just by accident, I had to go to the library to get an article out Nature. As you do, I couldn't find it. And I just glanced at a, through the thing, and there was an article called Evaporation Losing Its Strength. Which reported a decline in pan evaporation over Russia, United States and Eastern Europe. And there in the, in the measurements, they said that the, the pans had on average, evaporated about a hundred millimetres less of water in the last thirty years.

NARRATOR: Mike knew how much sunlight was needed to evaporate a millimetre of water. So he put the two sets of figures together - the drop in evaporation with the drop in sunlight.

DR MICHAEL RODERICK: And so you just do the sum in your head. A hundred millimetres of water, less a pan evaporation, two and a half mega joules, so two and a half times a hundred is two hundred and fifty mega joules. And that is in fact what the Russians have measured with the decline in sunlight in the last thirty years. It was quite amazing.

NARRATOR: It was the same with Europe and the USA. The drop in evaporation rate matched exactly the drop in sunlight reported by Beate Liepert and Gerry Stanhill. Two completely independent sets of observations had come to the same conclusion. Though it seemed incredible, there was no doubting Global Dimming now."

[malfunction]

NARRATOR: Travis was not looking just at temperature - that varies a lot from day to day anyway. Instead he focused on something that normally only changes quite slowly: the temperature range. The difference between the highest temperature during the day and the lowest at night.

I say again - look at this:

http://www.bbc.co.uk/weather/5day.shtml?world=0008

1 degree variation between high and low today, 6 tomorrow and sunday, 5 monday and 1 tuesday. Is that because there's more flights planned on the 1 degree days?

It is - IMO - a load of cow poo. As per my first post I'm not saying it isn't having an effect - and I'm not saying that what we do to our planet is good. But:

It's a small thing in a big system

You think the planes make more of a difference than the masses of other things we've done as a race? Just because the planes stopped for 3 days the power stations and cars didn't stop, the changes made to the landscape weren't suddenly reversed.

It's too big a system to fixate on one small detail. It's irrelevant statistically and literally. There's no way whatsoever than what has been observed is anything other than a link - anecdotal evidence at best.

As for the pan evaporation thing - they themselves admit that both humidity and the wind affect it not just light. It's crackpot science - where's the control? Which factors matter the most... As for the decline in sunlight that in itself could also be attributed to changes in the global system - those not just down to man - or even changes in the sun's activity itself... One thing I'd like to refer back to - in Roman times people planted vinyards in YORK. Now obviously no-one from back then is around to say how good / bad it tasted but unless the Romans were total planks it's fair to say that the weather can and does change over time - and we all know that for a fact anyway - ice age, etc.

Edit - or how about this:

http://www.bbc.co.uk/weather/5day.shtml?world=0101

Difference there is 14, 4, 7, 8 then 3... So that's going to show up a 1 degree difference and be able to link it back to planes not flying over 3 days?