Anyone reading my first post in this blog will know that there have been four Great Ice Ages with varying amounts of evidence to support their existence. I was reading the Daily Mail yesterday and, to my great surprise, found an article about scientists who've been researching various deposits which confirm the theory of the Cryogenic Era. They were from St Andrew's University and had been researching ancient Irish rocks. According to the journalist, the theory was first 'coined in 1992' (sic) to explain the existence of massive glaciers at sea-level in the equatorial regions of that period. Also according to the journalist, the period lasted for about 10 million years. They are publishing findings which appear to give more detailed support to the theory.
The article was fairly short and it would appear that, as usual, a journalist has been given details on a topic they know little about, an article was written and then, thereafter, sub-edited down to fit the space available. In the process inaccuracies have crept in. I may be wrong on this but I wonder if the journalist was given a reference to the coining of the name of the epoch by Kirschvink (C.I.T) in the 1990s rather than the actual concept which was bouncing around a lot earlier.
Actually, the first Great Ice Age was thought to have been a Snowball Earth as there is some evidence which is replicated in the geological record during the period we now refer to as the Cryogenic period. That is a topic for another post.
I had to smile as I read the article. I first came across the concept/theory of the Snowball Earth in the 1960s as I studied Geology and Geography. There was quite a fair amount of discussion about it at the time. One thing was obvious though - the 10 million years mentioned above simply doesn't cut it for the length of time the Snowball Earth existed. As a matter of interest, this period and the whole issue of ice ages is dealt with in his usual superb inimitable style by Bill Bryson in his book "A Short History Of Nearly Everything". Well worth reading in my opinion. It's also worth mentioning that the theory is not without its critics - which is as it should be; any theory worth its salt should be challenged to within an inch of its life as far as I am concerned. That, of course, is why I militate so strongly against the "conventional wisdom" - based on limited knowledge as far as I can see - nonsense and scaremongering being peddled as facts about global warming / climate change by the media, those with certain political or 'green' agendas plus a certain 'wannabe' US president ('I don't plan to run again'. Oh yeah ?).
There are two points which can be made categorically. There is no 'unanimity' of world scientists. There are many, many climatologists, geographers, geologists who do NOT agree - many extremely well-known if not actually pre-eminent in their fields. Secondly, the science is NOT settled. In fact, ALL of the respectable science across a range of disciplines tends to refute all of the claims. For example, in "An Inconvenient Truth", Al Gore is correct to point out a correlation between CO2 and global temperatures. However, close examination shows he is wrong in his claim of which causes which. The CO2 levels actually follow climate trends not cause them ! Sunspot activity also gives a much closer correlation than CO2 and is considerably more co-terminous, suggesting sunspot activity is much more likely to be the cause than CO2. The problem is that he is likely to be dead before he is discredited.
Anyway, enough of the polemics. Back to the ranch.
The Snowball Earth Theory suggests that the Earth was covered in ice from the Poles to the Equator, hundreds of metres thick over most of the Earth, thinnning to perhaps only tens of metres in the equatorial regions. Most interpretations of the theory suggest that, based on biological information, some areas of ocean must have remained unfrozen. There is also the suggestion that there were local 'hotspots', possibly volcanic in origin, which kept some places just warm enough. Another suggestion is that there may have been places where the ice froze but remained clear enough for sunlight to penetrate. That's not common in nature but it does happen. I also read somewhere that nunataks [jagged horn peaks protruding through the ice - as opposed to mass onslaughts by little women in black dresses] may have been places with daily thawing and nightly refreezing. All offer the niches that life could have clung on to.
Why did it happen ? No-one's sure. A drop in solar radiation is thought to be one of the main causes. However, it is likely that that had to be combined with a fall-off in the production of greenhouse gases. Equally, in some way, the earth was unable to hold on to those it had already. It should be noted that greenhouse gases are essential to sustain us. Without them the earth would be a lifeless ball of ice.
What's the evidence ? Well, on to one of my favourite bits. Palaeogeography. We know that the continents have been moving about through the Earth's history. We can track them by looking at the orientation of iron particles in volcanic rocks for one thing. The Earth is a giant magnet with a field that stretches from Pole to Pole. It reverses from time to time, at fairly regular intervals. Again, a topic for another blog. The iron particles tend to align themselves with the earth's magnetic field whilst still molten. When the magma or lava begins to set that's them fixed. From the rocks we analyse, we can date them and work out where they were at various points in time. One of the pieces of evidence for continental drift / plate tectonics.
