Horizon - Global Dimming

[Fluff]

Horizon

New series. Global Dimming. What if all our predictions about the world's climate are wrong? Scientists have discovered a phenomenon that may have already contributed to the deaths of hundreds of thousands through drought and famine. At its heart is a study that shows that the average amount of sunlight reaching the Earth has diminished over a number of years, hiding the consequences of global warming in the process - a theory labelled 'global dimming'
BBC2 9pm-9.50pm

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- Just watched this found it quite disturbing. These facts are from memory.

The Earth has dimmed roughly 10% in the past 100 years.

Clouds formed from polluted air tend to have smaller water droplets than ones formed from salt etc. These smaller droplets are more reflective than normal 'clean' clouds.

Some scientist in America. Did a study of the difference between max and min temperatures. Where just one variable changed (over 9/11 where there were hardly any flights thus jet trails). Over those three days from the 11-14th there was a shift of +1 degree in the temperature difference. Which was the biggest in 30 years.

We are cutting pollution whilst still producing greenhouse gases.

Global dimming - pollution - reduce temperature (more reflection off clouds, more clouds).

Global warming - greenhouse gases - increase temperature.

An estimate is that there could be within 100 years a temperature increase on average of +10 degrees C

Seasonal rainfall patterns could be seriously affected. Similar to the ethiopina famine ages ago.

-Nice-

Oh and also at the bottom of the ocean in the sludge there is alot of methane stored which is 8 x stronger greenhouse gas than CO2

Methane Hydrate

The latest and greatest is the discovery of a very wierdo worm living on methane hydrate extrusions in the Gulf of Mexico. Methane hydrate is solid ("frozen") at the bottom of seas and oceans, even though the temperature is above what is sealevel freezing for this chemical - the pressure there allows the solid state to maintain despite a "non-freezing" temperature (but, never fear, it's cold anyway).
There is estimated to be just one humongous lot of this methane hydrate just under the seafloor along the continental shelves and since methane is just the greenhouse gas par excellence, we better hope that the oceans don't warm up enough to turn the solid hydrate to gas. Here and there the hydrate extrudes out from under the sediment and this was the locus of the recent discovery of ...

end quote.

[breezer]

This wa worse than the super volcanos and meteor programme as I is all caused by us.

We need to cut our co2 emissions now or else there will be major issue in the next 20 years.

[The PIT]

Or someone else thats wants more money for research.

[VJ]

I also saw it... it was very disturbing.

Fluff: the dimming is more: in the link I supply below, the mention 22% in the last 50 years!

What I found very disturbing is that the climate models that were (are?) used didn't take this dimming effect into account, thus underestimating the global warming effect.

The program info is here:

http://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_prog_summary.shtml

(there is even a full transcript of the program)



Jörg

[Umfriend]

Can we use that methane as an energy source?

[Fluff]

Not sure. Basically Nuclear power is probably the safest option.

[GNEP]

Isn't the same methane held responsible for the disappearance of ships in the bermuda triangle? It sometimes bubbles up and if a ship hits an upcoming bubble it sinks like a stone...

[VJ]

Could well be... (I saw a documentary on this subject where they tried sinking a small boat just by releasing air under water, and it worked!)


Jörg

[Brian Ellis]

Let's keep our feet on the ground and not our heads in the ozone layer.

1. The so-called methane hydrate has been there for eras. It would be very difficult to exploit and very dangerous to try.

2. Methane varies in its global-warming potential according to the hydroxyl radical concentration at where it is emitted. It can vary from about 20 to 75 times worse than CO2, but the average figure is generally considered as 35.

3. Methane (or natural gas) is terrible as a contributor to climate change. The atmospheric concentration has more than doubled from 800 ppbv in 1850 to 1,720 ppbv in 1995 and there was an annual increase of 0.6% p.a. in the 1980s but is higher, now. The increase is due to leaks in NG exploitation, increasing areas of rice paddies, increasing number of cattle (enteric fermentation, aka farting) countered to some extent by wetland drainage. This increase is due to human activity.

