One of the most dangerous phenomena of modern times is how the irrational greenies have hijacked the environmental agenda and suborned it in pursuit of their own political aims. No better example of this is offered than in a piece by Peter Schwerdtfeger, emeritus professor of meteorology at Flinders University in Adelaide, writing in The Australian. Schwerdtfeger is reviewing the work of internationally acclaimed cloud physicist Daniel Rosenfeld of the Hebrew University of Jerusalem, who asserts that the most awful consequence of the burning of carboniferous fuels is not the release of CO2 but the large-scale injection of minute particulate pollutants into the atmosphere.

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When a high pressure forms the activity of thermals in the atmosphere is suppressed. This means dust and smog remains concentrated near the ground and that no clouds form so there can't be rain.
How could such tosh be published as science?

That is not tosh ... in anti-cyclonic conditions, you get the creation of stable inversions and then the build-up of pollutants at ground level. Only in more unstable air do you get local, thermal-induced cu-nim, which will generate significant (albeit) localised rainfall.

Precisely what I meant so the idea that bad visibility causes lack of rain is tosh. Right up there with global warming being from the decline of pirates.

Richard,

If I understand it correctly the (or maybe "a") point of this paper is the fact that the "climate change" is due to local phenomena/pollution sources. This has been argued also by Roger Pielke Sr for a long time on his blog (climatesci.org) - see papers published by his research group during the last 20 years or more.

Also, IIRC, there was an article in the American Scientist (not Scientific American!) a few years ago by two eminent glaciologist/geographers explaining that the great symbol of global warming, the retreat of the snow cover from the top of Kilimanjaro was not due to warming but to reduced precipitation. And why the reduced rain- and snowfall? A change in the vegetation surrounding the mountain, due to changed agricultural practices.

It turns out that not only politics, business but also climate change is local!

(But of course to analyse local factors means lots of hard grinding work, where attention to details is required. Oh, horror!! And how many global conferences - preferably located in Bali or Acapulco or some other nice and distant resorts - can you call together to discuss the local farming practices in East Africa? )

If particulates are too small for water droplets to form, perhaps we should go back to less clean burning...

It's good that competing theories keep coming up. It does science, politics and the public no good that the greenies and their political acolytes have made it largely a closed shop of just CO2 = we're all gonna die. The first three paragraphs of Peter Schwerdtfeger's article are enough to be labelled a frontman for big oil in some circles.

I can understand water vapour having nothing to coalesce around might result in no rain. I can understand water vapour having plenty of stuff to coalesce around resulting in rain. I can't quite understand why particles of a particular size would both cause water vapour to coalesce around them and inhibit rainfall. What it sounds like to me is that big particles = rain, no particles = no rain, small particles = some kind of emulsion of water droplets.(In that the water is there, but is suspended in the air and doesn't fall) Does that sound about right?


It's a pity the article doesn't explain why the rainfall in mountain and densely populated are diverging. Both would be subject to increasing levels of minute particles inhibiting rainfall. A lack of precipitation when visibility is poor is surely because air is not circulating as it usually does rather than some just-the-wrong-sized particles.

I put a lot of stock in change of land use being behind any actual (rather than fiddled statistical) climate change. If the populated lowlands have become more densely populated over those 50 years there will be more heat from the urban heat island effect that may change things, plus better drainage leading to less standing water and less vegetation resulting in less water vapour reaching the mountain.

In the case of Kilimanjaro IIRC it has been suggested deforestation has created a more arid climate around the mountain.

Found it: The Shrinking Glaciers of Kilimanjaro: Can Global Warming Be Blamed? The Kibo ice cap, a "poster child" of global climate change, is being starved of snowfall and depleted by solar radiation



Yes, local deforestation.

No, the point is that the particles are too small so that water vapour does not coalesce. I thin what happens is that the pollution slick remains discrete at high altitude, displacing "normal" air and thus inhibits the rain-bearing cloud seeding.

This is from Daniel Rosenfeld mentioned in the article.


I understand it a bit better now. Water vapour coalescing on lots of particles don't become big enough droplets to fall as rain. Fewer particles lead to bigger droplets.