At this time, the continents were mostly in the area of the Equator, forming a clustering which is called Rodinia. Where do they get the names ? Rodinia, Pangaea, Laurasia, Gwondanaland ......... The evidence - the usual sort of glacial debris, markings, erratics etc - is sufficiently widespread to make it extremely compelling evidence. However, there's more. One interesting piece of evidence relates to iron. In our air iron oxidises ("rusts" to you and me). That's down to oxygen. Deposits of iron in non-glacial periods are oxidised. During Ice Ages - it's not, because oxygen levels are so much lower. Deposits from the Cryogenian period are unoxidised. Conclusion - Great Ice Age.
How long did it last ? Well it's far more than the 10 million years mentioned in the Daily Mail. Best estimates are around 170 million years viz. from 750 - 580 million years ago. Some estimates suggest even further back - to about 880 million years ago. The devil, as they say, is in the detail.
Why did it end ? How could it possibly have ended is actually a better question. The Earth reflects sunlight in various ways (The Albedo Effect). A giant snowball, 40,000 km in circumference, is going to reflect virtually everything. There would have been a clear blue sky without clouds. Nothing could stop heat being radiated back out into space. In theory, once having achieved that state, the Earth should have remained as a giant snowball thereafter.
One suggestion is volcanic activity. Look back a decade or so to the volcano beneath the Vatnajokul glacier which erupted, melting hundreds and hundreds of metres of ice which eventually poured down into the Atlantic as water. Could volcanic heat have begun punching through the ice ? Could volcanic emissions of Carbon Dioxide have begun to reconstitute the greenhouse gas layer needed to retain solar energy ? Once melting began, was there some form of feedback cycle which maintained and increased the melting process ? It's possible that Milankovitch's 3 cycles coincided positively towards the end of this period to begin the earth's temperatures rising again. Quite possibly all of these factors conspired. No-one's sure but we may find out eventually I suppose.
Footnote :
British geologists of yore were fascinated by the various rocks we call erratics today. They postulated floods and various other mechanisms to account for their movement. A suggestion was even made about a mythical race of giants carrying them as I recall. However, it was the Swiss who knew the mechanism was ice. From then theories and knowledge about glaciation have advanced, not without set-backs it has to be said. Noteworthy was Louis Agassiz. He became one of the best-known protagonists of the theory of glaciation although neither really feted nor well-known until he went to the USA and became a professor. Unfortunately, he tended to see more signs of glaciation than he was able to prove. Seeing signs of glaciation in equatorial zones was a step too far. He fell from grace when he proclaimed that ice had once wiped out all life before divine intervention restored it. He was actually closer than he knew. Time to rehabilitate him ?
Showing posts with label Milankovitch. Show all posts
Showing posts with label Milankovitch. Show all posts
Wednesday, November 22, 2006
Wednesday, July 12, 2006
Climate Change ? Let's get real !
How quickly and easily whole bodies of scientific knowledge can be swept aside or ignored if they don’t fit with the current political orthodoxies. If a theory does not challenge what the powers-that-be or the opinion-formers want then it exists happily with neither let nor hindrance.
There are, for example, few who would disagree with the idea that the continents are moving around all over the Earth’s surface. In geological time they’re zipping about and crashing into each other like cars on the peripherique around Paris ! More and more evidence to bolster the theory of plate tectonics accumulates all of the time. The devil, as they say, is in the detail and we have a devilish amount of detail to work with. The theory continues to develop and so now we can even postulate that the whole crust may be able to slip ’en masse’ should the distribution of land masses and ice caps become sufficiently unbalanced in relation to the rotation of the Earth. Clearly it would be catastrophic and, as yet, there is neither enough evidence nor a large body of supporters proposing it actually happened for the theory to be widely accepted. However, the evidence that is quoted already is compelling ................. and please note as well that proponents of this theory are neither vilified nor excoriated when they advance the theory and the evidence they’ve found so far. Some would use it as the underlying explanation as to the various myths about floods occurring around the world (Noah etc). I still can't make up my mind between that and the end of the last phase of the Ice Age - both are relatively close in time as far as we know. Actually, even as I write, I wonder if both could be responsible.................................