3. the earth's albedo is increasing, but this is due to a marginal increase of the atmospheric moisture loading, which is about 12 trillion tonnes of water (0.035% of the global fresh water), giving a greater cloud cover. This may be an effect of climate change. This is not catastrophic, as it is in a negative feedback cycle and tends to stabilise over time (several years)

4. It is simply untrue that man-made particular matter is significantly increasing the earth's albedo. There is about 1 million tonnes of particular matter of less than 5 µm diameter (the stuff that can float freely in the air, as an aerosol -- do not confuse with aerosol cans) in the global atmosphere at any time. The concentration in µg/m3 near the surface of different components is:
Sea salt 1300
Mineral particles 1500 (can increase during Saharan dust storms)
Volcanic 33
Forest fires and bio debris 50
Sulphates from natural H2S 100
Nitrates from natural NOx 22
Converted plant hydrocarbons 75

TOTAL NATURAL 3060

Industrial dust 100
Combustion (soot) 8
Biomass burning (soot) 5
Sulphate from man-made SO2 140
Nitrates from man-made NOx 30
Biomass combustion (organics) 80

TOTAL MAN-MADE 370

This shows that particular anthropogenic pollution is only 12% of natural level. This is practically negligible from the point of view of albedo or the nucleation of moisture, which is principally done by the massive amount of sea salt, which accounts for 38% of all the particular aerosol matter in the air.

I therefore refute this alarmist kind of report which is a) frequently misinterpreted by the media and b) propagated by people wanting to make themselves known, often financed by extremist ecolopolitical organisations and other ignoramuses. The IPCC make a much more serious study of this kind of information.

[GNEP]

Farting... after a decent night out I bet I have a measurable effect on the global greehouse effect

[breezer]

We should cut green house gas emisions as a precaution, I don't want to leave a less hospitable environment for my children.

The new experimental nuclear plant (france or japan?) should be built in both countries now as this is a potential source of abundant, cheap and environmentally clean.

Breezer

[Brian Ellis]

Originally posted by breezer
We should cut green house gas emisions as a precaution, I don't want to leave a less hospitable environment for my children.

The new experimental nuclear plant (france or japan?) should be built in both countries now as this is a potential source of abundant, cheap and environmentally clean.

Breezer

I agree.

What new experimental nuke plant? AFAIK, France, along with Finland, has ordered an EPR reactor, but this is hardly experimental as it uses tried, safe technology with 96% recycling of the fuel.

Japan has plans for a small experimental high temp reactor, but I find this an alarming idea, from the safety point of view (plus it does not recycle the fuel).

[VJ]

Originally posted by breezer
We should cut green house gas emisions as a precaution, I don't want to leave a less hospitable environment for my children.

I'm beginning the think not only for our childeren, but for us as well: last week I saw a documentary about the decreasing amounts of oil. They predicted economical problems in about 6 years (mainly due to the increasing prices)...
Now this global dimming...
Both are problems on a global scale, and getting everybody to cooperate *before* problems emerge is virtually impossible...



Jörg

[spadnos]

News just in From Slashdot:

There's a transcript here.

- Steve

edit: Of course, if I had followed VJ's link, I would have easily gotten here. Oh, well

[Brian Ellis]

OK, I've read the transcript. IMHO, it is alarmist and really unlikely. If one has a spherical framework of scientific fact, it is far too easy to weave a cobweb over it and pretend one has a football. I'm sure I could assemble a panel of experts who would weave a much more substantial covering over the same facts.

I stand by what I said earlier, but I'll add two more things: solar luminance and spectra are measured at thousands of met stations around the world. If it were true that significant lowering of light was observed globally, this would have been made known in scientific literature. And they use scientifically calibrated photometers and not pans of water to make their observations.

The other thing is that it is quite plausible that there is a difference between incident luminance between the N. and S. Maldives, because of the proximity of India. However, during the winter monsoon season, when the Maldives are on the lee side of India, there is a very strong, dry NE wind which is noted for kicking up dust storms. I would need to know the analysis of the particulate matter to determine the ratio of natural to anthropogenic causes. From the info, I cited above, I feel that natural causes are far more likely than man-made.

On this island, we get a few days per year of very low luminance, but we know the cause: it is dust blowing from the Sahara (probably the same cause as the citation in Israel, which is quite close to here).

I stand by my case, expounded above.