Global Warming, Is human activity the cause?

ooooooohhhh we've had this one before...

Heated debate (geddit?)

and

Here

Alarm and fear is certainly good for business in the scientific community. So are over-hyped medical breakthroughs and survey results.

The article is usually headlined something like..."Doctors Nearer to Finding Anti Cancer Drug" (or similar). The body of text is then full of words like "might", "could" etc. etc.

The sting is usually to be found at the end, something like - "a spokesman/scientist says - more research is necessary".

Steve

For all the criticism of the Al Gore film in court last week the one thing that remained absolutely unchallenged was that humans are the primary and far and away most significant cause of global warming. I seem to recall (without referring to the DVD sat downstaairs) that in the media scepticism rated at around 53% of articles suggesting this were not the case whereas the number of recently published and peer-reviewed scientific articles suggesting this was not the case was erm, 0%.

Mike

There are TWO basic questions

A) Is Global warming happening, and if so what is causing it

B) Can we (mankind) do anything to stop it, or do we just need to adapt to it.

There seems to be a predisposition in certain quarters to presumming the answers are "Mankind is causing it and therefore mankind can stop it"

I am not convinced that either part of this response is true.

My view is that "it is (almost certainly) happening but we don't (really) know what is causing it. My favourite theory at present is that it is (primarily) caused by 10,000 years of farming (and associated increase in population), topped up by 200 years of industrial revolution. We (almost certainly) don't have the collective will to do anything (significant) about the farming or the population and very little will to do anything about industrial pollution. No doubt nature will change and mankind will be forced to adapt. This will involve wide-spread drought in some places and flooding in others. There will be some attemps at mass-migration and this, together with food/fresh-water shortage will result in widespread war."

Cheers

Don

Buy your shares in umbrellas and desalinisation techniques now.

I am baffled by the claim that the incorrect method doesn't matter because the answer is correct anyway.

Method Wrong + Answer Correct = Bad Science.

With bad science, only true believers can assert that they nevertheless obtained the right answer.

quote:

For all the criticism of the Al Gore film in court last week the one thing that remained absolutely unchallenged was that humans are the primary and far and away most significant cause of global warming.

What caused global warming and for that matter cooling when the humans were not here?

BigH47 asked

"What caused global warming and for that matter cooling when the humans were not here?"

Here's what I said two and a half years ago....

"Global Warming is a disaster waiting to happen", said Mrs D yesterday. "Bollocks" was the gist of my reply, "It's already happened"

According to popular science (ie what I learned at school), the recent geological history of the earth (ie the last million years or so) has been dominated by a succession of ice-ages. These have helped to carve the current, familiar landscape out of the wind/water-eroded, crumpled fault-lines and thrust-mountains along the north and south tropics. We enjoy the resultant scenery in the Rockies, the Alps, the Norwegian Fjords the Andes and New Zealand's South Island (LOTR). ISTR from school that the ice-ages were associated with independent 100,000; 40,000 and 20,000 year cycles, the latter being due to a "wobble" of the earth on its axis. When all three effects are co-aligned, we get the more severe ice-age; with wobble-induced-fluctuations superimposed at 20,000 year intervals (I think this latter interval is actually nearer 22,000 years) .

circa 11,000 years ago, the last ice-age had already receded sufficiently for humans in Asia to move into North America; and shortly after for the UK to be cut off from Europe as the polar ice-cap melted etc. At this time we were all still hunter-gatherers (according to my uncle Albert who says he can remember) and I "presume" the earth was well on its way to that inter-glacial point in the glacial cycle, of maximum warmth, if not actually at that point.

I can't recall what drives the 100,000 year (shape of the solar orbits?) and 40,000 year cycles and which of the cycles is dominant. Does anybody know where we "should" be in the ice-age cycle(s)? I have a hunch that we "should" be at the coldest point in a 22,000 year ice-age. But I don't know where we are in the other cycles.

I say "should" because clearly, the burning of fossil fuels over the last 200 years could be having a significant effect on the earth's climate; and human activity in the form of wide-spread migration, farming, deforestation and the building of cities, (all over the past 10,000 years) could likewise have had a huge impact on the cycle. I am therefore not convinced that it will be enough to stop burning coal and oil. To save the planet as we know it today, I think we will have to dramatically reduce the population numbers (say) from 6 billion to 6 million and revert to hunter-gathering.