Now consider the thorny issue of climatic change and, in particular, global warming. Anyone who dares to challenge any of the current orthodoxy is treated in much the same appalling way as Copernicus.
David Bellamy and many other scientists with cases to make are effectively ignored or interviews are edited to trivialize their case. Try writing to mainstream press to make serious points contradicting the arguments currently being used and you’ll struggle to be published. Wear sandals, eat lentil (or tofu) burgers and splutter ‘global warming’ (preferably whilst frothing visibly at the mouth) then you are guaranteed as much time and column space as you like to make your case - no matter how unthinking or even downright wrong your points may be.
It doesn’t seem to matter that groups like Friends of the Earth have made some serious mistakes (not that they ever admit to them). They never - ever - experience the same level of intense sceptical questioning endured by people who question any of the environmentalists’ latest articles of faith.
Now a clear and unequivocal caveat. My position is absolutely clear. The world’s climate IS changing, as it has done from Day One. Let’s restate and confirm that – global climatic change is a constant (isn't that an oxymoron ? Oh well !). It is also virtually incontrovertible that those changes have occurred without any input from people apart from the last 200 years or so. The extent to which we are able to affect global climatic change is also highly debatable.
Now, let’s go back to my opening statement. Palaeogeography and palaeoclimates have been studied in great detail for quite some time now. There is a wealth of knowledge which is well-documented and which ties in well with other topics such as the afore-mentioned plate tectonics. What do these two areas of scientific study tell us ? The earth’s climate has undergone enormous changes since the beginning of time and I mean ‘enormous’. This knowledge is being systematically ignored.
This blog started out from a friend’s question: she asked me why no-one ever linked the issue of global warming to the fact that the Ice Age was over. The problem is that there are two separate issues in that question. The first is to do with what is taken to be the evidence for global warming. The second, to me is more fascinating. Is the Ice Age actually over ? I - and many other souls being ignored - don’t believe it is and I also believe it goes a long way to putting the issue of global warming into a far more accurate perspective. It is now virtually certain that the Earth has experienced three previous Great Ice Ages – together with a minor Ice Age - and we are currently in the grip of the fourth with absolutely no idea of when it might end.
As I’ve just said, no-one can be sure that the Ice Age has, in fact, ended. With no evidence to the contrary, we have to assume that it has not. We know that each of the four great ice ages has operated on a time-scale measured in many millions of years. The earliest ice age is believed to have been from 2.7 - 2.3 thousand million years ago. There is evidence although a bit sketchy for obvious reasons: each glacial advance erases much of the evidence of previous ice advances. The second which resulted in ice caps almost reaching the Equator (The Snowball Earth Glaciation aka The Cryogenic Period) lasted from 800 - 600 million years ago. Just how cold was the world then ? Brrrrrrrrrrrrrrrrrrrrrr. There also was a minor ice age 460 - 430 million years ago during the Ordovician period. After that, along came the Karoo Ice Age which lasted from 350 - 260 million years during the Carboniferous and early Permian epochs. A little reading around on the internet will reveal various really interesting things such as the impact of these on the flora and fauna of the times, including extinctions and sudden explosions of species – well worth while ! Obviously the world was significantly hotter in between each Ice Age. Look at the flora which flourished for some indications. The evidence is there.
However, back to the present. The present ice age began nearly 40 million years ago but intensified approximately 3 million years ago which is a mere blink of the eye, geologically speaking. Why can’t we be sure that the ice has gone / is going for good ? The reason is that ice ages are composed of cycles when ice advances (glacial periods) and periods when it melts away (interglacial periods). At this point most Geography teachers can take over and, yawning from extreme boredom, make all of these points in their sleep.
The present ice age has been operating on cycles of 40,000 and 100,000 years for the ice advancing and retreating respectively. The last glacial period finished approximately 10,000 years ago. Accordingly, we may have to wait rather a long time to find out if the ice has gone for good.
There are various theories as to the ways in which ice ages start and finish. Volcanic eruptions, variations in Carbon Dioxide and/or methane in the atmosphere and changes caused by continental drift have been advanced as possible causes.
