Global Warming/Cooling/Warming Oh I don't know any more!
A documentary film on BBC2 the other day began with the story of how a scientist had been examining ice cores, drilled from the Arctic.
The findings revealed massive and sudden changes in the region's temperatures over thousands of years.
The data showed that there had always been fluctuations in the earth's temperatures and this was more or less predicted by theory.
Analysed over a long period, this was shwon as sort of wave shape, with gentle rises followed by gentle declines.
However, on occasion, the temperature had suddenly plummeted and then climbed quickly back up to normal. The theory didn't explain this, so the scientist set out to discover what had actually happened.
Eventually, the programme and the scientist came to the "Atlantic Conveyor" theory. This has nothing to do with a ship of that name but rather refers to the Gulf Stream.
Warm water from the Central/South America region of the Atlantic flows north, via the Gulf of Mexico and along the eastern coastline of the US, across the Atlantic toward the UK where it backs to a more northerly course as it passes the UK & Ireland on its way to the Arctic.
Upon reaching the Arctic region, the water is cooled (presumably all those ice cubes floating around there have something to do with that). As the water cools, it becomes more dense (as salt water will do), and sinks. As it sinks and nears the ocean floor, currents down there take the water pretty much back the way it came but at a much greater depth, until it reaches warmer waters off the Caribbean/South American area.
Warming up decreases the density so the water rises toward the surface where it is warmed even further and off it goes once more in its Gulf Stream guise.
So, the scientist figured, it seems that, for some reason, this "conveyor" must have stopped at some point in its history.
As the Gulf Stream delivers warmth the equivalent of a million power stations to the UK, the sudden loss of this would be catastrophic. The UK would enter a big freeze and the climate would be more like that of Labrador (now, that would make the Jocks put some prpoer trousers on, wouldn't it?).
Then for some reason, the current started to flow once again and we all warmed up a bit.
Now came the panic mongers' bit.
If the Gulf Stream's salt content was to decrease at the point where it gets cold and dives down to the ocean bottom, the change in desity would be much reduced so the sinking of the water wouldn't happen.
The Gulf Stream would stop.
And we get back to the sudden and dramatic decrease in our temperatures in the UK.
Now, remember that bit. The next ice age cometh if the Gulf Stream takes a rest.
Fine, thinks I, that explains everything then. It seems like the old wags were right; "what goes around, comes around".
Cut now to the panic mongers busy gathering data in Greenland, Siberia and the Arctic Ocean.
These scientists are showing in detail how certain glaciers in Greenland are moving at a much faster rate than ever recorded before; how much the rivers flowing from Siberia into the Arctic have increased dramatically in volume and how much the salinity of the water at the Gulf Stream's turning point has decreased radically.
OK, got that, what's next?
Well, they pointed out how how global rainfall patterns would change. There was some good news in this bit as it showed the equatorial rainfall moving north. Sadly, they say this will mean the equatorial rain forests would disappear to be replaced by grassland and bush. Sad for equatorial tree collectors, I suppose but what about the poor sods in Sub-Saharan Africa? Currently, they suffer from repeated long droughts which cause massive crop failures and terrible famines in the region. Well, now it seems they may be in for some heavy rain for some years to come. Bonus!
They will then be able to grow crops and feed themselves. They will be able to thrive and prosper. They will cease to be recipients of billions of pounds worth of aid every year so that money can be invested elsewhere in the world economy. We are all going to be winners! Hurray!
Back to the Greenland glaciers et al for a minute.
Why are they seeing these changes? Easy; global warming is causing the ice to melt thus releasing more fresh water into the Arctic Ocean.
This causes temperate climates such as the UK to become big ice boxes (remember that bit earlier?).
When we get cold, we light more fires to get warm again, thus adding to global warming and speeding the cycle up.
Now it all gets a bit tricky.
Global warming causes the ice to melt and for the resulting fresh water increase causes the Gulf Stream to give up the ghost. When clouds form, they will retain their water content until such time as they become too dense to be able to carry all the water. This increase in density causes all that water to fall as rain. Generally speaking, what causes this increase in cloud density is a drop in temperature so most rain falls as clouds move northwards and cool(I am talking only about the northern hemisphere here; the reverse applies down under).
As the scientists predict that northern Europe and the Arctic will have become much colder as a result of severe Gulf Stream failure, what happens to all this rain?
It falls as snow and is frozen when it lands on the sub-zero ground below. It all piles up in massive ice sheets, glaciers and ice bergs etc.
So what's your point, Kelvin?
Simple; all that fresh water comes from the ocean. Take out fresh water from the ocean and you cause the salinity to gradually rise.
Keep that fresh water locked up on the ground in glaciers etc and it doesn't get back into the ocean to balance the change in salinity.
The water becomes more dense and, somewhere around the Arctic, it will begin to sink. As it sinks, it will draw more water from the south and bingo!
The Atlantic Conveyor is once more up and running, we all warm up again and so it goes.
I realise the yoghurt knitters and tree huggers will probably scream out in anguish but they may have to one day face the fact that this is the way it goes.
The earth's climate has been doing this on its own for millenia, since before MR and MRs Ug lit their first fire.
So why do the panic mongers think they can change the earth's climate when it is obvious the earth has had its own way of doing this since the creation of the planet?
Anyway, I thought this was God's job, not Ian McKaskill's!