Long-live Mr Archer and Mr Fletcher

Perhaps you have a better idea, or aren't so pessimistic?

Cheers

Don

Well I'm not a climate scientist (I'm an electrochemist), but here are a couple of facts:

1. The greenhouse effect is scientifically demonstrable (by laboratory experiments) and is an undisputed fact (if there were no carbon dioxide or other greenhouse gasses in the atmosphere, this planet would be very cold indeed).

2. Accepting that 1. is true, then putting an extra 7 billion tonnes of carbon dioxide into the atmosphere every year can't be a good idea and will almost certainly be a factor in current trends of planetary temperature increase.

It's true that during the past, there is evidence that the temperature of the planet fluctuated dramatically. This was most probably due to some fairly cataclysmic natural events (volcanic activity, meteor strikes etc). To use this as a reason for not doing anything about the current situation is asking for trouble.

1, CO2 is not the major greenhouse gas.

2, The amount of CO2 in tonnes isn't the relevant figure for the greenhouse effect, what matters is the probability of emitted infra red interacting with a CO2 molecule. This probability is not linear with increasing CO2 so there's a cap on the sensitivity to CO2 as a greenhouse gas.

I think it's generally agreed that the response to a doubling of CO2 from pre-industrial levels is about 1 degree C.

Paul

The four most significant "greenhouse" gasses are, (I presume), methane, sulphur dioxide, carbon dioxide and water-vapour. (but i am happy to be told otherwise).

Quoting isolated figures (such as 7 billion tonnes of CO2) doesn't convey much meaning to me. How much is here already? what effect does an extra 7 bn tpa have. If doubling the mass of CO2 has ocurred and the associated temperature increase is 1 deg C, what then? Is Global warming such a bad thing? (most of the BIG changes in modern human activity seems to have been associated with global warm periods)A North-West Passage might be a commercial benefit, or it might be the start of WW3...........

You may assume that I am of the opinion that a lot of politicians, scientists and businessmen aim to MILK the global warming cow for every penny or ounce of power they can get. Human fear and greed are the most powerful infuences on our behaviour.

BTW, I have always found Paul R's information (including that above) to be unemotional, plain, straightforward, helpful, facts.

Cheers

Don

I know this may seem an oblique comment but the questions that I think should be asked are

a) Are we in a phase of significant global warming (and climate change)?

c) How much will it change, and how fast?

b) Can we do anything about it?

Actually debating the poportion of the changes due to human activity vs natural phenomena seems to be a diversion. If the climate is changing then surely mankind should take steps to reduce further warming from human activity, irrespective of wether this is the prime or sole cause. Alternatively we just shrug and attrempt to adapt.

Bruce

quote:

If the climate is changing then surely mankind should take steps to reduce further warming from human activity, irrespective of wether this is the prime or sole cause.

welcome back King Canute.........

I actually agree with each of your comments. However, if the answer to "(c) Can we do anything about it?" is "no" then your statement "surely mankind should take steps to reduce further warming from human activity, irrespective of wether this is the prime or sole cause" is rather pointless. Your alternative "we just shrug and attempt to adapt" would be more appropriate.

Cheers

Don

There is not enough money to adapt to it and there are billions of people who can't adapt to it. Whatever is done will be too little too late.

Beano

quote:

Originally posted by Don Atkinson:
Quoting isolated figures (such as 7 billion tonnes of CO2) doesn't convey much meaning to me. .......

It has been estimated (although I don't know how how accurate this is) that natural carbon fixing processes i.e. photosynthesis, could cope with up to 2.7 billion tonnes of extra CO2. The 7 billion tonnes (and increasing) means that CO2 levels are likely to continue to rise. Paul Ranson states that CO2 is not the major greenhouse gas. This may be the case, but we are also producing plenty of the other greenhouse gasses as well. In particular, planes introduce a lot of high-level water vapour which also causes problems.

quote:

In particular, planes introduce a lot of high-level water vapour which also causes problems.