One of the major theories is that the earth has 'built-in' climatic change. This is far from being a new theory. It was first bounced around by the Scot, James Croll in 1860, not too widely disseminated and then more or less forgotten. The theory was reintroduced by Milankovitch in the 1930s using known astronomical data, bounced around and then ? That’s right – more or less forgotten until they came to write stuff on climatic change for geography textbooks........
There are three cycles which operate. The earth's orbit round the sun is elliptical but varies on cycles of 100,000 and 400,000 years where it is closer and further from the sun. Secondly, the earth's axis describes a circle on a time scale of 19,000 - 23,00 years (the circle of precession) and thirdly, the tilt of the earth's axis also changes on a 41,000 year cycle. Each cycle, therefore, results in variations in insolation (solar energy) reaching the earth - sometimes increasing, sometimes decreasing. Milankovitch was able to show that when these three cycles were simultaneously at the point where they resulted in the lowest insolation reaching the earth, major glaciations occurred. It’s a bit like biorhythms with triple biorhythmic highs and lows occurring in the cycles. When they all coincide on a high – great ! On a triple low – stay in bed ! So that’s the hotter and colder spells accounted for pretty well then.
This theory has since been linked to variations in carbon dioxide levels which have given the theory added strength although there are scientists who feel the theory does not explain things fully enough, especially with respect to variations within glacial and interglacial periods.
Now we move to the really interesting stuff. There is a great deal of evidence for large variations in climate in our present interglacial period: effectively the last 10,000 years. Pollen, varves, tree rings, ocean floor deposits, ice core analysis – it’s all out there to look up. What we do know is that the climate has been significantly hotter than it is just now eg the 'Atlantic' period of 6 - 7000 years ago where it was hotter and wetter than it is now. Minimum estimates are for about 2 -3 degrees more than at present. If nothing else, that alone challenges the current orthodoxy quite seriously. From then on the pattern has been one of slow and gradual temperature decline ameliorated with occasional warmer periods. It was still warm enough for many vineyards in middle and southern England in the 1100s AD.
At this point I believe we enter the period largely to blame for the gross over-reaction to global trends. From about 1250 AD temperatures started to plummet, giving us the Little Ice Age and the Frost Fairs with three temperature minima – the last was in 1850 AD. By this period of time we actually have some detailed written History which has a serious improvement in the quality of records available for analysis although, interestingly, historians tend to underplay the significance of the Little Ice Age. (And how, but that's another story for another blog and it's REALLY interesting) Let’s restate this – temperatures plummeted. There is a lot of debate about causes and how much of the world was affected but the basics are widely accepted.
Since about 1850 there has been a general warming with the occasional cooling blip caused by volcanic eruptions such as Krakatoa, Mt Agung, Hekla amongst others. Human activity may have played a part in raising global temperatures in the last 200 years but it is also quite possible that much of the warming may be a natural 'rebound' from the Little Ice Age. As things stand we have still quite a lot of warming needed to get up back to the levels of temperature the world enjoyed in the 1100s AD and even more to get back to 6000 years ago.
All the evidence is that the earth has experienced great variations in climate since the very beginning and is liable to continue to do so in the future.
Why is there such a current brouhaha about global warming ? I can’t help but believe we are seeing the confluence of several things. Firstly, I believe there is a general but genuine ignorance and lack of understanding of the Earth’s long-term climatic trends. There is too much emphasis placed upon the trends of the last 200 years and not enough on the long-term perspective. That perspective does not suit the establishment at the moment. I do wonder to what extent this selection of time scale is deliberate though. Conspiracy or cock-up ? Answers on a post card please ………………
Secondly, there are groups with agendas which require the spectre of global warming. How many can you think of ? There is a genuine, intellectually coherent argument for the development and use of renewable sources of energy together with the conservation and effective use of the earth’s resources. Global warming – as currently argued and exemplified – is not that case. It’s obvious why the anti-capitalists have latched on to the issue as yet one more stick. Their solutions though would condemn 6 thousand million people to an unsatisfactory life and no way of providing wholesale improvements.
