Global warming

A snowHead

Picked up from the BBC site
Not good reading!!!!!

Glaciers

"Mountain glaciers in non polar regions have retreated significantly during the 20th century." (Met Office)

Mountainous glaciers are retreating in many parts of the World and one particular area, scientists are concerned about is Alaska - around 500 cubic miles of ice have been lost from here in the last 50 years. The glaciers retreat when there is less snow in the winter than what is melted away in the summer.

Many of the mountains in the area are now severely depleted of snow. It is believed the situation is so extreme in Alaska that half of the water flowing into the oceans, globally, due to melting glaciers, is a result of the melting in Alaska.

In Europe, the situation is worrying too. Since 1850, half the volume of Europe’s Alpine glaciers has disappeared and it is thought that by the end of the century half of those left, will have gone.

In the last 100 years, sea levels have risen by 10-20cm globally and future rises are predicted to be much greater than this. Although melting glaciers aren’t the main cause of sea level rises (that’s thought to be the result of surface air temperature rises), the effects of glaciers certainly contributes and is a concern to scientists.

A snowHead

Anyone who extrapolates for a century ahead when dealing with the weather is not much of a scientist whatever his/her title may state. Makes you wonder/worry about anything else they say as scientific data.

Well, the person's real but it's just a made up name, see?

john wells, do you mean that we should do nothing to clean up the mess we're making of the planet?

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We're coming out of an ice-age, it's going to melt, with help from man-kind or not.

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Oh dear, I'm not sure I've the energy for this: this topic has been debated at length in the 'Disappearing glaciers' thread, which I think has pretty near iterated to a conclusion (or at least a stand-still).

I feel the need to comment on john wells point though. I understand where you're coming from, but I think your comment is a little extreme. The essence of science is to predict future events from observing past ones. Granted, for a system with multiple inputs, multiple variables, zillions of data points, complex feedback mechanisms, etc, this is going to be incredibly difficult. But I don't see why people shouldn't try. It's quite important to have some clue about the range of possibilities. Now, any good scientiest making predictions in the field should state his assumptions, indicate what variables are fixed in his considerations, give estimates for error ranges in individual calculations and state how errors could combine to affect the overall predictions. I suspect many of them do, but the trouble is, usually only the bald figures (and the more apocalyptic the better) get reported in the mass media. The media aspect, along with much else, has been discussed on 'Disappearing glaciers'.

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hehe I'm sorry, yes I am a girl but don't worry - I'll leave you to your malecowpoo whatever that might be.

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Kuwait ian: I'm not a vegetarian but I do eat a lot of vegetarian meals and meat substitutes etc. Believe me, these are not the answer to reduce stomach gases! Mr. Green

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Alexandra, jonpim's doubts about your sex are a product of several recent mistakes of his on that score. He is clearly demoralised.

I don't know if people know this, but I'm told the bottom end of the little stand-up lift from the train station down towards the Mer de Glace at Chamonix was originally close to the glacier. It is now a considerable climb above because the glacier has shrunk.

hayley t, that's a little bit more information than we needed to know

You know it makes sense.

kuwait_ian, is there something wrong with my soundcard settings?
I can't hear your cows.

Otherwise you'll just go on seeing the one name:

They're environmentally friendly low-noise, low emission, genetically-modified protein and lacto-product producers - not cows.

A snowHead

snowball didnt the Mer de Glace cut the valley in two 150 or so years ago?

A snowHead

Since everybody contributes to global warming. To kill the devil by cutting off its head is therefore xxx, right?

What is xxx then?

Well, the person's real but it's just a made up name, see?

Wear The Fox Hat - I figured we all knew each other well enough to be comfortable about these things! Don't worry, I'll draw the line at that.

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laundryman - I stand by my comment. 100 years is far too much extrapolation for something with as many variables as the weather. If you multiply together all of the error ranges which must be involved over such a long period the end result will have such a large potential error that any deductions are meaningless.

What we are being given is an educated guess and no more. The discusion as to where this guess came from would no doubt be interesting and educational but it is still a guess.

Just one example of the problem. If a large volcano exploded during that 100 years, another krakatoa (is that how you spell it?), the earth would be quite drastically cooled due to the dust in the atmosphere. How do you allow for such a possibility in a forecast calculation? There are just too many possible random events in 100 years.

I agree with your comments about science, at least for some scientific disciplines, but in my view taking a 100 year timescale for weather prediction extrapolations is stretching things far too much.

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I think Laundryman has it about right. And unless you have access to the data, specific expertise in the field, asserting that the science itself is error-strewn, the conclusions meaningless... well one could level the same criticisms at your own comments! Wink

Sure, there are variables. * If a mere 25 mile diametre comet struck Cairo 2,000 miles away, travelling at 50 km/s, at an angle of 45°, we'd be hit by an earthquake of 11.9 on the Richter Scale ten minutes later, greater than any earthquake in recorded history, ejecta on average 26 feet thick would rain down on us after 16 minutes, 1300 mph winds arriving after 3 hours. All buildings would collapse, 90% of trees would be blown down. There'd be a fireball 45 times larger than the sun, clothing, grass and trees would catch fire, people would suffer 3rd degree burns. Anyone surviving that little lot wouldn't last long!

Sure, the further ahead we try to predict developments, the more subject to error forecasts will be. Still, I'd rather 'educated guesses' than none at all....

* If anyone wants to have 'fun' (?) predicting the effects of meteor/comet impact, the Earth Impact Effects Program has an interactive website at:

http://www.lpl.arizona.edu/impacteffects/

A bit morbid, but ..... aren't the odds on winning the Lottery greater than being struck by a meteorite???

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john wells and PG, the discussion on volcanoes and comets puts me in mind of the technique of 'scenario planning' in business. After a few years, you can't make sensible predictions on the basis of extrapolation, because there could be 'seismic' changes to the economic, political, social or technological landscape. These don't just perturb extrapolated outcomes, but lead to radically different scenarios. It is important to test strategies against a range of such scenarios, so that the shareholders can have a reasonable degree of confidence that, come what may (barring catastrophes like comets landing on Cairo!), they will have a thriving business in ten years time.

The International Panel on Climate Control have adopted a similar method, modelling 40 scenarios in terms of population growth, economic growth, use of renewable energy, etc. They haven't assigned probabilities to the scenarios and stress that their 'predictions' really amount to 'computer-aided storytelling'. They do not (I think) include scenarios with major volcanic eruptions, which is a shame because I don't think it's that improbable that a Krakatoa-size eruption would occur in a century.

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Interesting BBC article on effect of variability of cloud cover on earth's albedo (reflectivity) and hence on global warming/cooling.

The synopsis is that cloud cover decreased during the 80s and 90s, leading to a warming affect greater than that caused by the increase in greenhouse gases (according to the researchers). However, something of a reversal in the cloud cover trend may be happening now.

The experimental method is ingenious: measuring the brightness of the dark portion of the moon, which is illuminated by the earth but not by the sun.

Help!!

Global warming

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