This might well be an interesting area to explore - and I don't know the right questions to ask or the answers.

nevertheless, my understanding is....

The earth's atmoshpere remains remarkably consistant up to about 60km. 78% Nitrogen, 21% oxygen and 1% other gasses including the "greenhouse" gasses.

Water vapour varies around the globe, measured in gms per kg of air. It remains remarkably constant and largely depends on the source air mass. eg tropical maritime air arriving over the UK from the Azores, has a relatively high water vapour content - say 10gms per kg. This tends to be distributed throughout the Troposphere by convection currents, but doesn't seem to get up into the Stratoshphere very easily. I am unsure how much natural water vapour is found in the lower regions of the stratosphere.

Most "commuter" airliners operate within the troposphere. It is usually only the long-distance planes that use the lower reaches of the stratosphere.

So, how much water vapour do aeroplanes add to the troposhphere and how much do they add to the stratosphere and more importantly, what effect do these additions have on the global environment?

Cheers

Don

The last bit of my last post should of read - Whatever is done will it be too little too late?
---------------------------------
Global Warming is NOT the problem - it is a symptom.

Making a mad dash at fixing the symptom will not address the problem.
The problem remains.

The problem is as Don has already stated and I share his view, that there are about 5 billion more people on this planet than it can sustainably support.

And that problem will be fixed. If we don't do it ourselves, because from where I’m sat, it’s all going according to plan for nature will inevitably, do it for us.

And it won't be pretty. Imagine a Worldwide rise in sea level of 7metres if Greenland’s 3km thick ice cap was to melt and, we all know that Nature doesn't care about pretty.

Beano

A lot of concern about the recent opening (and now closed again) of the North West Passage and how this is due to Global Warming. My geographical knowledge here is faint but surely the fact that it's called a 'passage' implies it has been open before (similarly the North East passage I presume)?

And surely the advertising of this particular feature is more to do with Canada's assertion of sovereignty (and thereby shipping rights) rather than climate change.

Or am I being to cynical..?

quote:

Imagine a Worldwide rise in sea level of 7metres if Greenland’s 3km thick ice cap was to melt

And we all know why it's called Greenland.

quote:

Originally posted by JamieWednesday:
A lot of concern about the recent opening (and now closed again) of the North West Passage and how this is due to Global Warming. My geographical knowledge here is faint but surely the fact that it's called a 'passage' implies it has been open before (similarly the North East passage I presume)?

And surely the advertising of this particular feature is more to do with Canada's assertion of sovereignty (and thereby shipping rights) rather than climate change.

Or am I being to cynical..?

You are being far too cynical. Keep it up.

Actually some of the research there is aimed at going very deep and trying to gain more understanding of global change over a much longer time. Rather than the paltry (in Earth age terms) experience of the last few hundred years that get trotted out all too often.

Steve

quote:

And it won't be pretty. Imagine a Worldwide rise in sea level of 7metres if Greenland’s 3km thick ice cap was to melt and, we all know that Nature doesn't care about pretty.

Well, imagine the rise in sea level if the canadian and European icecaps that existed 15,000 years ago were to melt..........

Oh sod it, they did.

And we now have England and the English Channel, and we have the First Nation people who occupied North America and........

If our ancesters were able to survive, presumably we could????????

Cheers

Don (whose second home is 2,500' above sea level in the Rocky Mountains)

Don (whose second home is 2,500' above sea level in the Rocky Mountains)


And you'll be able to grow your own Mango's too!

Beano

Chaps

If scientific opinion is divided on this, then you lot know nothing and your views are worthless. You have no knowledge and hence should keep quiet.

I agree that reducing pollution is good but it is only a guess that it leads to global warming. The truth is no one knows.

China, India and America are all going to continue shitting up the environment no matter what we say, so best to concentrate on building flood defences etc.

Regards

Mick

quote:

And you'll be able to grow your own Mango's too!

Always look on the bright siiade of life, da dah, da dah, da dahdi di dahdi di dah....

Cheers

Don

It probably take about a thousand years to reach 7 metres though!

Anyhow I found this flood map which is quite interesting.

http://flood.firetree.net/ll=48.3416,14.6777&z=13&m=7

Beano