Thirdly, a combination of the need for ‘bad news’ together with nostrums no matter how ineffective. It gives certain types of politician and environmentalist with grandiose ambitions -- and sound-bites to match - the opportunity to strut on the world stage with a global audience: “24 Hours, Four Minutes And Eleven Seconds To Save The Earth” (or was that the National HealthService ?), signing meaningless agreements which are largely a waste of time and effort. It certainly diverts attention away from serious domestic issues. It allows the imposition of ‘green’ taxes (less to do with saving the environment and more to do with meeting budget shortfalls and bottomless financial pits like the National Health Service) whilst window-dressing them with supposedly noble intentions. It’s also another area for crusading journalism – don’t you just love politicians and journalists ? Just think if the 70 trillion dollars or so promised in the Kobe agreement to 'tackle global warming' was being wasted in any other clearly unacceptable way - imagine the outcry !
So where from here ? I’d like a genuine and open debate with vested interests shown to be exactly that. Everyone goes on about carbon dioxide as though it’s the Great Satan. However, methane is a far more effective greenhouse gas and it’s being pumped out into the air by rotting vegetation, termites and flatulent cattle in truly enormous quantities. What’s one of the signs of a country that has begun to arrive economically ? That’s it – they eat lots of meat. More beasts reared for meat = more methane. There are also very large amounts of methane crystallate on the ocean floors, kept in that form by low temperatures. If they are released then we have a real problem.
I’m not hopeful. Look how long Copernicus had to wait to be vindicated. There are some signs of hope though.
In conclusion
No journalist, politician or member of the "green barmy army" should be allowed to pontificate on global warming until they've described and explained the variations in the Earth's climate right back to the dawn of time. As pointed out earlier, there are serious and valid arguments for many of the environmentally friendly options BUT global warming is not and is unlikely ever to be one of those arguments. What a shame Copernicus wasn't able to blog.
There are, for example, few who would disagree with the idea that the continents are moving around all over the Earth’s surface. In geological time they’re zipping about and crashing into each other like cars on the peripherique around Paris ! More and more evidence to bolster the theory of plate tectonics accumulates all of the time. The devil, as they say, is in the detail and we have a devilish amount of detail to work with. The theory continues to develop and so now we can even postulate that the whole crust may be able to slip ’en masse’ should the distribution of land masses and ice caps become sufficiently unbalanced in relation to the rotation of the Earth. Clearly it would be catastrophic and, as yet, there is neither enough evidence nor a large body of supporters proposing it actually happened for the theory to be widely accepted. However, the evidence that is quoted already is compelling ................. and please note as well that proponents of this theory are neither vilified nor excoriated when they advance the theory and the evidence they’ve found so far. Some would use it as the underlying explanation as to the various myths about floods occurring around the world (Noah etc). I still can't make up my mind between that and the end of the last phase of the Ice Age - both are relatively close in time as far as we know. Actually, even as I write, I wonder if both could be responsible.................................
Now consider the thorny issue of climatic change and, in particular, global warming. Anyone who dares to challenge any of the current orthodoxy is treated in much the same appalling way as Copernicus.
David Bellamy and many other scientists with cases to make are effectively ignored or interviews are edited to trivialize their case. Try writing to mainstream press to make serious points contradicting the arguments currently being used and you’ll struggle to be published. Wear sandals, eat lentil (or tofu) burgers and splutter ‘global warming’ (preferably whilst frothing visibly at the mouth) then you are guaranteed as much time and column space as you like to make your case - no matter how unthinking or even downright wrong your points may be.
It doesn’t seem to matter that groups like Friends of the Earth have made some serious mistakes (not that they ever admit to them). They never - ever - experience the same level of intense sceptical questioning endured by people who question any of the environmentalists’ latest articles of faith.
Now a clear and unequivocal caveat. My position is absolutely clear. The world’s climate IS changing, as it has done from Day One. Let’s restate and confirm that – global climatic change is a constant (isn't that an oxymoron ? Oh well !). It is also virtually incontrovertible that those changes have occurred without any input from people apart from the last 200 years or so. The extent to which we are able to affect global climatic change is also highly debatable.
Now, let’s go back to my opening statement. Palaeogeography and palaeoclimates have been studied in great detail for quite some time now. There is a wealth of knowledge which is well-documented and which ties in well with other topics such as the afore-mentioned plate tectonics. What do these two areas of scientific study tell us ? The earth’s climate has undergone enormous changes since the beginning of time and I mean ‘enormous’. This knowledge is being systematically ignored.
This blog started out from a friend’s question: she asked me why no-one ever linked the issue of global warming to the fact that the Ice Age was over. The problem is that there are two separate issues in that question. The first is to do with what is taken to be the evidence for global warming. The second, to me is more fascinating. Is the Ice Age actually over ? I - and many other souls being ignored - don’t believe it is and I also believe it goes a long way to putting the issue of global warming into a far more accurate perspective. It is now virtually certain that the Earth has experienced three previous Great Ice Ages – together with a minor Ice Age - and we are currently in the grip of the fourth with absolutely no idea of when it might end.
As I’ve just said, no-one can be sure that the Ice Age has, in fact, ended. With no evidence to the contrary, we have to assume that it has not. We know that each of the four great ice ages has operated on a time-scale measured in many millions of years. The earliest ice age is believed to have been from 2.7 - 2.3 thousand million years ago. There is evidence although a bit sketchy for obvious reasons: each glacial advance erases much of the evidence of previous ice advances. The second which resulted in ice caps almost reaching the Equator (The Snowball Earth Glaciation aka The Cryogenic Period) lasted from 800 - 600 million years ago. Just how cold was the world then ? Brrrrrrrrrrrrrrrrrrrrrr. There also was a minor ice age 460 - 430 million years ago during the Ordovician period. After that, along came the Karoo Ice Age which lasted from 350 - 260 million years during the Carboniferous and early Permian epochs. A little reading around on the internet will reveal various really interesting things such as the impact of these on the flora and fauna of the times, including extinctions and sudden explosions of species – well worth while ! Obviously the world was significantly hotter in between each Ice Age. Look at the flora which flourished for some indications. The evidence is there.
However, back to the present. The present ice age began nearly 40 million years ago but intensified approximately 3 million years ago which is a mere blink of the eye, geologically speaking. Why can’t we be sure that the ice has gone / is going for good ? The reason is that ice ages are composed of cycles when ice advances (glacial periods) and periods when it melts away (interglacial periods). At this point most Geography teachers can take over and, yawning from extreme boredom, make all of these points in their sleep.
The present ice age has been operating on cycles of 40,000 and 100,000 years for the ice advancing and retreating respectively. The last glacial period finished approximately 10,000 years ago. Accordingly, we may have to wait rather a long time to find out if the ice has gone for good.
There are various theories as to the ways in which ice ages start and finish. Volcanic eruptions, variations in Carbon Dioxide and/or methane in the atmosphere and changes caused by continental drift have been advanced as possible causes.
One of the major theories is that the earth has 'built-in' climatic change. This is far from being a new theory. It was first bounced around by the Scot, James Croll in 1860, not too widely disseminated and then more or less forgotten. The theory was reintroduced by Milankovitch in the 1930s using known astronomical data, bounced around and then ? That’s right – more or less forgotten until they came to write stuff on climatic change for geography textbooks........
There are three cycles which operate. The earth's orbit round the sun is elliptical but varies on cycles of 100,000 and 400,000 years where it is closer and further from the sun. Secondly, the earth's axis describes a circle on a time scale of 19,000 - 23,00 years (the circle of precession) and thirdly, the tilt of the earth's axis also changes on a 41,000 year cycle. Each cycle, therefore, results in variations in insolation (solar energy) reaching the earth - sometimes increasing, sometimes decreasing. Milankovitch was able to show that when these three cycles were simultaneously at the point where they resulted in the lowest insolation reaching the earth, major glaciations occurred. It’s a bit like biorhythms with triple biorhythmic highs and lows occurring in the cycles. When they all coincide on a high – great ! On a triple low – stay in bed ! So that’s the hotter and colder spells accounted for pretty well then.
This theory has since been linked to variations in carbon dioxide levels which have given the theory added strength although there are scientists who feel the theory does not explain things fully enough, especially with respect to variations within glacial and interglacial periods.
Now we move to the really interesting stuff. There is a great deal of evidence for large variations in climate in our present interglacial period: effectively the last 10,000 years. Pollen, varves, tree rings, ocean floor deposits, ice core analysis – it’s all out there to look up. What we do know is that the climate has been significantly hotter than it is just now eg the 'Atlantic' period of 6 - 7000 years ago where it was hotter and wetter than it is now. Minimum estimates are for about 2 -3 degrees more than at present. If nothing else, that alone challenges the current orthodoxy quite seriously. From then on the pattern has been one of slow and gradual temperature decline ameliorated with occasional warmer periods. It was still warm enough for many vineyards in middle and southern England in the 1100s AD.
At this point I believe we enter the period largely to blame for the gross over-reaction to global trends. From about 1250 AD temperatures started to plummet, giving us the Little Ice Age and the Frost Fairs with three temperature minima – the last was in 1850 AD. By this period of time we actually have some detailed written History which has a serious improvement in the quality of records available for analysis although, interestingly, historians tend to underplay the significance of the Little Ice Age. (And how, but that's another story for another blog and it's REALLY interesting) Let’s restate this – temperatures plummeted. There is a lot of debate about causes and how much of the world was affected but the basics are widely accepted.
Since about 1850 there has been a general warming with the occasional cooling blip caused by volcanic eruptions such as Krakatoa, Mt Agung, Hekla amongst others. Human activity may have played a part in raising global temperatures in the last 200 years but it is also quite possible that much of the warming may be a natural 'rebound' from the Little Ice Age. As things stand we have still quite a lot of warming needed to get up back to the levels of temperature the world enjoyed in the 1100s AD and even more to get back to 6000 years ago.
All the evidence is that the earth has experienced great variations in climate since the very beginning and is liable to continue to do so in the future.
Why is there such a current brouhaha about global warming ? I can’t help but believe we are seeing the confluence of several things. Firstly, I believe there is a general but genuine ignorance and lack of understanding of the Earth’s long-term climatic trends. There is too much emphasis placed upon the trends of the last 200 years and not enough on the long-term perspective. That perspective does not suit the establishment at the moment. I do wonder to what extent this selection of time scale is deliberate though. Conspiracy or cock-up ? Answers on a post card please ………………
Secondly, there are groups with agendas which require the spectre of global warming. How many can you think of ? There is a genuine, intellectually coherent argument for the development and use of renewable sources of energy together with the conservation and effective use of the earth’s resources. Global warming – as currently argued and exemplified – is not that case. It’s obvious why the anti-capitalists have latched on to the issue as yet one more stick. Their solutions though would condemn 6 thousand million people to an unsatisfactory life and no way of providing wholesale improvements.
Thirdly, a combination of the need for ‘bad news’ together with nostrums no matter how ineffective. It gives certain types of politician and environmentalist with grandiose ambitions -- and sound-bites to match - the opportunity to strut on the world stage with a global audience: “24 Hours, Four Minutes And Eleven Seconds To Save The Earth” (or was that the National HealthService ?), signing meaningless agreements which are largely a waste of time and effort. It certainly diverts attention away from serious domestic issues. It allows the imposition of ‘green’ taxes (less to do with saving the environment and more to do with meeting budget shortfalls and bottomless financial pits like the National Health Service) whilst window-dressing them with supposedly noble intentions. It’s also another area for crusading journalism – don’t you just love politicians and journalists ? Just think if the 70 trillion dollars or so promised in the Kobe agreement to 'tackle global warming' was being wasted in any other clearly unacceptable way - imagine the outcry !
So where from here ? I’d like a genuine and open debate with vested interests shown to be exactly that. Everyone goes on about carbon dioxide as though it’s the Great Satan. However, methane is a far more effective greenhouse gas and it’s being pumped out into the air by rotting vegetation, termites and flatulent cattle in truly enormous quantities. What’s one of the signs of a country that has begun to arrive economically ? That’s it – they eat lots of meat. More beasts reared for meat = more methane. There are also very large amounts of methane crystallate on the ocean floors, kept in that form by low temperatures. If they are released then we have a real problem.
I’m not hopeful. Look how long Copernicus had to wait to be vindicated. There are some signs of hope though.
In conclusion
No journalist, politician or member of the "green barmy army" should be allowed to pontificate on global warming until they've described and explained the variations in the Earth's climate right back to the dawn of time. As pointed out earlier, there are serious and valid arguments for many of the environmentally friendly options BUT global warming is not and is unlikely ever to be one of those arguments. What a shame Copernicus wasn't able to blog.
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